GM's Throttle Body Injection Was Bulletproof!
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- Опубликовано: 23 мар 2024
- In today's video, we'll talk about GM's Throttle Body Injection system. You'll get a brief overview of how it works, some of it's components, and a take on why it was phased out.
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These systems were bulletproof. Ran them for lots of years and different vehicles and was never left stranded, easy to work on and parts were cheap and everywhere. And easy to swap to a non fi car
The spring and diaphragm are the weakpoints, a mod for the 305 was to use 350 injectors, ive overhauled 1 before
The only thing that would leave you stranded was the fuel pump. The Cadillac version could have issues with the ISC motor.
Just think that it's junk compared to an ole quadrajet
@@JoshuaFarei disagree. i had a 89 camaro i swapped in a 350 TBI. i changed the cam, the heads, installed a bored throttle body, ran the correct PROM chip. changed the fuel pump. the car stock came with the L03 305. just swapping the 305 for the 350 had a limited improvement, but when i changed the heads it made a huge difference.
this system delivered better drive-ability (no warming up, no sticking float issues), no pumping the accelerator. the problem with the system was the junk "swirl port" heads, bores that were too small, and a cam with poor lift and duration. frankly it was more reliable then a quadrajet and the engines lasted longer. a carburetor can run the engine too lean or too rich getting the proper fuel mixture at all times is nearly impossible. the TBI will deliver a mixture that is much closer to 14.7:1. running an engine that is too rich or lean is not great for longevity.
I had one, died, sat in the garage for a decade till the kid found a little wire from the battery that was broke, gave it to him 😂
I actually love this system. I’ve had a 1994 full size Blazer for 27 years. These systems are so good at what they do. Simple, reliable, and cheap to maintain. It seems most people curse them because of limited performance potential for the throttle body and motors on which they were typically installed, but the drivability and reliability have always been fantastic. There’s a reason you don’t see revival videos on these. They just work with out drama.
Yup It costs 25-50 usally to fix these when there is a problem and you are back on the road. Most weird problems are just fuel pressure related FPR, Fuel pump ETC. I cleaned my TBI out real good better than I did like 18 years ago and it really runs nice now. I had alot of built up carbon in the vacuum ports used picks and wires I didnt have 18 years ago haha. People always bash them because they are low powered but they still run down the highway at 85 mph. Will go 100 if has to.. I pretty much grew up as a kid with this TBI system since I started driving many years ago.
300+ hp is fairly obtainable, these systems can produce the horsepower. i did it once, i built a L05 that was a runner. it was installed in a 1989 camaro RS that was stock with the 305. i wished i still had it. it had a bored out throttle body, edlebrock cam, L98 heads (heads from an iroc), short tube headers, 3" cat back exhaust. i never had it dyno tested but it had to be 275 + hp. it was no slouch.
the biggest choke on these engines was crappy stock heads (swirl port flow like junk), a overly mild cam, restrictive exhaust manifolds. the stock heads were really junk from a performance standpoint.
my point is, it is possible to build a performance TBI engine.
I had a 92 K2500 light duty, 5.7 tbi. Traded it for a 78 K30, best trucks I've ever owned.
My 91 C1500 is my Daily...with 520000 on the clock. The 5.7 gets 20 mpg when I take it easy. Damn fine system.
That's 520000 kilometers, right?
@@zephead4835😂 no he means miles and many have made it to the one 100000000 mark
@zephead4835 The mileage isn't hard to believe. My one owner 1990 k1500 with the oe 5.7 and tbi has 510,000 miles on it. It's also our daily driver. 🤔🤔✌️✌️
@@bartbarnett2811 that's amazing. I also have a 91 c 1500 with a 5.7 in it
What kind of oil and filter do you run in yours?
@@zephead4835 'Merican Miles
Much better than the electronic carbs, simple and very durable.
I'd take a quadrajet over tbi. I already have tbi. Quadrajet will make more power and fuel mileage while being just as dependable.
The feedback QuadraJet is no different that an older QuadraJet aside from having an electronic solenoid instead of a vacuum plunger on the primary metering rods. The rest of the system is essentially the same as TBI in terms of distributor, emissions controls, and ECM. I've had several of both, including an '87 Cutlass that my parents bought new and I still have, and the ONLY problem I've ever had with the electronic carburetor system is one throttle position sensor dying. I've had more problems with TBI systems -- dead fuel pumps, dead idle air controls, leaking fuel injector o-rings...
@@KevinJames-yg9eu i have an 85 c20, original no computer. Brother has a 94 t.b.i. Both are solid, but the t.b.i does require maintenance and repair, aftermath doesn't work right, or last. It does last a long time, and is more expensive to repair than a carburetor.
The '98 Mastercraft boat I've owned since year 2000 is still running a GM oem TBI system. For a seasonal use application like on a boat engine this system is ideal. It never gums up over the winter and needs rebuilt like a carburetor would with alcohol fuels. I disassembled it and had the injectors professionally cleaned once because the engine was indicating it was running lean. It's worked perfectly since then for the last 6 - 7 years.
The TBI unit is bullet proof, they always work and never have troubles, one of my trucks a 93 K1500 with a 305 and TBI has over 340000 km on it and has never triggered the engine light once in it's life, it always starts and runs perfect. Also have an 88 S10 with the 4.3l V6 and it also is flawless, super simple system that always works.
Had it on my 93 k2500. It was great.
Only the diaphragm/spring wear out
@@FirstLast-we8cbit was on 1987-1995 trucks
I love the GM TBI, nearly every carb'ed car I've had in the past decade has been converted to use a GM TBI and a Megasquirt
Driving-wise, you couldn't tell it wasn't a high tech EFI system. It always started, idled perfectly and didn't care about temp or altitude. I did many, many conversions for friends while in high school. To convert a carb'ed GM V-8 or V-6 to TBI just required a trip to PickNPull, a little grinding on the intake bolt holes and some simple new parts and changes. The same engine would sound crisp and throaty, with no exhaust changes, just from having a leaner/correct mixture. All my conversions received CA smog referee approval so my auto shop teacher would always give me an "A" despite the fact I was doing almost the same work each time.
Did you just bolt the tbi right onto the existing intake? My intake is a 4bbl and this is the change I eventually want to make, I have the harness and ecm in addition to a running example.
Definitely a power loss at altitude
You've apparently never driven one in actual cold weather. If it's below 32°F, the idle air control is probably going to stick shut, so you have to push the throttle pedal to get it started and nurse it to keep it running until it's happy, and if it's below 0°F, you better have a can of ether. It's really no better at starting cold than a QuadraJet. The ones that don't have an intake air temperature sensor run lean in cold weather and rich in hot weather. Extended idling in cold weather causes it to drop out of closed loop fueling, and then it jacks the idle speed up several hundred RPM. It's mostly reliable, but there is plenty of room for improvement in terms of function.
@@KevinJames-yg9eu I agree the tbi with air temp sensor runs better. There was also recirculated coolant passage to avoid icing. I guess icing could be a problem in humid conditions.
@KevinJames-yg9eu I have never had to do this to my TBI in cold weather. Starts right up and idles fine without having to ever touch the throttle. I'm talking in between 15 and 28 degrees cold starts.
This was the system that turned me on to fuel injection. I pulled the 350 engine and wiring out of a 95 Chevy truck and put it in my 69 Nova. Spent some time with factory wiring diagrams to strip out the wiring I didn't need and shorten some wire lengths. The cool thing about the setup was the ability to run the classic-look chrome air cleaner.The hardest part was the gas tank mods for the fuel pump (there were no aftermarket tanks with the in-tank pump option back then). When all was said and done, I went from a Nova that I had to tinker with to enjoy to a Nova I could just hit the key and go, regardless of what the weather was doing. Loved the system so much, I stripped another system from a junk yard and adapted it to the AMC 304 in my CJ-5.
These were so easy to work on. And they worked great
Absolutely. They were deadly reliable and simple. They would run (poorly) with a broken tps, broken ect, or O2 sensor. They didn't need much to at least get you home.
They get a bad rap for not having power. But that was the heads, cam, compression, and terrible exhaust that did that 😂.
@@geoffmooregmthat’s partially true….you can only get so much airflow through a two barrel system. The year GM went to multiport FI there was a significant increase in power output without changing any of the internal specs of the engine itself…were the heads restricted? Yep, but that’s true of ALL GM cylinder heads 😂…were the cams mild? You bet, but so are ALL GM stock truck motors…compression was 8.5:1 which was pretty standard for cast iron V8s that run on piss…as for the exhaust, not sure what point you’re making there as it’s been well established for 70 plus years that stock exhaust is restricted for sound and emissions 🤷🏼♂️
I worked for GM at the time. It was a big Oldsmobile dealership. The difference was night and day! Basically trouble free. I remember one winter, 1986, we were expecting a blizzard, so we brought as much of the dealership inventory into the shop prior to the heavy accumulation so we could plow snow. The fuel injected cars fired right up and didn't skip a beat in the cold. By that time the only cars with carburetors we still had were the Olds custom cruiser wagons with the Oldsmobile 307 engine and a few Cutlass Cierras with the Buick 3.0 V6. Crank...pump the gas a few times, start stall. Repeat. Let it warm up a bit.
Great set up and not complex. Just worked.
Funny back when GM were using these I had a 68 Dodge military crew cab 4x4 with a 318 in it that I put a 340 cam in the engine and updated the ignition to the Mopar performance electronic ignition & topped the engine off with a Edelbrock dual plane aluminum intake manifold and a 600 cfm Edelbrock carburetor jetted for performance rather than milage and that truck would start right up after sitting all night in -20 below temps and would stay running on its fast idle until it was warm enough to drive it to work in the mornings for years . I remember seeing brand new Ford F-150s back then stranded on the highway and roads that were fuel injected that were having issues running in the cold MN temps and my old Dodge with the old school 4 barrel kept on driving & me laughing at them stranded on the side of the roads while I drove by them on my way to work . I remember seeing on the news that Ford had a recall on those trucks because of this & thought what a crock of crap paying that much for a brand new truck and you can't even drive it on the cold winter mornings or days because it would leave you stranded .
Did the 3.0 (or 231) ever get tbi? I was considering adapting tbi to my 231 before I finally got the hang of ccc.
Now I have a e4me on the 231 and it runs really strong.
Your supposed to pump the gas to the floor twice before you crank in a cold start with a quadrajet.
@@DaMan-jt6dh Says on the visor on my 72, and the manual in my 85. "gently depress accelerator to floor, slowly release, start. If if fails to start, repeat'. The accelerator pedal shoots gas out when you do that. If vacuum lines and tuning, choke settings etc. are correct. Like high idle settings, they fire perfectly even at -40. Easy to flood them by pumping.
320,000 miles on my silverado with the original 4.3 v6 and a GM tbi, and the only parts Ive replaced on the TBI was a idle air control solenoid and 1 of the injectors.
I love my 94 silverado 5.7 tbi. Almost 220k miles and no problems, just regular maintenance. If you ever have a problem with these engines it’s always either no fuel or no spark. Very easy to work on.
You are dead on man!....Hard on dist. caps.
GM TBI was one of the few times they got it right. Simple, reliable, easy to work on.
They got it right plenty of times.
@@DaMan-jt6dh always did until they abandoned almost every system they had been improving for decades
Didn't really have to work on them they usually out last two engines...
@@Rick-qf5de 451k plus on my brother's one owner 94. Just cleaned and resealed everything again. Original injectors are still perfect. Motor is still strong
If they put a slightly bigger cam and better flowing heads... And larger TBI blades like the 454 TBI had they would of made alot more HP and TQ too. 94-95 (Maybe 93 too) has a remarkable fast ECM I think too compared to the earlier TBI systems. MAN those computers slow live data SLOW. I even had some limited bi directional controls on my 94 hah
I worked on hundreds of these years ago and they were a very good system that was easy to work on. GM/Delco ASE Master Technician.
One of the coolest things about these systems was being able to see the actual spray paterern of the injector thru the use of a degree variable timing light. And while watching it, if the injector wasnt sealing correctly, you would actually see the fuel dripping straight down from the center of the injector. Only fault would be when a coolant temp sensor wasnt working correctly and would dump way to much fuel and the engine had trouble starting, which in some casez caused a backfire and then there would be a small fire in the throttle body. Nothing a little wire and new injector clips couldnt fix. Oh, and Isuzu used this injection system on its 2.8l and 3.1l V6's, which were actually GM engines anyway.
I have a ‘91 GMC Sonoma 4.3 V6 that I bought brand new. It’s got 271,000 miles and the TBI has performed flawlessly for 33 years. Never replaced any sensors, but I did install a new base gasket a few years ago to correct a vacuum leak. It has been bulletproof.
Nice description of the components and operation of such a simple fuel system!
Only thing I've ever done to my C3500 454 (second vehicle I've owned with TBI) is an O2 sensor. The check engine light came on. Looked under the truck, and the OEM one had rusted in half. Put in a new $19 sensor. Zero problems since. I'd still be driving the first one I owned, but I lost it in my divorce. A friend of a friend owns it now, and it still runs 100%. Good ol 350 van.
I still have an 87 Sierra classic with a 5.7 TBI. Still has all the o.e. emissions controls and runs as designed. No complaints.
I recently rebuilt one of these units. Very simple and straight-forward. The regulator diaphragm took the most attention but it went smoothly. It should work well for many more years.
I worked at a Chevy dealer for 11 years.. TBI systems were bullet proof, simple and cheap to work on. Loved them over the electronic carb systems hands down.
Thank you for a great synopsis of this important step in the evolution of GM's fuel-delivery systems.
My 1988 4.3 cubic inch S10 came to me new from the factory. I sold it 12 years later with almost 200k mostly city/suburban miles on it. The fuel system never needed attention, apart from normal service and fuel filters. Ran great, sold it to a friend. We're still friends.
I had a 93 GMC, and 94 chevy truck with this system. I was the last fuel system where a TB spacer would make a difference in torque numbers. So easy to rebuild when needed. I would have another truck with TBI in a heartbeat.
Reliable and long running. I’ve had several GM trucks with these and never any issues getting 200k-300k mi.
I had a 1993 Silverado with a 5.7 V8 and this type TBI setup. It worked great and trouble free for years. Around 1999 it needed a new IAC valve. I also installed a 1" spacer from Summit Racing between the TBI unit and intake manifold. That very noticeably increased low end torque for very little money and work.
It actually came out in 1980 on Cadillac's with the 6.0 V8 engine under the tradename "Digital Fuel Injection". It was used on Cadillac 6.0, 4.1, and 4.5 liter engines til 1989.
Retrofitted this from a 90 suburban into my 83 c10. Runs great
Also- saying that an EFI system such as the Holley sniper is similar to the GM TBI is like saying that the 350 Chevy is similar to a 460 ford. Sure, they are both v8 engines that use 2 valves per cylinder but that’s where the similarities end. The Sniper uses about 48 PSI of fuel pressure while a TBI uses 6-12 PSI. The sniper has 4 injectors while the TBI uses two at the most. The GM TBI has an external engine computer while the sniper houses it on the front of the system which works especially bad with ford because of distributor location. GM TBI works quite well while the Holley sniper is a turd that I would never recommend installing on a vehicle- I’ve seen quadrajets that haven’t ran in 30 years work better then Holley snipers right out of the box.
I have heard lots of good things about the Holley systems. But results will certianly vary because of the vast array of engines they are put on.
The GM TBI system is great but they are a pain in the ass to tune. But that is simply due to the technology of the era. On my Trooper I swapped out the original 2.8L for a freshly built 3.1L (bored to 3.2L) with a new cam and higher compression. I fiddled with swapping computers, injectors and fuel pressure. I ended up with a 3.1L computer from a Rodeo/Lumina APV and slightly elevated fuel pressure. I monitored it with a wideband O2 gauge to get it as good as I could.
I’ve installed four snipers- three on customer vehicles and one on my own. I will never do it ever again- the only one I installed that works mostly correct was on a 69 nova with a 396 big block. I put one on a 66 mustang 302- that was horrible. I put one on a 86 c10- that one sort of worked ok. I put one on my 66 Chevelle 383 stroker and that one has been pure garbage. It smoked the first wideband O2 sensor at 200 miles. I will be taking it off and selling it. I have a rebuilt Holley 600 that will be replacing it. My boss went to Holley school where they train you to tune and properly install them and basically everything they told him was “everything in the installation manual is wrong and any issue with a sniper is purely your fault. These are not self tuning” even though they claim to be self tuning. I had one holley support guy on the phone tell me that you cannot use a return fuel system with snipers. It is literally built into it and designed to have a return system! I will never again buy fuel injection stuff from them.
@@stevenvanheel3932everyone has horrible experiences with sniper. I learned from others peoples mistakes. No sniper for me, Quadrajet is the way to go.
@stevenvanheel3932 Aww, that sucks to hear. Considering the $1000 price tag just to get started, I would expect better! I wonder if Fi-Tech is any better?
@@geoffmooregmI put a Fitech on a 1975 ford f250 crew cab 4x4 with a 460 and 5 speed swapped into it. It ran excellent except for cold start idle- I bet I could’ve gotten that tuned out of it but I didn’t get to spend enough time with the truck to figure it out. The guy has since sold it to buy a Harley (total mistake, that truck is a holy grail dentside that I would’ve bought if I had the funds) so there will be no more opportunities for me to mess with it. To be honest i probably will not install another fuel injection system on an old vehicle. It’s not worth it for the price and the customers are never happy with it (I don’t blame them)
I own a 1994 Chevy K1500 Suburban and a 1995 Ford F150 XLT 4x4. The Chevy has the 5.7 TBI, and the Ford has the 5.7 with sequential injection. Both systems have a billion miles on them, and I absolutely love them both equally. I love how easy the TBI is to work on, and it always, always starts at the touch of the key. The Ford is similar, but I ultimately love the reliability of their system. The TBI needs more periodic maintenance as it can get gummed up easily, whereas the Ford doesn't really require much attention aside from running a fuel cleaner every 100k miles or so lol. I drove a 2024 Expedition recently, and despite all the technology packed into it, it still only averaged 16 mpg on economy mode. My '94 Suburban gets the same mileage. Just goes to show you how well those systems were engineered back then.
they were great. So simple, the least amount of moving part of ANY carb or injection system. I had a 1994 1500 chevy V6 and all it got in 300 000km is a fuel pump and a throttle body sensor. Still my best vehicule to date as far as ease of maintenance
I liked those! The intake manifolds and the throttle plates always stayed clean.
Great video! We have a ‘92 C1500 with a fresh 4.3L V6 and a 5 speed stick to toss in for my youngest daughter. The entire engine bay is clapped out, sitting outside with no hood for a good number of years (more than 10). I’m contemplating the simplicity of a carb and HEI, vs finding the reliability in a stock TBI system. Decisions, decisions.
I had a 90 1/2 ton 4wd. Liked the heck out of that truck. Put true dual exhaust on it with that TBI sounded great!
An excellent system. And pretty good diagnostics.
I had a '92 Silverado with the 350 V-8 and TBI. Over a total of 330,000 miles driven, the only problem I ever had with the TBI unit was the TPS (throttle position sensor) wore out at around 250,000 miles. It was confusing the computer and making the EGR valve oscillate on and off when under anything above an idle. About drove me crazy trying to run down the cause. Replaced the TPS. Simple fix and back on the road. Had GM still made that same design I would have gladly bought a new truck from them. But they don't so I didn't. Damn shame.
HAD ONE ON A 1983 S 10 WITH A 2'8 V 6 NO PROBLEMS OUT IT WORKED VERY WELL
I love them as well. Tremendous off idle torque and rock solid reliability. I still run them to this day in my rigs.
Awesome system I've run it for years and never had more than seconds worth of a problem with it it's nice that you can actually take a peek at it and see how your injectors are actually firing the Mist (which mine always did perfectly) whenever I sitting wondering why I traded my cherry 89 Silverado pickup I always think about that cool throttle body fuel injection system it had and how simple and bulletproof it was I did have a coolant temperature sensor go out on it once man it flooded out like crazy it took me 5 minutes to replace the sensor and I was back on the road again running flawlessly yep I miss a little pickup and then lightweight rims and low profile Tires and with aggressive in town driving I still got right at 20 MPG
TBI was great. Had a few issues over the last 30 years, but never had one I couldn’t fix!
I was a mechanic back when they were on most all GM cars. They were great. Used to get people come in for a bad idle 90%of the time it was just the base gasket cracked. Had a bunch of 4.3's that the PCV had low vacuum from carbon build up under the TBI. lack of oil change kind of people.
Don't forget to check throttle shaft play and look for rusty springs in the fuel pressure regulator . A good rebuilder can rebush the housing where the shaft goes .
I grafted on onto my Olds 455 powered motorhome. Still drive it, runs awesome!
I like this system, easy to work on and learn how to fix.
The only issue I have is the aluminium aftermarket intake manifold and the cold weather. Engine does not like to run cold.
I drove a 1993 Chevy 1500 that had one for 22 years. Never had a single problem with the throttle body.
I did a Chevy swap on my Jeep wrangler yj over 22 years ago and use this system it came out of an Astro van and it still works to this day
Great system. I had one on a supercharged 5.7. The hardest part was once the 2 injectors were sized large enough for full power the idle became very tricky.
My 84 Fiero had a single injector TBI system on it. I never had an issue with it!
One of the best ideas GM ever had. I have run mine successfully for several hundred thousand miles on a 5.7 Caprice. Rugged, Bullet proof to say the least. I can always count on it operating perfectly each time. Never an issue with it.
Agreed!!! Excellent system! I’m proud to say I’m still driving a 5.7 1989 Caprice Sedan. Gets great gas mileage! I’m a mechanic myself, and I take care of it myself! I will say, good quality parts can be hard to get for the TBI today. I really enjoy driving my Caprice. Hint, it is hoped up a little!!!🏎️
It always amazed me how well rochester tbi runs and I still have plans to convert my ccc 305 some day.
I did the lawn mower carb hack on my gm... work so much better than any over engineered system... and I make 40mpg with my 350
They worked well.
I am still driving a 90 Cutlass Ciera with the 2.5L 4 cylinder engine and TBI. I have never ever had any problems with the fuel injection system at all, and the car has well over 350,000 miles on it. Before that, from about 1979 - 1981, these engines had the Varajet (2SE and E2SE) carburetor installed on them. I personally liked the Varajet carburetor, and did not find them that difficult to work on, but apparently some people did. Emissions and driveability had to be the reasons they switched over to TBI. You didn't have to deal with the choke anymore going out of adjustment. You don't have to worry about the choke pull off leaking as it gets older either. The fuel mixture was so rich when the choke was needed on carbureted engines. There was no way to really control carbon monoxide and excess hydrocarbon emissions on carbureted cars when the engine was cold and the choke was needed. They tried having the choke release as quickly as possible by using an electrically heated coil - but even this could lead to stalling out as the engine was warming up if the adjustment wasn't exactly right. They also used air injection pumps to try to burn the excess hydrocarbons that went down the exhaust. With TBI, you didn't need to worry about any of those things.
I owned several trucks, Suburbans and full sized vans that had this system, very reliable. The only fuel system component I had to replace in this system was the in tank fuel pump.
My 1989 G20 Van ran to 199 K when the 700R4 transmission failed . I did replace the fuel pump around 120 K when it failed . Other than a few fuel filter changes , the TBI never failed .
I'm at this stage now with 05 Blazer 215 klm. But it's a minor set back I'll keep her running as GM and others have nothing to compare it with. The DI engines are a nightmare with the intake carbon issue. So. I'll restore this one and upgrade the interior. We will see many more backcountry fishing and camping, and skiing trips. All so this little Blazer is great in the snow Posi track rear and LS front great combination ❤😊👍
Have an 88 G20 still running strong with that FI system. Never touched it except for inline fuel filters. The 1988 G20's still had the Turbo 400 transmission. I bought the "leftover" 1988 G20 instead of the 1989 because I was warned about the new transmission.
@@maryhausler8900 I did get 199 K out of the 1989 with the 700R4 . It was used for work but not abused .
@@billsmith2212You did good with the 700R4. Usually would only last 100k. Especially if you were doing alot of towing.
TBI system was the best and is still the best fuel injection system as of today. I still have two trucks of mine that are TBI
Bendix Electrojector
The Bendix Electrojector is an electronically controlled manifold injection (EFI) system developed and made by Bendix Corporation. In 1957, American Motors (AMC) offered the Electrojector as an option in some of their cars; Chrysler followed in 1958.
I remember watching the TBI for the first time injecting the fuel and was like dam thats alot of fuel but in reality the 4.3 5 speed got remarkable fuel economy ! And felt like a 305 v8 on the road ! 1989 Cheyenne ! Still runs to this day !
I've been working on cars since the early 70's and have seen the changes from simple carbs with mixture adjustment screws all the way to present day FI. The throttle bodies were as you stated bulletproof. The only issue that I have noted is worn throttle shafts and the bores they go through causing vacuum leaks.
This was a good system. Very reliable and easy to service.
If you have one of these, get you a rebuild kit and clean and replace all the gaskets in the kit and your old engine will run as if brand new. It's amazing how well it runs after a kit rebuild.
I agree that they are the best fuel injection system GM ever used. The only thing I think GM should have done was provided a 4 barrel version of this system for higher horsepower and flow on bigger trucks and v8 engines. My 95 S10 with the 4.3 vin z runs and drives so well with the TBI system but there’s no room for upgrade due to the 2 barrel design. I’d love to add some aftermarket heads, headers, a bigger cam and different intake manifold but then I’d have to get rid of my TBI and I’d lose that reliability. If only they offered it in a 4 barrel!
There is room to bore it out and use the 454 size throttle body if you want. Keep in mind that you have the same size TBI unit as the 305 and 350 engines had. So, you should be able to make quite a bit more power before the TBI unit becomes a restriction.
@@geoffmooregmopening the TBI requires more fuel to match more air even at low rpms and that will kill your fuel mileage. TBIs are worthless when it comes to making power max HP without boring is 230. You are better off ditching it for quadrajet. This is the route I'm going, the quadrajet runs and is every bit of reliable and durable vs TBI but more power and mpg. The only other option (I don't understand why more people don't do this) even on a vortec 350 just get an eldelbrock rpm intake, drill it for injectors just go to the pick n pull and get the 5.3 Vortec fuel rails, injectors regulator, fuel pump wiring harness and PCM. Wiring is very easy as the only wires you need go to all your engine sensors, then all the wiring you need to the vehicle is 4 wires, and the fuel pump. They make electronic throttle bodies that just bolt on to the rpm intake. Now you have EFI that is equal to what the Vortec truck motors run, which are just as reliable but make way more power stock and have all the room in the world to grow, your limit only being fuel pump and injectors.
95 Chevy was my favorite had the newer interior but still had the throttle body damn things just worked
TBI is awesome. totally reasonable power potential, insanely simple, and functions wonderfully.
I have an 87 XJ with a 2.5L four. It has an idle stepper motor like from the electronic carbs. Never has any issues with the computer system, and runs every time. Much more robust than a carburetor.
Great video on a deserving system (even though mine was an early version with the fussy TPS and the external Idle Speed Control motor... 😉 )
BTW, this was introduced in 1980 6.0L Cadillacs, as you might expect, in their move from analog EFI to digital-computer DFI.
Kool video my daily drive ol 86 1.8 tbi camira gm j chassis runs flawless 😃
There are upgraded factory ECMs you can buy that have more optimized code and way more memory to do additional things that these systems never did from the factory. I personally tuned a TBI retrofit on a Chevy 292 inline 6 with a turbo and intercooler on an 83 C10. Still runs great to this day. I could talk for hours about the project but one fun fact is the TBI injectors love higher fuel pressure. The 292 I mentioned uses a vacuum/boost referenced fuel pressure and fuel pressure into the 30s at full boost. That's on injectors designed for 9-13 psi.
It's still only 9-13psi to the injector. Even if the fuel pressure "looks" higher on a gauge. The fuel pump sees the added pressure but the injectors themselves do not.
@@BillyWillicker I'm not sure what you are saying but this truck has an external fuel pressure regulator so it's really running the pressures I said. Also you can increase pressure on stock TBI by shimming under the regulator diaphragm. Been there, done that, over 20 years ago.
@kevin9c1 What he means is if the injectors are in a pressurized box, because you are running boost, then the boost pressure that exists at the nozzles of the injectors will mean the injection pressure, at the outlet, will always "look like" the same pressure if your regulator has a 1:1 reference. However the supply pressure will increase as boost goes up.
@@kevin9c1 Yes, it's running the pressures you said. The TBI has a sealed "carb horn" correct? Is the regulator referenced to atmosphere or manifold? Manifold pressure is what? It's variable, with a turbo it goes above and below atmospheric. There are two pressures in an engine's fuel system. Fuel pressure over atmospheric and fuel pressure over manifold, a gauge in the feed line will show pressure over atmospheric.
Knowing and understanding the different pressures is key to tuning a turbocharged engine.
You can also get or make an adjustable spring seat for the TBI to more easily adjust the running pressure.
@@geoffmooregm Yes. Understanding pressure differentials is a big part of being able to tune well.
That system lives on in the Howell FI conversion for 6 cylinder Jeep engines (I installed one one my 89 Jeep about 10 years ago... still going strong). Howell gives the GM part numbers for the service parts so you can get replacements wherever you are
I put that Howell system on my 79 CJ5, replacing the PoS Carter 2 barrel that always dumped liquid fuel into the manifold. I also switched to Clifford intake and headers at the same time. WOW, what a positive difference it made on both performance and fuel economy. It really brought that 258 to life. My understanding was that Mr. Howell was the original TBI EFI designer for GM and started making conversion kits after leaving GM. Best part was that the CJ kit was also CARB legal for street use! Bravo.
Will the Howell system operate a locking torque converter?
@@thisisyourcaptainspeaking2259 The Howell system is for the older 4.2 carbed engines. As far as I know they were not equipped with an electrically locking converter... but you can call Howell... they are very helpful at answering questions.
I had a problem with my 91 Corsica's Idle Air Control valve, even though it passed all formal testing by the manual.
I knew something was still off and it would often run rough, so I suspected a vacuum leak somewhere. Well, I had a really simple but nonstandard test in mind.
With the engine shut off, I disconnected one of the vacuum lines, put the hose into my mouth and blew into it. Towards the back of the throttle body, I heard air leaking out, fairly rapidly no less.
I felt around as I did this, and found the air coming out of the *back* end of the IAC valve. Now they don't even tell you to test the back end of the valve, that's not supposed to fail right?
Well apparently mine failed on the back end factory installed seal inside the solenoid mechanism. My IAC used 3 pressure fit pins to hold it together, but with a gap between the back end and the body of the valve, where presumably there was a rubber gasket or O ring meant to seal it internally.
So, I took some JB Weld around that factory assembly gap, lightly sucked on the valve to pull some of the epoxy a bit further into the gap, and let it harden.
After that everything worked and ran perfectly! Note again that even the Haynes and Chilton manuals mention absolutely nothing about testing the back side of that valve, they only have you check the pintle of the valve and the solenoid connections.
So my faulty valve technically checked out, according to official diagnostic procedures. I just went on a whim of a different way to check for vacuum leaks, and ended up discovering a completely unexpected failure mode of the IAC valve.
Edit: I could have went ahead and bought a new IAC valve instead, but given that it passed all other tests, well why would I buy a new valve when I could (successfully) test my findings and theory on the old valve and actually learn something, while also saving money...
That's putting the SHADE TREE in Mechanic. 👍
I raced a camaro with the tbi and added nos for the 2003 season at Gainesville it works
So True on All you mentioned....My Newest Chevy I drive here in East Tenn. is a 95 chev k1500 350 T.B.I. and is my dailey driver with 260,000 on it....I,m a carb. man and have worked till few years ago at Chevy and Nissan as a mechanic on the newer stuff/injection...they are stable across the board for sure/trouble free,the gas miliage is like a carb is only bad thing no matter how you drive them and not twist the engine over 4500 rpm...but great normal/torque which is what makes a normal driving engine..My Dad drives a 87 full size blazer with alot of miles still at the age of 78 with the T.B.I...Not bad for old stuff! Nice you did a piece on the Throttle Body....most have been took off and a carb. put on.....Not me man.
I'm daily driving a 93 K1500 Blazer. Never had a problem.
I always wanted to put two of these on a dual quad tunnel ram intake, just to see what they could do.
A carburetor ran off of a partial vacuum, so it was only a few PSI difference in the venturi compared to the atmospheric PSI in the bowl. The TBI ran on a consistent pressure regardless of altitude, and that pressure differential was more than a carb, so it got very good atomization. Then, it had an altitude air-pressure sensor and a air temp sensor, which provided a more precise real-time adjustment when you drove up a mountain, or the engine finally warmed up. Chokes were mechanical, which is cheap and reliable, but they were sloppy under the best conditions. TBI accurately changed the air/fuel mix in rapidly changing conditions. Just as the seals on an old carb can dry out and crack, the sensors that a TBI depends on can go bad, but the trouble-shooting was straight-forward for anyone with a $20 multi-meter and they could read the book. It did require a fairly simple ECU, but the wiring harness was not as integrated as they are today. A TBI ECU is easy to wire up to an older engine, and the newer MPI harnesses are a nightmare of wires.
Simple system, super easy.Had a 91 with it ran it 17 years 177000 miles no issues.
My 95 1500 runs great on this setup I don’t think there’s a more reliable system in 18 years I had to replace the iac these 90s trucks are the most dependable longest lasting trucks on the road like a rock 👍👍👍
I have a 93 GMC G 2500 Van .It still has one on it. Some work done to it, fuel pump, and Throttle position sensor and keep a clean air filter on it and it runs good ..Use Marvel oil fuel treatment.
I had one in my 1987 Chevy Astro van 4.3L V6. It ran rich, and no one could figure out why. Made great V6 power though!
GM techs in the mid 90s warned me that TBI was way better than what followed over the long haul. They sure were right!
The LS fuel injection system is superior in every way to TBI.
My '94 K1500 with 300,000 kms and it's still running flawlessly.
Tbi was a really good system for the era. The electronic carburetors were too finicky for owners after the warranty expired, and took a lot of work and money to keep them running. TBI was phased out because they couldn’t comply with OBD II, since there is no way to shut the fuel off to a single cylinder in the case of a misfire, to keep a catastrophic catalytic converter meltdown from happening.
Thats the only good reason for Multipoint FI I have ever heard!
😪oh boo hoo.😢
I agree with your take in the video, these were inexpensive and ran so much better than the leaned out complex carburetors they replaced. There are still tons on the road today. The cold start & driveability was such an improvement over carbs, overall they were a good transition to multi port EFI.
'90 Z71, K1500 5.7 TBI that my dad bought new & ive owned 16 years now. Needs 2 new injectors but with 340,000 miles with only a fuel pump, ignition module & pickup in the dizzy. This thing is beyond bulletproof, damn near bombproof.
Love my 93 350
I love GM tbi except for one thing - it’s gutless. Apart from that, I’ve seen dozens and dozens go 200-400k miles with literally no issues. Like someone else said, if they had made it in a 4 barrel version I think it would’ve been more likable. For anyone looking for cheap tbi upgrades or to make power with one, Holley makes a 670 cfm unit for about $500. Personally, in a GM truck application, I prefer a Holley 4 barrel.
Had one on my 1990 Silverado.
Yup ; should kept her 😁
I had a 1990 454SS pickup.I put a nitrous injection plate under the throttle body.150 extra hp at the flip of a switch.
I have a buddy that built a 383 stroker for his obs truck. He put a mild cam in it and everything. Ran with the tbi system without changing anything. That mffr was doing burnouts and racing people every chance he got!! Ran like a beast!
Shoutout to the Ford version, CFI.
Main reason I like them is they had a 1bbl and 2bbl versions that bolt directly onto Holley 1bbl and 2bbl intakes.
I met the man that designed TBI for gm He died about 8-9 years ago, I bought a stand alone system he made for hot Rodders, I have still a complete to install in any car I choose, I have installed this on older 454 engines that came off 350 engines and worked just fine, If I wanted more Performance use big block injectors, Best system out there. This system can and has beat tpi on race tracks,
Chrysler had a nearly identical set-up during this timeframe. The biggest difference was that the Chrysler had double the fuel pressure, which seemed to break the fuel up better. Had both a Dodge Truck and a Chevy Truck of the same timeframe, and if you took the air cleaner off you could see a slightly more atomized fuel spray on the Dodge. Did it make a difference, not really, both worked fine. I wish they never got rid of them, they were KISS and about the only thing that killed them was dirt or that tank fuel filter gas line splitting dropping fuel pressure below working norms. That was fun to troubleshoot if you didn't know hydraulics well, most of the time at an idle, even if the pump fuel line was failing you would see the acceptable fuel pressure. However if you road tested, without a fuel pressure guage installed, it would miss and stumble badly. With the increased fuel demand the pump couldn't supply pressure at the volume demand.
I would agree, those electronic carburetors will very complex as opposed to the TBI. TBI was very reliable and easy to service.
Have the same TBI set up in my 71 jeepster with a buick 350 and it's been running strong since 1995 and somehow even with 37" inch tires I still get 18 MPG
These were great. My 89 RS Camaro with a 305 v8 5 speed manual could achieve 30mpg on the hwy.
My dad has 98 gmc 4.3 tbi...runs lole a champ. Im ony second tbi, 88 firebird woth 5.0 tbi..had one a while back and honestly i loved it...course im a simple person and odd to...lol...
fun fact I found out. If the fuel pump relay goes out Chevy had the bright idea of using the oil pressure sensor. So if the relay was bad when you were cranking the fuel pump would not come on until it sensed oil pressure. Took me a while to figure out why my 5.0 was hard to start.
When I worked at Empire die casting in the mid seventies I used to make (pouring the molten aluminum into a mold )the main body (Throttle body)
They are good and simple
My 90 454ss had one. Flowed quite a bit cfm.