glad i could help out! I've since torn that engine apart and put it back together, fixed countless other things, sold the truck and bought a new truck just like it any questions just ask
its a 5.7 vortec haven't been able to hook up a code reader. its starts fine an idles good in park but as soon as I put in drive its starts to bog down and my rpms drop under 500. ive changed mass air flow. tps . camshaft position sensor.
codes would help a lot. but it could be fuel pump, fuel pressure regulator, 02 sensors, intake or exhaust manifold leak.... get to an oreilys and they'll read them for free
Oh I remember when I did my intake manifold gaskets you have to be very specific on the torque spec on that intake manifold if you're not the damn thing won't stay running
Kodiak I have cleaned all mine with 90% rubbing alcohol and it’s always worked great just an idea, because I believe mass cleaner is mostly alcohol but may be wrong
My 2001 tahoe was doing the same thing then a few days later the water pump went out and after we replaced it. It started fine but the oil pressure would drop to 0psi it still does this to this day for about 3years. But thats the kind of behavior i'd expect from a 400,000 mile truck. And its a 5.3L
Hey Lucas I have a 2000 Silverado Silverado 5.3 4x4 LT Z71 with like 216k on engine. I have an issue where the truck starts but it almost wants to stall and a bit of a rough idle on cold starts. But on warm starts it's a little better. Sometimes there's hesitation and engine almost wants to stall when I accelerate and come to stop. Might seem like it could be electrical may be ground wires are corroded or terminals on them are dirty because I hae a flickering gear odometer display and when I try to lower both windows the instrument display lights fade and engine seems to have lower RPMs. I just cleaned my throttle body, replaced all spark plugs, replaced the IAC, ran seafoam through gas tank, and throttle position sensor seems good but still have problem. What do you think it could be?
today i got a 2000 chevy silverado 1500 and while i was sitting at a light i noticed it idles rough not like my other car which is quiet... i will watch your video to fix my that problem i like it nice and smooth and QUIET
So i had my 1999 chevy silverado 5.3 motor rebuilt already, it starts fine and drives fine, but once im at a light or sign it idles funny, it revs up and and revs down and shakes a bit, its never died out on me tho
Sorry I know this is a few years old. Just got a used 02 silverado. Has a rough startup. How much does it cost to replace the fuel pressure regulator? Will that fix the entire problem??
Can you help me I have a 4.8 onyl on cold it starts very rough it scares me but I hood it to 1200 rpm for about a minute and It idles normal had a coolant temp sensor code so I changed it and idk why it feels worse
Yes, troubleshooting this problem would be the same. MAF, throttle body, vacuum leak, Intake leak, exhaust leak, 02 sensors. There not a way to "set" the rpms without a computer flash.
i went through all the same shit with my truck -injectors -coils -pcv -manifold gasket -maf -02 sensors I had a lean code though. but my truck is running a lot better now but u can still tell the idle fluctuates
My truck starts fine, and after it runs for awhile and shut it off and turn it back on it starts. Almost dies but stays on. i was wondering maybe if it was the Vapor canister in front of the fuel tank maybe
Pretty pronounced exhaust manifold leak at the broken heads on both sides. Bank 1 misfire at idle. When it warms up a bit I'll (hopefully) get the manifolds fixed and re-test. No lean codes though...
@lucasbradshaw2545 pff I got a good one for ya. Got a 02 4.8/nv3500 2wd. Rough starts, low idles, has random misfires at idle but not driving. Live data shows super rich (negative trims). P0175 and 72 along with a p0300 I have yet to solve. New fuel pump, filter, injectors, coils, plugs and wires. Cleaned the maff and readings are about 4 at idle. Purge valve works. Cats aren't clogged, o2s read like they should. No vacuum leaks. WHAT IS WRONG!?!
@@RogueKnight33 Mine ended up being a vacuum leak on the manifold gasket. I couldn't get it to respond with a spray of carb cleaner but i'd replaced everything else. Truck rusted apart and is gone now though.
Did it do this out of nowhere or did it slowly start to idle at low rpms? My iac is dirty too but my rpm’s are just low it rarely dies on like it did in this video
Intake manifold... By bad if I wasn't clear. I also had broken exhaust manifold bolts, which were once a recall on vortec engines. The best fix and what I ended up doing was drilled out the old bolts and replaced them with hardened studs. An exhaust manifold leak can and will trigger some of the same issues but it will make your truck run rich. Upstream 02 sensors are picking up more oxygen so then they command more fuel. But yes, primary issue was intake manifold gasket leak.
My 2000 is acting up. Has slightly rough idle. When I first start it and accelerate, it hesitates (lack of power). Then after a few seconds of driving, it accelerates normally.(1/4-1/2 throttle). New pump. Wires. Plugs. Cleaned ground connections. Strong battery. Cleaned throttle body. Didn't clean MAF sensor yet. I'm struggling. Could it be the FPR? EGR valve? I'll be testing fuel pressure this week end but with a new pump I don't suspect poor pressure
while the engine is running: spray some starter fluid around your intake manifold. IN SHORT BURSTS it's flammable. IF the RPM's rise that says you have an intake or vacuum leak sucking air into the system from somewhere other than your air box. If that's not it, you're on the right track of checking fuel pressure at the rail. You may want to try just cleaning your maf sensor, but usually you'll have problems throughout your drive AND and engine code if the MAF is bad
start cheap and easy, then work your way up. I personally haven't seen an EGR cause that problem, unless it is just gunked up beyond a starting problem. Fuel pressure regulator is just a diaphragm. if It's bad and your pump is bad you'll see way high or crazy fluctuating pressure with engine running
You can take the TPS off and measure the resistance . There will be specs in the book. It will have you watch the resistance while moving the TPS, resistance should move simultaneously with TPS.
Jeff Banfield thanks for the input. Unfortunately I wish that's all it was. Intake and exhaust manifold gasket leaks and failing fuel pump. I followed this video up with a few more as well as updates in the coments
it's a fuse under your hood . Looking at your fuse box it's a 10 fuse toward the bottom right of the box when you are looking at it from the drivers side tire
@@lucasbradshaw2545 so the new one you put in was bad also? So what exactly was the fix, intake gasket, exhaust manifold bolt or the pump? I changed my fuel pump and now i have a low idle problem, cant even run ac because of it. Idles in gear around 400/500 rpm.
@@jordancomeaux6888 Yes, the first new fuel pump was bad so i warranty exchanged it. IF you've had a bad fuel pump for a long time, your CPU has to re-learn the fuel trims. but it should adjust the more you drive it... Did you change your fuel filter too? Do you have known good O2 sensors? Is your MAF sensor new and/or clean?(i have a video for that) Do you have a vacuum/intake leak? all of those will cause a low idle as well
I have the "fuel spider" instead of regular injectors ... replacing the manifold with that monster is a nightmare in my opinion ... mostly bc I live in the city so once I open my truck it's like when dorthy landed in munchkin land ... everyone is peaking out their windows, looking and watching and monday morning quarterbacking... lazy sobs
Justin, YES I finally got it. sorry I haven't loaded a video for it yet... A common problem with this series of LS motors is the EXHAUST MANIFOLD BOLTS. First, check if you can see black soot or build up on your cylinder heads around your exhaust manifold. this is a tell tale sign you have a leak from the manifold. Also, even if you do see the soot, physically verify that all 6 manifold bolts are present and tight (while doing this video I only made sure that they were there and didn't actually touch them or verify they were tight). The forward-most bolt on the Bank 1 (driver's side) and the aft-most bolt on Bank 2 (passenger side) were both sheered off, but the heads of the bolt were still there, which is why I never investigated this. I removed the exhaust manifolds, (#30 then a #21 *cobalt* drill bit)drilled through what was left of the shaft stuck in the heads and used an easy out (passenger side is a bearcat!) Fix your exhaust leak, and you will fix your truck! good luck. feel free to comment again or leave me a private message
Carey collins, do you mean of the exhaust manifold bolts? I did this project about 3 years ago and don't have any pics. I do however own the same truck and could try to do that for you. Intake Manifold Gasket replacement video is on the way. I just haven't had time to edit it
this comment is for people looking for answers. clean or replace your mass airflow sensor thats what runs your fuel banks and tell them if there running to rich or not
Jake's Lawncare thanks if I wasn't clear... Again, there's kind of a series, if you will, on my channel of troubleshooting this and other very common 5.3 problems. I even have a video showing how to clean the MAF. And in this video I actually found an intake leak. Thanks for the input!
My 2000 Silverado does the same thing but it idles low for about 3 seconds after turning the key for about 15 seconds before it starts but after it runs for about 3 seconds it goes normal
glad i could help out! I've since torn that engine apart and put it back together, fixed countless other things, sold the truck and bought a new truck just like it
any questions just ask
Hey man I have 1998 chevy Silverado and it has a rough idle I was just gonna see if you could help me out if you wouldn't mind
No problem! What engine is in it, what codes are you kicking out? What's it doing?
Feel free to email me. lucas.a.bradshaw@gmail.com
its a 5.7 vortec haven't been able to hook up a code reader. its starts fine an idles good in park but as soon as I put in drive its starts to bog down and my rpms drop under 500. ive changed mass air flow. tps . camshaft position sensor.
codes would help a lot. but it could be fuel pump, fuel pressure regulator, 02 sensors, intake or exhaust manifold leak.... get to an oreilys and they'll read them for free
What did you end up replacing ?
you should use only mass ait flow sensor cleaner that stuff will leave a film on your sensor
Oh I remember when I did my intake manifold gaskets you have to be very specific on the torque spec on that intake manifold if you're not the damn thing won't stay running
got to my issue checking this vid out. when u mentioned the maf sensor, did just that and that was it. nice!!
Never clean mass airflow sensors with anything other then specific mass airflow sensor cleaner!!
Kodiak I have cleaned all mine with 90% rubbing alcohol and it’s always worked great just an idea, because I believe mass cleaner is mostly alcohol but may be wrong
My 2001 tahoe was doing the same thing then a few days later the water pump went out and after we replaced it. It started fine but the oil pressure would drop to 0psi it still does this to this day for about 3years. But thats the kind of behavior i'd expect from a 400,000 mile truck. And its a 5.3L
xXFLARE_29Xx replace your oil pressure sensor on the back of your intake it will solve that
Change oil pump or oil pressure sensor
Hey Lucas I have a 2000 Silverado Silverado 5.3 4x4 LT Z71 with like 216k on engine. I have an issue where the truck starts but it almost wants to stall and a bit of a rough idle on cold starts. But on warm starts it's a little better. Sometimes there's hesitation and engine almost wants to stall when I accelerate and come to stop. Might seem like it could be electrical may be ground wires are corroded or terminals on them are dirty because I hae a flickering gear odometer display and when I try to lower both windows the instrument display lights fade and engine seems to have lower RPMs.
I just cleaned my throttle body, replaced all spark plugs, replaced the IAC, ran seafoam through gas tank, and throttle position sensor seems good but still have problem. What do you think it could be?
today i got a 2000 chevy silverado 1500 and while i was sitting at a light i noticed it idles rough not like my other car which is quiet... i will watch your video to fix my that problem i like it nice and smooth and QUIET
email me with whats up with your truck. I'll do my best to help you out! lucas.a.bradshaw@gmailcom
So i had my 1999 chevy silverado 5.3 motor rebuilt already, it starts fine and drives fine, but once im at a light or sign it idles funny, it revs up and and revs down and shakes a bit, its never died out on me tho
sounds like fuel trims are out of wack... check for vacuum leak
The fuel pressure regulator can cause it to act like the fuel pump is going out and it does throw the SES
Sorry I know this is a few years old. Just got a used 02 silverado. Has a rough startup. How much does it cost to replace the fuel pressure regulator? Will that fix the entire problem??
I'm late as well but it cost me around $100
Again ples hw to check if MAF sensor is bad turn the car off, unplug the maf s, switch on the car if it runs good means sensor is bad?
how many miles, which engine, what codes are you getting? I completely rebuilt that truck, so i have pretty good knowledge
Can I have ur number I jus got the truck myself
Can you help me I have a 4.8 onyl on cold it starts very rough it scares me but I hood it to 1200 rpm for about a minute and It idles normal had a coolant temp sensor code so I changed it and idk why it feels worse
It will stay running if you unhook your mass airflow mine does the same dam thang but mine is a 02 GMC Sierra SLE 1500
Would it be the same on the bigger 350 V8? I have a 99 suburban that the previous owner set the idle to 500rpm... way too low.
Yes, troubleshooting this problem would be the same.
MAF, throttle body, vacuum leak, Intake leak, exhaust leak, 02 sensors.
There not a way to "set" the rpms without a computer flash.
i went through all the same shit with my truck
-injectors
-coils
-pcv
-manifold gasket
-maf
-02 sensors
I had a lean code though. but my truck is running a lot better now but u can still tell the idle fluctuates
My truck starts fine, and after it runs for awhile and shut it off and turn it back on it starts. Almost dies but stays on. i was wondering maybe if it was the Vapor canister in front of the fuel tank maybe
Having the same issue this sucks…
Camshaft position sensor. Crankshaft position sensor. Change them both. Ac delco and not Chinese’s autozone junk
The only vehicle I've owned that rivals my '90 Caddy Seville in diagnosis and maintenance nightmares has been this '04 5.3
frankbergmanII have any questions lemme know. I've gotten quite learned on working on both of my NBS Chevy's
Pretty pronounced exhaust manifold leak at the broken heads on both sides. Bank 1 misfire at idle. When it warms up a bit I'll (hopefully) get the manifolds fixed and re-test. No lean codes though...
@lucasbradshaw2545 pff I got a good one for ya. Got a 02 4.8/nv3500 2wd. Rough starts, low idles, has random misfires at idle but not driving. Live data shows super rich (negative trims). P0175 and 72 along with a p0300 I have yet to solve. New fuel pump, filter, injectors, coils, plugs and wires. Cleaned the maff and readings are about 4 at idle. Purge valve works. Cats aren't clogged, o2s read like they should. No vacuum leaks. WHAT IS WRONG!?!
@@RogueKnight33 Mine ended up being a vacuum leak on the manifold gasket. I couldn't get it to respond with a spray of carb cleaner but i'd replaced everything else. Truck rusted apart and is gone now though.
@@frankbergmanII I'll have to try it I suppose
Man I'm thinking we have the EXACT problem mine occured after doing head gaskets I know it's just a vacuum line
🤣🤣🤣🤣🤣. Always check your vacuum lines these vortec love to fuck yoy and disconnect. Coming from a 300k original mile owner
This is how you start fires
Wouldn't be fun enough doing mechanics if it didn't 😅
Did it do this out of nowhere or did it slowly start to idle at low rpms? My iac is dirty too but my rpm’s are just low it rarely dies on like it did in this video
Its an over time issue.. exaggerated with climate changes. Cold mornings, hot afternoons
So fixing an exhaust leak fixed your problem?
Or do you mean intank gasket..
Intake manifold... By bad if I wasn't clear. I also had broken exhaust manifold bolts, which were once a recall on vortec engines. The best fix and what I ended up doing was drilled out the old bolts and replaced them with hardened studs. An exhaust manifold leak can and will trigger some of the same issues but it will make your truck run rich. Upstream 02 sensors are picking up more oxygen so then they command more fuel.
But yes, primary issue was intake manifold gasket leak.
When I cold start the truck it like revs itself a couple times then has a really rough idle anybody know what the problem may be ?
My 2000 is acting up. Has slightly rough idle. When I first start it and accelerate, it hesitates (lack of power). Then after a few seconds of driving, it accelerates normally.(1/4-1/2 throttle). New pump. Wires. Plugs. Cleaned ground connections. Strong battery. Cleaned throttle body. Didn't clean MAF sensor yet. I'm struggling. Could it be the FPR? EGR valve? I'll be testing fuel pressure this week end but with a new pump I don't suspect poor pressure
while the engine is running:
spray some starter fluid around your intake manifold. IN SHORT BURSTS it's flammable. IF the RPM's rise that says you have an intake or vacuum leak sucking air into the system from somewhere other than your air box.
If that's not it, you're on the right track of checking fuel pressure at the rail. You may want to try just cleaning your maf sensor, but usually you'll have problems throughout your drive AND and engine code if the MAF is bad
start cheap and easy, then work your way up. I personally haven't seen an EGR cause that problem, unless it is just gunked up beyond a starting problem. Fuel pressure regulator is just a diaphragm. if It's bad and your pump is bad you'll see way high or crazy fluctuating pressure with engine running
@@lucasbradshaw2545 Thanks a bunch for your inputs. Troubleshooting can be a long and tedious road
@@JasonTylerRicci yes, yes it can be... it's truly my pleasure. i'd love to hear what you find
You're probably left something unplugged when you were reassembling the intake manifold double check your work
Pressure regulator on the fuel rail
So what was the problem
You can take the TPS off and measure the resistance . There will be specs in the book. It will have you watch the resistance while moving the TPS, resistance should move simultaneously with TPS.
Jeff Banfield thanks for the input. Unfortunately I wish that's all it was. Intake and exhaust manifold gasket leaks and failing fuel pump. I followed this video up with a few more as well as updates in the coments
it's a fuse under your hood . Looking at your fuse box it's a 10 fuse toward the bottom right of the box when you are looking at it from the drivers side tire
Tyler Lyles no... it was a bad fuel pump, again. thanks for your detailed insight though!
@@lucasbradshaw2545 so the new one you put in was bad also? So what exactly was the fix, intake gasket, exhaust manifold bolt or the pump? I changed my fuel pump and now i have a low idle problem, cant even run ac because of it. Idles in gear around 400/500 rpm.
@@jordancomeaux6888 Yes, the first new fuel pump was bad so i warranty exchanged it.
IF you've had a bad fuel pump for a long time, your CPU has to re-learn the fuel trims. but it should adjust the more you drive it...
Did you change your fuel filter too?
Do you have known good O2 sensors?
Is your MAF sensor new and/or clean?(i have a video for that)
Do you have a vacuum/intake leak?
all of those will cause a low idle as well
Coolant temp sensor guys ! Easy fix
Why do you say it's the coolant temp sensor?
So what ended up being the problem??
Looks like bad EGR. His truck was revving when he sprayed there with the carb/intake cleaner.
I have the "fuel spider" instead of regular injectors ... replacing the manifold with that monster is a nightmare in my opinion ... mostly bc I live in the city so once I open my truck it's like when dorthy landed in munchkin land ... everyone is peaking out their windows, looking and watching and monday morning quarterbacking... lazy sobs
Did you solve the issue yet?
Justin,
YES I finally got it. sorry I haven't loaded a video for it yet...
A common problem with this series of LS motors is the EXHAUST MANIFOLD BOLTS. First, check if you can see black soot or build up on your cylinder heads around your exhaust manifold. this is a tell tale sign you have a leak from the manifold. Also, even if you do see the soot, physically verify that all 6 manifold bolts are present and tight (while doing this video I only made sure that they were there and didn't actually touch them or verify they were tight). The forward-most bolt on the Bank 1 (driver's side) and the aft-most bolt on Bank 2 (passenger side) were both sheered off, but the heads of the bolt were still there, which is why I never investigated this. I removed the exhaust manifolds, (#30 then a #21 *cobalt* drill bit)drilled through what was left of the shaft stuck in the heads and used an easy out (passenger side is a bearcat!)
Fix your exhaust leak, and you will fix your truck!
good luck.
feel free to comment again or leave me a private message
Lucas Bradshaw Hey Buddy, Have you had a chance to show a vid or pic of what your talking about?
Carey collins, do you mean of the exhaust manifold bolts? I did this project about 3 years ago and don't have any pics. I do however own the same truck and could try to do that for you.
Intake Manifold Gasket replacement video is on the way. I just haven't had time to edit it
Throttle position sensor
Jae Eversole No... If you watch the other videos and more of the troubleshooting it was intake manifold gasket...
this comment is for people looking for answers. clean or replace your mass airflow sensor thats what runs your fuel banks and tell them if there running to rich or not
Jake's Lawncare thanks if I wasn't clear... Again, there's kind of a series, if you will, on my channel of troubleshooting this and other very common 5.3 problems. I even have a video showing how to clean the MAF.
And in this video I actually found an intake leak.
Thanks for the input!
Oh lower intake manifold gasket. Replace.
My 2000 Silverado does the same thing but it idles low for about 3 seconds after turning the key for about 15 seconds before it starts but after it runs for about 3 seconds it goes normal
Zack3ry 01iver did u ever fix it
Oil pressure switch
have you checked your inline fuel filter
That Guy
fixed this about 2 years ago. it was a combination of 2nd bad fuel pump and intake manifold gasket
I have a 2000 Silverado 1500
Ok
Ok
Mine idles real funny when I'm at a stop sign... It revs up and down a couple times before it eventually stops...
Engine coolant sensor
Did you ever find out what it was my 99 1500 stalls out at lights.
I'm having the same problem
1: Check fuel pressures
2: what check engine codes do you have
3: check for intake manifold leaks
it looks like the egr hose
J Dizzle read more comments
Fuel regulator
Check the choke pull-out.
Fuel pressure regulator
Maf not mas
why not want run?
Patrick Benoit
...what?
Spider injectors
feul regulator
antitheft
Luis De La Cruz no, again... it was a combination of bad fuel pump and intake manifold gasket