Those are just plain throttle adjustment screws not IAC adjustment screws. The IAC auto adjusts as you change the throttle settings but you will have to turn the engine off and on to reset the throttle positioning sensor to 0 or else the ECU thinks your stepping on the gas. The secondary screw is for taking up slop in the linkage as the throttle blades really need to be in time with each other or else the front two bores will run lean while the back two will be rich just from the difference in air flow. Any time you adjust the front throttle screw you should adjust the rear as well, you can do it with just your fingers. Besides that, you got a clean looking setup.
Hi there. Yes, I’m well aware of how it works. I hope that I didn’t lead folks to believe that the screws actually drive the IAC in some way. They simply adjust how much air is metered through the blades so that at nominal load the IAC is minimally open, and the majority of the air comes through the blades. This gives the IAC the most ability to compensate when load increases. As far as the TPS goes, yes. If you open the throttle adjustment you either need to use idle set mode or cycle the ignition to reset the TPS to zero. I prefer to use idle set mode. Keeps you from having to turn the engine on and off. As far at the second screw on the secondaries goes, it’s my opinion and what I have found, that only using the front screw keeps the lash out of the linkage and keeps the blade sync consistent.
Don't know if it makes a difference but - There are 2 separate IAC control screws. The one that is easy to see in the front and then the one that is on the opposite corner in the rear. Supposedly these are to be adjusted in equal turns from where set of butterflies just barely start to move.
Yep. There are differing opinions on this. Personally, I like to just use the one screw. It keeps the lash out of the linkage. I found that using both of them changes the adjustment more with heat expansion than it does with just one.
the issue with mine was sticking throttle from cold start. i found out that there's a threshold on the iac screws, front and back. if i turn it ccw far enough it'll cause the plates to bind against the barrell walls. so i turned it cw until i hear a click/pop which releases the plates from the bind. from there i'm gonna start setting the iac steps with linkage disconnected. hopefully it works out.
My front blades open a tiny bit more before the rear i haven't set iac yet and i am worried once i get them set they will still not be syncd should i take up the play with the linkage baron the side or back off rear screw once i get iac set?
Brian Goad yep I noticed that, though I think mine was taken off. It’s the only explanation. It was adjusted right, then after Fitech replaced the ECU it was way off. I’m not sure, maybe it makes harness access easier?
Thanks for the videos - I have a similar fitech install and would like a fuel pressure gauge setup like yours - do you have a BOM to duplicate what you did?
I don’t have a list of part numbers, but I get asked this a lot so I should probably make one or do a video. It’s not really difficult though. It’s 9/16-24 thread on the throttle body. So 9/16-24 to -6an male/male adapter. Then -6an female to 1/8” npt male adapter, 1/8” npt elbow, 1/8”npt gauge.
I want to make sure I understand and answer your question correctly, but I think you're asking how to tell how a tell where a particular engine likes the IAC to be set at. The answer to that question is, it shouldn't be engine specific. All engines should be able to be set up where the IAC is at 3-10 steps in neutral with your average accessory load. 3-10 steps is what Fitech says, and I happen to agree with them because this puts your average "in neutral" load idle mainly through the barrels, and gives the IAC headroom. Make sure when you set it that you check it again and re set it once you're at full operating temp and full heat under the hood (things change dimension with temperature). There may be exceptions to this for real small cubic inch engines, but in general 3-10 should work.
ndubb1 yeah I think it’s more like it should stay within the 3-10 range. I try to get mine around 7 when I set it. It will wander around that range though.
Those are just plain throttle adjustment screws not IAC adjustment screws. The IAC auto adjusts as you change the throttle settings but you will have to turn the engine off and on to reset the throttle positioning sensor to 0 or else the ECU thinks your stepping on the gas. The secondary screw is for taking up slop in the linkage as the throttle blades really need to be in time with each other or else the front two bores will run lean while the back two will be rich just from the difference in air flow. Any time you adjust the front throttle screw you should adjust the rear as well, you can do it with just your fingers. Besides that, you got a clean looking setup.
Hi there. Yes, I’m well aware of how it works. I hope that I didn’t lead folks to believe that the screws actually drive the IAC in some way. They simply adjust how much air is metered through the blades so that at nominal load the IAC is minimally open, and the majority of the air comes through the blades. This gives the IAC the most ability to compensate when load increases. As far as the TPS goes, yes. If you open the throttle adjustment you either need to use idle set mode or cycle the ignition to reset the TPS to zero. I prefer to use idle set mode. Keeps you from having to turn the engine on and off. As far at the second screw on the secondaries goes, it’s my opinion and what I have found, that only using the front screw keeps the lash out of the linkage and keeps the blade sync consistent.
Great advice!
Don't know if it makes a difference but - There are 2 separate IAC control screws. The one that is easy to see in the front and then the one that is on the opposite corner in the rear. Supposedly these are to be adjusted in equal turns from where set of butterflies just barely start to move.
Yep. There are differing opinions on this.
Personally, I like to just use the one screw. It keeps the lash out of the linkage. I found that using both of them changes the adjustment more with heat expansion than it does with just one.
the issue with mine was sticking throttle from cold start. i found out that there's a threshold on the iac screws, front and back. if i turn it ccw far enough it'll cause the plates to bind against the barrell walls. so i turned it cw until i hear a click/pop which releases the plates from the bind. from there i'm gonna start setting the iac steps with linkage disconnected. hopefully it works out.
How do you adjust the throttle linkage? I have the same issue.
My front blades open a tiny bit more before the rear i haven't set iac yet and i am worried once i get them set they will still not be syncd should i take up the play with the linkage baron the side or back off rear screw once i get iac set?
I noticed that you have coil over plugs system on non LSX. Do you have a video as to the Installation?
There is an overview video of it. It’s one of my first videos.
It is an MSD Direct Ignition System (DIS)
You don't need to take off linkage to replace ecu. Although it does look that way. It's stupid easy.
Brian Goad yep I noticed that, though I think mine was taken off. It’s the only explanation. It was adjusted right, then after Fitech replaced the ECU it was way off. I’m not sure, maybe it makes harness access easier?
Why is the ecu going bad?
On my 5th ECU
Thanks for the videos - I have a similar fitech install and would like a fuel pressure gauge setup like yours - do you have a BOM to duplicate what you did?
I don’t have a list of part numbers, but I get asked this a lot so I should probably make one or do a video.
It’s not really difficult though. It’s 9/16-24 thread on the throttle body. So 9/16-24 to -6an male/male adapter. Then -6an female to 1/8” npt male adapter, 1/8” npt elbow, 1/8”npt gauge.
@@mechtrician1 Thanks - I just saw you posted the same on another video of yours. I appreciate you posting it once again for me. Cheers!!
@@mechtrician1 would you happen to have the part numbers or information for the adapters you used for fuel gauge? Thanks
How do you actually know where to set the iac at? How do you tell where your engine likes to run best at?
I want to make sure I understand and answer your question correctly, but I think you're asking how to tell how a tell where a particular engine likes the IAC to be set at. The answer to that question is, it shouldn't be engine specific. All engines should be able to be set up where the IAC is at 3-10 steps in neutral with your average accessory load. 3-10 steps is what Fitech says, and I happen to agree with them because this puts your average "in neutral" load idle mainly through the barrels, and gives the IAC headroom. Make sure when you set it that you check it again and re set it once you're at full operating temp and full heat under the hood (things change dimension with temperature). There may be exceptions to this for real small cubic inch engines, but in general 3-10 should work.
@@mechtrician1 yes thank you that is what I was asking. Just wasn't sure how to tell if the engine likes 3 steps or 10 steps better.
ndubb1 yeah I think it’s more like it should stay within the 3-10 range. I try to get mine around 7 when I set it. It will wander around that range though.