Strange idle question. (1 Viewer)

[HawkGunner]

I finally got my truck running OK, but it has a weird idle issue I've been trying to fix.

I can't get the idle screw to lower the idle past about 1250ish once its warmed up.

I replaced the o-ring on the idle screw and put teflon tape on the threads. The TPS has been ohmed and adjusted properly, I cleaned out the throttle body and adjusted the stop screw properly, I've tested my computer against a known good computer. I tested/ohmed the VAFM, it seems to be functioning properly.

I checked the coolant hoses to/from the IACV for obstructions and found none.

I checked replaced all the vacuum lines with new hose, and then tested with propane for any vacuum leaks and found none.

Timing is set to ~10° when engine is retarded from diag box, and it advances properly per the FSM

I checked the power and ground signals to injectors. All good.

When I blip the throttle, the engine revs up appropriately, and then when the RPM's drop, it acts like it wants to die... if I tap the throttle it resumes its previous high idle. If I turn the engine off, it is difficult-ish to start again once its warmed up. I have to give it some gas and try for a while. Or let the engine cool and it'll fire right up again.

It fires right up when cold. Idles high to warm up, then lowers the idle like it should... sort of

-coil is new
-ignitor is new
-plugs are new and gapped properly
-dizzy cap and button are new
-temp sensor is new
-starter is new
-batter is new

It's driving me nuts that I can't seem to figure it out.

EDIT: I'm leaning towards it being the IACV or VAFM, but I dont want to replace either one randomly. I dont like throwing parts at a problem or wasting money.

 

[HawkGunner]

Any suggestions?

 

[BlueCruiser84]

I really Don’t have any ideas. It sounds like you have been pretty thorough.

Are the valves adjusted correctly? EGR functioning properly (not stuck open)?

 

[pappy]

It sounds like you have been pretty thorough.

Ya, I agree. The only other option I can think of is cracked intake couplings.

 

[Gumby]

It sounds to me like a vacuum leak. The 22re is known for them. Try a propane torch turned on, but not lit around the intake manifold and hoses. Try pinching off the vacuum lines with a pair of pliers.
It would be nice to compare to a known good AFM, they are all getting pretty old now. Corrosion on the variable resistor slider could cause the problem too.

I fought and fought with mine. Got it fixed, then fixed it perminantly with a 3rz.

 

[HawkGunner]

I really Don’t have any ideas. It sounds like you have been pretty thorough.

Are the valves adjusted correctly? EGR functioning properly (not stuck open)?

The valves are adjusted properly, and I blocked off the EGR because I thought that was it too. Not it.

Ya, I agree. The only other option I can think of is cracked intake couplings.

Checked. Nope

It sounds to me like a vacuum leak. The 22re is known for them. Try a propane torch turned on, but not lit around the intake manifold and hoses. Try pinching off the vacuum lines with a pair of pliers.
It would be nice to compare to a known good AFM, they are all getting pretty old now. Corrosion on the variable resistor slider could cause the problem too.

I fought and fought with mine. Got it fixed, then fixed it perminantly with a 3rz.

I already checked for leaks with a propane torch. I didn't find any, but replaced all the vaccum hoses anyways.

I ohm'd the AFM, and it seems to be functioning properly.

Have read through everything I can find, the only thing else I can think is that it's either clogged coolant passages to the IACV, or the IACV itself.

If the IACV fails open or part open, or if it's not getting the hot coolant it needs to actuate properly, it would basically act like a vaccum leak.

I just got a new one last night. I'm heading out to swap it shortly. I'll report back whatever happens... I'm sure I won't be the last person to have this issue.

 

[BlueCruiser84]

Let us know! It drives normally otherwise?

 

[HawkGunner]

Let us know! It drives normally otherwise?

It drives normally until its warmed up, then it drives like it's got a huge vacuum leak.

Spits and stutters at a stop, until the computer evens it out I guess, then it drives fine. Once I stop again, it does it again.

 

[BlueCruiser84]

Interesting. My “new” motor swap does something similar. Haven’t really dug into it. The 22re seems to be a pretty finicky motor.

 

[HawkGunner]

Replacing the IACV fixed my problem.

You can see the old on was all crudded up carbon and stuff down on the thermostat valve.

Vs. The new one

And since I needed to damn near cut the old screws out that were holding it to the throttle body, I went to Fastenal and got some allen key socket head bolts to hold it down. For easy replacement or cleaning in the future.

Additionally, if you think yours is bad, i.e. you've done everything and can't figure out why your idle wont turn down or its fluxuating wildly with no obvious explanation, there is a simple test you can do.

Inside your throttle body, before the throttle plate, there is a port in the bottom where air is allowed in via the IACV. Once your engine is warmed up, put a piece of duct tape over this hole to block off any erroneous air being sent by the valve.

If that fixed your issue, you need to replace or clean your IACV.

 

[BlueCruiser84]

Congratulations! And thank you for posting up the conclusion. I have a feeling this will be helpful to me in the near future.

 

[KLF]

Lol... I had to do this same thing on mine 4 years ago, posted the same diagnostic method, same result. Where did you get a replacement? I bought new OEM, it was not cheap (like over $200 IIRC).

 

[BlueCruiser84]

Lol... I had to do this same thing on mine 4 years ago, posted the same diagnostic method, same result. Where did you get a replacement? I bought new OEM, it was not cheap (like over $200 IIRC).

22re performance sells one. I believe you can clean and “rebuild” your old one? Maybe I’m mistaken.

 

[HawkGunner]

Lol... I had to do this same thing on mine 4 years ago, posted the same diagnostic method, same result. Where did you get a replacement? I bought new OEM, it was not cheap (like over $200 IIRC).

I got this one from Oreillys. It was $115 I think. Still not cheap...