through all of this unless I intentionally unplugged something, I've gotten no codes, but I've been clearing the ECU every time.

My next test is to let everything cool down AGAIN, and try to see if I can find a vacuum leak that I missed.

Any thoughts are greatly appreciated!

Tom

 

Hi Guys,

Before I spend another day messing with this car, I've got a question.

Once the engine warms up, and I put my finger over the FITV port, shouldn't the engine idle O.K. (albeit low) with just the IACV plugged in? I'm trying not to just randomly pull things off.

The reason why I ask is when I tried to set base idle, and I pull the plug off the IACV, the engine idles pretty badly to where I cannot let go of the throttle to set the idle screw.

Tom

 

Hello Everyone,

O.K., here's what I found so far:

I've eliminated the FITV. I removed it, inspected, and tested. The plunger is moving with some heat, and after I installed it and let the engine get good and hot, no more vacuum is found at the port leading to the FITV.

I've eliminated vacuum leaks from the two manifold gaskets and other vacuum tubes by spraying some propane around the intake area. No idle change.

While I had the coolant drained, I removed the IAC and checked it. It was a little dirty, so I cleaned it. I applied 12v and heard the solenoid click.

After reinstalling everything, I made extra sure I had no air in the cooling system. I even left one of the pipes leading to the FITV to wait for coolant to flow through.

The engine started right up from cold, but as it's been, the car idles high from cold, but once it warms up the idle drops and after I blip the throttle, the engine idles down too slow and stalls. It won't start without applying throttle.

I tried to get the base idle set by unplugging the IACV, but it doesn't want to run with the IAC unplugged. I started the engine with throttle and slowly released the throttle cable, all the while turning out the idle screw. I got the engine to idle (barely) without applying pressure to the throttle, but with the IAC plugged back in, the idle does not rise, and idles very low. I probably have to wait for the engine to cool down, reset the ECU, and allow it to relearn the throttle setting?

I've turned the idle adjustment screw all over the place, so I have no idea where it should be set, but it seems pretty far out. Is there a base starting point with this screw, like 1 or two turns?

If nothing changes on this next heat cycle, I may try buying a new IACV.

Am I heading in the right direction?

Tom

 

I've lost count how many times I've tried to fix this car, but here's the latest.

I let the car cool down so I could check the idle settings from last time time, and the car fired up fine. As it warmed up without any throttle the idle settled down to a nice even 800 rpm. I waited until the cooling fan cycled on and off before revving the engine with the throttle cable, but as the revs dropped when I released the cable, the engine dropped below an idle speed to keep running.

I checked for voltage at the IACV, and that's fine. I'd have to remove the IAC valve again to check its resistance, but does it sound like I'm narrowing it down to the IACV?

Tom

 

I would check the EGR. It may have something lodged in it from the intake job and is not closing all the way.

 

Thanks Chris,

I'll take a look.

I am making progress however. I found that if I jump the SRS plug when setting base idle, I can get a much better low idle. I think it stops the ECU from adjusting timing when I'm fiddling with the base idle screw.

I got the car to idle smoothly at about 500 rpm with the IACV unplugged and the SRS plug jumped, but when I reset everything, and wait for the car to warm up so the ECU can readjust, the idle falls off too low the first time I blip the throttle.

Tom

 

Yes, jumpering the SCS connector prevents the ECU from adjusting the spark timing.

Sounds like you got it good that far, idling 500rpm with the IACV unplugged. Now you want to force the ECU to re-learn the idle behavior.

- Reset the ECU (disconnect battery or pull back-up fuse).
- Let it cool down completely.
- Plug the IACV back in, remove the SCS jumper.
- All loads turned OFF (AC, headlights, window defogger, etc.)
- Start engine WITHOUT TOUCHING the gas pedal.
- Let it warm up completely WITHOUT TOUCHING the gas pedal.

 

I would try what JimBlake recommended first

 

And if later on, you need to mess with EGR or anything else, do that re-learn procedure again after you change or adjust stuff.

 

Since you replaced the manifold gasket, I would check that you have all of the vacuum hoses routed properly. The online manuals link in the DIY section has a spooner site I posted with a 94 shop manual. The routing of the vacuum hoses is shown in there.

Also, it could be possible to switch the TPS and the MAP plug. I think that they are identical. Check that the three wire leading into the MAP plug are yel/wht, grn/wht, and wht/yel. The three wire colors going to the TPS are grn/blu, red/blk, and yel/blu.