A bit stumped here

[yukon101]

Greetings again, I am having a bit of an issue with my E32 that I cannot seem to find. My issue is that my idle never rises above 550~ (usually 500) rpm hot or cold. I have rebuilt the entire intake manifold and replaced every known gasket for it and checked for cracks. I have checked the ICV and it was stuck but I got it moving again and it tested fine. I have tried wacking the MAF with the back of my hand and no change. I tested the TPS and found it was out of spec and reading partly open at idle, replaced that with a new HELLA one that tested good. After the TPS change the car did shift far better than before however the idle issue is still the same but with the introduction of when cold I will pull up to stop lights and at about the 10 mph range when it should begin idling it will misfire but then corrects itself and in some cases has stalled, it does start right back up however. Today I tried the last thing on the list and that was replacing the injectors, I still have not had a change. Both coolant temp sensors are good, I can tell the ECU one works by watching the fuel consumption hot vs cold and there is a difference in the consumptions. I decided to check for misfire at idle too and after pulling each ignition coil they all forced the engine to run way worse equally. Any other thoughts that I have not tried yet?

[PJs e32]

Two things you might try. One, lift off the air cleaner lid, then turn on/off the air conditioner (engine running) you should hear the sound change, which will let you know that the ICV is actually working. Two, disconnect the battery for ten minutes, then reconnect. That should reset all the base setting for the computer, it will have to re-learn idle speed ect. You will have to go for a drive to help this re-learn idle ect.

[Avec]

I believe that to force a reset and relearn, you need to disconnect both positive and negative cables and hold them together for a short time.

[yukon101]

Here's a wrench in the gears, the idle control valve is functioning. If I turn the AC off my idle drops to a steady 490 then when I turn it back on it goes up to a 510. As for the ECU I just reset it 2 days ago hoping that was it too, it brought throttle response back but that's it.

[yukon101]

I swapped in my spare ICV that I pulled the other day where it tested fine, there has been absolutely no change. This is starting to get frustrating.

[yukon101]

Bump, Doug DeMuro from YouTube said he wants to review my E32 so I need to get it in tip top shape.

[CamE32]

Just a guess, but have you ruled out fuel supply issues?

[yukon101]

Much newer, better fuel injectors that are firing great. The fuel pump is great and puts out great pressure, the only possibility would be the two filters that have been changed according to the records between 100k-200k beyond that and I don't have many records until 300k.

[CamE32]

Perhaps the fuel pressure regulator?

For what it's worth, I'd consider changing the fuel filters first and foremost if you're not sure that they've been replaced in the last 100k.

[yukon101]

Fpr maybe, filters should be replaced but aren't bad. I drive up the steepest legal incline every day and it has no issue going up that.

[yukon101]

FPR is in fact good. The stalling I figured out is actually the torque converter not releasing fast enough on hard braking and not unlocking completely when coasting either. Replacing fuel injectors did solve the miss fire part of the stall, today I completely reset everything in the car for twenty minutes. On my way back home the shifting was a lot better and more responsive and did not stall on hard braking but it was already hot when it doesn't usually have much of an issue. Tomorrow will tell if the stalling has been fixed. I also decided to order Carsoft so I can see what the ECU is seeing and figure out why it always idles low.

[XAlt]

Go ask the E34 guys, there's a lot more 540s than there are E32 V8s.

Make it look good for Doug

[yukon101]

I'll get her all pretty for Doug, mine will be the first E32 reviewed by a large YouTuber. I was chatting with one of my mechanic friends who does 80s Toyota and they had a different approach, they suggested the coolant temp sensor to the DME isn't reading right since it only happens in a specific temp range. And oddly enough it didn't happen during my second full warmup today.