intermittent pig rich

[E30 Man]

Hello, I have been a long time follower, but this is my first time posting. I have a 1986 325e that I have owned for about 6 months. Since purchase, the car has run good, but slightly rich; however, every other run cycle the car will suddenly go pig rich and become undrivable. the only thing that I have found to temporarily fix this is to unplug the idle air control valve and let it run in it's default mode for a few seconds and plug it back in. After I have done that it goes back to running normal for a while.

the following parts have been replaced:
blue top coolant sensor
two prong coolant sensor
brown top coolant sensor
rebuilt injectors
fuel pressure regulator
afm
oxygen sensor
distributor rotor and cap

I checked the cold start valve and that is not leaking. Throttle position sensor checks out. I cleaned the idle control valve. I checked the fuel pressure during the malfunction and it is within range. I checked the sensor inputs at the ecu and they check out to the specifications in Bentley. Looked it over for obvious vacuum leaks, and haven't found any. I also cleaned the throttle body.

The fact that I can unplug the idle control valve and plug it back in for a temporary fix is leading me to believe that I have an issue with the ecu or the idle control unit. However I do not have access to spares of either to test with, and I am not sure if I am even on the correct path. Any advice would be greatly appreciated.

[325e '87]

Have you tried unplugging the cold start injector permanently?

If i remember right, injectors fire when grounded, so maybe clean/inspect injector wireharness and connector pins?

Might be a bandaid solution, but try to source a new DME chip that is performance oriented. The eta has a very solid HP gain with a chip. I got a used one here in the classifieds section and it made my son’s car “like new”. Big improvement.

Our eta wont run with the afm unplugged, so for whatever reason you are better off than us.....

I’m not one of the experts here, so I’m just trying to help you brainstorm. Aren’t many eta’s left, so lets hope help is on the way.

[E30 Man]

Hi 325e '87,
Thank you for your response, I wanted to get back to you sooner but revlimited was down. I did try unpluging it and also pulling it out while it is running rich but there was no change sadly. I should probably inspect the injector wireharness and clean the pins like you said just simple because it is old and that could be the problem. Does anyone have anything else?

[E30 Man]

Update
So it turns out that my ecu was the problem. I got a used one off of ebay just to test it. So far it has fixed it, I took it out for two different test drives.