M20 High idle when cold/running rich?

[RipJaws 3]

Ever since I bought this e30 M20, well over a year ago it has never run right.

Fitting a new engine, I thought all my woes would disappear! Unfortunately not quite but nearly - still have this minor issue.

When the car is started from cold it revs up around 2k rpm and acts a little weirdly until it is warm then the problem seems to disappear. It seems to be using too much gas and the smell is quite apparent either from the exhaust or around the engine bay (not sure exactly what I'm looking for in the way of smells here but it does smell quite rich). When the engine's temp is just below half the idle is rock solid at around 800rpm and it drives beautifully. I can't really determine if its still running rich when its hot but all I can say is that I'm quite sure generally the car uses too much gas. On a side note, the other day after the car got warmed up and was driving for a while the revs went up high again for just a little more added confusion.

I have fitted a new MAF sensor as I thought I would start there, unfortunately it doesn't seem to have fixed the problem. When I start the car cold and unplug the MAF sensor the revs level out much lower... would this suggest a faulty MAF sensor?

If the car is hot and idle is smooth when the gas pedal is sharply pressed the car's revs jitter and it stumbles to keep up with the sharply pressed gas pedal - I have looked at the TPS, unplugged it when the car is running (no difference) I can hear the sharp click of it when I move it when the car is not running.

My next guess is blue temperature sensor, lucky I have a spare to try.

Any ideas/guidance/help would be greatly appreciated, thanks.

[yng_750 247]

M20 can get corrosion on some loom plugs near the injectors that can lead to richness. But thats usually all the time rather than just when cold. Did you swap looms too?

Sent from my GT-I8160L using Tapatalk 2

[Etwenty1 45]

what year is the car/engine?

[RipJaws 3]

Sorry for the confusion before I posted a response from my old account on here.

When the engine had been removed I made sure all the loom and wires/plugs in the engine bay were tidy, I also checked the C191 plugs from the old engine and all the wiring looked immaculate. I especially checked the one which goes up and connects to the C191 injector plug. The engine came with another C191 injector plug as well. I can't really rule that out nor can I rule the MAF or o2 sensor as they all aren't new, just spares basically.

The car is a 1988 and the engine is from a 1990. Here is a video that might show the problem a bit better:

http://tinyurl.com/mwo5jmx

[Etwenty1 45]

was your old account sierra something?

from your vid, thats not the check engine light its the check panel which will usually light up brakelights on the overhead display until you touch the brake pedal, then it goes out.

What parts came with the new engine and which parts are from the old one? Is the intake manifold from the old or the new? who put the new engine in?

[RipJaws 3]

Yes it was, I introduced myself again for this account in the new member introductions. My old account was just set up in order to get some minor help. Anyway, yeah I suspected that's all the check light was on for. The whole engine was complete minus some pumps but it had done 135k kms and was all still together so the intake came with it. I put it in myself. I sincerely hope this isn't a vacuum leak is that what this might be more leaning towards? It does seem like unmetered air getting in.