Mechanical cause for craptastic cold idle?

[DirtyBlueVan]

The issue(s): when cold, it starts, but runs like complete garbage. It sounds like a cylinder is dead. It may or may not die without throttle input. Once it starts to warm up it starts to smooth out and eventually runs and idles well enough. I noticed that holding it at 2k (while bleeding the coolant engine warm) It pops like it is backfiring with small +\- 50-100 rpm fluctuations. The plugs are black from running rich(I think) and burning oil (258k)


I'm still battling this issue, all sensors check well and are within parameters. Re adjusted the TPS and hear audible clicks at full and idle.

Things I still need to do:
-Check for vaccum leaks with propane, I found one small one but it made no difference after I fixed it. no high idle, so I'm not holding my breath.

-Check fuel pressure, I don't have a way to test this so this will happen last resort

-take apart the cold idle valve and check it in depth


Someone obviously tinkered with the AFM.

My main question is, the seemingly dead cylinder when cold started. Are there any mechanical issues that would show during a cold start but not when warm? It does smoke upon starting and goes away almost in time with the engine smoothing out. It's not a serious amount of smoke.

Thanks for all the help so far everyone. What a great resource.
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1989 Syncro Westfalia 2.5 smallcar subie

[0to60in6min]

there are many things that lead to the problem you described.. since you mentioned mechanical.. I would say that you have at least one leaking injector. The injector(s) leaks and flood the cylinder(s). When you start the engine it will run very rich in one or 2 cylinders until the excess of gas is gone - the fouled/black spark plugs is the clue.. - and once the excess of gas is gone it runs normally... till you park the car overnight...

other than that anything from AFM, Temp2 sensor, coil, bad grounds etc etc.

[vandam]

check engine compression.
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84 GL, 2.1 rebuilt

[DirtyBlueVan]

150,150,130,120. No complete leak down done
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1989 Syncro Westfalia 2.5 smallcar subie

[Wildthings]

The TSII sensor is what enriches the mixture during cold running. I would start there.

[Westified]

I had a problem with cold idle on my 1984 1.9 Westy, replacing the Auxiliary Air Regulator solved the problem. Good luck.

[DirtyBlueVan]

just to update, replaced temp 2 still no good, checked aux air per bently, rpms fluctuate appropriately.

I have gas in the oil, found an exhaust leak and patched it.

Any other ideas out there?
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1989 Syncro Westfalia 2.5 smallcar subie