poor running fiero

[medicman]

HI everyone, I'm new here but not new to cars. I have a problem with my stock 86 2.8 fiero gt. This car has never seen a winter and still has its original exhaust.

To get right to the point, cylinders 2,4,6 plugs are black and it blows black out the tailpipes. Plugs 1,3,5 are perfect, light brown no issues. I have been over this car with a fine tooth comb but have run out of ideas. To review the things I have done, I have done a complete tune up, rebuilt the heads,(was under 100 on the front head, now 150 psi per cylinder x 6). Taken off the exhaust at the manifolds to check for a blockage (nope not that). I have tested the 6 pin weather pack at the injector harness and it tests good. I have a obd 1 scanner and it shows I'm running rich.

One thing that has got me baffled is that if I pull injector fuse 1 which controls injectors 2,4,6, the car dies right away. I put the fuse back and pull injector fuse 2 which control injectors 1,3,5 and the car keeps running without any change.

The car starts like a champ and will idle all day long, not perfectly smooth but not bad, I find it does rev high (approx 1200). When I put it into drive (basically under a load), the idle gets real rough and the car stalls out within 10 seconds

I'm looking for ideas where to go from here.

cheers

[The Dark Side of Will]

You've had it apart.
Did you replace any injectors or have it cleaned? If some larger injectors happened to be in those cylinders, it could produce the symptoms you describe. Can you see enough of them to check the part numbers without taking the engine down too far?

Not sure if it should die right away when pulling an injectors fuse... I would expect that it would struggle to idle, and the ECM would open the IAC further. If extra fuel is being delivered to the rich bank, it may have an easier time idling under load than the bank that runs stoich.

Also, you should ring out your wiring to make sure that everything is correct between the fuse block and the 6 pin weatherpack and the ECM and the 6 pin weatherpack. It sounds like you've only checked from the weatherpack to the injectors.

[Shaun41178(2)]

someone might have rewired the harness and all the injectors are on one fuse now? each injector fuse I think is only a 5 amp. id verify that. I say oversized injectors or clogged injectors.

[Emc209i]

Is the EGR tube intact?

[The Dark Side of Will]

Is the EGR tube intact?

Good point... I had assumed the high idle he mentioned was related to warm up, but if the hot idle is 1200, it could have a vacuum leak and obviously the first suspect is the EGR tube.