Okay, my 1985 2m6 V6 auto has developed a problem.

When the left-front caliper seized in August of last year, the engine was running just fine. I parked it in the garage for a few months while I dealt with a bunch of other stuff; when I finally got back to the Fiero and pulled it out of the garage to work on the brakes, it was not firing on all cylinders.

Today I took the dist. cap off and the inner terminals were corroded, so I used a brass wire wheel to get the corrosion off. The engine ran SLIGHTLY better.

Pulled the plugs to inspect them.

Rear bank of cylinders:

#1 looked more or less normal

#3 black and sooty

#5 black and sooty.

Front bank:

#2 was kind of black, but not very; smelled of gas.

#4 black and sooty

#6 black, sooty, wet, stong gas smell.

Cleaned the plugs, put them back in, started her up; she ran pretty much the same, so I started thinking about it being fuel rather than spark--and hit on the idea that it could be the cold start injector.

Am I stupid, or on the right track?

Thanks!

Ed

I'll say stupid....

quote Originally posted by Gall757: I'll say stupid....

Yeah, but that's pretty much a common trait amongst all Fiero owners.

Before blaming the cold start injector, try these two things

Electrically unplug the MAP sensor and see if the engine runs better. If so inspect the vacuum lines to the MAP sensor. If the MAP sensor is getting full vacuum, but the engine still runs better with the MAP sensor unplugged, try replacing the MAP sensor.

The MAP sensor is the #1 sensor used to determine how much fuel to inject. If the vacuum line to the MAP sensor has broken down, or cracked the MAP sensor might be telling the ECM that the engine is at full throttle, and the ECM would be firing the injectors as such.

The other thing to look for is to pull off the vacuum line that runs to the fuel pressure regulator. If there is gas in the vacuum line, the FPR diaphragm is leaking and letting gas run directly into the intake manifold.

Could also be the coolant temp sensor. If it's telling the PCM that the engine is colder than it is, it will tend to run rich.
This will be independent of what the gauge is reading. They're two different sensors.

I will check these things at my earliest opportunity...which might be on Wednesday if something else doesn't come up.

Thanks!

Ed

Maybe this will help. Remove the cold start injector and see if its wet. While your at it reconnect it at the fuel rail end and leave the injector end exposed. Remove the elecric connector from the injector as well. Don't start the engine but turn the key on and off several time to prime the system. If the cold injector gets wet you found your problem.

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut