Car: 1989 Firebird Formula 350.

Problem: Car starts and will sit and idle with no problems. Car can be driven LIGHTLY without any hiccups, i.e., keeping your foot out of it.

Open the throttle, however, and Houston we have a problem. Car seems to load up and flood itself, begins to idle/drive poorly. If you shut if off, you're rewarded with a Service Engine light and not being able to start it again for a while.

Recently replaced the plugs, wires, cap and rotor and all the filters. Tested the coil and the ignition module, both are fine. No codes in the computer. Fuel pressure at 43 psi. at start-up, and will drop SLOWLY, likely a leaky injector.

What causes this? The ECM is the most common culprit, apparently. Can somebody explain the possible malfunction and how to fix it?

 

Start by pulling codes from the ECM...it'll give an idea what to look at.

ECM is most likely the LAST cause of the problem.

 

you said it yourself, bad injector.

 

dose your fuel press drop while it is running? if so, how low dose it go? if it gos below 40lbs that would be a problem.
also look into the CTS coolant temp sensor, that would not let it start after it was hot, and would start again untill after it cooled down, and didn't set any codes when it happened to mine.

 

fuel injectors.... just went through the same problem and dumped loads of money into mechanic guesses and finally went with mine and that was it... its crazy how it acts w/ just 1 bad injector