84 fiero... timing gear was stripped but that was replaced... has a sort of consistant runs rough every 10-20 seconds... after driving for a few minutes it will start to loose power under load, pop and miss, and if you push in on the clutch it will die but after a few minutes it will start and run... what gives with this thing???

zroc

 

ZROC,

You poor SOB. I know your pain. Pick one:



These ECMs/engines are very sensitive to fuel pressure and MAP input. They seem to be very tolerant of TPS and timing changes. Remember that the ignition timing needs to be set based on the averages of the #1 and #4 cylinders, and the base timing needs to be forced by jumping the diagnostic terminal on the ALDL in the center console.

If you have a testing fixture, check to see that fuel pressure is between 11-13 PSIG. Low pressure can actually make the mixture run excessively rich in closed loop because of the large corrective steps of the ECM programming. Of course, a clean fuel filter is essential.

Check the ignition coil resistance, and preferably while it is hot. Intermittent coil problems can be temperature related. Make sure the distributor cap and rotor are clean and dry.

Watch the fuel injector spray pattern while the engine is running to make sure you have a nice, regular cone-shaped pattern with no dribbling. There is only one injector, so everyting is riding on it.

An incorrect MAP reading can create havoc for the ECM, so inspect the electrical connection and vacuum lines. Don't overlook the PCV valve, since a sticky PCV can alter vacuum a lot, and cause the MAP to drop signal. The ECM will try to compensate and will fail, causing very poor operation or stalling.

Ain't it fun?