Bens3rdGen

My car is running really rough and it has almost no power. Fuel presure and pump voltage are good. 13.1v and 48 psi.

I believe its a spark problem. I put on new cap, rotor, ignition coil, plug wires and Igntion module. They made the problem a little better but did not fix it. I pulled a couple plugs and they look ok.
I dont have a timing light right now, I'm trying to get one. But if the timing is off where should I start looking? I know how to adjust timing but if it's bouncing all over the place, where should I start? Thx

Ratchet

If it is bouncing all over it could be a couple of things but this is what I would check in the following order.

1. put the timing light on number one spark plug check timing if it is fluctuating put the timing light on number 2 and check timing if it stops number one spark plug or wire is bad.

2. check to see that the vacuum advance is disconected. Variation in vacuum can cause timing to bounce.

3. lock out the mechanical advance by tying it up if it stops the mechanical advance is bouncing around.

Ric

Bens3rdGen

I checked base timing. I couldn't check computer controlled timing because the timimg light didn't have an advance dial. In any case, base timing is a steady 6 degrees, same as I set it before.
Tried to hook up a OTC diagnostic tool but it couldn't communicate with my ecm.
I checked almost everything that controls spark and my car still isn't running well. What else can I check? Maybe the MAP sensor is bad? Can you test those with a meter? Bad fuel injector maybe? To find which one I can just disconnect them one by one and listen for an rpm change right?
Any other ideas? Any hlp is appreciated.

Vader

For the purposes of problem diagnosis, keep the EST bypass disconnected until the solution(s) is found. Entering another variable, such as unreliable timing, won't make diagnosis any easier.

You can test the MAP output (KOEO) by back-probing the MAP electrical connector and checking voltage at a measured vacuum. A handheld vacuum pump is useful for this, although a vacuum gauge and running engine will suffice. Compare the MAP voltage to the table:



If your car has a stock TPI/HEI distributor you can disregard the vacuum and mechanical advance theories, since it isn't equipped with either.

Bens3rdGen

Thanks for the MAP chart, very helpful. I'll keep ya posted on what I figure out.