After my never ending MAF problems (-> here) during the last year the new season is starting even worse…

After running for 500 meters the motor died. I tried to start several times, the starter was running, the engine fired up and died immediately.

After a few attempts I disconnected the MAF and the motor started with no problem and stayed running. I switched off the motor, reconnected the MAF, it started without any problem.

On the next day the scenario was the same. I tested the fuel pressure and it was within specs.

As a next step I changed the MAF with one of my buddies car. The symptoms are still the same. With my MAF his car is running and with his MAF connected, my car will not start.

Conclusion: MAF is ok.

I replaced the ignition coil, the ignition module and the pick up coil. The rest of the ignition parts are 1000 kilometers old.

The pre-owner of the car disconnected the O2 ground from the rear of the cylinder head on the right side and replaced it with a new wire running from the ECM to the body. I rewired the ground as should be.

Still the same problems…


What I found out in the meantime:

The EGR solenoid was removed by the pre-owner of the car and the EGR was connected directly to the throttle body by a vacuum hose. I will fix these things tomorrow.


Any ideas what could cause this problem?


Jens

 

Unhook and plug the vac hose to the EGR valve. Having the EGR valve open all the time (by feeding it full manifold vacuum) could easily cause the type of problem you're experiencing.

I don't understand the MAF correlation, except that maybe having it unplugged caused the ECM to dump enough fuel to compensate for the "vacuum leak" caused by the EGR being open. It's a stretch, but it kinda makes sense.

 

Maybe a MAF relay went? Though typically when you re-connect the MAF the car will stall again. Worth maybe swapping them around individually with the f/p one if it's the same on your car.

 

*** UPDATE ***

After rewiring the EGR circuit and adding a new EGR solenoid I started the car today.

It started with the third attempt and stayed running, but after driving for 200m the SES lamp came up and the scanner gave me a Code 34...

I've sprayed around the throttle body and the plenum to check for leaks, but found nothing.

As a next step I replaced the ECM with a rebuilt one from the GM dealer. The motor started without any problem, no codes.
The next cold start will show more.

@ Red Devil: I replaced the MAF relays in the middle of 2003. Since then I was driving the car for 2000 km...


I will keep you informed.

 

***UPDATE 1***

No more starting problems, problem (hopefully solved).

Thanks for support