Engine Stall within seconds

[bradartigue]

When you start an L-Jetronic equipped car these things happen, in this order, which can cause it to run briefly and shut off:

1. The ignition switch, in the start position, triggers the ECU.
2. The ECU fires the injectors in a full rich mode for a predetermined time (think a second or two at most)
3. The ignition switch goes into the run position
4. The ECU relies on the AFM to tell it the car is running, and enters a normal running state.

In other words, the correlation between running just after the starter is engaged and continuing to run when the starter is disengaged is one you cannot make. I have to agree that NONE of the cold start stuff is going to make it not keep running. Nor is the O2 sensor. It will run with all of this stuff malfunctioning, poorly perhaps, but it will run.

To summarize, if your car is running for a few seconds and then flat out dies, you need to start your diagnosis on the things that control normal operation - the coolant sensor, the AFM, the ECU, the injectors, the fuel pump. Everything else is just there to help it run.

PS I think when they are referring to the idle control adjustment screw they mean the idle air bypass screw on the plenum. It won't cause the car to not run (it will cause it to idle low or high, depending on how it is set).

[wikkid]

To the OP, what diagnostic guides/manuals do you have at your disposal, to help you through the testing process?
Brad, the previous poster, has a great manual on his web site: http://www.artigue.com/fiat/

Also, Brad's fuel injection guide

And This Guide

And Here.

And of course the shop manual.

There are others as well.

HTH.
-Chris

[rdavidson52]

Great resources and guidance Guys. Really appreciate it. During the many years I owned my E30 M3, the SIG was a hugely beneficial, technically smart and wise group, and, I am happy to see this group is, at the least, just as good.

Given some work on our new generation projects, I probably won't get another chance this week until early Saturday. Think the first test will be cold start valve. Checks out, then the fuel pressure. All else has been checked out before, except for the ignition and ECU. Will get to all I can this weekend.

Thanks,

Robert

[rdavidson52]

Soooo! At 6:39 this morning I'd had a cup of coffee, wnt out and picked up the paper, noted it was finally cooled down the lowest I'd yet seen it (57 degrees), gone out to the garage, uncovered opened the hood and pinched off the return line from the Cold Start Valve. Put the key in, it started as usual and...kept running. Let it run for about 10 minutes, release the line, and it still kept running. Turned it off and restarted, letting it run about 5 minutes each time. Maybe the valve was stuck as part of sitting for so long. But, I will go ahead and order a new one...just in case.

When I get back late this morning, I plan to go ahead and do a proper tuning of the TPS and double check the timing, then throttle adjustment (running a little high now). With all the other activities today probably won't be able to do a good test drive until after racquetball tomorrow morning.

Boy!!! So Far Feels GOOD! Looking for even BETTER!!

I'll post another follow up.

Thank you to all,

Robert
Thanks