Ok, Here goes...I have a Plymouth Grand Voyager 3.3L that all of a sudden didn't want to start well. Turn the key and the engine turn doesn't fire. It does this for a few minutes and then fires and dies, does this for a few minutes and fires and runs and dies, does this for a few minutes and then run rough, put it in drive and it dies, does this for a few minutes and then stays running in drive, give it gas and it dies, does this for a bit and finally it is off a running fine for the rest of the day. You can shut it off and start it right back up again. Next morning you have to repeat the procedure. No code (12 55)

I know what you are thinking, fuel Pump or regulator maybe? Well, here is what I have replaced: Fuel pump, fuel pressure regulator, fuel filter, air filter, spark plugs (good spark), O2 sensor, AIS motor, Temp sending unit, Coolant temp sensor, Throttle body gasket, Map sensor, and TPS. Now, after all of that I get code 25 (AIS) and 41 (alternator) but the alternator works fine and the AIS is new and IT STILL STARTS THE SAME!!!

Good spark, good compression, fuel pressure is good. So, like, what gives?

 

Yep, no replies. That is what I thought.

 

Goodness, throwing parts at it.

I’m fighting a similar problem with a 1994, that is a later version of the FI systems. On the 94 the cam-crankshaft sensor pair are suspect as the ECM needs one or both to sense rotation to open all the injectors to provide some fuel. But then it expects meaningful information on cylinder position to time injection and spark, without that it will shut ignition and fuel off.

As for no replies, this seems an erratic forum, people ask spur of the moment questions and don’t check back, etc. Without the knowledgeable people that a competitive forum has.

 

Mine now “appears to run”, unsure if was the new MAP sensor or bending/wiggling wiring of MAP, TPS, cam, or crank sensors while I was testing them that made the difference.

Note you need to clear codes, as fiddling with sensors can create codes. I use a procedure to clear Adaptive Learn:
- disconnect negative cable of battery
- turn ignition ON
- hold brake pedal depressed for five minutes
Other people just disconnect the battery overnight.

BTW, re MAP sensors, apparently they are sensitive to vacuum leaks nearby, noting the PCV valve is nearby and Chrysler’s elbows on the manifold fitting deteriorate quickly.