Engine shut down

[hookoo3]

I have a 2001 3.2 L. I'm on a road trip right now. I could feel that the car was not accelerating. Eventually the engine just shut down and I was able to pull over to side of road. I attempted to restart engine 2 times and it would immediately stop. The engine now will not restart at all but cranks over. I have codes with my simple Elm code reader of P 1126,P1132,P1125 and P1133. I'll be towing the vehicle home. What are the most likely repairs that need to be done?

[Newsguy]

Air, fuel, spark.
All there?
Sounds like a fuel issue, but you need to diagnose.

[Liam986]

Codes P1125, P1126, P1132, and P1133 indicate that the engine control module (DME) in your Porsche 986 is at its enrichment limit, meaning it is detecting an excessively lean fuel-air mixture across both cylinder banks.

If the MAF sensor sends a corrupted or incorrect reading, the DME cannot properly calculate the air coming into the engine. You can try cleaning it with CRC Mass Air Flow Sensor Cleaner. If the problem persists, the MAF will need to be replaced with an exact Bosch equivalent.

Any unmetered air slipping into the system after the MAF sensor will cause the computer to register a lean condition. Check the rubber intake boots, the resonance tube flapper, and the oil filler tube/cap for cracks or loose clamps. A mechanic can perform a smoke test to locate these leaks precisely.

A torn diaphragm in the AOS can introduce excess unmetered air into the intake manifold. Fuel Delivery System: If the engine is starved for fuel, it will read lean. Check for a failing fuel pump, low fuel pressure at the rail, or a severely clogged fuel filter.

[hookoo3]

I'll first start with the MAF, even tough it probably only has 10K km on it. I'll also check for air and vacuum leaks. Ai indicates that the main cause is probably the AOS. I'll replace it. The fuel system may also be a cause so I will do a pressure test and check the fuel pump and fuel filter. A smoke test is also on the list.Thanks for the suggestions.

[boxwrench]

I had an adventure with P1126 and p1133 last summer.

Fuel pressure is an easy test with a gauge. Screw it into the test port, turn the car on, etc.

You can look at fuel trims in Durametric. RKAT numbers are idle, often affected by vacuum leaks, purge valve, aos, etc. FRA is load/cruising trim, which is less affected by small vacuum leaks and more by fuel delivery issues (fuel pump, regulator, filter).

You can also see MAF numbers in durametric. You can also try just disconnecting the Maf and see if the car will run.

In my case it was a dying fuel pump, but a clogged filter or failing pressure regulator can do havoc as well.

Good luck.

[tcoradeschi]

I believe that the 01 has a replaceable fuel filter. If your pressure is zero, or close to it…

[hookoo3]

I replaced the fuel pump and the car is now running the way it's supposed to. A couple of things that came up for me were: Ai is not very reliable for diagnosis. This forum works. Ai did identify all potential causes however it was more insistent that the problem was the AOS. Aos was fine in my case and after test drive does not show any problems. In testing for fuel problems it would have been nice to do a fuel line pressure test. There are lots of fuel pressure test kits out there but i couldnt find one specifically for Porsche that didn't cost $1200. The best I can determine is that the Schrader valve on the fuel rail is M12*1.5, none of the test kits that I could find, had that size of adapter. Lots of reference to Actron test kits but they are not available. I was able to determine that the fuel pump wasn't working by removing the fuel pump relay and jumping the connectors. New pump is installed and working. Thanks

[boxwrench]

It's always good to see these threads end well.

FWIW, the fuel pressure gauge I have is an Innova 3640, it's on Amazon for around $30us. Comes with adapters for lots of things, but screws directly into the test port on this car with no issue.

AI sucks for cars. I've tried a few just for yucks, but they'll hallucinate when they don't know the answer, on anything from exterior care to torque specs. This forum is a pretty good supply of Actual Intelligence, and more importantly, experience.

[JFP in PA]

Problem with AI automotive diagnostics is that the system will always default to the statistically "most likely" reason; and on these cars, the AOS fail way more often than the fuel pumps, sending you off on the wrong direction.