Engine hesitation, CEL on and then off ??

2001 Cab 42.5K miles IMS bearing changed at 37.5K. Running smoothly until last night. I went out for an appointment last night and on the way out, after a decent warm up, i drove it hard. Car ran happy as usual. On the way back, about 5 miles out in heavy traffic and going around 45mph, I shifted and the engine acted as if it died and the CEL came on and then off. My first reaction was to get to the far right and shut it off, but it was running normal and i thought it cant be IMS. I kept driving it normally and nothing happened, but it has never done that before and seems like a symptom of something but don't know what. Any ideas? Thank you guys

Quotes source post: 13707141

Pull the codes and see what got logged.

You need the codes, but i had a very similar experience, in 2002 cab at 46k miles, it actually came to a stop, power just cut out on motorway. tried to start it wouldn't then 5 mins later fired back into life like nothing was wrong. was fine for a few months until it went for a service. drove from the dealership to a restaurant. after dinner wouldn't start. tow truck back to dealership and it was the fuel relay. At the time was completely ignorant about the IMS and other potential issues. So didnt know not to start Interesting to note nothing on the service sheet about the time it cut out. all it said was investigated codes and cleared. and when i phoned them to say the car wouldnt start 10 miles from the dealership they looked into it, and couldnt find any thing that could be wrong so instructed a tow truck. Hopefully it is nothing.

I went to Autozone and the guy came out with his reader, it says it was done, but there was nothing to read as the CEL was off. No codes to read. So very similar to Sammaw's experience because the car runs perfect, but that was not normal. Yeah, my first reaction was to pull to coast to the side and call a tow truck but the light went off and then engine was running normal and no weird sounds (although I have heard from people that have had the IMS failure that if you hear weird sounds, it is too late). My bearing was actually in great shape and did it just for peace of mind. I guess I'll take it to the dealership and see what they say.... thank you all. I love this car, looks like new, always keep it in tip top shape, so these little things drive you crazy.

Look for PENDING codes. Use Durametric/PIWIS - your best local Indie has this. Dealership is very expensive for such work.

The weird thing is that the code that lit up the CEL may or may not point you in the right direction. Remember, the CEL is mainly for engine performance/emission related issues, and it may have gone off because the DME detected something amiss with the engine performance (which is right) but maybe it and the code will simply say - something went wrong and the engine performance/emissions went awry. Think about what would make an engine cutoff - mainly, no spark or no fuel. So the CEL code could point to misfires or O2 sensor feedback, when in reality the fuel pump did a hiccup, the fuel filter got clogged, or the ignition switch cut out. Good idea to find out pending codes or any codes that lit up the CEL. But to have an engine entirely die, then come back and run normally, it has to be the main fuel or ignition spark related systems.

A lot of shops do not have the right code readers or they say that the car is too old for their $6,000 reader. This one was using a SnapOn tool that connected to the standard port and did not read anything. So he pulls it out and walks over to a 2013 911 and he shows me all kinds of data. Trying another place on Monday. I drove it hard on the highway and ran happy ...strange.

Forget SnapOn. Just ask if they have PIWIS .If not, move on. Give your specific location and maybe a Rennlister in Indiana will recommend an Indie. Someone in Indiana certainly has at least Durametric. A regular or enhanced code scanner may be useless.

I wonder...it happened just as you shifted. Could it be your clutch interlock switch is loose or going bad? You could check that yourself. Not to say that would make your engine die, but it does have to do with starting and cruise control. Just trying to think through the problem.

Coil Packs cracking, maybe....

Could be the fuel pump on the way out. Have you driven it since then?

As the suggestions above indicate, some faults do not trigger OBD codes. To be fair, the PIWIS is only as good as the guy using it ,so finding an expert is key and hopefully somoen from Indiana will chime in.

Absolutely need a Porsche specific scanner, otherwise don't bother. No reason to even suggest something without knowing that, along with your long term fuel trims. We have Durametric, along with a high end Snap-On scanner, they they do well with this chassis.

A guy with PIWIS is a Porsche specialist and hopefully M96 specific . Getting a code is the easy part, you need some knowledge of the M96 eccentricities to propose a diagnosis from a specific code.

While the engine mechanical might be considered exotic, the basic strategy of the ecu is the same. Fuel and spark.

Quotes source post: 13708378

Probably had the SnapOn code reader locked on CAN. Your car's OBD2 communication is probably ISO-9241-2 or possibly KWP2000. There is a documented protocol discovery process that a code reader can go through to, well, discover the protocol the car's OBD2 system is using. If you are interested you can buy an OBD2 code reader/data viewer at a well-stocked autoparts store (or this being the 21st century online). Really I do not consider owning a good OBD2 code reader/data logger a waste of money as these can pay for themselves in just one use. I've owned one since sometime in 2000 and it has paid for itself many times over.