JPodesto

Bought this 2000 996 C2 from a guy in the neighborhood where it was getting neglected in his driveway. It ran with a jump, it was cheap, and he had a lot of service records within 20k miles. So why not.

So at first when it was hot out it was throwing misfire codes all over the place. So I replaced all coils(behr) and plugs. Improved the hot misfire almost completely.

So the problem im having is the car will drive great for a 20-30 minutes and a pending P0153 kicks on and the car starts to misfire. P0300 p0301 p0304 are the most common.

I have changed all O2 sensors with Bosch units, plug and play.
MAF Sensor
Gas Cap
Smoke test for intake leaks
Cleaned and visually checked connections on o2 sensors

More history --- The PO parked the car after a failed smog test in 2018.
Failed with p0153 p1411 p0410 p0430 p0455 p0650

Only code in common now is the p0153.

I did replace the passenger catalytic on a whim because of the earlier failure p0430

At this point i don't have a Durametric scanner. Just your common hand held unit.

Any help to get this car smogged and running good would be helpful. Thanks in advance.

DBJoe996

https://rennlist.com/forums/boxster-...3-is-back.html

JPodesto

Thanks DBJoe! Ive read that thread many times. That's where i came up with many of the ideas, O2 sensors MAF etc.

I also checked my fuel pressure today and its running at 47 psi. I read these cars should be 55+-3 PSI. Could that be causing my misfires??

JPodesto

Still have this recurring problem. If anyone has any other ideas that would be great.

I decided to drop the trans to check the IMS and low and behold it was about to fail. At least i can sleep better knowing that is done.

I also did my AOS as well since it was having issues. As well as a fuel filter.

Test drive was going great car was running good, no misfire codes and boom about 20 miles in the P0153 came back and the car started running poorly again.

I am wondering of i have a bad harness? I am at loss with this car.

jumpy chunky

A couple of things....You changed your cat for bank two, check for exhaust leak.
Since the car sat outside neglected at your friends house there’s a chance the wiring got chewed on.
Check for frayed wires. Can also remove connector at DME and ohm out pin 18 to socket 4 at sensor.

Imo000

How did you determine the intermedia shaft bearing was about to fail?
Since you already fired the parts cannon at the car, might as well spend the extra couple hundred to get a Durametric. You needlessly spent way more already than the scanning software.

808Bill

My thoughts to the T.

JSETarga

Buy the durametric. From my experience so far I will say it wont be the last time you will need it. Also, fuel injectors were a culprit for some of the misfires I have had.

JPodesto

Great Thank you, I will try that.

JPodesto

Great, I will check that.

Ill inspect again for exhaust leaks.

Thanks

JPodesto

I pulled the trans just to check it, and change the AOS which was failing. Too many bearing failure stories. Glad I did.

Durametric in my future.

Imo000

Thanks for the pick. Yup, that bearing failed.

dporto

So, # 1 - The bearing wasn't "about to fail" - it did fail... It just wasn't a "stage 4 catastrophic failure" that took out the rest of your engine. Congrats on catching it when you did! Now the question is how much of the failed bearing/races do you have floating around inside the engine? At this point, it would be a good idea to drop the sump plate and inspect what's in there. If you're showing magnetic material (IMS bearing as opposed to main/crank bearings) it may also be a good idea to do a couple short interval (a couple hundred miles ?) oil changes to try to remove the offending particles... In the mean time, you can keep trying to diagnose the misfires. Seeing as the car sat for quite a while, I would be looking at the X51 connectors in the engine bay for oxidation/corrosion, and of course I wouldn't rule out rodent damage to wiring insulation... Good luck

JPodesto

yes, It came out complete, once I pulled the seal when it was on the bench the ball bearings came out.

Thanks for all the pointers.

Imo000

Anything left of the bearing cages?