MichelleJD

It does act like a bad vacuum leak, but I checked again when I regapped the sensors and I couldn't find anything apparent. I'll try to crank it and listen for a hiss, but as rough as it is running it'd have to be a serious leak and I don't see it.

Bri Bro

Did the ref/speed sensor plugs get switched?

MHT

iS THE SHIELD AROUND THE SENSOR STILL IN PLACE, i worked on a car a few years ago that was cranking and running very badly, the bell housing had been cut out and the sensors were picking up a lot of electrical noise and sending an almost unrecognizable signal to the DME. Apparently the aluminum of the bell housing act as a shield for the sensors, the late model cars had a Mu-metal shield around the speed sensor, if yours is missing, that may be the cause of your problem. Unfortunately the only way to know if there is interferance on the circuit is to hook up an oscilloscope and look at the pattern.

Good luck Mark T.

MichelleJD

It's not the DME, nor is it the gas. I swapped out a spare DME and put 11 gallons of 93 octane in. Still backfires.

MHT - what shield are you talking about? The sensors have about 600 miles on them and look almost new. I did cut the BH; could that have caused a running problem?

MHT

on the late model cars there is a tubular shield, it looks like a sleeve, that the speed sensor sit in. It is there to stop the sensor from picking up interferance. The shield look like an aluminum tube about 2 inches long and just large enough in dia to house the sensor.

Mark T.

MichelleJD

Is it the one built into the bracket? Or does it actually attach to the sensor? If it's the one on the bracket, it's there.

Tom M'Guinn

Did you remember to re-install the little ring-spacer thing ? It goes one of the sensors...

MichelleJD

Yeah, it's on there - BOTH times!

Ski

grounds are on the bell housing? I notched a bell housing on an 86, no issues on Rhob's old car.

MichelleJD

Yeah, grounds too.

Tom M'Guinn

How did you change the clutch without pulling the crossover, crossmember, etc. -- i.e., sure you didn't touch the motor at all? Any chance to pinched the O2 or ref sensor cables between the motor and BH?

MichelleJD

I have a 2-piece crossover, so no need to pull it.

951Porschiste

This is out of left field but could it be that you're only running on 3 cylinders? I know it has nothing to do the clutch, but check the plug wires.

Good luck

MichelleJD

I put brand new wires, cap, and rotor on Saturday. I really am lost.

Van

That tube MHT is talking about is the FULL length of the sensor.

It is literally an aluminum tube that goes around those whole sensor. I just found the p/n for it - 944.101.320.00

It's here: https://techinfo.porsche.com/techinf...88_KATALOG.pdf on page 335.