An ill Carrera GT

[PaulHere]

Register member Chris rang me today about his GT.

It has terrible running problems above 4000rpm after an engine rebuild, the latest suspect is a impulse sensor (or speed reference centre) which is about matchbox size and found inside the bellhousing. This gadget reads the crank speed and signals the electrics what to do (I'm told)

Its part number is 931 606 021 00 - it is apparently found in the 924 Turbo model as well.
Chris has tried all the obvious places to source the part (Porscheapart/PH autos and Porsche Centre et al) but all say it is not available.

Can anyone help?

 

[924nutter]

I dont know whether it would be possible to fit a distributor with contact breakers and rig up some kind of basic ignition circuit to isolate the ecu and sensor to prove a point, because this is one of those parts that is definately made from unobtainium. I took mine out when, mistakenly, I thought this was a culprit for my intermittent misfire. Even S.A.M.E.S. in Southend, who can source and supply the induction coil, spider and set screws to recondition a 924 distributor (breakerless ignition) couldn't source one even using the Siemens part number. The good news is that when this sensor fails it is unusual for it to work intermitently. My thoughts are that if the engine runs then it's sending it's signal. (I could be wrong). Although I have never seen under a gt bonnet, somewhere there will be a cluster of of earth wires which amongst other things I think carries the earth for the flywheel sensor. If these are loose and make intermittent contact the car will misfire completely at random. My series two turbo cut dead on the way to work and it was trailered to an OPC, whereupon it fired up, the jolting on the journey having made the contact again. Needless to say it was crap when I took it home and I suddenly realised it was only spluttering every time I hit a bump. I got home and looked for some loose wires and that's when I found out how important it is to have these earth leads tight. It could well be that at 4000 r.p.m. there is sufficient vibration to disturb the connection and it is rather like activating the overboost switch.

 

[gregsy]

Just a thought:

Check the condition of the pipe which runs from the intercooler to the wastegate, there were some cracks in my Carrera GT's pipe (in the rubber section of the pipe) and it played havoc with the boost and general running on boost. I believe its rubber at the top near the intercooler and changes to metal as it goes down to the wastegate. The pipe is still available to order but quite pricey

Greg