[eurospeed]

Here it goes:



Car quit running on my a couple years ago. Took it to shop. Shop replaced fuel pump, crank reference sensor and DME. Got the car back and had a terrible stumble around 4k rpms as well as temp problem. OBD showed code for Cam reference sensor. Replaced. No improvement! Car sits then goes to shop again. Shop says bad valve cover gasket is causing plug wire to be saturated with oil which is causing spark to arc against valve cover. Replaced as well as fan temp switch. Get the car back after a long wait. Car is still missing at around 4k as well as overheating. In addition to these problems abs light comes on every once in a while, odometer works sometimes, speedo quits working sometimes, seatbelt light comes on when I hit the dash board with my fist. Also when I hit the dashboard, the temp needle moves a bit. Another thing I notice is when i turn an accessory on (even just the turn signals) my voltage gauge starts to fluctuate.



Is it possible that all of my problems stem from a bad ground? Any way to tell where the bad ground is located? Is there anyway to confirm this with a multimeter? I'd really hate to dump more money into solutions that won't work.



Thanks in advance.

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[Grandpa#3]

Bad grounds would be my first guess to any electrical problems. All ground wires are BROWN in color. Find, take apart and clean good with a wire brush I then put some dielectric grease over the ground. The Dash Gage Instrument panel has 3 electrical connections that can be cleaned with a pencil eraser and 4 football shaped grounds. The Main Ground is located on the top side of the bell housing. Be sure to put tape over the open Inspection hole to prevent objects falling down into the clutch area.



http://www.clarks-garage.com/shop-manual/elect-07.htm



Cheers,

Larry

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[eurospeed]

Thank you. I think I am going to start with the main ground and go from there. It seems some strands broke off from where the battery hooks up.

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[eurospeed]

I adjusted the clamp for my ground to the bell housing. The gauge cluster seems to be working a bit better but I'm still having temp. and stumbling issues. I took a voltage reading at the battery while running and I'm getting around 12.8V. Would a bad ground cause low voltage, or is this more likely caused by a alternator or voltage regulator?

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[paulzebo]

Low voltage it typically the voltage regulator. Higher voltage ones are available so search the forum and find were to get one. I doubt it will fix the stumble @4000 rpm's though. Anything over 12.6v is charging the battery and anything over 10V is capable of running the engine.



Does the miss only occur at 4000 rpm's? In other words, does it go away at 4500, 5000 rpm's?



If you are suspecting it's running out of fuel, was the fuel tank filter, 928 201 081 04 (item 25 PET) replaced at the same time as the fuel pump? #25 filters the fuel prior to the fuel pump. If it gets restricted, you will not be able to get sufficient volume out of the fuel pump. A fuel pressure gauge would show this as a drop in fuel pressure @4000 rpm's and beyond.



   

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[eurospeed]

Yes, the stumble typically occurs between 3500 and 4k rpm and then the engine will usually go to redline without any problems, although occasionally it will stumble a couple more times. The fuel filter was replaced just before the fuel pump. As for fuel filter #25, if this is the screen that sits at the bottom of the tank, then I already checked and cleaned this part for debris when I first started having this problem. I also want to emphasize that I am having this problem under load. Engine has no problem revving in neutral, but there does seem to be a vibration present that didn't used to be there.

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[banditsc]

Has the O2 sensor been replaced yet?

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[eurospeed]

No, but I'm not getting a flash code. I have one more theory on this. When I replaced the crank ref. sensor it was stuck, so I ended up destroying the bracket. At that time I couldn't find a 968 replacement so I installed an S2 bracket. I believe the sensor to be gapped correctly. Could the difference in brackets be throwing off the resistance the ECU is getting?

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[banditsc]

The gap does need to be proper. As far as the O2 sensor I had a similar issue as your with the stumble around those RPM's and it turned out to be my O2 sensor that was only maybe 4 years old. The computers on our cars are not the most advanced, so it doesn't always logs faults or see them. Another sensor that can be an issue is the cam sensor on the distributor housing, the connector tends to break apart.

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[eurospeed]

Yes my cam sensor had that problem. Has been changed since. I will check on the o2 sensor. Hopefully I can get one locally.

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[banditsc]

Get the proper Bosch one not the universal, that one didn't last very long for some reason. I think I got my last one from RockAuto.

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[eurospeed]

I replaced my ground ground today going from the battery to the bellhousing. It was in much worse shape than I originally thought. Also had a peak under the car. One of the large wires running from the starter is missing a bunch of insulation, so I'll be replacing that soon. I also replaced my distributer cap. While doing this I noticed the front part of the cam gear housing is warped like crazy. I decided I would see if it would work and as soon as I started the car I heard the rotor rubbing against the cap. I'm guessing this is what is causing my stumbling issue. I found a couple reproduction sets, but they run $500 a set. A lot of money to spend on something that may not even correct the problem and even if it does, there is still a lot of work to do. Does anyone here happen to have cam gear covers they would sell me? I'm almost tempted to put the car up for sale at this point.

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[paulzebo]

I can't see where it would warp on its own. Can attach a photo of what it looks like?

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[banditsc]

You can get the original set from Porsche for about $470 right now. If only one is having a problem then you could just replace that one. My back housing was having a similar issue that caused the rotor to grind on one corner also. When I had to buy that back piece it was over $700 at the time.

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[eurospeed]

I think i will get the reproductions since they are made of aluminum instead of the magnesium that porsche used. Supposedly they won't warp like the originals. Although if I can find a set of originals that are in good condition for far less money, then I would obviously go that route. I need both pieces since one of the bolt holes are stripped where it goes together under the T-belt cover. Looks like the previous owner used a bunch of thread locker to hold the bolt in there. I'm lucky that thing didn't fall out on to the timing belt.

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[banditsc]

The new ones are also aluminum now..

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[paulzebo]

I checked the PET manual and the replacement for a 1989-91 944 S2 is the same as the 968. Here's what you may want after doing some research on your own to verify the cover.



http://forums.pelica...parting-s2.html





Cam Pulley Covers, completely intact, Hall Sensor has typical crumbly connector

$200 + shipping

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[eurospeed]

I may have to take those off your hands. Are you sure the threads are good, and the covers are straight (not warped)?

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[paulzebo]

Follow the link in the post. It was on Pelican Parts. If someone doesn't grab them I will.

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