Mcardenal

Hi gang,

I have been enjoying my GTS (94 automatic) for about 3 months now with no issues (running strong and smooth). I was about to post about my stereo and speaker repair (I know..big deal) with my new iPod mount. Well today was our local chapter PCA annual family picnic and I hand waxed the shark last night ready to show her off. Headed out in the morning and that is when I noticed a few very concerning issues;

First thing I noticed was the engine rpms dropping (along with the volt meter) when I came to stop lights. Second thing I noticed was a stutter in the transmission coming out of stops.
I noticed the rpm and volt meter stopped dropping when I turned off the AC but the transmission stutter was still there!?

The day before she was running like a champ.

Please help!

IcemanG17

could be a weak battery and weak alternator.....if the voltage drops too much at idle (650ish) my guess is dead battery can't keep up since the alt doesn't charge it enough....

Mcardenal

Thanks for the quick input Brian. Would that also affect the transmissions behavior?

MainePorsche

Agree with Iceman on this. Check battery and alternator output. Alt. belt tension ? Clean your Masse Punkt (MP) - your ground points - especially the deep ones atop the bell housing - they ground your major engine controllers.

Mcardenal

Cool!
Will do.

Thanks again guys

MainePorsche

check search box for ground points - there's one thread with great pics

Landseer

Martin,
What was crank endplay measurement when you bought this car? Which aftermarket clamp did you decide to use to stabilize the crankshaft movement?

When you burst onto the scene dialogue went very quickly to esoterics like navigation install and stereos. There is a serious design defect with later auto-outfitted cars that can manifest itself like your symptoms, requiring some preventative moves. I just don't remember us ever asking you about that issue/fix situation.

Landseer

On the electrical front, some coil end corrosion or coil wire arcing, esp after washing car, can give those symptoms too. Can seem like trans, but its engine.

Good luck, hopefully very easy fix, but do be sure to deal w/crank movement deal if you haven't already. Bill ball has a great write up on making the measurement and installing an aux clamp

WallyP

There should be small pieces of clip-on black plastic trim on the inner edges of the front fenders above the coils. This trim keeps the wash water from running down onto the coils and causing misfire and corrosion.

Mcardenal

Don't know anything about crank endplay, aftermarket clamp or crankshaft movement. I am embarrassed to say I jumped in pretty bare with 928 know how (didn't know about rennlist until just after I bout it). I jumped into the stereo stuff right away because that was about all that was wrong with the car until Sunday. I had a post inspection by a PCA member recommended shop and they told me she was good to go for the exception of motor mounts and valve cover seals. The engine and transmission always ran like a champ.

Mcardenal

Wally,
Would this happen over time or give me emediate consequences? It ran great the day before I washed it. Note: have washed her several time since I bought her with no issues?..

MainePorsche

Do you intend to work on you own car, or are you going to farm it out ? Flexplate tension/crank endplay should not be 'new' terms to you, a new 928 owner, because this 'PCA recommended shop' should have mentioned this status to you for you did buy a late model auto that they 'inspected'.

If you are going to do your own work ask for advice, Forum Search wisely, and you will be able to do what needs to be done. If not, ask in the Forum who should do the work on your car in your area. You should trust who the Forum recommends. See Randy's thread at the top of the Forum for new visitors. Lot of useful info. there.

Mcardenal

Thanks,
Saw the beginners threads with recommended shops. I am willing to get my hands dirty for some basic stuff to start learning, but would definitely defer to an expert for the heavy lifting.

MainePorsche

Martin,
See dwaynesgarage@norcal928.org for the flexplate procedure. This how I did mine the first time. This is a very straightforward, and I might say easy, thing to do. By leaving off the 2 rearmost flywheel cover bolts, I can check, and relieve, the flexplate tension as easy as I can change the oil and filter. Actually I check the tension about every 3rd oil change while I have the car up. The only thing Dwayne forgot to mention was that the first time to do the procedure you have to remove the 6 exhaust flange bolts/nuts and there is a gasket that has to be removed and replaced for each side of the exhaust. Small 5.00$ item from Roger. The six bolts/nuts from exhaust flange were pretty beat up. I got them off without complications, but replaced with new ones. Google 'pet porsche' for the comprehensive parts listing - used this for bolt/nut sizes - you will also see the gasket and can give the part number to Roger.
I do all the work on the car (that doesn't involve painting). It is my hobby and I enjoy the planning, doing the detailed quality work, and most of all driving with everything functioning as it did the day it left Stuttgart. This would be a good (and important) procedure for you to start with. I recommend 'Porken liftbars'. See the site. You can also see the Porken torque tube clamp (PKlamp). I put one on.

Landseer

artin,
Only a dyed in the wool 928 enthusiast following very closely this forum would know the reality and seriousness of potential of thrust bearing failure on these cars, so don't feel embarassed. Nobody associated with the manufacturer nor the mfctr club will even speak openly about it. Much like IMS bearing failur with boxster. Read Bill *****' threads about measurement, and Dwayne's. You might also search for posts made by Constantine who did deep engineering research and created on stabilizing solution.

I've got a Constantine clamp on one automatic car. On two others I've used the Porken auxillary clamp, which is an easier install though not as rigorous a solution perhaps, it should be adequate.

Any PPI on an automatic 928should address the issue by returning a number in mm of end play. Its pretty much the 900 lb gorilla in the room, but its a test the enthusiast needs to lead the typical PPI team thru. Don't feel bad, its a secret, too much liability potential upstream, from reading between lines but its real. Has been reported on low mile cars. Check for it, stabilize, drive on. t