der Mond

Got the Carrera out of winter wraps and she runs superbly. However, my gas guage is flickering, which it never did before, and the tach, upon deceleration only, wavers also sometimes. Any ideas? Also, anyone get a bit of a groan for a second or two from "back there" upon startup? It doesn't do it fully warmed up.

butzip

When My alternator was on its way out, I had flickering lights. All of them.

Mike Murphy

My druck press gauge always flickers, but none of the others. If they all do, then it's a common ground or electrical issue. Check for loose connection and possibly check for voltage spikes with one of those cigarette-lighter voltage meters if you don't have any other volt meters installed.

Amber Gramps

IT'S THE PAINT

Peter Zimmermann

Dennis: Check your alternator output...
Idle: 13.2 - 13.4 volts, no spikes.
2500 rpm: 13.7 - 14.1 volts, no spikes (yes, it can be a little lower or a little higher, this is an average range).
Put your VOM leads across your battery terminals and have someone hold the throttle for you. Do the 2500 check for at least a few seconds.

scottb

Sounds like an alternator about to go belly-up.

der Mond

Thanks, guys, I just returned from a 650-mile round-trip in which I barely made it home. The gas gauge settled down but every time I decelerated, the tach needle went south, then all over. Rough running started with a hesitation at 4500 rpm that eventually became hesitation any time any rpm, except after a re-start and idle. Last night I checked the cold battery terminals and got 12.6 and at idle it was at 13.6 but ranging a bit. I'll do what's suggested this weekend. I have a K3 alternator from Australia which was expensive to purchase 20K miles ago and I was hoping it wasn't that, but I suspected same. Let me know if the description I gave above corroborates your suspicions. The lights and other accessories seemed steady. After deceleration I would idle and the tach needle would be at zero but the engine was still running. I still have my Valeo alternator but it needs new long attachment screws - anyone know where to get those? No one locally has anything like them.

scottb

I've heard of some people using threaded rods, with nuts on each end.

Good luck!

der Mond

The alternator reads at idle 13.7-13.8V with no spikes. At 2500 RPM and up it is rock-steady at 13.86. I put my spare DME relay back in at the suggestion of a guy on Pelican, which made no difference. It seems fine initially; what seems to particularly trigger it is WOT up to about 4500 rpm. Then it acts like the rev limiter is kicking in. Upon deceleration then the tach continues to waver back and forth rather wildly from zero to actual rpm. Upon deceleration from the 4500 RPM bucking bronco experience, it sputtered/backfired for a split second. Could the old APE chip be failing? I don't have the original to swap out. Could the DME be failing? I thought maybe fuel pump but that doesn't explain the tach and why it is a deceleration issue with that. Could any sensor cause it? Doesn't seem like it. It has a new head temp sensor. Doesn't seem like a flywheel sensor would cause this. I'm a long, long ways from a Porsche mechanic, guys, any help would be appreciated.

Mike Murphy

Sounds to me like you're getting an electrical connection issue. Possibly from a bad ground or bad lead. Getting the engine above 4500 RPMs just means that you'll pulling more current and will exacerbate the bad connection issue.

Regarding the DME possibility, I would look at how the gauges connect into the DME. I'm not sure if the gas gauge goes through the DME for any reason, so if you can prove that it doesn't, or doesn't have any effect on the gas gauge, then you can rule out the DME. Make sense?

der Mond

At Pete Zimmermann's suggestion I thought carefully of everything I did in the fall and got some electrical contact cleaner. I D/C the head temp sensor and flywheel sensor connectors and fuel injection system connectors and sprayed cleaner/lubricant in them and reconnected. I D/C the six ground points I could reach, cleaned them and reconnected. I found that the ground on the fuel injection manifold riser left side was very slightly loose. Probably that was it, but whatever it was the problem is completely resolved. Thanks for your responses.