Q: 964 C4 with warm stalling problem
 

So there I was, sitting at Starbucks Saturday morning, minding my own business, when a nice, top-heavy blonde interrupted me. Seems she had been admiring my Carrera and asked me if I could help her with hers -- a '92 964 C4 Cabriolet. It has started to stall in traffic and it scares her. Although I used to own a 964 Cab myself, I am not all that familiar with its idiosyncratic problems, but I know you guys are. Maybe you can help.

Okay, I'll bite ... I followed her over to her place (condo on the beach, just around the corner). She opened the garage and, "Wow, nice car lady!" -- 35K miles, black paint with a fully optioned, full leather tan interior with black piping.

She tossed me the keys. We got in. It started right up. We went for a drive, with the A/C on, for twenty minutes. Air temperature here on coast of So-Cal was F 75-80. We drove in traffic, stopped for a bottle of Techron and a fill-up, went hard through the gears on the highway ... no problems at all.

Now the engine was fully warmed, with the temperature needle just above the halfway mark (~ F 230?). Trying to get the car to act-up, I turned the A/C off, then on again. About that same time, I stopped for a light at a busy intersection. The revs dropped to zero. Crap! Check engine light came on too. I restarted the engine and had to keep the revs near 2000 RPM to stay lit. The CEL stayed on. I turned the A/C off. It drove okay to the next red traffic light, but it died when I stopped. CEL still on. Started back up. Had to keep revving it. Started to go, then had to stop for cross traffic. Again, it stalled. Yet again, it started right up. Tired of this, I drove straight back to the condo. By the time I got there, the CEL was off and it was running and idling normally. I tried everything to recreate the situation, but could not. A/C on and off. Nothing!

I inspected her records. Notes / clues / questions:

1.) She takes it to a Porsche mechanic for a "do whatever it needs" service once a year (she drives it about 1500 miles per year these days). I explained that the car needs to be exercised more. Said mechanic charged her for a new clutch at 25K miles and dinged her $3600.

2) When I first drove away from the house, I *think* the engine sputtered once accompanied by a muffled pop or backfire.

3.) The engine seems to run a little rough at about 4K RPM with the A/C on. It's not as bad with it off.

4.) The distributor needs the vent hose update. She thinks the belt was changed once already.

5.) After fully warmed, the oil level gauge read 100% full. Overflow into the intake?

6.) Could the 35K mile, 12-year-old O2 sensor need replacing?

7.) Is there a head temperature sensor update with the 964? I seem to remember there is one.

8.) DME relay getting warm?

The car is dangerous as-is and I want to give her a punch list to take to her mechanic. I did a keyword search on the problem before I posted this, but didn't find that much. Any thoughts from you are appreciated. Many thanks.

I think we need a pic of the top-heavy blonde to make this an official thread :)

Sounds to me like a DME thermal shutdown problem or maybe a funky vaccum leak at the higher engine temps.

If it's a '92 California car, then you should be able to read out the DME fault codes using the CEL. If you take a look at the following
http://members.rennlist.com/billwagner/CheckEngine.html
It should help you find out why the CEL was coming, and staying on. If you want to poke around the car, remove the air filter, and see if it's oily on the air flow meter......... that would tell you if the oil level is causing problems......... My 90 had the updated head temp sensor, so I think it was earlier than 92.......
-Eric
90 C2
NER/PCA

And, we will be much more helpful with pictures.........ah y'up..........

Thanks guys. I am putting the punch-list together for her to take to her wrench. It'll blow this mechanic of hers away that she walks-in armed with Porsche-specific information and not just an open check book.

Have you tried the Penthouse forum BBS ?... where is the part where you say "this never happens to me but.." ????

Hey, I didn't schtupp her, I just helped her with her ill-running Porsche. This is the So Cal coastal area, so there are as many silocone blondes as there are Boxsters, and Boxsters are a dime a dozen. :D

Actually, the more I think about this problem, the more I suspect it *may* be an overfilled oil tank. This is because the problem only happens when the engine is fully warmed (now September, when it's the hottest here), and at a stop light, when the oil tank fills back up.

Yea that sort of thing always happens to me too. I keep a bat in the P-car to beat them away sometimes.

Tell her to head out to Ventura this weekend!

Hmmm ... I'm still not seeing any pics on this thread??? :(

You should check for lipstick on the dipstick.