Recurring issue, water related, DME
 

Two months ago, I came to a stoplight, and the car sputtered and died. It would only start after a few minutes. I replaced the DME and all was fine. The next week, the car started sputtering and losing power. Mechanic replaced the distributor and plugs. It ran fine for a couple months.
This morning, it runs for 20 seconds and dies. I replaced the DME, and it seemed to run fine. I drove it up the block and it started sputtering, just like before.
Previous to both sputtering episodes, I had driven the car in the rain the day before. Coincidence? Ideas? Thanks.

Drain holes by battery and fusebox clear? My water related issue was with the one on the battery side, and it took out my KLR. It was raining hard for close to 2 hours. Car started fine, idled, and warmed up. I was even toying with the stereo for a bit. However, as soon as I released the clutch, it died w/out moving so much as an inch...
http://forums.pelicanparts.com/uploa...1337444047.jpg

You don't say if it's an early or late car.

You're sure the problems are with the DME? Have you seen any moisture/water in the passenger side footwell?

Late cars, the DME is located in the passenger footwell. Frequently battery acid eats holes in the metal under the battery and then water drains almost directly onto the DME.

Pull your battery out and see if there's any rust filled holes underneath. Between my son and I, we've owned 5 944's and every one of them has had this problem.

It's a 1987 NA.

So have you found the passenger floor getting wet when it rains?

The mechanic drove it around for a a couple of days, and it ran fine. It's been a rainy week, but I don't think he drove it in the rain. I drove it home, ran fine. Tried the old DME, ran fine.
So, it seems that driving it in the rain causes water to get into somewhere it shouldn't. After it dries, the car runs perfectly fine. Mechanic recommended that next time it happens, I should try unplugging the mass air flow sensor and see what happens. I will keep you posted.

I will check the passenger foot well too.

I'd think carefully about what these experienced folks are saying.

They're saying it's unlikely to be the DME (which, goodness knows, you've swapped in and out now several times). But instead wet wiring leading to it.

When you replaced the DME, did you do so with a used DME?

I know that it's likely that the problem might be elsewhere, but changing an old DME with another old one might could give you similar results.

Also, check both the TDC and RPM sensors How To Test RPM & TDC Sensors in 944 and 911 3.2 Carrera Porsches - YouTube when they go bad they tend to give you intermittent running issues like the ones that you are talking about.