1988 911 stops dead

Graham Wild · 05-09-2008, 10:37 PM

Our 1988 911 3.2L Carrera stops dead after it has been running at highway speed for about 30 - 60 minutes. When we pull over and stop and wait for about 5 minutes it will start with a cloud of black or white smoke and run for a few more kilometers and stop again. If you let it idle when it is restarted it does not idle smoothly. It surges or hunts up and down in rpm and eventual settles down.
I have replaced the following items, DME relay, fuel pump, fuel filter, distributor cap, distributor roter, spark plug and coil leads, cylinder head temperature sensor.
I have only just replaced the sensor and have yet to take it for as long drive to see if i have solved the problem. The car has 206,000 Km on the clock and has never given any trouble until now.
Has anyone else had a similar problem or the same problem? If so what was the fix?

DonMo · DonMo's Garage

You might have a problem with the ECU or Motronic brain. Cold solder joints and component failures can cause strange things to happen.

It sounds to me like a heat related component faiure. As car heats up (and the ECU gets hot) the connection or circuit degrades and then you get symptoms. Find a friend or a fellow pelican and see if you can put your Motronic in their 3.2 and get the same symptoms.

I am in So. Florida if that helps. There is a guy down here that rebuilds and diagnoses ECU issues. He fixed mine good as new with a 3 year warranty. Around $300 as I recall. I can already tell you have been doing the chase (changing parts). Frustrating isn't. I have done the same. Good luck.

hcoles · 05-10-2008, 06:38 AM

here is a wild idea - put a bag of ice over the DME box under the seat.. see if it starts...and runs a bit longer, that is a clue. You could also rig up a fan to blow air across the DME box to keep it a bit cooler and changes behaviour.. this reduces the condensation related risks compared to the ice idea.

jbrinkley · 05-10-2008, 06:43 AM

I have only just replaced the sensor and have yet to take it for as long drive to see if i have solved the problem

your symptoms are what happens with a bad cht
you dont have to drive it, just let it sit there and get hot.

WI wide body · 05-10-2008, 05:02 PM

What about the O2 Sensor?

Does it stutter and miss first or just quit all at once?

Blackie911 · 05-10-2008, 06:21 PM

Had a similar problem and coincidentally Steve Wong (God bless the guy) posted below link the same week. Sure enough it was bad solder joint(s) in my DME- and the ones under the transistor as he had predicted- these are the joints that take the most heat. You will need to take it to someone with at last 10- 14 x magnifier and good soldering gear with experience to not damage your board. I also replaced a capacitor on the board. Runs like a champ now. When you reinstall the DME, mount it on a sponge or something to absorb some of the vibration.

http://forums.pelicanparts.com:80/showthread.php?t=391126

Don't be afraid to carefully remove and open case. Order a Wong chip while you're at it...

rick-l · 05-10-2008, 09:40 PM

Quote:

Originally Posted by Blackie911

Had a similar problem and coincidentally Steve Wong (God bless the guy) posted below link the same week. Sure enough it was bad solder joint(s) in my DME- and the ones under the transistor as he had predicted- these are the joints that take the most heat. You will need to take it to someone with at last 10- 14 x magnifier and good soldering gear with experience to not damage your board. I also replaced a capacitor on the board. Runs like a champ now. When you reinstall the DME, mount it on a sponge or something to absorb some of the vibration.

http://forums.pelicanparts.com:80/showthread.php?t=391126

Don't be afraid to carefully remove and open case. Order a Wong chip while you're at it...

You were very lucky to have that resource available to you. If you can't solder about the only option you have is pay someone $400 to "rebuild" it.

Blackie911 · 05-10-2008, 09:50 PM

An audiophile buddy did it for me in about 45 mins- I had to force him to take $100

rusnak · 05-10-2008, 10:12 PM

Graham, if you have not already done so, buy the 3.2 Carrera workshop manual by Bentley Publishing. If you can use a digital multimeter, then you have almost everything that you need to diagnose and fix the problem. Hate to see you buy more parts trying to guess.

Graham Wild · 05-12-2008, 03:08 AM

Hi everyone. Thanks for all your comments and suggestions. Took the car for a long drive today (200Km) and it performed flawlessly so looks like the cylinder head temp sensor was the problem. I seem to have awakens a few sleeping horses as well with what i have done as it seems to go a lot better. As a few people seem to have had problems with the computer i will take it out and check it. Sound straight forward enough. Thanks once again and regards to all.