gbailey911

Thanks to all who read and respond. I am new to Rennlist after joining just yesterday. I have owned my first Porsche, a 1987 911 coupe, for a little over a year and the experience so far has been fantastic. On to my problem: Last weekend I broke one of my cardinal rules and backed the car out of the garage into the pouring rain for a trip to visit my father. The weatherman called for rain on and off all weekend, but my 75 year old father said I couldn't come unless I drove the Porsche so he could drive it. The trip up was uneventful and I realized the car does fine in the rain and the windshield wipers actually work. Saturday afternoon, while my father was driving, after a quick run up to about 80 mph, there was a noticeable pop from the engine area and the engine quit completely. The car was still in gear as we slowed down but it did not fire at all as the drive train turned over the engine. We pulled off the road, turned the key off, and I opened the engine compartment to look for any problemes. Everthing looked OK so I asked my father to try and re-start the engine. He turned the key and the engine started immediately. We drove the remaining 30 miles as if nothing had happened, the engine ran just fine. Later that evening, I headed back to my house, about a 100 mile trip. Seventy five miles into the trip, it happened again, this time without any noticeable pop and this time I had been running at a steady speed. I pulled to a stop, turned the key off, waited 10 seconds and re-started the engine and drove off. The engine ran fine before and after the shut-down.

Just for info, I recently had just changed the distributor cap, rotor button, spark plugs, adjusted the valves and changed the oil and filter at 75,000 miles.

Does anyone have any idea what might be happening and the cause?

Thanks in advance,

George

Steve Weiner-Rennsport Systems

Hi George:

First, congratulations on the nice car and welcome to the Rennlist Community.

From your description, I'd say that your DME relay (under the driver's seat) is failing and you need a new one. The device controls power to the fuel pump as well as the engine ECU so its VERY critical.

Most Carrera owners know to carry a spare relay in the glove box for such occasions. Its very cheap insurance.

88911coupe

I was running into similar probs with an '87 Cab. It would cut out and stall in heavy rain but I could not find any obvious problem. I replaced the plugs, wires, dist cap/rotor and it worked perfectly from that point on, regardless of weather. Not sure which was at fault and did not want to replace things one at a time. It's always good to check the DME and relay though to make sure water is not leaking into the floor.
Good Luck

gbailey911

Thanks to everyone that has looked at the thread and especially to Steve at Rennsport Systems and 88911coupe. The DME relay sounds exactly like the culprit since I thought the car acted like it had no fuel. I have already ordered two new relays, one for the car and a spare.

Thanks to all,

George

Here is a picture of my car, I hope

gbailey911

Ok, I received the new relay yesterday, and much to my surprise, the car wouldn't start with the old relay or the new one. I tested both relays on the work bench and they both checked out so now I am stumped. I jumped out the relay to see if I could hear the fuel pump and it clearly was running. I installed a new fuel filter and before I connected the top line, I cranked the engine and I definitely have fuel to that point.

Does anyone have any ideas what could have happened, the car ran great last weekend and now I can't get it to run?

Thanks in advance,

George

yelcab1

DME computer is my next logical guess.

gbailey911

Ok, I have narrowed it down one more step. The car is not firing the plugs. I think I am getting fuel because I can smell fuel after cranking the car, but I pulled off a spark plug wire and tested for spark with a spare plug and had no spark at all.

The last post suggested I may need a new DME computer. Do these things fail that often? I had heard they were fairly reliable. My car has a performance chip installed. Could the chip have failed and caused this?

Thanks again,

George

dtunnicliffe

George,

Hi,

You say: "I pulled to a stop, turned the key off, waited 10 seconds and re-started the engine and drove off. The engine ran fine before and after the shut-down."

So, you managed to drive home okay, but subsequently, even with a new DME relay, it refuses to start?

Well, ECU's have memories, it may be that yours has 'remembered' you have shut if off a couple of times at the DME relay - so to speak.

For my money, I'd disconnect the battery for 5 mins or so, reconnect (with the old DME relay in place - since that's how you got home) and see if it runs. If it does, power off, replace the relay and see if it is sorted. You might then care to go through the power off, disconnect the battery for a further 5 mins, reconnect, power up and run for 20 mins at idle to allow all sensors to report back to the ECU.

964's are notoriously bad for this, but 3.2's less so. It can do no harm and the test is free.. Love your car by the way. Take a look at:

http://www3.us.porsche.com/40years/e...t_1_page_1.htm

Sort by Highest Rating.. Enjoy!!

Dave

(Verglas) 87' 3.2 Sport Coupe

gbailey911

Dave, thanks for the suggestion of removing the battery terminals to reset the DME computer. Unfortunately, it didn't work. Right now I am still dead in the water. I know I have fuel to the injectors and can smell it after cranking the engine. I also know I don't have spark at the spark plugs. I have replaced in the last month the plugs, distributor cap, rotor button, fuel and air filters, and the fuel pump/DME relay. The car was running perfectly prior to last weekend.

Does anyone have any thoughts before I arrange to have the car towed to my local Porsche mechanic?

Thanks,

George

donnieknoxville

You might try replacing the temperature head sensor. The one thing I've learned about Porsche electronics and troubleshooting is that you can replace just about all of the problem components for an all in cost of $250 and it doesn't take that long to run up a $250 labor/dyno bill.

In my case, I spend about $1,600 replacing everything from the ECU to the DME to checking spark plugs, distributor, rotor, etc. Which helped me find some other interesting maintenance items. In the end and after great frustration on the part of a 25 year veteran of Porsche engines, they finally got a failed reading on the dyno on the temp. head sensor. Once it was replaced - all was well again.

In my situation the sensor failed in such a way as to cause the engine to completely shut down for just a second or two - usually when running about 60-70 mph. Some days it was better than others but it almost always happended about 30 minutes into my commute home.

TC_SJ

gbailey911

My car have similar problem like your, my car stalled when I make a quick turn and happened 3 times, the first time I able to restart the car and ran fine for 2 weeks and then stalled again, this time the car can not start. I towed it home, follow the Bentley manual and check everything, included swapped DME and tested the relay , like you car, my does not have any spark at all, I then remove the ECU connector and checking the votlage input, measured OK, I cleaned both connect and plug them back car start fine, run for 4 weeks, car stalled again. This time I towed it to the shop for diag, the mechanic plug his test ECU box and car fire right away. I now know there is something wrong with the ECU, I later touch-up most solder join on this box, car been running fine so far,

You can tried to clean the ECU connector and see if it would start

Good luck

gbailey911

Ok, I have run out of options given what I know about 911s. I suspect the ECU but don't have another to try so I will let my local experts check it out.

I will post what they find.

Thanks to all that have helped me along the way.

George

TC_SJ

Hello George

wondering what the shop find out about your car

TC_SJ

gbailey911

The shop says the DME computer is at fault. They are going to send the computer off to be rebuilt for an estimated cost of around $500 guaranteed for 1 year. Is this reasonable?

Thanks,

George

rbcsaver

George, that sounds high to me. There is a "guy, " LorenFB who pokes in and out of the forums. He has a reputation for being able to bebuild these DMEs and a bigger one for absolute hate, dispise for aftermarket chips and is usally derogatory to those who make/use them. However, I have read that he IS the person you want to rebuild yours. Contact him via www.systemsc.com
The issue will be the chip. Some info may be on his website.
The DME is not difficult to remove from your car.

Do you know who's chip it is? I had one in my car that created alot of problems, but I did install a new one this year from Steve Wong, at www.911chips.com Steve's chips are by far the best out there and he customizes them for your specific car with or without mods. DO NOT mention SteveW, to Lorenfb. See my first paragraph.
regards,
Steve