notthd

Sorry for the long write up but I am out of ideas. I have a friend with a 951 who one day after running perfect forever would not start. He has the Autothority MAF conversion that I sold him out of my car some 5-6 years ago. If any one has any ideas or things he can do to "follow up" behind his mechnic I would so appreciate it. Here is Jim's e-mail to me- He is a great guy and needs your help.- Cheers, Mike

Yeah, what an adventure! I have come to the conclusion that it all went down something like this,.......I park the car in the driveway and put the fitted all weather cover on it, and go to bed. After starting and running perfect each and every time I ever drove the car in the five years I've owned it,....four weeks later it won't start. Well, my first mechanic while trouble shooting it, notices that the plastic parts housing the crank sensors, are somewhat deteriorated. Now see what you think about this theory Mike,.....as soon as he messes around with the sensors, they now begin to sense again, and the car was ready to start at that moment! But here's the thing, we didn't think to try to start it after he checked the sensors, because he put a meter on them, and they reacted correctly. Instead, he goes right to the DME relay, and removes the cover and checks to see if anything is amiss. Its not, so he replaces it, then starts going down the "spark" items ck. list. When he gets to the coil he somehow determined that it wasn't putting out like it should. (I had gone in the house to make a call) When I came back out he had removed the coil, and said we needed to find one like it, because its specific to to that system. I would lay odds that if we would have tried to start it then, it would have started! But we didn't. So we drove to the shop where the guy who usually works on it,...was. He had a used (good) coil, so we drove back home and installed it, ....the car started right up. As I told you before, we thought problem was solved. The heating and cooling of the car sitting under the cover in the hot sun for the next three days, (and its been hot!) could have very likely had an effect on the deteriorated plastic on the crank sensors, causing them warp slightly again, and to brake contact again, ....which is probably what was the very cause of the problem in the first place,.....Now when I finally get it towed to the shop, a few weeks later, the next mechanic and the first one get together, and between them they now determined that the ECU isn't putting out any current. His wife has an '86 T, so he then pops hers out and hooks it to my car, and it starts. I have spoken to several people about this, and they all said that its the first time they have heard of one failing. I think you even commented in that direction, Mike. But, watch this,.....after buying a used ECU out of a running car, (Parts Heaven in Calif.) and installing it, It still did not want to start! The only way they could get it to start was after he decided (reluctantly) to turn the potentiometer. He got it to run after doing that. But one of the things he also did was to reenforce the deteriorated plastic over the crank sensors with some sort of glue or something. ; >) And it ran perfect. Started well and all. But he failed to test drive it, and told me to come and pick it up. The rest is history. We now know from Autothority that turning that potentiometer is the reason why its backfiring upon full throttle. the mixture is out of whak to the lean side! Ponder all that Mike and let me know if you think its possible to go down like that--that way. And, would the crank sensors not sensing have anything to do with the ECU emitting proper current at start-up?
Thanks for listening Mike, Head is up, and one thing at a time. Regards, Jim

P.S. You had metioned something about you having cars for sale I think,....I have a friend who is looking for a clean Porsche. He doesn't know which one he wants yet. If you do, let me know.

----- Original Message -----
From: NOTT Michael (AREVA)
To: jamesfwallace
Sent: Monday, August 16, 2010 7:43 AM
Subject: RE: 1987 944 turbo trouble


Dam Jim, what an adventure... Want to borrow a car in the meantime? I am very interested in finding out what all of this was. Keep me posted and keep your head up- almost fixed.

Cheers, Mike

Michael J Nott, PMP
Plant and Outage Services Manager
Pump and Motor Services
PM, Nuclear Services
AREVA NP Inc.
An AREVA and Siemens company
155 Mill Ridge Road
Lynchburg, VA .24502
Phone: 434-832-4044
Mobile: 434-942-2916
Fax: 434-832-3565
TMI 717-948-8539
The information in this e-mail is AREVA property and is intended solely for the addressees. Reproduction and distribution are prohibited. Thank you.




--------------------------------------------------------------------------------
From: jamesfwallace [mailto:flyyboy@clearwire.net]
Sent: Sunday, August 15, 2010 12:37 AM
To: NOTT Michael (RS/IB)
Subject: 1987 944 turbo trouble


Mike;

Just a note to let you know just when you thought it couldn't get any worse,....then it did get worse! : ) They at Autothority sent me the wrong harness. It seems that somehow one of the old "prototype" harnesses they used to use, way back in the mid eighties,...got on the shelf, and someone picked it up and sent it to me. And as you might guess,...it didn't fit. They have used the Ford type connectors for years, but they initially used the GM type connectors, and I guess they thought they were all discarded, .....except for this one! And I end up with it. What a deal.
So, I am in the process of sending it back, and hopefully they will correct this mistake. I will keep you posted, (hope you don't mind) and hope you have a good week.
Regards, Jim Wallace



----- Original Message -----
From: jamesfwallace
To: michael.nott@areva.com
Sent: Sunday, August 08, 2010 11:42 PM
Subject: 1987 944 turbo trouble





Hello Mike;

Just a note to let you know I forgot to add the first "dot" in your email address. I guess I mistook "dot nott" for just plain "nott" and so it wouldn't go through! Anyway, I will send this email off a third time (third time is a charm) but I finally got in touch with a guy at Autothority who was willing to listen, and he figured out the problem right off. He asked it the Potentiometer had been turned, to which I had to answer "yes, turned and then some!" Then he told me I needed to purchase a new harness, which includes a "factory set" and "sealed" potentiometer. I asked if he couldn't just give me the specs. and he said they were set by the vendor who produces the harness, and that those settings were copywrighted of something. Anyways, I paid one hundred and eighty bucks for a new harness and it should arrive on Tuesday. He thinks without a doubt that it will fix the backfiring problem the car has now.
Ok Mike, I will keep you posted on events, and I guess there's really no need at this juncture for you to send all this info. to "forum", as we will try the new harness first!
Thanks again sir for your willingness to help! Regards, Jim Wallace


----- Original Message -----
From: jamesfwallace
To: michaelnott@areva.com
Sent: Thursday, August 05, 2010 11:59 PM
Subject: 1987 944 turbo trouble

Hey Michael;

Sorry its taken so long for me to get this email to you, but I have been very busy, and I didn't have all the facts either.

Timeline of events for one 1987 944 turbo, w/123K mi., w/Autothority MAF conversion, and Autothority performance chips, test pipe, and burning only high test fuel.

I don't drive the car that much, maybe two to three K mi. per year. Pulled it into my driveway one evening after driving it a bit, running perfectly, and always very responsnsive,... and it sat maybe a couple of months, (which is normal) and when I tried to start it to take it out for exercise, ....it wouldn't start. It turned over several times, (it normally starts very quickly) and then the battery was very low. I slow charged the battery then tried to start it again, and nothing. It would turn over nicely, but wouldn't start. I called a friend who knows Porsches well, and he came over and begin testing things, ie. crank sensors, DME relay, coil, fuel, etc. and determined that the coil could be the culpret. He said it wasn't putting out acceptable current. He then changed the coil with another (used) coil and the car fired up very quickly! I was amazed. We then started it several more times, and shut the hood, thinking the problem was solved. This was on a Tuesday, and I didn't have time to drive the car that day, so I waited until the following Saturday for that. When I got in and turned the key,....it wouldn't start again, just as before. It would turn over nicely, but would not start. I then took it upon myself to change the coil again, with a 'universal' coil a friend gave me to try, and nothing. (I later learned it has to be a specific coil) I then went to the person who sold me the second coil, the one that started the car several times. I returned that coil to him, and he gave me a second 'Bosch' coil and told me that this one was removed from a "running car." I took it home and installed it to find that it did not start my car. Now my advice was to bring the car to his shop, (the guy who had given me both coils, a master mechanic, specializing in Porche, Audi, BMW, Mercedes, and Volvo... ("Autobahn Daytona" 386-615-7993) which I finally did. (Towed it) After some extensive testing he told me that the ECU was not putting out any voltage. He said the ECU had failed. He then removed the one from his wife's 1986 944 turbo and hooked it to my car. He said my car started right up!
I asked him if he had tried hooking my dead ECU up to his wife's car, and he said he hadn't because he was sure from testing mine, that it was bad. Ok, so I then orded a matching numbers ECU from Parts Heaven in California, $380.00, and they said it had been removed from a running car, and included a 90 day warranty. As soon as it arrived, my mechanic installed it and told me it wouldn't start! When I asked him what was up,...he replied that it wasn't "his" box, and it may be bad as well. I didn't speak with him for a couple of days, then got a message that my car was running and ready for pick up. He said he reluctantly readjusted the potentiometer at the MAF, (fuel/air) and finally got it started. I picked up the car at night, and simply drove it home (two miles) and parked it and covered it. This was Wednesday, and on the following Saturday I did take the car out for a test drive. I drove it normally without getting into the turbo any, until I came off an onramp to a highway, and I was in third gear, and I slowly put my foot to the floor, and as the turbo began to spool up, ....it suddenly backfired through either the intake or possibly the exhaust, (sounded like it came from under the hood) but I then shifted into fourth gear, and continued on. At the first traffic lite, I noticed the engine had a defined miss which had not been present before the backfire. I arrived at my destination and shut the car off, ...came back out within five minutes, and it would not start. I tried it two to three times, then let it set for a few minutes, whereupon it started and I was able to drive it home. It still ran normal, except it didn't want to idle correctly, and when I tried a second time to spool up the turbo, this time in second gear, it definately backfired through the exhaust that time, and also another attempt before I returned home.
I then returned the car to his shop, and told him of my troubles while driving it. He seemed in disbelief, and drove the car himself, and reported the very same results. He told me to leave it, and gave me a ride home. I spoke with him the following day, and he told me while doing more tests, he had discovered a wiring harness plug associated with the Autothority MAF system, that was intermittent. He had to resolder each connection,...but it had little or no affect on the problem. He told me he thinks that the MAF may not be functioning properly. He has attempted to set fuel/air mixture with the potentiometer associated with the MAF, while probes are sniffing exhaust gasses. He said when the adjustment is right within limits, it doesn't stay there. He cannot seem to get the carbonmonoxide level to remain constant, using the potentiometer. He has checked under the distributor cap, cleaned all contacts, checked the rotor position, etc. At this writing I have not heard from him, which means he is still working on it.
If you can put this information to forum, Michael, I would certainly appreciate any help anyone can lend. I miss driving my car! And, I have to date spent some $850.00.
Thanks very much for your willingness to help! Jim Wallace or email flyyboy@clearwire.net

toddk911

Sounds like the crank sensors are the issue and they got off track with the ECU and coil.

Just need to adjust the potentiometer back to original with new crank sensors.

JohnKoaWood

likely speed and reference sensors, the ref sensor harness wiring, connectors or a combination of the 3.. FWIW I have NEW sensors and harness on my car that I am ditching to goto a stand alone...

tell him to get it all put back together, and see if it will start... Is his car located in Forest as well?

There are a few of us arround who might be able to assist hands on....

Ronin-951

Does'nt anyone ever look for Tach bounce anymore?

quinnfiske

I have had two ECU's fail. Bad output to the ignition coil so no spark. Found it after replacing sensors and harness.

mclarenno9

+1 me too

toddk911

Nice reminder for everyone!

DME only bad if no tach bounce when key is turned. as well as stock boost gauge.

apitts73

im having a similar problem too....but it only happens when the car warms up!! i changed the speed/reference sensors and still the same.
very frustrating!

joster86turbo

did you change just the sensors themselves, or the entire run of sensors and harness into the DME?

quinnfiske

This might be due to a bad DME temp sensor. In the head at the front of the engine near #1 intake runner. When working properly richens the mixture until coolant comes up to temperature.