Starts but will not run in drive - Page 2

Danglerb · 12-18-2013, 09:43 AM

When I went on a maf hunt buying up some spares, I found zero that didn't need in most cases a full rebuild and new wire. Its a part that ages and slowly goes out of spec.

stepson · 12-18-2013, 12:52 PM

Neil, I wish you had posted your ideas on the forum instead of in a PM so we'd all know what direction you are thinking. Your ideas might help someone else down the line. Just a thought.

neil30076 · neil30076's Garage

Quote:

Originally Posted by stepson

Neil, I wish you had posted your ideas on the forum instead of in a PM so we'd all know what direction you are thinking. Your ideas might help someone else down the line. Just a thought.

John, good point and I will; just jumping in and doing a MAF swap is in my opinion not the best path ( in over 30 years of 928 ownership I have yet to do so) , and I was going to explain how to check the MAF resistance setting and the CO setting ( without using PorKens 'the blink'r). I'll write it up at some point and publish. I was just going to send the OP the Porsche shop manual for the same adjustments but do not have his email address.

Cheers
Neil

stepson · 12-18-2013, 05:06 PM

That is a real good point Neil. I was just saying to possibly test his MAF into a known good car to verify that the MAF is an issue. He could send it out after that if need be, but you are right that there are much more technical tests available. Thanks for letting the rest of us in on your thoughts.

SeanR · 12-19-2013, 08:59 AM

One thing I don't see mentioned yet. On the 85/86 there is a harness that goes to the Throttle Position Sensor (TPS) and these are known to go bad and when it happens, the car will exhibit these exact symptoms. It is located at the diagnostic connector at the front of the intake, it's a 3 pin connector and goes from there to the TPS next to the Y on the intake, beneath the runners.

neil30076 · neil30076's Garage

Quote:

Originally Posted by SeanR

One thing I don't see mentioned yet. On the 85/86 there is a harness that goes to the Throttle Position Sensor (TPS) and these are known to go bad and when it happens, the car will exhibit these exact symptoms. It is located at the diagnostic connector at the front of the intake, it's a 3 pin connector and goes from there to the TPS next to the Y on the intake, beneath the runners.

Sean, good point. I had to rewire that whole harness on my 86 as it was falling apart, car still started and ran, also the Temp II wires close by it.

SeanR · 12-19-2013, 12:54 PM

Forgot to mention that those are being built and supplied by Roger as a complete piece. Good stuff so you don't have to tape or zip tie the old ones together.

Danglerb · 12-22-2013, 05:37 PM

Take pictures of stuff like that.

Does the MAF have a temp sensor in it as well as the hot wire? Or does it rely on the one in the air filter box?

SeanR · 12-23-2013, 05:25 AM

Quote:

Originally Posted by desertspirit

Do you have a pic for the location of this harness?

Perhaps I jumped the gun on that MAF. I sent it out to Roger who suggested the symptoms were indeed the MAF. So I will trust his findings. If in fact it is bad, I feel comfortable he will rebuild it correctly. If he finds it is not bad, I am sure he will inform me of that also. Either way I will find out what is the condition of the MAF.

Incidentally, when I had the MAF out in my hand, and took off the screen, there is a very, VERY thin wire in there that is shaped like a triangle. This very, VERY thin wire on one side of that triangle was broken. I am not talking about the larger thermal wire.

Sorry, don't have a picture of it on hand, will look and see if I have one somewhere.

As to the MAF, if the wire is broken then you definitely do have an issue there.