Ed Hughes

Exactly, and is why it was suggested early on in this thread. It would be the first thing to change, to take that out of the equation.

ron mcatee

The DME relay is attached to one corner of the DME box under the drivers seat. It is a 10mm nut that is easily removed. I always disconnect the battery before unplugging and plugging in the relay to prevent any shorting, etc. It unplugs like any relay would. When you finish plugging/unplugging, see if the car will start. If it does , you may have found the culprit. Then just put the relay back on the stud and replace the nut.

Snakeoiler

Okay....I'll pick one up tomorrow. Do the local parts stores stock them....or is it better to order online?

The cylinder head sensor checked out fine with the ohm test. The throttle body sensor also checked out okay with the ohm test. I used the chart in the Bentley book that tells you what you should read with outside temps.

Any ideas what will keep me from getting a reading on pins 1 to 3 and pins 2 to 3 on the crank and speed sensors? I am getting the correct reading on the 1 to 2 pin reading. I am not getting any reading on others. The book tells me I should get 100,000 ohms on the 1 to 3 and 2 to 3 reading. I am not getting any reading. Could both sensors gone bad at the same time? How hard are those to change. The manual doesn't really tell much on the subject.

I am heating the garage as I type. Once it is warm enought for it to start.....I will test those pins with the new ohm meter I bought.

Any advice on how to change these would be great.

rusnak

Oh man.....I was thinking that you followed the advice already to change out the DME relay.

+ 100 on buying a good one. It is not a waste of money. What happens is that eventually the contacts can go bad, and stick or fail to make contact. The dme relay is by far the likliest culprit.

Something tells me the sensors are not bad because they don't usually go bad only at certain temps. when they go bad, they usually stay gone. My advice is to be damn sure that you are testing the right pins, because this is not a failure mode that sounds familiar.

Yes, you can change them. The critical thing is the spacing. If you can get them out without moving the holder, then you are home free. Big if. Otherwise you may need to do an engine drop. Like I said, be damn sure that they are bad before messing with the sensors. In contrast, the dme relay is a cinch to replace. It's under the driver's seat. I take the seat out of mine to change the dme relay because I have sport seats, and want to be kind to the wires/ dme socket.

Snakeoiler

I ordered one online. No one local had one.

I'll swap that out once it comes in a see if that fixes it.

Some one local suggested cleaning all the ground points. Does that sound like a possibility?

Thanks for everyone's help.

theiceman

..you may as well do someething while your waiting .....

rusnak

I agree. The Bentley manual makes good reading. Find the ground points (front trunk, next to fuel fiter in engine compartment, intake runner, ) for the dme system. Chean them with a small brass brush. If you do take the driver's seat out, then clean your dme relay socket with air, and check the contacts for the dme brain. It might not hurt to unplug it and let it drain and restart it after a day or so of being unplugged. I'd also clean the battery clamps and posts, already mentioned. Charge the battery, and check that it's not shorting.

dshepp806

A lot of people ignore cleaning up the female connector side of the DME relay...When I have my seat out, I make sure I give her a go-over,..nice coating of Progold......

DME relays? Hell, I keep 2 spares (it's THAT common-an-issue).....I change them out every year, PREVENTIVELY!!!!!!!!!!!!

Best of luck

Snakeoiler

My Bentley manual does not have a table for the coil resistance. Does anyone's manual have the correct table. My table B is for the crank and speed sensor values. It appears to be a misprint.

rusnak

Here you go - see post #8) http://forums.pelicanparts.com/porsc...ce-values.html

http://forums.pelicanparts.com/porsc...985-911-a.html

And a few tips on testing coils by Early S Man (Warren Hall), a very respected ex member of the Pelican board, may he rest in peace: http://forums.pelicanparts.com/porsc...-bad-coil.html

theiceman

they are so unreliable even i should carry one

rusnak

haha...^^

..and whaddaya know? I was googling around just now and came across this.....print and tape it to the manual.

It's a bit generalized, but it might help someone. http://www.systemsc.com/diagnostic.htm

Thanks, Loren.

Snakeoiler

It appears the culpert was a bad ground on teh intake. It looked fine, but when I took it apart it needed to be cleaned. I put it back together and it started right up. I hope this was the fix. I will keep that DME in the glove box for a spare. Next time it won't start, I will try that first. I plan to take all the other grounds apart and clean them as well.

Thanks for everyone's help.

theiceman

...you'l be back

pingman

Snakeoiler,
I have been through all you are going through. The chances of a bad top dead center, (TDC), or speed reference sensor, are slim. I replaced both of mine due to a no start issue. I did not listen to the good advice of the iceman and Loran and replace the dme relay first. After replacing both sensors at $185 each still no start. replaced the dme ($50) no start. Did ohm test found new sensor bad. Put old sensor back on (with all the insulation gone) car fired right up. Total downtime on car 6 mos! Moral, listen to these folks, replace the easy things first, give back when you can. Mark