Notices
928 Forum 1978-1995
Sponsored by:
Sponsored by: 928 Specialists

Help!! I'm at my wits end.

Thread Tools
 
Search this Thread
 
Old 04-25-2015, 12:27 AM
  #16  
Fronkenstein
Burning Brakes
 
Fronkenstein's Avatar
 
Join Date: Aug 2013
Location: Northeast USA
Posts: 948
Likes: 0
Received 0 Likes on 0 Posts
Default Help!! I'm at my wits end.

Just makes me SO happy I own a 78 euro powered by a CIS injected m28.22 engine. NO BRAINS. ALL BRAUN:-)

Fronkenstein
Old 04-25-2015, 12:34 PM
  #17  
outbackgeorgia
Pro
 
outbackgeorgia's Avatar
 
Join Date: Feb 2010
Location: Atlanta GA metro, OTP North
Posts: 618
Likes: 0
Received 1 Like on 1 Post
Default

It still has symptoms of a failed LH.
Swap it out again, you may have my old one!
Heat sensitivity is not usually tested, try putting a heat gun on the LH to see if it fails when temp is elevated.
This is of course after all other diagnostics/repairs have been done.
Dave
Old 04-26-2015, 09:31 AM
  #18  
Fabio421
Man of many SIGs
Rennlist Member
Thread Starter
 
Fabio421's Avatar
 
Join Date: May 2005
Location: Florida, USA
Posts: 8,722
Received 11 Likes on 5 Posts
Default

Originally Posted by Speedtoys
So..how's that 14-pin harness plug doin?
Ive had this at the side of the road before..

14-pin connector corrosion and age
"Tampa 928s" and I checked the 14 pin connector. We pin'ed it out and checked for continuity to the CE panel. He was on the 14 pin side of things and I had my head under the dash but he would have said something if there was corrosion. Since it doesn't take much effort to re-check it, I will do so.

Originally Posted by SeanR
Do the RPM's drop low before it stalls? Faulty wiring for the ISV can cause this.
No, the engine just stops like you turned the key off.

Originally Posted by OTR18WHEELER
The ambient air temp clue leads me to think it could be a bad wire critical of ignition, expanding and breaking contact as it gets warm, or a loose coil wire. Check the coils and the ignition.

Originally Posted by soontobered84
Check and clean engine grounds at the back of the Vee,(saw that you did that already) the coil grounds, and remove clean and replace the main engine ground under the car on the passenger side. When the computers find a ground, the car will run great, when they don't find a ground, the engine will shut off just like you turned a key off. The car will crank just fine, but not start until the computer happens to find a ground, then it happens all over again. No rhyme or reason as to when the computer finds that ground.
This problem happened exactly like this on my '89. Cleaned the main engine ground and have not had an issue since.
I've thought about this. Upon inspection this ground looks to be in extremely good. It's such a cheap part I may just replace it anyway.

Originally Posted by SQLGuy
I would start with the engine idling and the hood open, and poke around with a dowel to try to aggravate the problem. One area to poke would be the cam position hall sensor and its harness. I would also poke around the ISV harness, and knock sensors/harnesses/connectors.

I hate shotgunning... though it probably doesn't hurt to replace the items you've replaced, if you don't know the history of the car, you may be replacing stuff that was replaced not too long ago anyway.

I wonder if a Durametric or Sharktuner could tell more about the "hiccup."

I would also try tapping and shaking things in the CE area and in the connectors for the two ECUs.

The fact that it hiccups quickly, does sound more like an ignition related problem than a fuel related problem, but that still leaves plenty of possibilities.
Thanks for your input. I'll check it out.

Originally Posted by hessank
When mine did the same thing it was a coil gone bad.
I replaced it with an MSD coil and that was 3 years ago.
Thank you. I'll check it out.

Originally Posted by GregBBRD
The most common cause of this is high resistance in one of the spark plug wires....and this includes the coil wires.

This can be "green corrosion", burned up resistors, burned up ends into the caps, not completely pushed in coil wires at the coil, the wrong coil wires at the coil, and a poor brand of spark plug wires.

ANY spark jump or very high resistance (corrosion) will force the spark to "jump" around the rubber boot and short to the actual coil primary terminals. The car will instantly die, but will restart....exactly like you describe.

There's a supplier of spark plug wires, out there, that has ends that go into the distributor caps that make a 90 degree bend, but the actual wire can pull out of that 90 degree piece. The wire will stay inside the "boot", but will be completely disconnected, allowing a spark jump and "coil flame out".

There's two completely different designs of coil wires that go into the actual coils....and two completely different kinds of coils. (A genuine Beru set of spark plug wires includes both kinds of coil wires.) There is a style that had a "pin" inside the coil (just like at the distributor cap end.) This needs a female style end to connect over that internal pin (just like the connector at the distributor cap end.) The other style is a traditional "American style" coil with a male end that connects to the brass contact inside. Many times we will find the wrong style coil wire at the coil end, which forces a "spark jump" situation.

The other common problem is the plastic rain caps that are on the coils. The coil wire MUST go over the top of the inner edge of these rain caps, in order to make a good connection at the coil. The rubber must go over the top of this plastic by about 4mm. There are poor quality coil wires out there that are too small and will not go over this inner edge....they butt up to the plastic and stop. When this happens, the coil wires are generally not be connected internally and, once again, the spark will have to jump.
Thank you very much Greg. I will start here. You've had your hands on more 928's than most of the rest of us in the this thread combined.



Thank you very much to all of you for your input. I am currently out of town but I will check these items and report back here once I get back to my car in the next couple of days.
Old 04-26-2015, 03:33 PM
  #19  
Randy V
Addict
Lifetime Rennlist
Member
 
Randy V's Avatar
 
Join Date: Jun 2000
Location: Insane Diego, California
Posts: 40,449
Received 98 Likes on 66 Posts
Default

Originally Posted by outbackgeorgia
It still has symptoms of a failed LH.
I agree.

Try removing the CE board cover and the adjacent carpeted cover to allow the LH better cooling and see is that eliminates the problem.

That's how I verified my LH was the issue.

https://rennlist.com/forums/928-foru...ermittent.html

The resolution:

https://rennlist.com/forums/928-foru...l#post11200529

edit - looks like you posted in that thread with this issue back then.
Old 04-27-2015, 12:03 AM
  #20  
Fabio421
Man of many SIGs
Rennlist Member
Thread Starter
 
Fabio421's Avatar
 
Join Date: May 2005
Location: Florida, USA
Posts: 8,722
Received 11 Likes on 5 Posts
Default

Originally Posted by Randy V
I agree.

Try removing the CE board cover and the adjacent carpeted cover to allow the LH better cooling and see is that eliminates the problem.

That's how I verified my LH was the issue.

https://rennlist.com/forums/928-foru...ermittent.html

The resolution:

https://rennlist.com/forums/928-foru...l#post11200529

edit - looks like you posted in that thread with this issue back then.
Randy, I read your thread and I thought that was my issue. I first built a little air damn around the compute and piped the air conditioning tube from the glove box into the lh air damn. It made zero difference. I then swapped out both computers from a running car and the same problem persisted. I wish it was the LH but I'm fairly certain at this point that it isn't. Thanks for trying to help. I do appreciate it.
Old 04-27-2015, 12:48 PM
  #21  
soontobered84
Rennlist Member
 
soontobered84's Avatar
 
Join Date: Mar 2002
Location: Texas
Posts: 5,992
Received 282 Likes on 199 Posts
Default

Originally Posted by Fabio421
I've thought about this. Upon inspection this ground looks to be in extremely good. It's such a cheap part I may just replace it anyway.
At the very least, just remove it and clean it and the mounting positions.
Good Luck.
Old 04-27-2015, 06:52 PM
  #22  
Speedtoys
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 13,582
Received 1,034 Likes on 623 Posts
Default

Done this yet?

https://rennlist.com/forums/928-foru...l#post12236833



Quick Reply: Help!! I'm at my wits end.



All times are GMT -3. The time now is 06:48 AM.