Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 924/944/968 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
echrisconnor's Avatar
 
Join Date: Dec 2001
Location: Boulder, CO
Posts: 809
Garage
Angry My car eats computers!!??? (DMEs)

Help. I've got this 87 924s that eats DMEs. Each year the computer craps out. Each year I buy another one from a junkyard, plug it in and it starts right up again. This is the 4th one in a row now over about the last 4 years.

I used to think the problem was moisture, since I had a battery compartment leak as well which commonly created moisture around the DME and a wet floor. That's been fixed and I still lose DMEs. I've checked the voltage, and I'm getting about 13.6V constantly. No peaks to note... Maybe that's a little low, but could that and the VR in the Alt. be the problem?

Any advice would be appreciated.

Chris
__________________
'76 911 Carrera 3.0
Old 07-02-2007, 01:05 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Ornery Bastard
 
Join Date: Sep 2001
Location: Bellevue, WA
Posts: 2,872
The 942S DME is mounted under the steering column, not under the passenger floorboard... Did you mean 944S?
__________________
Shifting is an art. Learn it, love it, live it.
---------
Silver 1998 Volvo S70 T5 <- Daily (Anja)
Guards Red 1986 951 <- Seattle car (Gretchen)
White 1976 914 2.0 F.I. <- Prodigal car, traded away then brought back again (Lorelei)
Old 07-02-2007, 01:23 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Burn the fire.
 
Brando's Avatar
 
Join Date: May 2003
Location: Orange County, CA
Posts: 5,966
Garage
You've possibly got too much voltage going to the DME, or possibly a short in the harness going to the DME.

I'll check my PDFs when I get home, but you should bust out your multimeter and start checking leads...
__________________
[x] Working | [_] Broken: 2017 Victory Octane
[x] Working | [_] Broken: 2005 Ram 1500 SLT w/5.7L Hemi

"Drive it like you stole it."
Old 07-02-2007, 01:46 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
echrisconnor's Avatar
 
Join Date: Dec 2001
Location: Boulder, CO
Posts: 809
Garage
Thanks all,

To note: yes this is a 87 924s. The note of the water on the floor was to indicate that there had been water leaking in to the vehicle, and not to suggest that the DME was on the floor.

Regarding voltage, it would seem that somehow spikes are killing it, but given that it only happens once a year or so, they must be very intermittant. I'd like to explore along these lines though.

chris
__________________
'76 911 Carrera 3.0
Old 07-03-2007, 07:11 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Apr 2007
Location: Buffalo, NY
Posts: 1,628
Send a message via AIM to Icey1174
What are they doing to the DME? Are you just getting bad DMEs with cold solder joints or is it a bigger problem than that? I would try resoldering one of the old ones if you still have one and see if that helps any.
__________________
John
'87 944 N/A (first Porsche)
'95 E-350 Diesel
'03 S-Type Jag 3.0
'03 Taurus SES
'06 Eddie Bauer Explorer

RIP SoCal
Old 07-04-2007, 07:04 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Eldorado's Avatar
 
Join Date: Apr 2005
Location: Ontario, Canada
Posts: 4,553
i'd agree with John. Inspect all the solder joints.
__________________
Kyle

2008 Mini Cooper // '83 Porsche 944 // '01 Mazda Protege [sold] //
"Never break more than you fix!" - SoCal Driver
Old 07-04-2007, 08:56 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered User
 
Join Date: Mar 2004
Location: Leesburg, Georgia, USA
Posts: 1,567
Garage
Before you buy the 5th DME, try opening the last one that failed and you may be able to see the failed component.
When my DME failed, I bought a used one, and they are not cheap. DME failed due to water leak in pass side.
I installed the spare used DME just to test it and the car fired up. I got spark.
Pulled it back out and tried to repair the broken one. Luckily, I found the component that got hot that broke the PCB copper trace.
Posted the burnt pcb on Clarks-garage and georgeb was kind enough to post the original pcb copper trace.
All I did was put a jumper wire to connect the copper trace and it worked.
Turned over the car to my son and still driving on the repaired one.


__________________
1993 964 C2 still makes me smile
1996 318ti (280k miles)
2011 Silverado for hauling (32k miles) - SOLD
2018 Suburban Z71
Old 07-04-2007, 09:04 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Apr 2007
Location: Buffalo, NY
Posts: 1,628
Send a message via AIM to Icey1174
Is there anyway to seal your DME unit to make it water tight or reasonably water tight? The correct fix would be to fix the root cause, but this may save the some of life of the new DME.
__________________
John
'87 944 N/A (first Porsche)
'95 E-350 Diesel
'03 S-Type Jag 3.0
'03 Taurus SES
'06 Eddie Bauer Explorer

RIP SoCal
Old 07-04-2007, 11:58 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
ae1969's Avatar
 
Join Date: Jul 2001
Location: Edmonton, Alberta, Canada
Posts: 4,530
Send a message via ICQ to ae1969
Check and clean all your grounds. If the grounds are not making a good connection then the DME becomes your ground.

Not good.
__________________
Alex - PCA Polar Region - Boxster Muncher
86' 944 Turbo - Megasquirt - 326 rwhp/340lbft @ 18 psi SOLD
www.edmontonhomelife.com
www.edmontonrealestate.ws
Old 07-04-2007, 11:58 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 03:21 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.