Dougs951S

Good eye, it is indeed a 911 box and yes my injectors were shorted, which is what caused the failure.

Joe Baumbach

Scratch that. I just realized that pic is off the web. Ignore the tech babble. lol

Dougs951S

yes, should have been more specific. The box in the picture is a 911 box, mine is a 944 box that failed due to shorted injectors.

Joe Baumbach

Are you going to try to repair your old 944 DME? If you need any parts shoot me a PM and I will send whatever you need out to you. I have lots of cores lying around...

Dougs951S

Thanks a bunch, yeah I'd like to try and repair it. I've had great luck repairing other vital circuits in both turbo and N/A DME. I have a replacement used DME in the mail, but I'd like to have a spare. I'm thinking I'm going to have to replace both RBDT's and the 0127 since the car was powered up for a good while and cranked quite a few times during diagnosis with 4 shorted injectors, before I realized they were junk. The DME was definitely dead before that though, it was the reason the PO took the car off the road in the first place over 3 years ago (though he lied through his teeth about the car running and whatnot, I bought it anyway knowing it didnt run, and after calling him a liar to his face. It was immediately obvious the car hadnt run in years and was not in running condition despite him swearing the opposite). That should get it working; the spark output stage still works fine.

The PO directly caused all the issues im dealing with on my new car because 1, he was kind of a dumbass, and 2 he was lazy and the car was way behind on PM. Its been sitting in my driveway for almost 2 weeks now, just waiting on parts that keep coming in as I keep finding more and more wrong with the car. I'm hoping to be driving it in the next 2 weeks. So far I've replaced:

Balance and Timing belts
alternator belt
new fuel injectors
new air filter
replacement DME in the mail
new DME relay
new speed and reference sensors
replaced all vacuum lines
New coolant cap
new coolant bleed screw
new clutch master cylinder
new clutch slave cylinder
new brake master cylinder
new battery
new hood struts
New front strut inserts
new springs
1 new wheel stud
a bunch of bulbs
several other relays

Its also going to probably need new rear shocks, plus I want to swap the front end to steel control arms to get new bushings and ball joints, and I'll replace the tie rods while I'm at it.

And I still havnt even started the damn thing..

drive135mph

Great Thread! My 944 DME took a dive recently and i can't wait to see what your solution is. I don't like the idea of buying another old DME in hopes of it working, i'd much rather understand my car and fix it. Thanks again. Let me know if there is anything I can do

Joe Baumbach

Sounds like you have a nice project on your hands, reminds me of all the fun I had with my 951. Question, why go with steal control arms? I thought bushing and ball joints where available to rebuild the aluminum arms?

Dougs951S

They are, but I can get 2 new steel arms, 2 ball joints, and all the bushings and parts I need to switch to the early style sway bar setup + an alignment for the cost of just replacing the ball joints on 2 alloy arms, I'm a cheap bastard and this is going to be a DD. My 951 runs steel arms too.

AlexTRD

Hello, hoping to revive this thread to resolve a fueling issue on my 88' 924s. The ground side of the injector circuit (pins 14 & 15 @ DME connector) is getting about 10.5v when the DME is supplied power. The harness is good, and this problem still persists when I power the DME on a workbench. I tested the rbdt65a transistor and it seems to be functioning. Pins 14 & 15 seem to be giving the same exact voltage coming from pin 10 of the 0127 IC. Is the IC supposed to be supplying voltage here? Pin 10 on the IC also branches off to a couple capacitors, so I'm thinking either one of those have failed, or its the 0127 IC. I can find no info on this damned chip, so if anyone knows what the function of pin 10 is that would help immensely, thank you.

Dougs951S

More than likely the failure is the 0127 IC and the DME is trashed since a replacement chip is impossible to source.

Alaska Cabrio

Stumbling around trying to find out what wrong with my N/A 1990 S2 Cabriolet. it runs, but once warm, it has a habit of returning to idle. If I let it idle for about 30-seconds it will run great for awhile before doing it all over again. Replaced the relay without success.


After reading about this DME and where to find it, decided to take a look. Pulled it out, brought it down to my workbench. Pulled the cover and found a bunch of corrosion on the pins associated with the ribbon connector. Water has been getting inside it.


Looks like it has been getting hot as well (outside case is different color).


My question is, how can water be getting in it?


Next question is, can this send enough current to the TPS to cause issues with it as well? Checked mine tonight and it does not pass the OHMS test mentioned at Clarks Garage.


Probably not a good idea to replace until I find the water path.


Mike

AlexTRD

My DME had rust inside and the car has been in AZ all it's life, which is a very dry and arid state (not to mention it's located under the dash). I suppose if mine can develop rust, anyone else can. Sounds like a bad TPS is your issue, you might be able to open it up and clean the contacts.

Dougs951S

Water ingress into the DME is a common issue on 85.5+ cars that had the DME under the passenger side kick board. What happens is the battery tray rusts, and water then makes its way down the firewall into the floorboards where it soaks the DME. Both of you guys need to pull your battery out and examine the tray because I can 100% guarantee it's rusted.

AlexTRD

My car is rust free ... Except for inside the DME lol. My DME is located under the steering column, opposite the battery

Dougs951S

You have an early car then, pre 85.5. Sorry, I did not realize that.

water damage on early DME's is a much less common issue. Another thing to mention is that there really isnt any ferrous metal either in the case or the inside of the DME so it really won't rust. Do you have rust proper in there, of did you just mean it was corroded?

I'd be looking at the seals between your brake and clutch master cylinder and the firewall or potentially cracks in the firewall in that area; that is the main way for water to get into the driver side under dash area.