3.6 ECU Woes

[Bravoaloha]

Hey Everybody,

Sorry in advance for the long post. Purchased an '86 911 with a '96 3.6 Vario in her back in the fall. Soon thereafter she started acting up (intermittently cutting out) and the issue got progressively worse. My shop narrowed the issue down to the ECU, sent it out to be repaired and we still had issues when it came back.

My shop feels that I need a replacement (which I agree with, and to me makes more sense than pouring money into the one I have that looks like its been to hell and back)

I have called many parts recyclers and a couple other people/shops that I thought may be able to help me and no one can source one. Steve Weiner from Rennsport has been very helpful in narrowing down exactly what I need which has been helpful, but I have been unable to source one.

I have figured out that I have two options: find a used one or buy new from Porsche. I have been unable to find a used one (there's one on ebay but it looks beat to hell like mine) so I am looking into one from Porsche. The issue here is that Steve told me explicitly only Bosch part numbers 0 261 204 649 or 0 261 204 376 will work in my car and unfortunately the Porsche and Bosch part numbers are not consistant.

As I understand it, Porsche had a number of different Porsche part numbers (I've found at least 5), but they are not congruent with Bosch numbers, so basically I could order a Porsche number and end up with a Bosch number that doesn't work for me.

The ones from Porsche come from Germany and all the dealers I talk to say there is no way to contact the German Porsche guys to ensure I get the right Bosch number and its basically a crap shoot.

Sooooo.... my questions are.. does anyone have any contact with someone at Porsche in Germany that can help or have (or can point me in the right direction) of a 993 ECU with Bosch numbers ending in 649 or 376?

Any help would be greatly appreciated.

Thank you!

[mikedsilva]

ecu problems are a pain.

How feasible would it be to go aftermarket?

[Raceboy]

I can offer VEMS PnP (that plugs directly into factory harness) for 993.

[175K911]

Steve Weiner is knowledgeable and a good source. But you also have probably one of the best varioram into Carrera experts just south of you- Steve Timmins at Instant-g in Delaware. In fact I would bet that the conversion hardware in your car came from him, he’s probably supplied more conversions than anyone else. He also keeps lots of 3.6 engines and parts in his warehouse shop. And I mean LOTS! His day job is a PhD professor at UDelaware so might not get back to you instantly but will always reply within a few hours. Timmins@instant-g.com

[Bill Verburg]

Originally Posted by Bravoaloha

Hey Everybody,

Sorry in advance for the long post. Purchased an '86 911 with a '96 3.6 Vario in her back in the fall. Soon thereafter she started acting up (intermittently cutting out) and the issue got progressively worse. My shop narrowed the issue down to the ECU, sent it out to be repaired and we still had issues when it came back.

My shop feels that I need a replacement (which I agree with, and to me makes more sense than pouring money into the one I have that looks like its been to hell and back)

I have called many parts recyclers and a couple other people/shops that I thought may be able to help me and no one can source one. Steve Weiner from Rennsport has been very helpful in narrowing down exactly what I need which has been helpful, but I have been unable to source one.

I have figured out that I have two options: find a used one or buy new from Porsche. I have been unable to find a used one (there's one on ebay but it looks beat to hell like mine) so I am looking into one from Porsche. The issue here is that Steve told me explicitly only Bosch part numbers 0 261 204 649 or 0 261 204 376 will work in my car and unfortunately the Porsche and Bosch part numbers are not consistant.

As I understand it, Porsche had a number of different Porsche part numbers (I've found at least 5), but they are not congruent with Bosch numbers, so basically I could order a Porsche number and end up with a Bosch number that doesn't work for me.

The ones from Porsche come from Germany and all the dealers I talk to say there is no way to contact the German Porsche guys to ensure I get the right Bosch number and its basically a crap shoot.

Sooooo.... my questions are.. does anyone have any contact with someone at Porsche in Germany that can help or have (or can point me in the right direction) of a 993 ECU with Bosch numbers ending in 649 or 376?

Any help would be greatly appreciated.

Thank you!

Besides the ECU other issues that can cause cutting out can be related to the fuel pump relay or the immobilizer. The ECU and immobilizer are both subject to cold solder failure from age. where was it sent for repair?

W/ an OBD1 ECU these are easy enough to check, much more difficult w/ your OBD2 ECU

[clutch-monkey]

possibly dumb suggestion but mine would intermittently cut out on down shifts at low speeds in traffic.
turns out the crossover pipe in the manifold, the silicon joiners and clamps were loose and must have acted like a vacuum leak at certain times..

[Bravoaloha]

Thanks for all the responses guys!

Originally Posted by mikedsilva

ecu problems are a pain.

How feasible would it be to go aftermarket?

I have no idea but this was suggested by my local dealership, they suggested Haltech?

Originally Posted by Raceboy

I can offer VEMS PnP (that plugs directly into factory harness) for 993.

Can you provide a little more info? Will this be ok for the street? I would like to keep it factory but I'm open to suggestions.

Originally Posted by 175K911

Steve Weiner is knowledgeable and a good source. But you also have probably one of the best varioram into Carrera experts just south of you- Steve Timmins at Instant-g in Delaware. In fact I would bet that the conversion hardware in your car came from him, he’s probably supplied more conversions than anyone else. He also keeps lots of 3.6 engines and parts in his warehouse shop. And I mean LOTS! His day job is a PhD professor at UDelaware so might not get back to you instantly but will always reply within a few hours. Timmins@instant-g.com

Awesome! I will contact Steve for sure- thank you!

Originally Posted by Bill Verburg

Besides the ECU other issues that can cause cutting out can be related to the fuel pump relay or the immobilizer. The ECU and immobilizer are both subject to cold solder failure from age. where was it sent for repair?

W/ an OBD1 ECU these are easy enough to check, much more difficult w/ your OBD2 ECU

Originally Posted by clutch-monkey

possibly dumb suggestion but mine would intermittently cut out on down shifts at low speeds in traffic.
turns out the crossover pipe in the manifold, the silicon joiners and clamps were loose and must have acted like a vacuum leak at certain times..

I trust my guys and they said they had the cover off the ECU with the car running, if they tapped it or touched the chip it would cut out and I think that is how they narrowed it down to the ECU.

Thanks again for the help guys.

[Bill Verburg]

Originally Posted by Bravoaloha

Thanks for all the responses guys!



I have no idea but this was suggested by my local dealership, they suggested Haltech?



Can you provide a little more info? Will this be ok for the street? I would like to keep it factory but I'm open to suggestions.



Awesome! I will contact Steve for sure- thank you!





I trust my guys and they said they had the cover off the ECU with the car running, if they tapped it or touched the chip it would cut out and I think that is how they narrowed it down to the ECU.

Thanks again for the help guys.

Ok, So yes that sounds like the ECU, I've had great results from Specialized ECU

As I said the most likely cause is cold solder failure, very common w/ age

[mysocal911]

Originally Posted by Bill Verburg

Ok, So yes that sounds like the ECU,
As I said the most likely cause is cold solder failure, very common w/ age

Actually, those late 993 DME ECUs are extremely reliable and rarely if ever have a "cold solder failure", e.g. an intermittency.
What does happen, though, is when those ECUs are modified for "performance", that does result in problems, especially intermittencies.

[mysocal911]

Originally Posted by Bravoaloha

I trust my guys and they said they had the cover off the ECU with the car running, if they tapped it or touched the chip it would cut out and I think that is how they narrowed it down to the ECU.

A posted picture of the ECU and the area the guys touched to re-create the problem would be helpful.

[175K911]

It's quite possible the chip itself is bad. Easy to fix- send it to Steve Wong for better software. Much less expensive than a new ECU.

[mysocal911]

Originally Posted by 175K911

It's quite possible the chip itself is bad. Easy to fix- send it to Steve Wong for better software. Much less expensive than a new ECU.

The '96 and later 993s don't have removable chips. Guess again!

[175K911]

Originally Posted by mysocal911

The '96 and later 993s don't have removable chips. Guess again!

Don't the chip guys solder in new chips? Or do they get flashed? If they get soldered in, that could be the issue. But my ECU for my 3.6 conversion is a '95 so I'm not up to speed on the later ones.

[Bill Verburg]

"95 are OBD1 55 pin w/ a user replaceable chip

'96 up are OBD2 88 pin w/ a soldered in chep

'96 was a one year only twin chip design. non flashable


'97 - 98 is a one chip design that a skilled shop can unsolder /flash/ resolder

[Raceboy]

Originally Posted by Bravoaloha

Can you provide a little more info? Will this be ok for the street? I would like to keep it factory but I'm open to suggestions.

Yes, it is perfectly ok for street. I have made and sold over 120 VEMS PnP kits (for many Porsche models, including 993, 964, 911 3.2) and I also have German TÜV approval for 944 n/a/924S kit (and soon 944 Turbo kit also), that indicates that it is perfectly suitable for street (in order to get the approval kit goes through rigorous tests).

993 kit comes as ECU and WBO2 sensor, plugs right into factory harness and runs the engine. Some minor tuning is needed (only to enable autotune and drive for a while), but it is very-very easy.

[clutch-monkey]

Originally Posted by Bravoaloha

Thanks for all the responses guys!

I have no idea but this was suggested by my local dealership, they suggested Haltech?

Can you provide a little more info? Will this be ok for the street? I would like to keep it factory but I'm open to suggestions.

Awesome! I will contact Steve for sure- thank you!

I trust my guys and they said they had the cover off the ECU with the car running, if they tapped it or touched the chip it would cut out and I think that is how they narrowed it down to the ECU.

Thanks again for the help guys.

ah
yeah i am going haltech with my 3.6.
they are the apple of the ECU world- not the best, but more than enough for the task, streamlined and everyone knows how to tune them.