Engine ECU

[Roger1965]

I have a question regarding the engine ECU. I have taken my 2001 Boxster to a local indie mechanic and it has been diagnosed as having a faulty ECU.

I trust this shop as the two owners/mechanics formerly worked at Porsche dealerships here in town. Some years ago , all the Porsche dealerships in my town when out of business except for one. It is my understanding that only the dealer can recode a replacement ECU. Is that a correct assumption? I would really like to avoid the dealer if possible because it is about 30 miles away and I received poor service last time I was there.

My question is: If I were to send my old ECU that was original to the car out to one of the outfits that rebuilds them would that unit have to be recoded after being rebuilt?I've searched the forum here but cannot find an answer to that specific question

Thanks in advance to everybody I've gotten a lot of great information off this site

[JFP in PA]

You will need either a PST II or PIWIS unit to code the DME, and will also need the car's immobilizer as well (they need to talk to each other to work), so it would be easier, and cheaper, to take the car to someone with the correct systems to do the work. Doesn't have to be a dealer, but not that many independents are that well equipped.

[Roger1965]

Are you saying I need a new immobilizer as well? Or that the old one will need to be coded as well. My mechanic quoted me the dealer price for a new ECU and then told me I could order the ECU used and didn't mention anything about reprogramming issues so I assume they have the equipment to do it. I was having a brain fart at the time and forgot to ask him about the coding issue

I just recently did a little searching on the Internet and remebered about the recoding issue so I couldn't talk to the shop about it because they're closed today. They are the highest highest regarded indie in town so my choices are them or the dealer. But the necessary equipment is not exclusive to the dealer, correct?

There are a lot of Boxsters and Caymans in their parking lot so I assume they have the proper equipment. I just remembered this coding thing on the weekend and I'm freaking out about it.

My issues here are less about cost and more about building a relationship with a good shop, something I don't think I can do with the dealer here

[JFP in PA]

Originally Posted by Roger1965

Are you saying I need a new immobilizer as well? Or that the old one will need to be coded as well. My mechanic quoted me the dealer price for a new ECU and then told me I could order the ECU used and didn't mention anything about reprogramming issues so I assume they have the equipment to do it. I was having a brain fart at the time and forgot to ask him about the coding issue

I just recently did a little searching on the Internet and remebered about the recoding issue so I couldn't talk to the shop about it because they're closed today. They are the highest highest regarded indie in town so my choices are them or the dealer. But the necessary equipment is not exclusive to the dealer, correct?

There are a lot of Boxsters and Caymans in their parking lot so I assume they have the proper equipment. I just remembered this coding thing on the weekend and I'm freaking out about it.

My issues here are less about cost and more about building a relationship with a good shop, something I don't think I can do with the dealer here

No, I'm saying that when the DME is coded, it needs to have the immobilizer present to make sure that they are communicating, otherwise the car will not run. They need to be coded as a pair.

Anyone (with $20K for the first year) can lease a PIWIS system from Porsche, which is why not that many outside the dealers have them. The PST II is the older version, which will also work on your car, so you would have a better chance of finding one of them. But you have to have one or the other, nothing else will do the job.

A more interesting question would be why does your wrench feel you need a new DME? They do not fail all that often, and the codes that appear when they do go bad are pretty specific. I'd first be sure you really need one, as they are not cheap, nor is the process of setting the car up.

[Roger1965]

Okay, what about my original question : If I have my original DME rebuilt, will it need recoding at all? The DME is not sending a signal to the MAF.

[JFP in PA]

Originally Posted by Roger1965

Okay, what about my original question : If I have my original DME rebuilt, will it need recoding at all? The DME is not sending a signal to the MAF.

To answer your original question, yes it will still need recoding and testing with the immobilizer to make sure they are pairing correctly, otherwise the car will not run.

That said, if the exact reason that they feel you need a DME is "the DME is not sending a signal to the MAF", you have a bigger problem: They do not know what they are doing. On your car, the MAF sends signals to the DME, not the other way around. The DME takes information from the MAF and other sensors to make corrections in the fuel mixture, etc..

I'd suggest getting a qualified second opinion from a shop that works specifically on Porsche's, and has a Porsche diagnostic system. You cannot correctly diagnose these cars with "global" OBD II scanners, you need the correct system.

[Roger1965]

I probably worded that wrong. The DME and MAF are not communicating, and the MAF is new.

[Deadeye]

I have had good luck with ecu doctor in FL. They can repair and program your ecu and warranty their work.

[Bootlegger]

Exactly what is the car doing (or not doing). Symptoms...??

[Roger1965]

I just talk to my shop and they do have a PIWIS. I am going to take the computer up there now and I'll let you guys know how it all turns out. I appreciate everyone who responded to this thread I learned a lot

[jpl2407]

So put your old, of different maf on the car and see if it talks to the DME, If it does, the issue must be with the new MAF I would have thought.

[Roger1965]

Same issues with two different MAF. The old MAF I think was damaged from oil leaking past the AOS which was replaced last year.

I think what happened to my DME is it got damaged by water from the leaking coolant overflow tank. The inside of my trunk was like a sauna when summer hit.

Condensation on the trunk lid and I think the humidity in there probably damaged the MAF. It was like locking the MAF in a steam box. And coincidentally the problems all started when it got really hot here last summer with temperatures in the 90s. But the car never overheated or anything.

Anyway this is all just conjecture on my part it's in the hands of my shop now they have the right diagnostic systems and experience I think they can fix it.

[Roger1965]

@Bootlegger: Surging idle, poor throttle response, car would die occasionally if the tank was less than half full, check engine light on.

Shop also mentioned possible problems with fuel tank breather system and or fuel pump

@Deadeye:I looked into them and they seem like a great option for the future they reprogram your DME so it is a plug-and-play replacement

[VGM911]

Just a thought.....as a person who drives 50 miles to work each day (100 miles round trip), a 30 mile jaunt to the dealer seems like a piece of cake.

[Roger1965]

It's not the distance. The service there is extremely bad. I will never set foot there again unless forced.