redhorse

I am posting this to solicit feedback and advice from forum members who have had a 944 Motronic ECU repaired or rebuilt by a vendor. I am aware that there are at least a couple of vendors in the US that will repair your ECU, exchange, or sell a replacement outright. My preference is to have the existing unit repaired and refurbished. What experiences can anyone share? Looking for name of company, cost, what was the turn around time, satisfaction with the result, any subsequent failures and warranty (if any) experiences, that sort of thing.

John_AZ

redhorse,

I notice you have 7 posts since 2008 so you may not be aware of member "ECU doctors".
Not a sponsor but many have been helped.

This post will give you an idea on cost and such.

https://rennlist.com/forums/944-turb...u-doctors.html

I see you have a '90 S2.

GL
J_AZ

Van

I've been very happy with Jose at ECU Doctors.

F18Rep

Here's a completely different approach - reflowing circuit cards in Mom's oven. I would have never thought to even try it...Bruce

redhorse

Yeah that option is interesting....and entertaining after a liter of cheap wine

StoogeMoe

I wouldn't recommend putting the whole DME in the oven. That can't be good for the analog components. It would probably dry out the electrolytic capacitors and change the values of the resistors.

Just because it's on the internet, doesn't mean it's a good idea.

redhorse

Definitely agree...that was the point of my tongue in cheek comment about that approach being entertaining.

I appreciate the feedback...guess I learned that one vendor is well regarded so I will probably be contacting them in January when they start taking orders again.

I have opened the ECU and had difficulties doing it. One of the screws that held the base (and the lower pcb) to the phenolic connector refused to come out....it would just turn forever without stripping or breaking off. I eventually used a drill bit to cut off the head. So, finally have the unit out of the case. But, I cannot figure out how to get the one circuit board loose from the Bosch connector. This version of the ECU is different from the ones shown in the videos on the web, and apparently does not release like they do.

Wow, I just wish they had engineered the electronics as well as the screws and the phenolic connector. Even though there are some surface mount components used, the circuit board design and quality look like something from a 1970s electronic hobby kit. There is crystallized solder flux everywhere, which makes my skin crawl just to look at (I'm an aerospace engineer used to dealing with space rated "stuff"). There are some weird looking electro-mechanical devices in these things.

Anyway, there is no visually apparent reason for failure. It could be a solder joint that became too resistant finally, and open capacitor, shorted resistor or a dead 20 cent transistor. Don't have the test equipment or schematics so it is best to send it off to have it rebuilt by someone who does. Hope they give the thing a bath before reassembling it.

peanut

have you definitely resolved that your ECU is defective by substituting a known working ECU and testing your car works properly with the substitute ?

redhorse

I have a lot of spare parts for this car, but ECU is not one of them. But, if I did it would have been the first thing tried. Used ECUs I am finding for sale are all described as "works perfectly" (without letting us know how the seller knows that) and cost almost as much as the rebuild of my unit. Seems I may have to send the ECU in and pay for a diagnosis. Just cannot justify buying another ECU of the same age and unknown condition (might work today, but not next Saturday).

Does anyone know an alternative way to evaluate the function of an ECU, that does not involve another similar year 944 and costs less than $150?

If it is not the ECU, then it might be the alarm module. Should have checked that first, but didn't before disassebling the ECU. Next step is to hook it up in the passenger floor and do the alarm bypass and see if she starts.

It could also be something in the wiring between the ECU and whatever.....but it is a car that sat in the garage about a week (from the last time it started) with nothing happening except the passage of that time. But, it's possible that corrosion of a connector or connection can happen sitting still, and with electronics exceeding a tolerance in a week so that something does not work. But borrowing from the sellers of used ECUs, it was working perfectly...a week earlier. Whatever went wrong, probably happened as a result of switching off the car (voltage), or something like a transistor going bad as it cooled. I am betting something like that happening between starts.

Given that an old ECU could still function across the board, while filled with old electronics that could be operating at the limit of their tolerance (and fall out of tolerance and not work the next time) is still something to be concerned about. The only comforting thing right now about this box of electronics is that none of the components were made in China.

Van

That is why I recommended ECU Doctors. They have real test equipment that looks at the function of everything.

A few years ago they did my turbo DME and found that there were actually some bad components that needed replacing.

peanut

well from what you have said it would seem to me highly unlikely that there is a fault with your ECU unless it has suffered an electrical surge, been damaged by a welder or had water ingress.

You should carry out a proper sequential check of everything else to establish what is faulty before you incurr unnecessary expense and work replacing stuff at random.

I can supply you with a full ECU test proceedure and spec from Bosch but you could easily damage the ECU by applying voltage at the wrong terminals from your multimeter.

It would be more productive to test all the ancillary components ,wiring and sensors first to eliminate them.

Can you at least tell us what problems you have been having with the car and a bit of history perhaps of what you've checked /replaced etc ?

StoogeMoe

Why don't you ask the fine members here on Rennlist if you can rent a spare known good DME to try out. The only thing you would have to pay is the shipping back and forth. That can't cost more than $50.

blopper

Hopefully they are stand up guys. Just got a rebuilt put in and now the car doesn't idle above 600rpm and lacks power. Gotta call them when they come back from vacation. Will probably just get my original repaired at this point.

redhorse

Recap:

I have owned the car since early 2007, but it is a garage queen because I do not know everything it needs therefore I only drove it occasionally over the years. Yeah, if life and the economy every settle for two minutes, it is my intent to do a full cosmetic and mechanical restoration.

Any problems during that time? NO. Started and ran great. And when I bought it (because I was ignorant of what could have happened) I drove it straight through from Tampa FL to near Nashville -- no problems. In fact, despite the fact that it was not being driven regularly, it would start up and was ready to go.

So, the "problem" occured after the last shutdown (about three weeks ago) and before or during the attempt to start it last time (about two weeks ago, so a week in between give or take a day). There were no repairs during that time, or even opening the door, so whatever happened, happened due to shutting the ignition off with the key in the ignition switch or due to aging one more week. And there are no rodents to chew on wires, the garage is part of my home....however, I have done an extensive visual check for loose wires and such. Everything is in very good condition and there is no contact corrosion anywhere, which surprised me because of what I have read. This car has spent its life in garages in warm dry places so that might have something to do with that outcome.

It has the tach bounce....it is not the DME relay, and it gets gas. So, for whatever reason, there is no ignition. I did go over the ignition components and they are not the problem. All of the fuses are good. The engine just spins and no sounds like partial firing or misfiring or anything of that nature. The cam belt is in place. I have worked on lots of cars, and the sound from the engine is that of one that has absolutely zero ignition spark.

I have read something about the alarm module sometimes causing a no start, but as I said, I did not check that first. During the holidays I intend to hook up the ECU and bypass the alarm module and see if it starts. I also read a posting somewhere, where the owner of a similar vehicle commented that his car "could be suffering from the convertible problem". That might be some off the wall comment, or he might have been referring to something real. Anyone have a clue what that might have meant? The only thing I can think of is that it might have something to do with the security system being different between the coupe and the cab.

Electronic components degrade over time, mostly transistors and capacitors, but diodes burn open as do resistors, and some components create a short when they fail. All those discreet components are there for a purpose, and it could be something as simple as a transistor that experienced thermal breakdown (as it cooled down from the last run). There are too many people experiencing this problem so it is not a situation that requires some extraordinary event. In fact, it occurs to me that the ECU could be experiencing high heat because of its proximity to the exhaust. That would cause components to fail more readily.

I think I have seen a couple of simple lists of things to check, and except for the alarm module, I have done them all (did not pressure check the fuel, but there is plenty of fuel). If you have a comprehensive list, or can point to one, I would be grateful. As it is, I am using my general automotive experience and what I can read to guide me (my knowledge of the quirks of the 944 is nonexistent).

Thanks all.

F18Rep

Red...Not to be too direct but I think you need to know what you think you know. Do you have fuel pressure? Really, you've checked it? Do you not have spark? Really, youve put one of those cheezy ignition testers on the plug wire and verified? These are simple tests that can be done with equipment that is as cheap as $35 (form our sponsors) . How about a noid light on the injector harness - just about any parts place has a Bosch noid light - and with that you would know your injectors are pulsing. I'l bet one of those tests can give you something to grab onto and begin troubleshooting.
If you want to theorize some more, OK, then maybe download the DME KLR test plan. It has trouble trees for the turbo cars but a lot of the DME engine interface is the same for the NA and the document might at least give you some ideas. ...Bruce