ok, i paid a dealership $300 to tell me that i need a new computer, which cost more than the computer itself! i finally get the part from PGA, disconnect the battery, and unplug the old one, plug in the new one and it didnt work, same problem.

i have exactly all of the same problems that i had before, so i seriously doubt that it is the used computer that i bought, so it must be the dealership's diagnosis (and then they were going to charge me $2100 for work that i didnt need!)

first, id like to make sure that there isnt some special procedure for replacing the engine computer (part #008-545-50-32) so that i can go over to the dealership and get my money back.

then i need to figure out what else it could be. i would ASSUME that they would have tested the wires to the EGR before making me buy a new computer, but who knows. maybe the wiring harness to the computer?

the original problem was that the EGR and intake flap vacuum transducers werent getting a signal, so they were releasing all of the vacuum and nothing worked, including the turbo and transmission.

all of the vacuum transducers have been replaced, all of the vac lines have been checked and replaced. when that was done, the car was perfect for about 30 minutes, then went bad again.

im out of options, none of the shops i take it to can figure it out, im totally worn out, but not about to give up. please help if you can.

thanks

__________________
1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350

How about the issues identified by your earlier post?

turbo vacuum/wastegate problems, need advice

The boost control system on this car is not all that complicated, you need 1) signals from the ECU to the actuators 2) A vaccum source and 3) Actuators that work.

All these things are easily checked with a vaccum guage, a voltmeter and your eyes.

Since your shop apparently did some work on the system I'd start by studying the routing lines for the vaccum circuts and seeing if maybe the shop made an error somewhere.

You also mentioned that the transmission was effected by this problem, are you aware that the transmission control circuts are totally seperate from the boost control circuts?

It's sounding more and more like you "computer" problem is actually some sort of vaccum supply problem.

Tim

yes, i realize that ive posted on this same thing numerous times without really any new details, and i guess you guys are about as sick of it as i am by now, so i appreciate your patience. but isnt it interesting how the facts have changed spontaneously over the last 3 months though? (2 days became 30 minutes and $200 became $300!) my roomate tells me i have a problem with "hyperbole".

youre right, i should go back and check the vacuum lines again, which i havnt done personally since it stopped working after i got new transducers, before i took it to the dealership.

the reason i was so convinced it was the computer was because it worked great for a few miles after i got new transducers, then stopped working. in that period, i never even opened the hood so nothing changed and the vac lines were fine when i tested them. someone told me that it takes a few miles after the computer is reset before it logs an error and opens the wastegate. my theory was that it was logging a flase error because of a short. also, the dealership told me it was the computer, but maybe they were just estimating the most expensive problem because they couldnt find the real cause.

i have plenty of vacuum supply as long as the transducers arent hooked up(at least that was the case when i last tested). the EGR and intake flap transducers were losing 2.5"mg each and the wastegate transducer was losing 6"mg. the transmission is only a problem when those are hooked up, because of the lack of vacuum.

the following thread details the earliest developments of my problem, if anybody wants to be filled in on the details.

disabled EGR, now what?

thanks

__________________
1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350

i havent checked the vac line connections yet, but something occured to me the other day that i hadnt realized before. i realized this when i went back and read the oldest posts i made on this topic in that other thread.

before i got the new transducers, the turbo was working fine but was leaking vacuum so i disconnected them because the transmission was just too rough. now that i got the new transducers, the turbo doesnt work AND it leaks vacuum when connected. so the new transducers actually caused a new problem.

question:

the new transducers dont look like the old ones did, theyre smaller and they dont have the blue aluminum cover on them. i figured thats just the way they make them now, but is it possible that theyre the wrong transducers made for a different system? or are these things pretty much interchangeable? wouldnt the dealership have noticed that they were the wrong ones? or is that a stupid question?

Im pretty familiar with the vacuum circut diagram, ive kept a copy of it in my toolbox for the last 4 months, so i think i would have noticed if something was plugged wrong, but ill check it. hopefully ill get out early today and be able to go see my mechanic.

later

__________________
1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350