Major DTC Issues with 1996 BMW 318ti M44 OBD2 HELP!!

[halifax130]

Hello! I'm currently trying to sort of an issue with my buddies 318ti Once and for all.

The Ti was purchased a few years back with a bad engine, piston 3 was seized to the cylinder wall and so the engine had to be replaced.

Luckily another friend did an m52 swap on his low mileage 318ti, also a 1996, so I installed that engine and the car ran fine.

After a couple months, the DME started illuminating the MIL and when I went to go replaced related parts, the codes would either change, stay the same, or many more codes would pop up. After changing many parts, bench testing "bad" parts and finding out they were fine, and the engine continuing to run fine as if there are not any issues, I started thinking the DME might be the issue. Coincidentally, around this time my buddy who owns the Ti lost his key and BMW was not able to match any more keys to his DME. So I decided to get a donor car, and I changed all the locks, igniton, Ews, Dme, and got more keys cut.

Now here's my current problem. The car is finally due for emissions and registration and still has the MIL on. Turns out, soon after I installed the DME and other parts to the car, the MIL turned back and he told me everything was fine. Now I'm in a hurry to get these codes gone so the car can go through emissions and registration. Although the codes change, come and go, currently the codes are P1453-Permanent P0203-Pending P0451-Pending P1145 Pending. And the car continues to run flawlessly. I'm very confused at this point and can really use a second opinion. I have changed the engine, computers, many sensors, gaskets, other miscellaneous parts.

Any help I can get will be greatly appreciated. Thanks! -Mike

[bmwdirtracer]

P-codes just aren't going to do it, Mike. The actual BMW codes are obviously translating incorrectly to your OBD code reader. I Googled P1453...and it's "exhaust gas temp sensor 1", which this car doesn't have. P0203 is injector circuit cylinder 3, which really doesn't make sense either, since the car is running fine. When I Google p1145, only Nissans show up, no other manufacturer.

Have you connected to the BMW diagnostic port with a real BMW diagnostic computer, and scanned all modules and cleared codes with the real BMW capable device? In '96, nothing coming through the OBD port was worth a damn.

[328 Power 04]

And even then, if you have some sort of stable codes,...
1. They never tell you specifically to change one component,... and 2. Don't just throw parts at it randomly. ECUs, multiple EWSs? These cars aren't hard to work on and figure out, but first, use proper diagnostics to get real codes, and then use the codes, tests, plus symptoms to make guided conclusions about what may be wrong.



Other potential issues you may have is that there are 2 different m52 engines, with different software and different sensor setups in the DME. I didn't see one tiny detail about what was swapped or anything.
I'd love to help, but this is too haphazard.

[halifax130]

Hey thanks for the reply. You've helped me in the past so i'd like to thank you again for digging into this. Anyways the codes being unrelated was sort of what brought me to write the post in the first place. To be more specific, the car is a 1996 318ti with an m44. The donor engine is from another 1996 318ti with an m44, and the Dme, Door locks, key, ignition, and ews is from a 1998 318ti with an m44. I've had an autel scanner on it before and have scanned it under dealer specifications. Hasn't been done in a long time and i don't think the new DME was in when i scanned it. I'm pretty sure now that the 98 DME is looking for different parameters than the 96 engine provides. The only noticeable difference between the engine in the car currently and the DME donor car was the secondary air pump which I had erased from the DME. Again, the car runs fine the only real noticeable issue is the MIL on. I'll try to link it up to the autel or a solus sometime soon and get you more information. But from your knowledge, is the DME really that different between these few years? I've done swaps with 6 cylinders across a larger year range with little to no issues. This M44 is driving me nuts.

- - - Updated - - -

I'm sorry that i was pretty vague before. If you read my last post it'll give a little more information. Also I have gone through diag process' with the vehicle. The part swapping was to see if there were problems with certain parts, and to test and rule things out. Did solve some actual small issues in the process. But I have multiples of many parts laying around so it was just a quick and easy way to see if I could rule things out. At this point i'm really thinking that the DME is not getting the correct information from the engine because of the 2 year difference in build month/year.

[328 Power 04]

It's all good, my reading comprehension wasn't at it's highest yesterday after a very long day. Do you have a Windows laptop you can use as a diagnostics laptop? There are easy methods to align EWS without ever having to change ews modules and things.

Also how did you 'delete the secondary air pump from DME"? From a tune, or how?

[bmwdirtracer]

Halifax, Abel's the best BMW computer guy around. Trust him.

Now, as for computer swapping from '96 to '98:
It always depends on the exact years and vehicle involved. You can swap a '97 6 cylinder M52 E36 DME for a '99, but you can't swap a '96 for a '98.

As for the M44, I do not know, off the top of my head, whether the '96 sensors are going to be plug and play into the '98 DME. Chances are good that if the '98 wiring harness plugged into the '96 engine, you'll be fine....but if you used the '96 harness, and plugged into the '98 DME, yeah, there could be a problem.

Trouble is, the wiring diagrams need to be compared, page by page. And that takes a while, and I'm already at least one beer past wiring diagram comparison. Sometimes it's easy, but on the other hand, I have spent many many hours comparing diagrams for some other two-year differences.

wedophones.com/BMWManualsLead.htm
if you want to get a head start.

The DME/EWS swap may not have been the best answer.

However, the fact that it took a couple of months for the issues to manifest is likely the real clue here. That would indicate the problem is not with the match up, but with a problem that has occurred since.

My best wild-assed guess is that the DME isn't properly bolted in place and thereby properly grounded, or that the DME compartment is, um,"overly humid" and connections are beginning to turn green.

Given your particular set of circumstances, I think I'd start by:
1) Read all codes through the 20-pin diagnostic port, with a good BMW specific diag program. Sure, the SnapOn can do it...IF it has been endowed with BMW software (that's extra) and you MUST go through the 20 pin
2) Checking / cleaning / rebolting all major powers and grounds, particularly those for the DME.
3) Unplug the DME plug, clean both sides with Wurth Electric Contact Cleaner Oil. While that's undone, open the DME and see if it's damp or green anywhere inside. After a drying, spraying with the aforementioned spray.
4) And then there are those wiring diagrams, which need to be compared.