Motronic 4.4 from 850, is A/C mod required?

[xnRS]

Hi, I have a Motronic 4.4 from 850 AWD(0 261 204 609), it doesn't run on my car(i tried, i think it's either because it need immobilizer or because this ecu is from car with AT)

I've heard that I need an A/C mod if I run M4.4 from S70, others say that I need A/C mod for any M4.4. Also on 850 M4.4 wiring diagram I didn't found any diffrence by wiring, and also 1997 850 have same A/C part number as 1994 850

Any ideas?

[erikv11]

To run m4.4 ECU from an S70 in your 94 850, you would definitely need the Ac modification, you can either do it by software (see viewtopic.php?t=86296) or by hardware. I don't have a link for changing the hardware as I've never done that.

[Chuck W]

So, those '97MY LPT M4.4 ECUs are oddballs.

My wife's (US Spec) 97 GLT (LPT with an M4.4 ECU -936) did not cooperate with ANY of the usual ways of the M4.4 upgrade stuff. I was able to compare with my 97 T5 (M4.3 HPT) car, so I had a good control subject on what worked and what didn't.

You need to find yourself a 98MY M4.4 ECU, and then you should have no problems.
If you use the 98 MY M4.4 ECU and do the software AC mod, as instructed on the M4.4 Wiki and the VS boards, the AC will work fine. You will probably also need to start with the M4.4 Wiki -607/608 bins, as those have the immobilizers removed.

On the US spec -936 97MY LPT ECUs, I know the internals of the ECUs were a little different. I also know that I could not flash them with a "good" 607/608 bin and get them to work, nor would flashing the -936 bin to another ECU. It took some work to get the AC to function in the GLT, as a stock 98MY ECU would not work, nor would a flashed M4.4 ECU with the AC mod. The car would run fine, but the AC would not function AT ALL. Not until someone helped out with some custom code.

[xnRS]

This ECU, I think is from Japan, i bought it from seller, who sells parts from JDM cars, and he, I think knows nothing about M4.3/M4.4 stuff(bought this one for 15$), and he claims that it was removed from 850AWD.

About flasing other BIN - can you remove Immo from 0261204225 bin? Or you need to work with 608/607 ecus?

[Chuck W]

If it was an AWD LPT 850. it's a 97MY ECU and not going to cooperate for you. At least not with my experience.

That -225 is shown as an M4.3 ECU (B5234T4 w/ 16T), according to Motronics Suite. It might *work* in your car ('94) as-is, unless the immobilizer is preventing it from doing so. Comparing it to the US R bin (-628), the boost map is mildly more aggressive and the VE map is a little altered up top. Does you no good if the immo is the issue, though. The MT vs AT makes no difference to the ECU. The car should start and run, but you'd have DTCs if you were trying to run an AT ECU on a manual car, due to the lack of communication in the TCU.

You're not "removing" anything from the bin, you're flashing a new instance to the ECU. The M4.4 Wiki 607/608 bins have the immobilizers removed and can be used as a "base" tune to get started. It takes a lot of work to decode the bins, so only those ones were "officially" supported. I know 1 or 2 of the guys on the VS forum have decoded the -609 LPT bins from the 98MY cars, but those do not work on a 97MY ECU. Tried it. Tried it all on our '97GLT. (It's now running on a modified '607 bin with the 97 GLT AC control code, and a few other base bits in a 98MY M4.4 ECU).

Start with an actual 98MY M4.4 ECU, and you can flash a -608 bin and tune from there.

You can also reflash an M4.3 ECU (With an M4.3 bin). They're just not a refined as the M4.4's.

[scot850]

I love reading this stuff! Way over my head, but I just find it fascinating. Thanks Chuck for the info. Not that I will likely ever need it, but I know at least who to ask!

Thanks,

Neil.

[Chuck W]

I love reading this stuff! Way over my head, but I just find it fascinating. Thanks Chuck for the info. Not that I will likely ever need it, but I know at least who to ask!

Oh, I'm no expert on this stuff. I just had to dig into it deeper than planned to solve the AC issue on her GLT after we did the RN swap and wanted to use the larger turbo and injectors AND keep the AC working. I had people WAY more knowledgeable than me doing the "heavy lifting", but I have learned a lot in the past couple of years between both of our projects.

[scot850]

I hear you on always learning. There is also always someone more knowledgeable than you out there you can learn from.

Neil.