'97 GLT ECU swap (M4.4 to M4.4), no AC afterwards.

Post by **Chuck W** » 12 Aug 2018, 19:39

OK, so quick backstory. Doing an RN motor swap on my wife's '97 GLT ('01 XC70 LPT motor). As part of the work, we swapped in a 16T, blue injectors, and a '98 V70R ECU.

Finally got all of the stuff wrapped up today and fired it up. Started on the first crank, with no noises, no warning lights, and no leaks. So that's a bonus.

The only issue that has popped up is that the AC doesn't work any longer. As a quick check, I swapped the original ECU back in, and the AC worked as before.

I know that there are known AC/ECC issues with swapping an M4.4 ECU into an M4.3 car, but the '97 GLT ECU is supposed to be an M4.4 unit, even though the '97 T5 and R HPT ECUs are M4.3.

I'm making a guess that the '97 GLT is an M4.4 ECU, it has whatever software mods that are needed to work with the 850 ECC units. Similar to what the "software mod" does (As listed below)

For now, I'd like to shake the car down with the HPT set-up, and just not run the AC. That isn't going to fly in the long term, however.

Looking at the M4.4 Wiki. I have 2 choices. I can flash another ECU with the 607 bin and do the software AC mod, or I can keep the V70R tune, and do the internal hardware mods.

I'm kind of intrigued about keeping the V70R tune, but in the end, it's probably not really going to matter much in this situation. I tried to find a V70R bin on the Motronic Suite, but didn't come across anything. (I'm very green at TunerPro and digging into this stuff).

Anyone have any input, or corrections to what I think is happening here? Any experience on either of the AC mods?

Thanks!

Post by **wizechatmgr** » 12 Aug 2018, 19:52

I think this will be a Misha type question.

Post by **erikv11** » 13 Aug 2018, 00:18

Yes the 97 GLT has a 4.4 ECU stock. Short answer is you have it right.

I had exactly the same question about 3 years ago (http://volvospeed.com/vs_forum/topic/17 ... n-a-flash/). Based on what I've seen since then, any 850 will need the AC mod if you put in an HPT 4.4 ECU/tune, but always best to just test it out - if the AC doesn't work when you install a 4.4 ECU, then the tune needs the mod. Or as you said, you can make a hardware mod but I wouldn't mess with that.

I'd flash on 607rev5b (and the A/C mod), you will definitely notice the increased top end power of the 16t compared to the LPT. You will also lose some peppiness in town in exchange for the extra power on the highway. Maybe get a spare ECU, they are cheap, so you can save the R tune in case you want it later. Or drop it in for comparison any time, you just won't have A/C.

Post by **Chuck W** » 13 Aug 2018, 07:00

Well, I do have 3 M4.4 ECUs currently. These two and a '98 T5 manual one that I stumbled across in the JY a few weeks ago.

Seeing as I'll need to flash any of them to run in our '97's, I guess it really doesn't matter.

The AC mod only works on the 607/608 ECU's, correct?

Post by **erikv11** » 13 Aug 2018, 08:19

Yes. Technically, 607 and 608 are the bin files the AC mod works with, does not refer to the hardware piece (ECU itself). You can flash a manual tune on an ECU that was auto from the factory, an auto tune on a manual ECU, it doesn't matter the m4.4 hardware is all the same.

TunerPro is a little fussy but works great once you get it going. If you will be bench flashing, and since you frequent junkyards, consider grabbing an ECU box and connector from an 850/x70. Just cut it from the engine wiring harness. Then you can connect your flashing wires to the corresponding wires on the connector, you only have to hunt them down one time. It makes bench top flashing much easier in my opinion, when you can just clamp on the connector and know you have good contact with the proper ECU pins.

Remember the only difference in the R tune is slightly higher boost map at the very top end, when RPMs are way up. I've heard people say they don't notice the difference, I didn't.

Post by **Chuck W** » 13 Aug 2018, 09:36

Right, I get that it's only the software that is the concern here.

I was probably going to bench flash for this project, but I do have a couple step-up X-formers I was thinking of installing in the cars, to allow for the in-car flashing. (I want to do a manual swap on the T5 and other mods to it).

I should still have a '96 engine harness, and if not, the harness from this '01 engine should work, correct? The OBD II connector would also come in handy for connecting the USB tuning cable, I would think.

I'll probably use the "extra" ECU I have to do the flashing, at least to get started.

Post by **erikv11** » 13 Aug 2018, 11:32

Just to be clear and maybe you already got this too, but the AC mod program alters the bin file before it is flashed to the ECU.

I've never looked at an 01 ECU, not sure if the pins and connectors are the same. But check it out, that may be.

Post by **Chuck W** » 13 Aug 2018, 11:40

erikv11 wrote: ↑13 Aug 2018, 11:32 Just to be clear and maybe you already got this too, but the AC mod program alters the bin file before it is flashed to the ECU.

I've never looked at an 01 ECU, not sure if the pins and connectors are the same. But check it out, that may be.

I've kind of read over the mod, but hadn't gotten that far to see what actually happens with it, but that is good info to have before I get too deep into it.

I think I still have my 96 harness, so that should be what I need. If not, I'll try and find time to get back to the yard for a proper connector.

Post by **misha** » 13 Aug 2018, 13:07

'01 is allready P2 ....it's totally different management.

Post by **misha** » 13 Aug 2018, 14:58

wizechatmgr wrote: ↑12 Aug 2018, 19:52 I think this will be a Misha type question.

Flashing an ECU is a bit beyond me.Never tried or did that so i'll rest this case to experts.