VS M4.4 tuning dead? Start again here?

Post by **Chuck W** » 20 May 2025, 05:26

The US-spec 850s never had an immobilizer as far as I know.

As far as the map differences, I have no idea, as I don't have the -926 bin available to compare. I would imagine any of the 98MY M4.4 2.5L LPT ECUs will work. IIRC, the -460 and -459 are US-spec LPT MY98 ECUs. The 97MY -936 ECU would also probably work.|

100% P&P, I can't say, but a good chance at a yes on that. The only difference I can see might be EGR and whether donor car for the engine originally has the SAS system. Both you can defeat in the ECU with hardware mods.

LaSof · Post by **LaSof** » 20 May 2025, 09:19

Gonna put that theory to the test I guess. I managed to find a -936 ECU, so I'll try to plug that, see if it makes any difference. Might as well since my ECU (-926) is a pain in the backside to get an immo off for. I should get it in 2 weeks time, I'll report back here for all the Euro peeps. Here's hoping

-LaSof

gwcook · Post by **gwcook** » 03 Jul 2025, 15:46

Hey all,

Installed a wideband O2 sensor and put the 608_rev5b tune on the ECU, and besides max boost level, it seems to be driving perfectly and within the proper stoichiometric range which is awesome. Actually a little better from stops, as the car used to run lean when starting to move with the auto tune (~16), and now seems a bit rich (~13), which I assume is a sort of stall prevention mapping on the manual tune. Unfortunately, now I'm getting a DTC for the barometric pressure sensor - with the old (original) ECU installed, it reads perfectly within range (somewhere around 0.7v, I believe the proper range is 0.5v-4.5v). I thought maybe I had messed up when disabling the SAS pump diagnostics in TunerPro, but even without those modifications, the highest reading with the "tuned" ECU I am getting is 0.001v. Tested multiple times, and the sensor is receiving 5v on the proper pins from both ECUs, so the issue definitely has something to do with the way the new ECU is communicating with the sensor. The specific code I'm getting is EFI-422; any ideas of what's causing this odd value from the sensor? I'd really prefer to avoid disabling the sensor altogether as my drive down to college involves going through the Appalachians.

Edit: The ECU I have been tuning is from a N/A car (-743), and perusing this thread it seems like that may be the issue? I went for the cheapest one I could find on the m4.4 list on the m4.4 wiki which I had assumed meant it would work. Can anyone confirm or deny this is the probable cause before I drop ~$100 on an ECU from a turbo car (seems like that's the going rate for a turbo one).

Thanks,

Garrett

Post by **Chuck W** » 07 Jul 2025, 07:42

Pretty sure the NA M4.4 ECUs don't have any of the components populated on the board for the boost control. What are you doing for your boost control?
Whether this is also the source of your -422 code, but it is highly likely.

There is coverage of that code HERE on this site.

I would source a turbo ECU, regardless.

gwcook · Post by **gwcook** » 10 Jul 2025, 11:26

Chuck W wrote: 07 Jul 2025, 07:42 Pretty sure the NA M4.4 ECUs don't have any of the components populated on the board for the boost control. What are you doing for your boost control?
Whether this is also the source of your -422 code, but it is highly likely.

There is coverage of that code HERE on this site.

I would source a turbo ECU, regardless.

Thanks for the response, Chuck!

For some reason, I assumed that any M4.4 ECU would work, so made no changes to any boost control hardware. I'm assuming if the ECU didn't have any boost control, that the rest of the boost control hardware on the car defaulted to a "limp home" setting, so allowed me to get around 3psi at WOT with some fun wastegate noises. Only took the car for a spin around the block so hopefully didn't do any damage to those components.

Was able to score a '98 R ECU on ebay for $50 so will now be using that as my base ECU for flashing, so I can still keep the original untuned ECU just in case. I'll post an update here if that fixes the issue.

Best,

Garrett

S23 · Post by **S23** » 24 Aug 2025, 11:27

Has anyone of you added to the original M4.4 wideband e.g. AEM Uego for AFR control via motronic instead of the original lambda sensors?

Post by **Chuck W** » 25 Aug 2025, 07:22

I've got a Spartan 2 on my '97 T5. I don't run an AFR gauge.

The general installation/mods to install a WBO2 are on the M4.4 Wiki.

I'm running one of VAST's WB Modulation bins on my car, but you can also just set things up to do general logging for tuning. That part is built into the .xdf for the 607/608 bins.

Turboforslund · Post by **Turboforslund** » 26 Oct 2025, 14:48

Hi guys!

Nice to see you starting something new, fresh and promising here. I really like the optimism and i'm happy to help out if needed!

// Turboforslund

Post by **Chuck W** » 27 Oct 2025, 08:59

Turboforslund wrote: 26 Oct 2025, 14:48 Hi guys!

Nice to see you starting something new, fresh and promising here. I really like the optimism and i'm happy to help out if needed!

// Turboforslund

Glad to see you here. Your info and experience will be very valuable!

kingartur · Post by **kingartur** » 27 Oct 2025, 16:07

Hello guys, does anyone have this file: 608_rev5b18PSINew.bin?

Thanks very much!