Temporarily disabling ABS in OBD2 E36 M3?

[95maxrider]

I have searched on this topic and found conflicting info, so I figured I should start a thread.

I daily drive and rallycross my 1998 M3, and after speaking with many of my competitors and driving their non-ABS equipped cars, I believe I would like to try disabling ABS while I'm racing in the dirt and see how the car reacts. I figured just pulling ABS fuses/relays would do the trick, but I've read that the DME doesn't like it when ABS fuses/relays are removed and will limit redline to something like 5500 since it likes to see wheelspeed signals. Does anyone know if this is accurate? I don't want to permanently remove ABS either, as the car spends most of its life on the street. Is this as simple as pulling fuses, or is the system more complicated than that?

Is it also correct that by disabling ABS my brake proportioning will be thrown off, and I'll be much more likely to lock up my rear brakes?

Thanks!

[aeronaut]

Don't know about the ECU on OBD2 cars (disabling ABS on OBD1 cars doesn't change engine management by ECU).

But to your second question, kind of yes. The mechanical bias on the E36 is rearward, and without ABS, rears lock up well before fronts. Disabling ABS doesn't technically change the bias, but the ABS stops managing the rearward-happy lock up.

[ScotcH]

You can pull just the ABS pump fuse ... it should leave the wheel speed functional, just not activate the pump. As stated, the lockup characteristics will change. For the better? You need to test.

I'm not sure about OBD2, but OBD1 uses diff sensor for speed signal for the DME, not ABS wheel sensors, it would not go into limp mode without ABS. Having said that, there are for sure ODB2 track cars with disabled ABS, and they don't have redline issues. But perhaps that's flashed out of the DME (but I don't think so)

[aeronaut]

You can pull just the ABS pump fuse ... it should leave the wheel speed functional, just not activate the pump. As stated, the lockup characteristics will change. For the better? You need to test.

I'm not sure about OBD2, but OBD1 uses diff sensor for speed signal for the DME, not ABS wheel sensors, it would not go into limp mode without ABS. Having said that, there are for sure ODB2 track cars with disabled ABS, and they don't have redline issues. But perhaps that's flashed out of the DME (but I don't think so)

Yea, thinking about this a bit more, I'm very confident the ABS and engine ECU are completely independent on both OBD1 and 2 cars. Hence, the ease to throw out the full ABS system and replace with MK60.

[95maxrider]

Alright, well I pulled fuse #38 as that appears to be the one for the ABS pump, so I'll see how it behaves on the street in terms of it affecting the redline, and then test the lack of ABS this weekend at the race. Thanks for the help, and I'll post back with the results.

[95maxrider]

Well pulling fuse #38 did the trick and braking feel and performance in the dirt was much improved with ABS disabled. I wish I had done this years ago!

[golgo13]

I removed my MK20 ABS and installed MK60 but didn't connect the newer ABS system to my older OBDII DME in my 1998 E36M.

Yes the DME got angry, but not once did it bother me on track nor did it limit the redline, etc.