Miller maf with bbr chip?

[actletpone]

I am starting to make progress on my new car. 1990 325i.
It has a rough idle sometimes and today it actually stalled at idle. I am not unfamiliar with e30 idle issues. I have tested all the common items TPS, coolant temp sensor, ICV, pulled the c191 connector apart etc. I havn't noticed any vacuum leaks. When you come to a stop the idle surges for about a minute and then evens out, although I still believe the idle is low when it evens out.

Anyway, the car has a miller maf. The other day I soldered the correct wires by the ecu together for the maf (as they were previously just twisted together). The ecu has a bbr performance chip in it. Can this combination work? I also got a miller chip with the car (which was sitting in the ash tray).

[digger]

pretty sure you gotta use a miller chip mate so its compatible with the MAF

[actletpone]

So I swapped the chips, figured it can't hurt anything. Just went for a test drive, at first it seemed to have unsteady/jerky acceleration. Also seems to have less low end power. Although I did not experience my rough idle problems, idle still seems low though (just above 500). When I rev it and let of the throttle with the miller chip the tacho slows it's drop around 800 and then gradually goes to just above 500 in a very controlled way. When I did this with the BBR chip the idle was all over the place, very rough would surge and nearly stall. I'll leave the miller chip in for a while and see how it goes, then swap them back and see if the rough idle returns.

[mpowerful]

Unless the bbr chip is specifically tuned for the maf it wont work.

[actletpone]

Unless the bbr chip is specifically tuned for the maf it wont work.

Unfortunately I don't know and I can't ask the previous owner

[E30-325iS]

Try disconnecting the battery for a few minutes to clear the ECUs trim memory and make sure the O2 sensor is connected and working.

[actletpone]

Try disconnecting the battery for a few minutes to clear the ECUs trim memory and make sure the O2 sensor is connected and working.

Drove it round a bit today, no change. Will disconnect the battery and see if it makes a difference. Going to do more vacuum leak hunting + clean up the engine bay next week. No 02 sensor from factory.

#Update/ disconnected the battery, no difference. I have put the bbr chip back in, I can only assume it must be tuned for the maf, the car accelerates so much smoother with the bbr chip than with the miller chip.

I don't have the stock chip to see what it is like with an AFM. With either chip the idle is low (just above 500). The only difference is after giving it a rev the miller chip sees the idle steadily drop to 500 but with the bbr chip it drops below 500, jumps up again then evens out at 500. Seems like a vacuum leak to me.