Won't rev over 2500RPM

[jaywood]

Hi r3v,

Just swapped a SETA m20 into my early 1985 325e
Round c101 on engine side snipped off, converted to square to match early chassis side harness.
Everything works. RPM, coolant temp, etc. It starts right up every time, no throttle needed and no hesitation or sputtering.

The only problem is it won't rev over 2500RPM/3000RPM.
I give it a little throttle to rev to 2000RPM it will maintain it all day.
The second I step on it a little bit more and it reaches 2500RPM-3000RPM the throttle cuts off completely. It doesn't hesitate/sputter, and then cut off. It's a clean cut off and drops right back down to idle.

I am using the ECU that goes along with this motor. It has some sort of performance chip in there, not 100% sure which brand it is.

Motor was pulled from a known good running car that was swapped for an S50.

I will check the CPS tomorrow and test that.

What could be the problem?

[Balleristic31]

Check the airflow meter. Did you swap the SETA one in when you did the swap?

[jaywood]

Check the airflow meter. Did you swap the SETA one in when you did the swap?

Good thought. I used one from an '89 335is.

Not the same AFM that came with the motor. Seller of the seta didn't include the AFM.

[jaywood]

I am leaning towards CPS or TPS after doing a fair amount of research on this.

[jaywood]

Issue resolved:

TPS was the culprit

Thanks r3v!!