M20B25 hesitation from 5000rpm to 6200rpm

Sat Apr 19, 2014 7:06 pm

Hi there! I have a problem with my M20B25 she has a hesitation from 5000rpm to max!!!

Please take in to consideration that my car was a M40316i and I have converted it to M20B25 the hi compression engine, before the swap I fully rebuild the cylinder head, changes all engine gaskets and sills, water pump, tensioner, timing belt put a new serviced ultrasonic clean M50B23 injectors, changed all water hoses, thermostat housing with thermostat, water pipes etc. Fully serviced the engine, new gearbox and differential oil etc, I have done a major work on it the engine reves freely up to 5000rpm pulls nice and strong and from there is flat (I feel a slight misfire, but I can not tell for sure).

I am planning to change the water temperature sensor, clean the AFM, any other suggestions?

Thank you in advance
Andreas

Sat Apr 19, 2014 11:29 pm

Throttle position sensor? Possibly not registering WOT signal. They're known to fail due to oil ingress.

Sat Apr 19, 2014 11:44 pm

Possibly cambelt out by one tooth? Which ECU are you using, e.g., 0 261 200 173.

Sun Apr 20, 2014 12:19 am

Speedtouch wrote:Possibly cambelt out by one tooth? Which ECU are you using, e.g., 0 261 200 173.

Hi! Yes the 173 ECU! Anything about the ECU?

The problem is that the car was revving much better and after a day of driving the above problem started!!
Is there a chance that the timing belt went out with brand new tensioner and 30 miles on it?

Thank you in advance
Andreas

Sun Apr 20, 2014 12:22 am

badassyas wrote:Throttle position sensor? Possibly not registering WOT signal. They're known to fail due to oil ingress.

I will check that also!! Are they any measurements that I can do for adjusting it? (The throttle that I am using came from a M20B25 with Automatic transmission I don't know if that plays a role????)

Thanks in advance
Andreas

Sun Apr 20, 2014 12:00 pm

http://www.e30zone.net/e30zonewiki/inde ... ion_Switch

Also could be worth disconnecting either the battery or ECU for an hour or so to reset it, let the engine idle for at least 10 minutes to enable base idle settings to be learnt, switch off then go for a drive throughout the rev range; this ensures full data transfer from the EPROM to the processor.