I installed a mugen chip in my 93 dx hatch. It doesn't want to rev any higher than it did before and when its idling on cold start up it fluctuates from 1500 to 2000rpm.
Does anyone no what the problem could be.

Thanks.

 

I don't know about the revving issue, but I know for a fact that the Mugen program has issues with cold starts. Does it idle fluctuate like that once the motor is up to temp? What ECU did you chip and what motor is it powering?

 

No only for about 1 minute then idle drops to 900 rpm for about 4 minutes then goes back down to its regular 550 rpms.

 

The motor is the d15b7 and I used the AUI coded ecu.