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Road Tuning/RPM Limit

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Hello everyone I have been doing some experiments on road tuning and wanted to ask the following , I have set up the rev limit at 4200rpm on purpose and I have been bring the afr to what I want (to admit it is tricky , road tuning is giving me a complex feeling of anxiety and fun at the same time :D ) . But my question is the following when I go near the rpm limit I see my afr going extremely rich , regardless if I try to alter it , it always goes around 9.5-10.5 .

My rpm limit is fuel cut . Is this normal or is there any setting or something I can do ?

What ECU are you using? different brands employ different strategies as they approach the control range of their limiters, what you might find is that the ignition is getting retarded and/or fuel delivery is altered to slow the engines rate of acceleration.

If you datalog the final ignition angle and injector pulsewidth as your approaching and hitting the limiter it will let you understand this more.

So its going rich around 4000-4200? I know you have wanted to set the limiter low but to eliminate that it isn't another issue have you tried raising the limiter to say 5500 and see if it still goes rich at 4000-4200?

If it doesn't go rich then I agree with Chris250 it is an ECU strategy

Thank you guys for your input . I was planning to set the rpm limiter higher , next just to see if it will alter , which I do believe that it will . I will update the post once its tried .

Thank you again

Chris Wall hit on my thoughts. I don't quite understand the low rev limiter and trying to tune with that as some sort of a handicap, but if you're looking through any of the rev limiting features and not finding anything, it sounds like something is not scaled correctly.

The reason of the low rev limiter is because it is a freshly rebuilt engine and me being really new to the ECU tuning taking things step by step . Seeing what I will encounter , see what I can adjust and do through the courses that are offered and through the help of the forum . As well as at the moment I am road tuning and taking advantage of the data logger etc.

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