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Sohc Vtec hell?

605 Views 4 Replies 5 Participants Last post by  DonkeyKong
okay well i didnt fix my header yet but i noticed that my car has a really hard time revving past 6.5k rpm. At 6.5rpm my car makes that pulsing noise that is almost the same as a CRX HF reving past 5k. Whats wrong with my Motor if there is anything wrong...and i know for a fact power drop off beyond 7k is allot more than my friends 92 civic si. his car pulls all the way to 7.8k rpm easy while mine struggles past 7k.

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if you are runnin a pm6, how do you control the vtec? what activates the vtec?
Are you sure you dont have an 88 ecu?

The pm6 ecu on 88 models has a 6500 rpm redline and ~7000 rpm fuel cut. I dont know if the 89-91 models are the same or different.

I also heard that the ecu will substitute around a 6500 rpm fuel cut if the car is cold. So check your coolant temp sensor to see if it is working right.

I would also suggest upgrading to a p28 ecu so you will have the correct fuel maps when vtec engages and then you will have a 7500 rpm fuel cut. It will also engage vtec when it is supposed to be engaged.

Other than that, all i can think of would be the timing and vtec actuation like PSIKOTICsi and CRX-RX said.
That sound after 6.5K could be you hitting some sort of fail-safe rev-limiter. Are you sure that your vtec is engaging? Also WTF were you trying to accomplish by revving a HF past 3K rpm? they simply don't have much steam after 3500 rpm max.
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