legacycentral bbs

I was reading up on trying to raise the stock rev limit in my '91 Legacy T with TD05, WRX IC and FMU. I keep bouncing off the limiter between 1st and 2nd gear shifts (auto tranny) and it really bogs me down. How could I clamp things off as mentioned below? I have lots of fuel control with the FMU. Thanks!


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Posted: Thu Feb 27, 2003 10:10 am Post subject:

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this is just a thought, but wouldn’t it be possible theoretically to "clamp" the cam and crank signals in order to raise the rev limit? Not allow the signals to go above a certain level. The ECU would think that the engine RPM is at the clamped value while it is actually higher then that.

I guess that idea is a little far fetched for something as important as RPM
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95 Impreza L - EJ20 swap

That'd be quite a bit tougher to do than say, clamping the pressure signal to remove fuel cut. The cam and crank signals are arranged pulses, not straight voltages like the MAP sensor.

Not to mention it would probably throw a lot of other crap off like timing and injection...

Not to mention that you would confuse the hell out of the ECU.
It would think that its spinning @ 6500rpm but the input from the cam sensor would tell it something different. It would send ignition pulses thinking it was spinning 6500rpm, so at anything over that it would probobly run like crap....thats the best case scenario.

there is a reason for a revlimmiter, to protect your engine, and unless you have had your car dyno'ed and know the power ban who knows if your even making enough power to raise it, also your car shouldn't bog when it shifts if tuned properly.

The car dosen't really bog, rather time on the track 'bogs' from 8.9 seconds in the 1/8 mile to 8.7 seconds. This thing pulls hard right up to fuel cut (limiter).

No big deal - I'll play around with the fluid level in the tranny to get it to shift before limiter... Part of my problem is that I am running 195/45R15's with the 4EAT 4.11 gears. RPM maps are not jiving!