I have a '94 LT1 (auto, 2.59) that I have a Hypertech PPIII on. The ignition coil had started to go and after replacing it with a moroso pro coil, it now hits the rev limiter when it downshifts at WOT @ ~30 mph. It had never done this before and I have now noticed it between shifts at wide open from 1st-2nd.
I didn't increase rev limiter on the PPIII because the car has 102K. Any suggestions on what to do ? Shift point adjustment or increase the rev limiter ? The car also has a set of LT4 RR, shorty hedders, hi-flow cats and a catback.
I'd put the stock program back in and see if you still have problems.
If you put proper springs on with the RR then you ought to be good to a little higher than stock redline. If you're on stock springs, better set the redline to 4000...
I believe the factory setting is 5850 on the rev limiter. Shifting is at 5750. If neither of these were changed, assuming you dont have a mechanical problem such as transmission slippage etc. It does not make sense you are hitting the rev. limiter. Bottom line is the transmission should keep you from it.
But, are you sure it is hitting the rev. limiter or could it be some other problem with the car such as ignition cutting out before 5850 rpms. Have you used anything such as datamaster to scan and see when it happens?
Aside from that, IMHO you could change the rev. limiter to 6000 or 6200 without taking any big risk of damaging the motor.
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93 Automatic White Vert. 4.09 gears, Yank 3000 converter, Hot Cam, ported heads, Exotic Muscle LT headers, magnaflow mufflers Meziere water pump, and professionally tuned by Alvin and it passes emissions!!
My best run 11.82 ET at 116.52 mph. and 1.66 60ft.
My wifes best run 11.71 at 117.31 mph.
362 rwhp
379 torque
93 6 speed White Vert. 383 with a rear mount 85mm turbo. water to air intercooler, 6 pt. rollbar. Gen. 7 dfi. and many more extras. No numbers yet!!
Thanks for the advice, I will try putting the stock program back in and see if that fixes it. If not, do you think its possible the coil is no good above a certain RPM ? It runs fine otherwise.
I wouldnt think the coil is the problem. Are you using datamaster or any data logging program? If not, how did you decide it was hitting the rev limiter?
It was at the top of the rpm band and (unfortunately) I have hit the rev limiter before manually shifting the tranny.
I took the PPIII and increased the rev limiter to 6000, and made sure the shift points were set at stock and took it out for a test drive. It didn't hit the rev llimiter at all and shifted just fine from a 30 mph WOT punch. Thanks for the input !
One other thing I have noticed a few times when reprogramming the car is that it feels sluggish for the first few miles. Is this normal ? It seems like the computer is able to compensate for whatever it is, but could this be indicative of a bad sensor ?
I took the PPIII and increased the rev limiter to 6000, and made sure the shift points were set at stock and took it out for a test drive. It didn't hit the rev llimiter at all and shifted just fine from a 30 mph WOT punch. Thanks for the input !
So you solved the symptom, but still don't know what the problem is.
One other thing I have noticed a few times when reprogramming the car is that it feels sluggish for the first few miles. Is this normal ? It seems like the computer is able to compensate for whatever it is, but could this be indicative of a bad sensor ?
If (1) the HPP resets the BLMs and (2) you have a bad tune or a mechanical problem which makes it want a different tune, then it would act like that.
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Rev Limiter settings
