Hitting rev limiter in all gears even after edit
08-21-2004, 05:16 PM
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Hitting rev limiter in all gears even after edit I have tried raising rev limiter and changing MPH shift point - still hitting limiter.
First a little background info: 99' LS1 & 4L60E out of F-body in a 57' Bel Air 2DR HDTP. Car ran great even after updating the PCM with edit to reflect the actual tire size of 225/45/17 and rear gear of 293:1. I don't know what the stock tire and gear was in the Camaro. I later changed rear tires to 245/55/17 and now have problems. Initial edit read showed 1-2 shift set at 37mph. After initial tire and gear change, 1-2 shift changed (on it's own) to 40mph. After updating with edit to the new 245/55 tires 1-2 shift changed again on it's own to 44mph.
I first tried bumping the rev limiter up by 100 but it still hit the limiter. Next I tried bringing the 1-2 shift mph down to 38mph. I thought that the 38mph along with upping the rev limiter up by 100 would fix it - no luck.
I then hooked up Autotap and had my wife monitor as I got on it. TPS went to 100%, indicated vehicle speed climbed all the way to 55mph and then the same old thing - hit limiter (6200).
All MPH changes have been accomplished in the "Normal mode shift speed" table and also in the front page "A4 shift speed" table. I have not changed any of the RPM's in the Transmission Calibration A4 Shift Speed box. All are 6000 except for the 3-4 nrml, hot, & perf which are 5900.
What seems strange is that all the mph's in the "Performance Mode Shift Speed" table are 255mph for all TPS settings. IS THIS CORRECT? HOW/WHEN DOES THE PCM DECIDE WHETHER TO USE THE NORMAL OR PERFORMANCE TABLE? Obviously I'm missing something here. If 1-2 shift mph is set at 38mph and rpm in the "Trans Cali A4 Shift Spd" box is 6000, shouldn't it shift when I hit 6000 rpm, no matter what speed I'm at as long as I'm over the set 38mph? DO I NEED TO SET THE MPH AT 55 AND RPM TO 6200 SO THAT BOTH ARE HIT AT THE SAME TIME?
Sorry it's soo long guys - I'm just trying to give you the best picture. BTW - Fluid level is correct. Just to clarify, I am having this problem with all shifts but lets just work on the 1-2 point for now. After/if I get this one worked out I will start on why the car shifts out of O/D at around 120-125mph. If I give it too much throttle above 125mph she down shifts and hits limiter. THANKS IN ADVANCE FOR ANY HELP.
First a little background info: 99' LS1 & 4L60E out of F-body in a 57' Bel Air 2DR HDTP. Car ran great even after updating the PCM with edit to reflect the actual tire size of 225/45/17 and rear gear of 293:1. I don't know what the stock tire and gear was in the Camaro. I later changed rear tires to 245/55/17 and now have problems. Initial edit read showed 1-2 shift set at 37mph. After initial tire and gear change, 1-2 shift changed (on it's own) to 40mph. After updating with edit to the new 245/55 tires 1-2 shift changed again on it's own to 44mph.
I first tried bumping the rev limiter up by 100 but it still hit the limiter. Next I tried bringing the 1-2 shift mph down to 38mph. I thought that the 38mph along with upping the rev limiter up by 100 would fix it - no luck.
I then hooked up Autotap and had my wife monitor as I got on it. TPS went to 100%, indicated vehicle speed climbed all the way to 55mph and then the same old thing - hit limiter (6200).
All MPH changes have been accomplished in the "Normal mode shift speed" table and also in the front page "A4 shift speed" table. I have not changed any of the RPM's in the Transmission Calibration A4 Shift Speed box. All are 6000 except for the 3-4 nrml, hot, & perf which are 5900.
What seems strange is that all the mph's in the "Performance Mode Shift Speed" table are 255mph for all TPS settings. IS THIS CORRECT? HOW/WHEN DOES THE PCM DECIDE WHETHER TO USE THE NORMAL OR PERFORMANCE TABLE? Obviously I'm missing something here. If 1-2 shift mph is set at 38mph and rpm in the "Trans Cali A4 Shift Spd" box is 6000, shouldn't it shift when I hit 6000 rpm, no matter what speed I'm at as long as I'm over the set 38mph? DO I NEED TO SET THE MPH AT 55 AND RPM TO 6200 SO THAT BOTH ARE HIT AT THE SAME TIME?
Sorry it's soo long guys - I'm just trying to give you the best picture. BTW - Fluid level is correct. Just to clarify, I am having this problem with all shifts but lets just work on the 1-2 point for now. After/if I get this one worked out I will start on why the car shifts out of O/D at around 120-125mph. If I give it too much throttle above 125mph she down shifts and hits limiter. THANKS IN ADVANCE FOR ANY HELP.
08-22-2004, 10:08 PM
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Normal mode is used when the PERFORMANCE "button" is not activated.
There is a button or switch that triggers Performance in the PCM. I think the button is on the shiter handle of the A4 Firebirds. That's how it is on my GTP. It is the TOW/Haul mode on the trucks and that button is on the end of the column shift.
Maybe someone that has the performance "button" will chime in.
TTT
There is a button or switch that triggers Performance in the PCM. I think the button is on the shiter handle of the A4 Firebirds. That's how it is on my GTP. It is the TOW/Haul mode on the trucks and that button is on the end of the column shift.
Maybe someone that has the performance "button" will chime in.
TTT
08-22-2004, 11:16 PM
#3
hmm. I don't recall performace mode being an option on any ls1 fbodys?? Thats why all performance mode settings are set to 255, gm seems to use that mph for unused pcm functions. Maybe somehow you kicked on perf mode if thats even possible. If so hell i'm mounting up a button and going to town on perf mode function 
08-23-2004, 10:31 AM
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I've searched that avenue thoroughly, only one or two
years in the LT1 era had "the button". It's communicated
through the BCM digital bus and not a straight PCM
wire-up.
It's better to just tune the part-throttle shitpoints to
"ease into" your own "performance mode" based on TPS
as a "demand signal".
As far as WOT rev limiter problems, it just needs a
methodical setup (presuming no faults or programmed
falsehoods like wrong speedo cal). Jack all of your MPH
and RPM way lower than you really want, set the RPM
points to clear OK, set the MPH points to clear OK. It
may take a few blasts to get things dialed in if you
want to get it close to the bone (and, you may tag
it for a bump or two depending on environmentals
sometimes if you don't leave it some slack. You have
to go past the good place and then back off some,
to know you did it just right. Not a one try and done
kind of deal; lots of variability w/ converters, gears,
tires and the engine power curve especially in the MPH
settings.
You do not state your gears & tires and it sounds like
maybe these settings could still be messed up. Have to
be right on that.
On my 3.23 car I run with 40, 80, 125 MPH points right
now. Have run higher but was getting to some 2-3
bumps as I improved my state of tune (RPM coming up
faster than road speed against the converter slip as
I made slightly more power). First order, scale these
MPH values times (3.23/{your gears}) for a nominal
6000RPM shift (which on my car produces a real
peak RPM of 6100 or so, against a rev limit of 6250).
Now, if you set RPM to 5000 and MPH to something like
20, 50, 80 (way lower than ideal for 3.23s) and it still
rev-limits, you have another order of problem.
years in the LT1 era had "the button". It's communicated
through the BCM digital bus and not a straight PCM
wire-up.
It's better to just tune the part-throttle shitpoints to
"ease into" your own "performance mode" based on TPS
as a "demand signal".
As far as WOT rev limiter problems, it just needs a
methodical setup (presuming no faults or programmed
falsehoods like wrong speedo cal). Jack all of your MPH
and RPM way lower than you really want, set the RPM
points to clear OK, set the MPH points to clear OK. It
may take a few blasts to get things dialed in if you
want to get it close to the bone (and, you may tag
it for a bump or two depending on environmentals
sometimes if you don't leave it some slack. You have
to go past the good place and then back off some,
to know you did it just right. Not a one try and done
kind of deal; lots of variability w/ converters, gears,
tires and the engine power curve especially in the MPH
settings.
You do not state your gears & tires and it sounds like
maybe these settings could still be messed up. Have to
be right on that.
On my 3.23 car I run with 40, 80, 125 MPH points right
now. Have run higher but was getting to some 2-3
bumps as I improved my state of tune (RPM coming up
faster than road speed against the converter slip as
I made slightly more power). First order, scale these
MPH values times (3.23/{your gears}) for a nominal
6000RPM shift (which on my car produces a real
peak RPM of 6100 or so, against a rev limit of 6250).
Now, if you set RPM to 5000 and MPH to something like
20, 50, 80 (way lower than ideal for 3.23s) and it still
rev-limits, you have another order of problem.
08-23-2004, 01:54 PM
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Thanks JimmyBlue. After sleeping on it I was thinking of the exact same thing - bringing everything way down to find a starting point. I'll let you all know how it goes. Once again - Thanks for the replies guys. V/R,
Jr.
Jr.
