HELP! can't keep off the rev-limit/fuel-cut
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HELP! can't keep off the rev-limit/fuel-cut 1998 C5 vette LS1 A4
SD OL tune, but I don't think it makes a difference with stock tune either.
I'm using EFI-live for tuning & scanning,
trying to raise the shift points beyond 6300 RPM, and it goes into fuel-cut.
Raised rev-limits to 7300, still fuel cut at 6100 RPM
Put ALL rev limits to 8000, but still PCM commanded fuel cut at 6100 RPM.
Several flashes at different settings... putting normal, hot, and cruise all at the same numbers, but no difference.
This car has the same re-limit problem a year earlier using Edit. I tried going back to stock tune, but fuel-cut remained.
I have tried many times over a few different days, and looked through ALL of the tables and cannot find anything that seems like it would cause this.
I don't ask for help often, but this time I'm at a loss and need a hint at least.
Please throw out suggestions. Hopefully this isn't one of those "vette features"
SD OL tune, but I don't think it makes a difference with stock tune either.
I'm using EFI-live for tuning & scanning,
trying to raise the shift points beyond 6300 RPM, and it goes into fuel-cut.
Raised rev-limits to 7300, still fuel cut at 6100 RPM
Put ALL rev limits to 8000, but still PCM commanded fuel cut at 6100 RPM.
Several flashes at different settings... putting normal, hot, and cruise all at the same numbers, but no difference.
This car has the same re-limit problem a year earlier using Edit. I tried going back to stock tune, but fuel-cut remained.
I have tried many times over a few different days, and looked through ALL of the tables and cannot find anything that seems like it would cause this.
I don't ask for help often, but this time I'm at a loss and need a hint at least.
Please throw out suggestions. Hopefully this isn't one of those "vette features"
Last edited by white2001s10; Feb 5, 2010 at 09:12 AM. Reason: to clarify details of problem.
There are two tables that need adjusted. The first table is Cutoff RPM vs. Gear. This needs to be set to you desired fuel cutoff. The second is RPM Limits. Set a four lines to the same values in the Cutoff RPM vs. Gear. For instance: I am using a cutoff of 6800 and a resume of 6799.
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Under the rev-limiter tab, I have ETC limiter and fuel-cut limters,
and I've raised both to 7300.
I don't have any tune where the rev limiter actually works right, so no I cannot compare. It was acting like this over 2 years ago when using Edit to try to raise the shift points. Since the rev-limiter couldn't be changed, the shift points had to come back down.
and I've raised both to 7300.
I don't have any tune where the rev limiter actually works right, so no I cannot compare. It was acting like this over 2 years ago when using Edit to try to raise the shift points. Since the rev-limiter couldn't be changed, the shift points had to come back down.
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Originally Posted by dws6
The parameters, B3330, B3331 and te Fuel cut off limiters B3303
B3303 = all set to 7300
B3330 = 7300
B3331 = 7000
still fuel cut at 6100
rev-limiter kicks in at 6100 RPM, and it is 6100 correct engine speed.
Last edited by white2001s10; Feb 5, 2010 at 09:13 AM. Reason: clarify details
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Originally Posted by Blacker
Do you have a shift rpm table under the transmission settings? Those should be set to the desired shift point rpm. Mine has Normal, Performance and Hot Tabs.
Yep sure do.
Can't set them to 6400 or higher without hitting the rev-limiter though.
The problem isn't when it shifts at all, but never being able to reach the desired point at WOT without hitting the rev-limiter.
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Ok well I lied, the TPS % does change from 99.6% down to 99.2%, and up to 100% sometimes, but since the change is so small I discounted it as a problem.
i worked on it all day today and failed to solve the problem.
No luck.
Shaka when the walls fell
i worked on it all day today and failed to solve the problem.
No luck.
Shaka when the walls fell
Last edited by white2001s10; Feb 5, 2010 at 09:15 AM.
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It looks to be fine to me.
On my logs the PCM looks to be initiating the shift solenoid a little early, maybe anticipating a delay for the shift in the transmission, but that's probably normal.
On my logs the PCM looks to be initiating the shift solenoid a little early, maybe anticipating a delay for the shift in the transmission, but that's probably normal.
Last edited by white2001s10; Feb 5, 2010 at 09:15 AM.
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From: Fairview Heights Illinois
Originally Posted by muncie21
Have you adjusted the abuse settings?
Changing a rev limiter is very simple tuner stuff normally. There's just something weird going on here. I'm wondering if the code got corrupted a long time ago by Edit. Everything else seems to work normally though, so maybe that's unlikely.
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This was posted on Corvette Forum, Im pretty sure you have already gone over this... A member posted a link to this post.
Originally Posted by FRC Tom
Shuts it off completely, but as you can see in the top table below the cut off is at 6600 and resumes at 5999 so the fuel is not off very long.
The second table is the electronic throttle control which cuts air and fuel at a given rpm, in this case 6600 rpms in 5th. You'll never hit the rev limiter in 5th with these stock settings.
These are 2001 Z06 tables.
The second table is the electronic throttle control which cuts air and fuel at a given rpm, in this case 6600 rpms in 5th. You'll never hit the rev limiter in 5th with these stock settings.
These are 2001 Z06 tables.
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Rev-limiter parameters:
ETC Rev Limit = enable/disable
Fuel Cut-Off in P/N = 7800
Fuel re-enable in P/N = 7700
Engine overspeed time allowed = 3.0 seconds
VSS failed RPM upper limit = 7800
VSS failed RPM lower limit = 7700
Fuel Cut-Off in gears: all set to 7800 C/O and 7700 re-enable
Abuse management parameters:
A/M in gear upper RPM threshold = 8000
A/M in gear lower RPM threshold = 1500
A/M P/N upper threshold = 7300
A/M P/N lower threshold = 1500
A/M time = 0 seconds
A/M VSS threshold = disables at 2 MPH
__________________________________________________ __
ETC Rev Limit = enable/disable
Fuel Cut-Off in P/N = 7800
Fuel re-enable in P/N = 7700
Engine overspeed time allowed = 3.0 seconds
VSS failed RPM upper limit = 7800
VSS failed RPM lower limit = 7700
Fuel Cut-Off in gears: all set to 7800 C/O and 7700 re-enable
Abuse management parameters:
A/M in gear upper RPM threshold = 8000
A/M in gear lower RPM threshold = 1500
A/M P/N upper threshold = 7300
A/M P/N lower threshold = 1500
A/M time = 0 seconds
A/M VSS threshold = disables at 2 MPH
__________________________________________________ __
Looks like you covered the bases pretty well.
Couple of suggestions, for whatever they are worth.
Change RPMs for ETC cutoff, even though the master ETC has been disabled.
Look at Torque Management. There are some tables listing max torque vs. RPM.
Are you hitting the hard stop (fuel cutoff) or soft (timing retard)? Just curious.
Couple of suggestions, for whatever they are worth.
Change RPMs for ETC cutoff, even though the master ETC has been disabled.
Look at Torque Management. There are some tables listing max torque vs. RPM.
Are you hitting the hard stop (fuel cutoff) or soft (timing retard)? Just curious.
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Originally Posted by muncie21
Are you hitting the hard stop (fuel cutoff) or soft (timing retard)? Just curious.
I've never seen the timing drop on any scans.
I'm 100% positive this is fuel cut, though it is so momentary it doesn't always show the PW drop out on the log. By lowering the resume RPM you can see the PW's go to zero though.
I don't think I can get to the ETC cutoffs, besides what I've listed here.
I never see the TPS go below 99% on any logs either.
I'll check the max-torque vs RPM in the torque management when I get home from work, and I'll post it.
Last edited by white2001s10; Feb 5, 2010 at 09:18 AM.