Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

Low rpm stumble...Have Tunercat

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Old Oct 6, 2005 | 03:40 PM
  #1  
vbxt's Avatar
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Low rpm stumble...Have Tunercat

Hey,

New 94 Z28 owner here. 6-speed. My main mods are a HOTCAM kit and LT headers. I have been working on my tune with Tunercat, and I am having severe drivability problems at low, 800-1500, rpms. I have gotten my BLM's straight with VE Master and that has helped a little.

I really have to slip the clutch to get a smooth launch, and it is really easy to stall unless I rev to at least 1800 to take off.

Traffic jams are a real pain. The car bucks badly when in first between 800-1300 rpms.

Until now I have tired increasing timing in that rpm range, that was no help. Do you think that pulling timing would help, or what else can I try?

Thanks

Last edited by vbxt; Oct 6, 2005 at 03:43 PM.
Old Oct 6, 2005 | 08:21 PM
  #2  
JPSartre12's Avatar
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From: Detroit Subs
Re: Low rpm stumble...Have Tunercat

Originally Posted by vbxt
Hey,

New 94 Z28 owner here. 6-speed. My main mods are a HOTCAM kit and LT headers. I have been working on my tune with Tunercat, and I am having severe drivability problems at low, 800-1500, rpms. I have gotten my BLM's straight with VE Master and that has helped a little.

I really have to slip the clutch to get a smooth launch, and it is really easy to stall unless I rev to at least 1800 to take off.

Traffic jams are a real pain. The car bucks badly when in first between 800-1300 rpms.

Until now I have tired increasing timing in that rpm range, that was no help. Do you think that pulling timing would help, or what else can I try?

Thanks
Does it stubble when cold and warm or just when it's not at operating temp?
Old Oct 7, 2005 | 10:05 AM
  #3  
RealQuick's Avatar
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From: Bridgewater, MA
Re: Low rpm stumble...Have Tunercat

It wouldnt hurt to try and pull timing.
Old Oct 7, 2005 | 10:08 AM
  #4  
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Joined: Jul 2005
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From: Okemos, MI
Re: Low rpm stumble...Have Tunercat

I thought that sort of behavior was normal with a hotcam.
Old Oct 7, 2005 | 04:41 PM
  #5  
vbxt's Avatar
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Re: Low rpm stumble...Have Tunercat

It bucks and jerks at all operating temps.
Old Oct 8, 2005 | 03:57 PM
  #6  
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From: GARDNERS,PA
Re: Low rpm stumble...Have Tunercat

Have you logged scan with Datamaster and looked at BLM's. You may have to tweek the MAF table to get low rpm BLM's in check. However, a hot cam is pretty mild, I'm surprised your having problems with mostly stock tables. Might want to verify good plug wires, Coil wire, Opti, etc. My guess is you have problems other than your tune.

Steve
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