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Part Throttle vs. WOT

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Old May 4, 2005 | 02:20 PM
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Default Part Throttle vs. WOT

I've already been WOT tuned on the dyno and am very happy with that, but I'm finally feeling comfortable enough with HPT to start on a little VE tuning to work on drivability (mainly this stupid surge I get from 1.2-1.7k RPMs).

If I save the values we brought my PE to on the Dyno can I just put them back when I get done with the VE tuning?

Or will I have to re-dynotune?

Thanks!
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Old May 4, 2005 | 02:29 PM
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retune
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Old May 5, 2005 | 09:39 AM
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Ok so you've been "dyno-tuned" Do this for me, take your PE table values, each one (each RPM interval) and apply this:

14.7/(PE value) = ???

This is the AFR that your PCM is commanding at WOT.

Now I'm betting that your AFR on the dyno was tuned out pretty darn close to 13.0 right? But I think you will find it interesting that your commanded AFR probably does not equal your actual AFR. This will be a reason why you want to retune anyway. Just cuz it's doing what you want, doesn't mean it's doing it the right way. If your IFRs are still stock, then you're already in a good place to where you can start on VE tuning. Undoing IFR messes shows you some VEEERRRY interesting things...
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Old May 5, 2005 | 05:19 PM
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Default Low rpm surge

I now have the same low rpm/part throttle surge now that I took 10 inches of intercooler pipe out. Changed some of the plumbing around. The symtom also seems to be affected by how I spin the MAS in the tubing.
Going for a retune anyway. Hope that issue is addressed.

02' GMC 6.0 Procharger
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Old May 8, 2005 | 08:02 PM
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Originally Posted by txhorns281
Ok so you've been "dyno-tuned" Do this for me, take your PE table values, each one (each RPM interval) and apply this:

14.7/(PE value) = ???

This is the AFR that your PCM is commanding at WOT.

Now I'm betting that your AFR on the dyno was tuned out pretty darn close to 13.0 right? But I think you will find it interesting that your commanded AFR probably does not equal your actual AFR. This will be a reason why you want to retune anyway. Just cuz it's doing what you want, doesn't mean it's doing it the right way. If your IFRs are still stock, then you're already in a good place to where you can start on VE tuning. Undoing IFR messes shows you some VEEERRRY interesting things...

Hmmm... I'll look at this and try it. My tuning session was more of a 'how to use HPTuners' with a very good tuner anyway. I think he wanted me to refine it when we got done. And then it'll only take a couple of pulls to get the WOT AFR back on track when I'm done, right?

Another question... I showed 0 LTFTs on the dyno, could I modify the other tables and not have to change the WOT at all?
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Old May 9, 2005 | 09:57 PM
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Originally Posted by CamTom12
Another question... I showed 0 LTFTs on the dyno, could I modify the other tables and not have to change the WOT at all?
Above 4000rpms with PE enabled, your car should always show 0 LTFTs. The car goes into open loop mode and discards the O2 readings used for trimming. I could be wrong, I'm still pretty new to the tuning world.
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Old May 9, 2005 | 10:28 PM
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Originally Posted by LS1 Sounds
Above 4000rpms with PE enabled, your car should always show 0 LTFTs. The car goes into open loop mode and discards the O2 readings used for trimming. I could be wrong, I'm still pretty new to the tuning world.
The LTFTs will lock at zero as long as there weren't any positive trims before entering PE.
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Old May 10, 2005 | 08:22 AM
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I thought they would lock to zero as long as the trims were zero +/- 4?
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