Rev Hang suddenly appeared after dyno tune

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soxfan143
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Joined: Mon Nov 12, 2007 5:09 pm
Location: lynnfield MA

Rev Hang suddenly appeared after dyno tune

Post by soxfan143 »

Hello Hondata. I recently was able to get my car in the dyno for a full tune session. My setup includes a Garrett GT2871R BB turbo, Full-Race turbo manifold, Full-Race 3" exhaust, TiAL 44mm gate with recirced dump, Skunk2 70mm exhaust, Walbro 255 HP pump, CTSC crushed FPR, ID 1000 injectors, GReddy intercooler, AEM IAT sensor, HKS SSQV2 BOV and a few other mods. Me and Mucter possibly found the cause but not how to rectify the issue. The car is not entering overrun and the plate isn't closing all the way. This is keeping the car from entering the open-cold fuel status preventing the S. Trims from resetting as well.

Now my issue is with rev hang. In the logs I posted there is a log from before todays tune and after todays tune. In the log titled 3-1 rev hang it starts at about 16 seconds in the log. You cans see the rpms stay at about 3k rpm until I get it into gear and again in the shift to 3rd from second after that first shift from first to second. I noticed the vacuum is a little higher than the next log, titled 2-26 home. And also the throttle plate is only closing to about 7% in comparison to the 2-3% in the second log. The second log also has a vacuum value of -24.7psi when the plate closes to 2%. The shifts I'm talking about in the second log are at 11.6 minutes and 31 seconds. If any of you guys could possibly take a look that would be awesome. I'll post up the cal as well. Thanks in advance
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soxfan143
Posts: 216
Joined: Mon Nov 12, 2007 5:09 pm
Location: lynnfield MA

Post by soxfan143 »

second log
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Hondata
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Post by Hondata »

The calibration has the same fuel values for all cam angles. This is not going to give a very consistent AFR.

Injectors are 1200 cc/min?

On the low cam tables make sure the cam angle tables go back to zero for the first two columns.

Otherwise you'll need to go back to your last calibration and make one change at a time to narrow the problem down.
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soxfan143
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Joined: Mon Nov 12, 2007 5:09 pm
Location: lynnfield MA

Post by soxfan143 »

I actually fixed it. I copied pasted the entire new cal into my ols cal and the rev hang is now gone. Identical values as the original cal. I have no idea why it worked but it did.
soxfan143
Posts: 216
Joined: Mon Nov 12, 2007 5:09 pm
Location: lynnfield MA

Post by soxfan143 »

Hondata wrote:The calibration has the same fuel values for all cam angles. This is not going to give a very consistent AFR.

Injectors are 1200 cc/min?

On the low cam tables make sure the cam angle tables go back to zero for the first two columns.

Otherwise you'll need to go back to your last calibration and make one change at a time to narrow the problem down.
Just curious, why would the AFR not be consistent if the fuel is all the same? My cam never really moves from 30* the entire time. And if it does it's only a 5* difference. Although I am having some small issues that Derek is working on.

The injector size is the same as what Injector Dynamics has on their included stat sheet for that fuel pressure. They have 1265cc flow at 70psi base.

I did also zero out the first 2 columns and it did help a little.
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Post by Hondata »

Even if you cam table is 30 degrees, the cam will spend some time moving around. The right way to tune for this is by each cam angle table. The AFR will be more consistent this way.
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Post by BV1 »

^^Agreed.

Livetuning makes this very easy to do and is particularly useful when on the dyno.

Steve
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