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      03-27-2018, 06:38 AM   #52
Michael9218
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Drives: 2007 Z4 M Coupe
Join Date: Oct 2012
Location: Woodstock, GA

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DSC glitch

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Originally Posted by Michael9218 View Post
The car was back in the shop to eliminate lingering bogus codes from the de-wire and to get the dyno tune. The dyno tune found 20 more hp from the off-the-shelf performance tune. There is an odd dip in hp at 7,200 rpm. Tuner thinks this could be some kind of harmonics with the exhaust as he wasn’t able to get rid of this. It’s not noticeable when driving the car. I do like the flat torque curve. I assume this is due to the stepped header design. Absolute values aren’t entirely relevant since different dynos and different days will produce different results. Motor is stock, with Supersprint stepped headers and catless exhaust and underdrive pulleys.

I believe I found the cause of this dip in power at 7,200 rpm. While at Road A this Sunday, it was wet and cold so I went out with the DSC left on. Climbing out of T7 on the backstraight I noticed a definite dip in power at 7,200, but only in 4th gear. So it appears to be speed related, not rpm related. As the day dried out, I turned off the DSC and the mystery dip went away. So it appears to be a glitch in the DSC causing a drop in power for a couple hundred rpm at that speed. Where it was happening on the track there was no traction issue, plus it was happening on the dyno rollers as well. Elsewhere on the track where I was accelerating through that speed were downhill so it wasn't noticeable.
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