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How meth affects current tune? And how to fix boost spike?

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Old 09-23-2007, 06:58 PM
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Default How meth affects current tune? And how to fix boost spike?

I had my controller basically turned off during tuning and wanted to know what kind of effect ill get from adding a small amount to my current tune. This is not to suppress KR as the car currently doesnt knock or pull timing, but its only been run in cool temps. I'd like to add the safety of the meth for hot days (like today). Im running a 50/50 mix.

Will turning on the controller to inject a small dose simply cool the charge or will it significantly change my AFR? I figure it would only run slightly richer if anything. Boost is staying the same, im mainly looking for cooler IATs.

Also, im still seeing boost spike after installing my boost controller. Its a manual version turned all the way counter-clockwise (not adding any boost). Car is setup with .4 bar spring but quickly spikes to around 8psi WOT and then drops back. It actually used to read 6psi for full boost but after settling (after spike) it drops to 5psi and stays. It feels like boost is bleeding off but it could just be that the car has more midrange than upper. Feels like if it were a leak that it would drop below 5psi after the spike rather than stay steady.
thanks for any insight.
Old 09-23-2007, 09:08 PM
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I just use mine to control heat. Set it on the lowest setting and log AF and IAT's to see what it does. I only have Hot track day data(+80*) so far on mine...IAT starts at 130ish and ends at 160ish without meth AF around 11.7:1. With meth the IAT starts at 130ish and ends at 100ish with AF around 10.7......with a little more tuning I'd like 11.5 with meth and 12.0 without as a backup if the meth fails.
Old 09-23-2007, 09:25 PM
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I figured I would set it to spray pretty mild and watch IATs. Its difficult to monitor A/F on my wideband because it goes off sometimes and others its dead on (with the dyno). Im mainly trying to avoid bogging the motor.
Old 09-23-2007, 10:59 PM
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If you want to avoid bogging the motor, use 100% meth. A water mix will cause a noticeable bog in such a mild use scenario.
Old 09-25-2007, 12:00 AM
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some updates from testing tonite.

edited the long winded post down some. Mainly just concerned about the boost spike:

-checked and the meth controller is working. I bumped up the controller curve and ran the car. Boost came very smoothly and as it rose to full boost, the car felt tremendously stronger, as though it suddenly had a small nitrous shot on top of the boost. Ive yet to feel the car pull that car. No hesitation.

-I couldn't get the laptop to read correctly so i turned the meth back off and moved on to addressing the boost leak. My new silicone came in and its nearly 3mm thicker so now my clamps fully tighten.

Did 3rd gear run, it holds full boost (6psi) all the way through 4th gear. So no leaks. It also doesn't feel like power is falling off anymore.

NOW, heres my problem. In 1st and 2nd gear the car still spikes boost. With the tweak to the boost controller it strangely spikes to 9psi for a split second then drops to 8 and temporarily holds it then drops to 6 rather than the quick spike and drop it did before. But in 3rd/4th gear it mainly holds at 6psi.

what can I do to address this boost spike? Why mainly 1st/2nd gear?

Last edited by JAvenger007; 09-25-2007 at 09:52 AM.
Old 09-25-2007, 07:26 PM
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I was wondering, how much does the boost ref line coming off the manifold affect the WG? Its a 1/4" line but I had to splice into it twice due to it being too short. Should I consider replacing it with one whole line? Its also coming off a vac block, would that make any difference?

It seems like boost spike isnt very common here



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