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Old 05-24-2007, 11:20 AM   #1
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Default Weird miss when I raise boost

Last weekend I adjusted my boost controller to give me a little more boost. I was running about 7-7.5 psi. I have a clocked Greddy w/ I/C and TEC3 ECU w/ 460cc injectors and a Hallman MBC.

The car has been running great, but then when I upped the boost slightly, as soon as it hits about 8 psi, it is like it loses spark. I thought the plugs may be gapped too far and adjusted them down to about .028 on the recommendation from a friend running a TEC2. I tried it again and the same problem existed. If you hold it to the floor it just goes through this bucking until it reaches about 4500 rpm then it will accelerate up to redline, possibly because it is back below 8 psi in that rpm range.

I took datalogs of the problem and it appears that my ignition advance goes to 0 right as the problem happens. I cannot see anything weird in my ignition or fuel tables that would cause this. Any ideas? When I drop the boost back to where I have been running, the problem is gone again.
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Old 05-24-2007, 11:30 AM   #2
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got a boost cut on that thing? maybe a knock sensor?
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Old 05-24-2007, 12:23 PM   #3
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If there is a boost cut, I have not found it, maybe there is one? Disabled knock retard just to see if that was it and it wasn't.
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Old 05-24-2007, 01:09 PM   #4
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check the rev limiter too.

also there's some setting somewhere in the Tec to set all the advance to zero. I'm not sure if it's a toggle or what.
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Old 05-24-2007, 04:03 PM   #5
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Definately not the rev limiter. The car runs great at 7.5 psi, but appears to cut ignition at 8 psi.
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Old 05-24-2007, 04:38 PM   #6
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I think I found it. There is an overboost fuel cut that I have active at 146 kpa! Didn't even know it existed. I will try it when I get home. Thanks for making me think. Sometimes all these extra enrichments and features are just more rope to hang yourself with.
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Old 05-24-2007, 04:42 PM   #7
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i figured...
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Old 05-24-2007, 04:54 PM   #8
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i dont know if i ever ran over 8 psi on that unit

did you check the map sensor settings? it's a 2 bar unit I think.

edit: hung out in this thread too long that you posted your own solution :P
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Old 05-24-2007, 08:24 PM   #9
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The boost cut was the problem. I was hitting about a 10 psi spike then it would taper off to about 8 psi. Do I need a helper spring on the Greddy wastegate actuator to combat that?
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Old 05-24-2007, 08:27 PM   #10
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yeah it helps. Greddies are notorious for that.
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