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Old 07-04-2005, 03:36 PM   #1
paulw
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Default Ecutek OL/CL crossover point?

I have a reflashed 05 STI with Green, FMIC and all other supporting mods. I have been experiencing hesitation and loss of power under light throttle from 10mm vacuum up to around zero psi. This is just at the point where the turbo starts to spool. If I go up a hill and hold the car right in this MAP range at around 2800-3000 rpm the car seems to lose power and bucks a bit. Give it more throttle and positive pressure and it runs fine.

I was thinking that it might be right at the transition point from closed to open-loop. Does anyone know what parameters Ecutek uses to make this switch?
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Old 07-04-2005, 04:59 PM   #2
jigga
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you migh want to return to your tuner so that they can iron it out for you..
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Old 07-04-2005, 05:16 PM   #3
paulw
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I will be going on the dyno in 2 weeks for a re-tune but thought I would ask anyway.
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Old 07-04-2005, 09:15 PM   #4
hondaeater69
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I believe ECUtek can change the crossover point, so it's going to depend on what they have it set at. . .
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Old 07-04-2005, 09:42 PM   #5
crazymikie
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There are a whole slew of parameters involved with the CL/OL crossover- TPS, load, rpm and the actual length of the delay values under different circumstances.

You might want to get some datalogs under the conditions where you are experiencing the problem and check them out. You might be able to see something in there. Please let me know if you need a hand.

Mike
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Old 08-15-2005, 01:55 PM   #6
paulw
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After much diligent logging with Tim B. from PDXTuning, we have figured out that the problem is some anomalous flow characteristics of the Perrin big maf in certain flow regions. At low flow, the maf voltage will briefly plateau or dip instead of ramping up smoothly as the car accelerates. Occasionally, the maf voltage spiked causing the fuel correction to go negative. This "tricks" the ecu into dropping or adding fuel since it looks like the maf flow is decreasing/increasing. This is more pronounced with the A/C on as the second fan's airflow must be causing some turbulance around the air filter which makes the problem worse.

Tim adjusted the maf curve as much as he could and the car runs much smoother now but still has the intermittent "cough". We are going to move the filter to the fender which should help with the fan turbulence issue.
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Old 08-16-2005, 11:18 AM   #7
mrbell
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The shape of your MAF housing is causing turbulence around the MAF sensor itself. Basically, at certain engine loads and speeds, the air doesn't get pulled in fast enough and circulates around the sensor giving it bad readings.
The curve can be adjusted but it can never be perfect because you're basically going to be reading two different situations as the same(low speed, where the engine isn't pulling much air, so it backs up over the MAF giving you a "double reading", and higher speed where the engine IS pulling the air in and you're getting a correct reading). I believe the only real solution is to fix the hardware problem
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Old 08-17-2005, 08:25 PM   #8
paulw
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Yes, Tim and I decided that the maf is acting exactly as you describe and tuning will only go so far. Do you know of any other "large mafs" that do not have this issue?
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Old 08-31-2005, 08:15 PM   #9
byroll01
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any news paul? you have PM
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Old 09-01-2005, 04:23 PM   #10
The Donnn
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Yeah Update ?
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Old 09-01-2005, 05:19 PM   #11
paulw
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Nothing new to report with my car. Still doing the same old thing.

However, I have noticed a number of other posts on the board with stock STI's having the exact same problem. Someone also mentioned that some of the 05 Legacy's are also having this. Makes me think it might be electrical or ecu related rather than the maf.
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Old 11-08-2005, 01:58 PM   #12
RainMaker
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I have a very similar issue. Tim has been workign on mine as well. Hopefully we can work out the hardware issue ( the BigMAF) with some help from Jeff P and the PDXTuning folks. It really is the chink in the Green'd STI 's armor.

chris
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