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Old 06-06-2005, 03:01 PM   #1
wolfemancs
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Question Fuel Cut or Ignition cut on an STi

Sorry if this question is answered daily like so many are (I tried searching and looking through the engine FAQs), but I've recently started auto-xing, and have realized that sometimes there isn't enough time to bother shifting and it's better to bounce off the rev limiter. I've heard that both fuel cut and ignition cut have their problems (running lean and sending un-burnt fuel throught the turbo/exhaust respectivley). I'm wondering if anyone knows for sure which it is?

C/N: If you KNOW (not just are pretty sure) if the STi has a fuel cut or ignition cut as a rev limiter please reply with answer.

Thanks everyone
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Old 06-06-2005, 03:52 PM   #2
serendipity
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Fuel cut. The ECU shuts off the fuel pump and injectors. In addition, on the STi, the ECU controls the drive by wire throttle and closes the plate.
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Old 06-06-2005, 03:53 PM   #3
mick_the_ginge
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Fuel cut

ECU cuts fuel by tuning off the injectors, then it turns off the fuel pump, then it closes the throttle
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Old 06-06-2005, 03:57 PM   #4
CMJ
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You should use fuel cut unless you are running n2o. Ign. cut has caused valve train damage to some posters in the past.
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Old 06-06-2005, 04:00 PM   #5
mick_the_ginge
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Sorry, is the question : What does the stock ECU do? Or is it which to use?

We have answered: What does the stock ECU do?

As for "which to use?" then what CMJ said, the only issue is that I think you are running a UTEC which does not have this feature for the STI yet.
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Old 06-06-2005, 04:34 PM   #6
wolfemancs
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Cool. That's what I was looking for (what the stock ECU does). As a follow-up, is there any real harm coming from bouncing off the rev limiter? I have a friend who's been around turboed/supercharged mustangs and they've had problems with fuel cut blowing head gaskets, so that's why I'm curious.

Thanks for all the help guys,
Craig
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Old 06-06-2005, 06:24 PM   #7
WRXout
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fuel cut, i had it in my sti when i had a full turboback with out any engine mangment i peaked at 22 psi and the car just died on the freeway. but now its tuned
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