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Old 04-13-2009, 08:26 PM   #1
Bluefoton
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Default open loop?

Isn't the engine supposed =to switch to open loop under full throttle? Playing with my scangauge I noticed that it always remained under closed loop with either normal cruising or WOT - switched to open loop when decelerating in gear though.
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Old 04-13-2009, 09:03 PM   #2
Skidd
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Your engine can sometimes decided not to go OL if the ECU has deemed that its' not running well enough for OL. I can't say exactly what the ECU is watching for that decides this though. Plus, OpenLoop on decel is normal, as your ECU cuts off 100% of the fuel going in on decel for economy reasons.
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Old 04-13-2009, 09:09 PM   #3
Bluefoton
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^ thanks. i wonder though if it's normal for WOT. In parallel, my gas mileage dropped a lot (ie ~5mpg consistent decrease @ same speed, distance, freeway etc with respect to last years). Given I have a new air filter, fuel fitler, and plugs,I'm wondering about the o2 sensor now.
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Old 04-13-2009, 11:21 PM   #4
GrundleJuice
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There is a delay for the switch to OL.. so it wont go to OL just because the TPS says its WOT. It has to meet a few other parameter values to make the switch to OL. Also, staying in CL should only help your gas miliage (at the cost of power)... as long as the AFR's the ECU is reading are correct.
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Old 04-14-2009, 01:12 AM   #5
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It's likely the CL->OL Transition Delay you're seeing. Go WOT at idle while watching the CL/OL status. Eventually, 3/4 of the way to redline, you should see it transition to OL. Get on the gas at a high enough RPM and you'll never have time to get it to transition.
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Old 04-14-2009, 10:05 AM   #6
Bluefoton
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Thanks. Checked this morning on a highway. Flooring it on the 5th gear at 2500 rpm results in open-loop after a 10-11 seconds delay.
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Old 04-14-2009, 07:58 PM   #7
GrundleJuice
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Quote:
Originally Posted by Bluefoton View Post
Thanks. Checked this morning on a highway. Flooring it on the 5th gear at 2500 rpm results in open-loop after a 10-11 seconds delay.
It's good to know that the delay isnt exactly a function of time. Time (clock cycles or something like that, inside the ECU) plays a part but its how much time passes WHILE all the conditions to switch to OL are being met. So in 5th gear the delay at WOT might be longer than in 4th gear. there are a few things that have to be satisfied for the ECU to finally make the switch.
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