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Old 06-22-2009, 04:29 PM   #1
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Lightbulb Eliminating WOT open loop

So, I had an idea today for those who practice heavy throttle + short shifting: All you have to do is adjust the TPS signal and it won't go into open loop at WOT! No expensive custom tuning necessary.

I googled it, and there is prior art:
http://www.mazda-speed.com/forum2/in...c,14706.0.html
They did it for a different reason, but to the same effect.

I'd love to know if it works, but I have no vehicle to try it on...I'm not going WOT in an automatic long enough to see open loop, and my manual doesn't do open loop (thanks to a wideband O2 sensor).
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Old 06-22-2009, 09:59 PM   #2
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Out of curiosity, how do you know it's not dropping into open loop? Is that one of the parameters available over the ODB2 port?
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Old 06-23-2009, 04:29 AM   #3
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I watch my a/f ratio. when I am running regularly, It reads about 14.6-14.7 when I hit open loop, it drops to 12.5 or so.

this is shown on the scangauge though I think it is an X-gauge feature. I can't remember. been a while since I set up my scangauge
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Old 06-23-2009, 05:56 AM   #4
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Yeah, AFR is a Scangauge feature that can be programmed in as an xgauge. I programmed it a while ago, but the number never changes on my truck. I stopped watching that a long time ago with my truck.
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Old 06-23-2009, 06:29 AM   #5
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Yes, it is OBDII data. Additionally, WOT has always been more efficient for me rather than less. It would be less if I was hitting open loop enrichment.

I first found out that my car with its wideband O2 sensor stays in closed loop at WOT when I had another OBDII device which was logging data. I was confused because even on all-out WOT high RPM runs it never hit open loop until I'd get off the gas and hit DFCO. I think I posted both here and on a VW forum, and someone eventually explained it to me.
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Old 06-24-2009, 12:04 AM   #6
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Is it really necessary to go WOT if your engine can max out its manifold pressure at a lower throttle angle? For example, at 2500 RPM my Aveo can achieve full manifold pressure at around 50-60% of WOT. Also, the DBW throttle on it lets you run it at WOT in closed loop as long as you don't actually press the pedal ALL the way down.
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Old 06-24-2009, 05:58 AM   #7
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That's a good question. I'm not sure. By my understanding, manifold pressure isn't a goal, merely an indicator; the goal being to open the throttle to reduce any pumping loss as the air passes the throttle.

Also, great point about DBW. That hadn't occurred to me but it makes sense, with DBW the "gas" pedal is a torque requestor not a throttle control, so why not put WOT closed loop at 80% of pedal position and then the last 20% could be open loop...
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Old 06-26-2009, 10:34 AM   #8
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Quote:
Originally Posted by theholycow View Post

I first found out that my car with its wideband O2 sensor stays in closed loop at WOT when I had another OBDII device which was logging data. I was confused because even on all-out WOT high RPM runs it never hit open loop until I'd get off the gas and hit DFCO. I think I posted both here and on a VW forum, and someone eventually explained it to me.
Yeah, I would expect that to be the case. A narrow band O2 sensor can only give a rich/lean signal, not the actual AF ratio. With a wideband 02 they can often read accurately much richer/leaner. Problem is, you may be getting WOT enrichment, but it stays in closed loop due to the wideband 02 sensor. I'd see if you can take a look at the signal coming off the O2 sensor to see if you can determine the throttle opening that results in a change from 14.7:1, that'd be the point where it kicks in WOT enrichment.
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Old 06-26-2009, 12:11 PM   #9
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I thought that with the better data and closed loop, there was no need to enrich the mixture. I'll have to try to come up with an AFR XGauge for the VW.
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Old 06-29-2009, 07:39 AM   #10
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There is a basic open closed readout on the scangauge w/o going into the xgauge.
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