TPS range - Page 2 - Mazda Forum
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post #11 of 21 (permalink) Old 02-11-2010, 02:45 PM Thread Starter
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First paragraph second page explains the PID loop for heavy load. It is not in open loop.

From that info the engine is only in open loop at stages 1, and 2. All other instances it's bound by constant feedback loops.

Never knew the coolant temp sensor played such an important role... makes total sense.
Think about all those guys driving around without thermostat... their ecm is probably dumping massive amounts of fuel trying to compensate OR leaning the mix out.

BTW with that feedback loop info (IE " Learning Correction") you can see how those stupid Ebay resistor mods would TOTALLY throw everything off.[/b]
By open or close loop I mean whether O2 sensors are in the loop or not. There may be other loops which includes several sensors (map, maf, temp). In heavy load zone O2 sensors are out of the loop.

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post #12 of 21 (permalink) Old 02-12-2010, 06:14 AM
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When my knock sensor was bad, the engine was a lot more powerful on moderate revs during warmup. I'm always at moderate revs during warmup (sub 3k).
I could feel how power changed between good and bad, probably when the temperature reached the point where it goes in closed loop, like it was going in and out of closed loop in cycles of say 5 seconds. After replacing the sensor it is less pronounced, but definitely still has more torque during warmup. This is probably a result of Warm-up volume increase correction. Surely it is possible to tweak the sensor resistance to fool the ECU. But I guess it also decides when to engage the TCC, so it would ruin milage, and probably not be wise to use during longer periods. Wos has this mod on his dragstrip 626 though.

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post #13 of 21 (permalink) Old 02-12-2010, 03:10 PM
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Newer emissions regulations will eventually require wide band (ie more expensive) sensors that aren't ignored under high load conditions. Lambda (switching) sensors just aren't accurate under high load conditions and have to be ignored. o2 sensors are the only sensors that measure the "result" of combustion (closed loop) while all others merely estimate the amount of fuel needed using pre-programmed air/fuel maps (open loop).

Most cars use the MAF/VAF, IAT, and TPS to estimate the amount of fuel needed (with an added fudge factor) when the o2 sensor cannot be trusted. Fool the MAF with a resistor mod and the ECU injects less fuel according to the pre-programmed map. Lean mixtures mean more power but more risk of detonation.
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post #14 of 21 (permalink) Old 02-12-2010, 09:03 PM
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I saw on a youtube video of a Milly S someone had installed this,
http://www.venom-performance.com/ind...content=vcn400
Think the Milly would benefit from this?
"The VENOM 400 Performance Module easily plugs into the throttle position sensor (TPS) and the mass air flow sensor (MAF) or manifold absolute pressure sensor (MAP). The VENOM Module takes readings from the output signals from these two vehicle sensors and makes adjustments to optimize the fuel and timing curve of the engine throughout the low and midrange of the power curve."



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post #15 of 21 (permalink) Old 02-13-2010, 05:22 PM
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I put my scanner on my car and my TPS is only reading from 11% to 76% at WOT. So is that normal?



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post #16 of 21 (permalink) Old 02-13-2010, 11:16 PM Thread Starter
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No.

It has some correction but for our case I think it is not enough.





So it corrects the lower end. Whenever throttle is closed the voltage is reset to Vidl (0.5). And the lower end of the range is reset to 10%. I think everybody will read the same number for closed TB. The problem is higher end will vary randomly with mileage. I couldnt find it now but I remember TCU assumes 7/8 TB opening as WOT and downshifts directly (if rpm range allows). 7/8=87.5%

I checked mechanically today and it is ok. It hits the limiter in TB side when the pedal hits the limiter on the floor. And TB limiter was very precise 2-3 years ago.

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post #17 of 21 (permalink) Old 02-14-2010, 02:11 AM
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[/b]
Where did you get these images from? My page K2-12 from the 1996 Mazda Millenia Worshop Manual is different.

Also, has anyone seen the quiz pages out there for mechanics? I saw a couple pages and it makes me wonder what else is out there.
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post #18 of 21 (permalink) Old 02-14-2010, 06:17 AM Thread Starter
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http://www.mazdaworld.net/forums/index.php?showforum=45

Those are technical highlights, no maintenance info.

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post #19 of 21 (permalink) Old 02-16-2010, 03:10 AM
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Hey Saint_

I can confirm this on my vehicle too. Idle is 9.8%. WOT on mine is around 76-78%

I took some time to adjust mine in October and make sure the throttle closed switch was within spec using a feeler guage. I always wondered why it was not going up to 100% in the ECU readout on my scanner. Unfortunatly I never had time to debug this before the winter set in, but it was on my "to do" list.

If you figure this one out I would be very interested in your findings.
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post #20 of 21 (permalink) Old 02-16-2010, 03:35 AM Thread Starter
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Hey Saint_

I can confirm this on my vehicle too. Idle is 9.8%. WOT on mine is around 76-78%

I took some time to adjust mine in October and make sure the throttle closed switch was within spec using a feeler guage. I always wondered why it was not going up to 100% in the ECU readout on my scanner. Unfortunatly I never had time to debug this before the winter set in, but it was on my "to do" list.

If you figure this one out I would be very interested in your findings.[/b]
I am still not sure if this is a problem or not. Everybody has similar readings. However not going to open loop bugs me..

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