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Old 01-23-2012, 04:16 PM   #1
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Default Diypnp tps idle issue.

I am running a '01+ TPS sensor wired into my '90 harness. When I calibrate the TPS with the engine cold I am seeing a value of about 114, but when hot I am seeing a value of 117. I am having an intermittent issue where the DIYPNP will not drop back into CL IDLE. Should I change my IDLE ACTIVATION TPS THRESHOLD % to 3.5% to reflect the 3% change I am seeing? Not sure if I am reading the IDLE ACTIVATION TPS THRESHOLD % correctly. I would think that when the TPS sensor is within 3% of being closed, it should drop into CL IDLE, but what are some of the other conditions that may be preventing this from dropping back into CL IDLE?
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Old 01-24-2012, 10:16 AM   #2
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What is your idle activation TPS threashold at right now? This is where it thinks the throttle is closed enough to go into closed loop.
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Old 01-24-2012, 10:24 AM   #3
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114 to 117ADC is causing a 3% change in the throttle positon?!
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Old 01-24-2012, 11:54 AM   #4
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114*1.03=117.42, so yes, when I am getting readings from 114 to 117 there is a 3% change. The original setting was 1.5% for the threshold percentage. I have set the the value at 115 with a 3% threshold. Not sure if this is correct, but it seemed to drop into idle 80% of the time.

Why would I see such variance in the TPS closed value? Am I getting a noisy signal, weak ground, etc?
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Old 01-24-2012, 12:11 PM   #5
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yes, technically 114 to 117 is a 3% change.

BUT

114 to 117ADC is a VERY small voltage change... when you consider that the full swing could be something like 114-1000 ADC, 114 to 117ADC could equal 0.003% of TPS% change.
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Old 01-24-2012, 12:36 PM   #6
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True, I think the TPS WOT is only 273 or so. What are the other conditions that need to happen for the DIYPNP to drop into CL IDLE? A better question would be, what else would cause the DIYPNP not to drop back into CL IDLE? Gets annoying driving with a perfect idle, go from one traffic signal to another and the idle is at 1500! I guess my next step is to make a log of the event and post it.

Thanks for the help so far.

I was just curious if the variance I am seeing on the TPS sensor is normal.
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Old 01-24-2012, 12:43 PM   #7
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The still doesn't seem like a large swing...the TPS should go from roughly 0-5v. My swing is something like 90-950ADC.

Still if 114 = 0% and 273 = 100%

moving from 114 to 117 should still only be a .02% throttle change - enough to be considered noise.

I'd set your closed ADC to 118, the CL TPS threshold at something around 0.5-1%TPS, and call it a day.
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Old 01-24-2012, 12:53 PM   #8
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Thanks, I'll give it a try.
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Old 01-29-2012, 01:30 PM   #9
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I am attaching a log from an instance of this happening. This is at idle, the car is not dropping into CL IDLE. I blip the throttle a few times and it finally drops into CL IDLE.

2012-01-27_16.53.08.msl
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Old 02-07-2012, 09:25 AM   #10
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Time for an update or sorts. I have been emailing DIYAUTOTUNE and they suggested to update the firmware on the unit and report back. I have updated the firmware, but with all the rain here in S. FL I have not been able to drive the car to see if there is a change. I hope that this solves it, but that being said, if the car has a high idle every once and a while, but runs as good as it does the rest of the time, I cannot complain too much. Once I get to drive the car some, I will update this post. Thanks for the help so far.
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Old 02-07-2012, 09:35 AM   #11
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On a 99-05, the TPS ADC values are ~ 110-760. That's on about 20 NBs that I've tuned myself. Another 5 NAs with NB throttle bodies that I tuned have the same values. If your max value is 273, you are doing something wrong.
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Old 02-07-2012, 10:26 AM   #12
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Quote:
Originally Posted by Reverant View Post
On a 99-05, the TPS ADC values are ~ 110-760. That's on about 20 NBs that I've tuned myself. Another 5 NAs with NB throttle bodies that I tuned have the same values. If your max value is 273, you are doing something wrong.
Also, just to clarify things, these values are for a MS2 or MS3 - if you're using a MS1 with a '99-'05 TPS, divide these numbers by 4. MS1 uses an 8 bit ADC while later MS versions are 10 bit.
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Old 02-07-2012, 10:30 AM   #13
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On an MS1 he wouldn't see 271, only up to 255 = 2^8-1.
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Old 02-07-2012, 10:31 AM   #14
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Could be that my number is wrong, I was going by memory. Either way, when I go full throttle, I get full throttle in TS. So you are probably right and I remembered my number wrong. Thanks.
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