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?

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.

114 to 117ADC is causing a 3% change in the throttle positon?!

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?

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.

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.

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.

Thanks, I'll give it a try.

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.

Attachment 32787

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.

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.

On an MS1 he wouldn't see 271, only up to 255 = 2^8-1.

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.