TPS position issue which leads to idle overspeed problems. Please help!

I'm tuning a car with an issue with the tps. It will vary the tps position at idle from 0% to 5%. My first though would simply be a sticking throttle, but that isn't the case. The car has a NW 90mm throttle body on it (4th gen f-body). At times, with more than 2% tps it would idle using the main spark table which would cause the idle to run away. So I raised the MIN TPS for the main spark table to 5% and that seemed to do the trick for 2 or 3% tps. On my last test drive however, the car decided to idle at 5% tps and when it did that the adaptive idle didn't seem to work. The car just idled on a steady timing as set in the idle table....and again the idle rpm was higher than it should be. When the adaptive does its job and the tps is between 0 and 3% the car idles great.

I have tried to relearn the tps, and it would show 0% as if it did relearn the closed position but as soon as the car is started the tps would jump back up! I also tried a different tps sensor and even a different pcm with no luck.

Has anyone else ever had this issue? The tps seems to work fine through out its range....it just seems to get some type of interference at idle only. Does the adaptive spark tables only work below a certain tps? I don't see a way to change that if so....

Check play in throttle blade shaft.
replace TB

The throttle body is tight. No movement what so ever of the shaft within the cables cam...no play of the shafts bearings.
I've had trouble with an ebay throttle body before, but this NW is very tight.

Check to make sure you put the TPS sensor in correctly. Sometimes they can be a little tricky depending on the TB. It sounds like you may have done this. Obviously the throttle stop adjustment screw should be adjusted and lock-tight added to the screw because it tends to change if you dont. Not sure if that helps but that is all I have based on the data you talk about.

Not to hijack - search brought me here. I have the EXACT same issue with a 90mm Edelbrock. Brand new out of the box. Their tech is helpful but I don't think they get what our issue is. The guy said to reset TPS while it was running...... I didn't try it yet but I could only assume that IF it worked it would find the new zero on next KOER. Then when vacuum hits it wham back to showing open. About to start drilling holes in TB, lol. I'm in for solutions!

engine>airflow>dynamic>dynamic airflow>idle zone tps but I am on a 2002 411vcm with a truck os. Turning it up a bit past the 0.8% open point helped for me and might help you, too. I do not know what other zone(s) it might cross at 5% though. You could always try it if that table is in fbody os. Maybe someone with more experience will chime in, hopefully. I just drove mine a litttle and no more sputtering. In case of it being a fluke I have some errands to run, so I'll use it and see if I have to drive two footed still, lol :pray:.

TPSes can wear out the area where they tend to rest,
over time. If the voltage is erratic but the supply and
ground are not, that's a possibility (if the TPS is not a
virgin piece).

Might check that the cables are not over-snug, and just
stopping the blade from hitting dead shut.

Knowing that the tps signal wire goes to the abs as well I started pulling abs fuses. The abs on this particular car is disabled anyway since it has 28" tires on the rear. After pulling 10 amp ABS IGN fuse in the underhood fuse compartment the tps voltage issue goes away. Plug that fuse back in and it is there again. I did this about 10 times while running and confirmend it every time.

I'm not sure why, but for this car the fuse will stay out and there will be no more tps issue.