Earlier today I took my car for a quick drive, round trip was about 20 minutes. When I pulled into the garage and put it in park, I let it idle for a few minutes just to see what the idle was like and it was quite high compared to what I've seen before. It was reading about 1050 RPM (per WinALDL). I noticed that the coolant temp was only to about 158, IAC was around 41 ( believe this was tied to the coolant sensor) and the TPS was at about 1.2% open when normally it should have been at 0%. I have verified that the sensor is set to .525v with a multi meter. I thought it was odd showing at 1.2% (I believe it was around .58v per WinALDL). I snapped the throttle real quick to see if I could get it to set back to 0% but it only dropped to 0.8% and the RPMs dropped to around 975.

I tried snapping the throttle a few more times but no change. As soon as i cut the engine off the TPS dropped to 0% (.525v) and if I restart it remains at 0%.I did notice once before in some data that I had collected that when I had a bouncing idle that the TPS was bouncing between 0% and 0.8% which I am assuming is causing a rich condition thus creating more RPMs. What would cause this?

TPS Sensor is brand new, ACDelco. I can put the old one on as I accidentally snapped it in half, hence the new one.

I can provide a link to a Google Sheets that has data if its permitted (Alternatively I can provide the link via DM). I've included a screenshot. The peaks are where I snapped the throttle and you can see the TPS dropped from 1.3% to 0.8% and the RPMs dropped a little as well. One thing I will mention is I don't think WinALDL captured the throttle response when I snapped it as it seems to poll data every 2.4 seconds and I didn't keep my foot on the throttle for more than a second.

 

Worn throttle shaft?

 

Possible, but I don't see why the TPS voltage would change from .58v to .525v by just turning the engine off and then back on and without doing anything with the throttle as well. Definitely not saying its not impossible but I would expect that if it was a worn throttle shaft that the voltage would remain consistent so if I turn off the engine and back on, I would think it would stay in the same position and thus reporting back the same voltage.

 

.58 to .525 is literally no difference and not your problem

 

You said you snapped the throttle and the idle speed drop. That classic sign of a worn throttle shaft. Any unwanted movement can cause erratic TPS voltage. Electrical noise also comes to mind too with erratic TPS voltage. But I would lean more towards a worn throttle shaft.

 

Have to agree with @Fly skids up!, this is classic shaft wear issues. Should be easy to confirm with a visual inspection by wiggling the shaft.

 

There is definitely some wiggle with the throttle shafts. I'm looking into companies to bush them and/or looking into bushing them myself. Any tips or companies to recommend would be welcomed.

 

If you're going to do it yourself there's throttle shaft bushing repair kits on eBay. I believe the throttle shaft is 3/8" on a CFI throttle body but I could be wrong. The kits are advertised as carburetor only. I don't know why this is, they work perfectly on throttle bodies.