I bought a code reader to read the codes for my CEL. The code just turned out to be for a loose gas cap One of the other functions this code reader has is it can show real time readings from some of the ECU parameters. So I was playing around with it and noticed the throttle position sensor was reading at 5.5% with my foot off the pedal. I pushed it to the floor and it only read something like 89.7% I noticed the cable was a little tight so I loosened it a smidge and adjusted the idle stop. It still only went down to 4.7% Is there something wrong with my TPS? I probed the wires a few months ago and the voltages seemed to be within the correct ranges IIRC and I couldn't find any jumps or holes in the voltage readings. I am interested in this because my car is having some intermittent bucking, missing, and power loss. I don't have a CEL or any codes stored in the ECU.

As a sidebar, I also experimented checking the TPS readings on our chevy silverado and it went perfect 0%-100%, so I don't really think there is something wrong with how the reader reads...

 

Different ECUs can do different things to sensor readings, such that a code reader might show odd numbers for one car but not another. I'd probe those wires again. If you're using a good meter the voltage numbers will tell you everything you need to know.

 

I get the exact same readings on my TPS using a Scangauge reader. My TPS is adjustable so I have tried to play with it but as I try to lower the idle setting closer to 0% then the top end reading drops lower as well. If I try to get the WOT reading closer to 100% then the idle reading goes up and the car idles too high. The PCM works off voltage readings from the TPS, not really % readings, so as long as it is getting the proper voltage range it may be fine.

 

Did you know the ecu sees "WOT" no vacuum at MUCH less than 100% tps...

Fueling and timing is primarily based on the MAP sensor.

The tps is mainly used to determine when the car should be idling, when the fuel should be cut (when u let off gas). The low range of the tps is important, the top %s hardly matter.

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Thanks for that info., that helps me out with my situation as my car has been running rich likely due to idle settings of my TPS, I should try to adjust it lower to get it closer to 0% at idle and not worry about WOT readings then. Thanks for that info.

 

I think your problems are elsewhere, the tps doesn't affect afr even at idle unless maybe the ecu is in limp mode. A reset should cause the stock ecu to recalibrate tps and relearn idle state.

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Thanks for the added info., yeah I am going to be looking at some other items that could be causing my rich issue, but the high TPS setting was causing a fast/high idle, that can't be good either way so I will try to turn it down closer to 0%.

 

Sorry if this is a thread jack, but I have a minor drivability issue in hot, humid weather (often in my town) and the A/C running. The engine bogs from a standstill unless I really rev it before clutch release. Since I don't go WOT too often, I'd rather have a fast idle, which I'm hoping would reduce the engine bog. I'm thinking of adjusting the TPS just like you to get the high idle.

Any downside guys?

 

If you get your TPS sensor to be adjustable , raising it upwards (turning towards the firewall) will increase idle, turning it downwards (towards the radiator) will decrease idle readings.

 

^Thanks, I'll whip out my tool (trusty Dremel) and see how it goes.