Throttle Position Sensor at 4.36 volts, not reaching 5...opinions?

[ravenp]

Okay, in my quest to solve my surging idle problem I cleaned out my throttle body today, along with the IAC sensor.

I decided to look at the throttle postion sensor and discovered that at WOT, it only reads 4.36 instead of 5volts as the Chilton's book suggests.

I took the bolts out and turned the sensor towards the rear of the car and tried it again, eventually by moving it about 1/2 inch I got a 5volt reading.

I drilled out the bolt holes as much as I could so i could mount it facing towards the rear abit, and when I got it back on, the best reading I could get was 4.46volts.

So, it appears my sensor is on its' way out.

My question is how will this affect performance? And will it affect my idle??

Thanks!@!

[Backfire]

I am not sure about that specific sensor, but I know on the LS1, the TB/sensor never actually gets to a 90degree/max voltage position. It hits a physical stop before it gets there. It stops short just like you are seeing. I don't know that it is anything unusual.

[black98V6]

I think you really need to run autotap or something like that.. so you can see how the computer is interpreting the throttle position..

[ravenp]

I wish I could... i'll be getting the software when I can afford it(wedding and house plans first [img]smile.gif[/img]

I think i'll call the dealer just to price a new sensor...if it's less than 100$ i might just pick one up.

If my pcm is not interpreting my WOT properly, this could be costing me valuable et at the track right?

That's really what I'm after here. If it's not hurting performance, I don't really mind it.

thanks guys...keep the feedback coming [img]smile.gif[/img]

[ravenp]

Okay, i seem to be getting some good help on the SS board at SLP... they're suggesting I pay more attention to the physical positioning of the butterfly valve, and less at the actual sensor.

I am going to try this weekend to determine that it closes fully when it should and get's as close to 90% open as possible when WOT.

If this is off, it could definitely be keeping me out of the 15's. :(

[Magnus]

I highly doubt its off.

The PCM goes into "WOT mode" at around 75% throttle or something, it doesn't need 100% to go into power enrichment.

I wouldn't worry about the voltage.

With autotap, check the TPS %.. the voltage may be a little lower but it still may show up as 100%.

[ravenp]

<blockquote>quote:</font><hr>Originally posted by Magnus:
I highly doubt its off.

The PCM goes into "WOT mode" at around 75% throttle or something, it doesn't need 100% to go into power enrichment.

I wouldn't worry about the voltage.

With autotap, check the TPS %.. the voltage may be a little lower but it still may show up as 100%.<hr></blockquote>

Thanks Keith... I think for piece of mind, i'm going to get a mirror and a friend to help determine that the valve is closing and opening properly.

Aside from that, I need to get autotap [img]smile.gif[/img]