Throttle Position Issues...
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From: Clarksville, TN
Throttle Position Issues... Hey guys, for some reason I'm having Throttle Position issues...
I was re-looking my HPT logs tonight and I noticed that on every WOT run I only get about 85% TPS. I know my floor mat wasn't in the way and I'm on my way outside now to double-check for anything that might catch on the throttle action under the hood at all, but I'm pretty sure it was clear the last time I opened the hood. I think this could account for my dismal 1/4mi times and low dyno #'s, too.
Do ya'll have any fix suggestions?
Thanks!
I was re-looking my HPT logs tonight and I noticed that on every WOT run I only get about 85% TPS. I know my floor mat wasn't in the way and I'm on my way outside now to double-check for anything that might catch on the throttle action under the hood at all, but I'm pretty sure it was clear the last time I opened the hood. I think this could account for my dismal 1/4mi times and low dyno #'s, too.
Do ya'll have any fix suggestions?
Thanks!
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From: Clarksville, TN
ok, I went out and checked the physical travel of the throttle and it's only opening about 85%. This would explain a whole lot...
Is there any way to adjust this? It's about 15 to 20% of the way from hitting the bump-stop on the throttle-body itself so I think grinding that would be somewhat useless at this point.
How do you adjust the throttle cable?
Is there any way to adjust this? It's about 15 to 20% of the way from hitting the bump-stop on the throttle-body itself so I think grinding that would be somewhat useless at this point.
How do you adjust the throttle cable?
The cable has an adjustment in it. Follow it from the TB, you should see a big bulge in the cable. You have to push a button or something on it and it releases the cable. Adjust the length and then release the button, it will lock it back into place. It's been a while since I've done it so forgive the vagueness.
There is a locator tang on the TPS. You can file it down a little or just lop it off altogether. Doing so allows you to rotate the TPS. The idle or WOT voltage value will change depending on which direction you rotate the TPS (clockwise or counterclockwise) before you tighten the fasteners down. You need to monitor the idle voltage and WOT voltage before you tighten the lock screws down. I think the voltages are 0.8 VDC for idle and 6.5 VDC for WOT, but you better get out the GM factory manual to be exact. It's been a long time since I did the adjustment so look up the exact value before making the final setting. The cable won't really effect your TPS values for what your trying to do if I understand what your trying to accomplish. You must be reading 85% on a scan tool. OK, you need to remember that that value is arrived at from the DC voltage output of the TPS. So you can "TRICK" the PCM into thinking it's at say 90% when it is really at 85% by slightly rotating the TPS in the throttlebody housing. Doing this changes the DC voltage output of the TPS for any giving position of the throttle as controlled by the cable. Just remember that you don't want you TPS to go over the upper DC voltage limit or you'll set the overvoltage DTC and turn "ON" your SES. Use a good Digital VOM to monitor these DC values.
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I was just going to monkey around with my gas pedal geometry (I want to bring it closer to the brake anyway for better heel-toeing), I'll look for that bulge you were talking about, though
Originally Posted by CamTom12
I was just going to monkey around with my gas pedal geometry (I want to bring it closer to the brake anyway for better heel-toeing)
I practice my heel/toe down shifting all the time on the street. I feel I'm a better driver for doing it.
Here's a pic I whipped up:
This is a TCS car. If you don't have TCS then the adjuster may be in a different location.
Last edited by JasonWW; Jun 19, 2005 at 08:33 AM.
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Originally Posted by CamTom12
I was just going to monkey around with my gas pedal geometry (I want to bring it closer to the brake anyway for better heel-toeing), I'll look for that bulge you were talking about, though
I think Cameron's car has TCS. If not the adjuster may be located elsewhere like down by the cruise control module.
GM pretty much HAS to have some way to adjust it.
There are several different variations depending on whether your car has TCS, cruise control or a combination of the above parts. So the adjuster gets moved to different spots depending on your combination of options.
GM pretty much HAS to have some way to adjust it.
There are several different variations depending on whether your car has TCS, cruise control or a combination of the above parts. So the adjuster gets moved to different spots depending on your combination of options.