Truck Surges At Stop Light

Mudddawg · May 22, 2008

Hi Guys,

My daily driver (91 s-10 2wd with a 4.3 v-6 and automatic tranny,130,000 miles) is driving me nuts

While sitting at idle in gear or out of gear the truck will intermittently surge. I have replaced the intake gasket, plugs, wires, IAC valve, rebuilt the throttle body and ran seafoam. I did not replace the injectors. While driving down the road the truck does not miss at all. Do you think this could be the throttle position sensor? I ask that becuase it does seem to have a flat spot while accelerating under part throttle. Any info would help. My 2004 2500hd has a 7" lift. With gas prices close to four bucks a gallon do I need to say anymore? I really would like to get this squared away. How do you check a TPS?

Mudddawg · May 22, 2008

Hi Guys,

My daily driver (91 s-10 2wd with a 4.3 v-6 and automatic tranny,130,000 miles) is driving me nuts

While sitting at idle in gear or out of gear the truck will intermittently surge. I have replaced the intake gasket, plugs, wires, IAC valve, rebuilt the throttle body and ran seafoam. I did not replace the injectors. While driving down the road the truck does not miss at all. Do you think this could be the throttle position sensor? I ask that becuase it does seem to have a flat spot while accelerating under part throttle. Any info would help. My 2004 2500hd has a 7" lift. With gas prices close to four bucks a gallon do I need to say anymore? I really would like to get this squared away. How do you check a TPS?

Sorry. Forgot to mention I also replaced the distrubtor cap and rotory button. All parts were AC Delco.

blackbay2005 · May 22, 2008

Torque Converter?

Mudddawg · May 22, 2008

Torque Converter?

Well, That was one of my first thoughts, but you can feel the engine surge while idleing in park or neutral also. Of course it is naturally more pronounced while it is in gear under "load". The TQ seems to be working fine while driving. I am just not aware of any noteable, honest mechanics in my area. I do not mind paying to get it fixed, however I WILL NOT pay a shop hundreds of $$$ and get the truck back with the same problem. I will shutup now. Thanks for the input!!

silveradobobby · May 23, 2008

Checking TPS is easy 3 wire setup, get multimeter, probe wires find one that has 5v on it with key on thats your refernce wire now there will be one that has about .3-.9 volts on it in idle leave meter on it and open throttle it should be smooth voltage increase idle should be around .5-.9v and full open 4.5-5.0v 5 volts being max and .5 being min. Also I would check the EGR for deposits and stuck open just a hair.