slow96ss

alright guys, so i made a thread a while back about how sometimes when i come up to a stop light/sign and pull it out of gear the car wants to spike up to 2,000rpm for about 10 seconds and then evens back out at 8-900. that problem had stopped for a month or so and now while im driving i can feel the gas pedal stick where it is and not come back out when i take my foot off. when this happens the only way to get it to unstick is to either tap the gas pedal till it frees up or slow down as much as i can while still in gear. if i take the car out of gear while it is stuck the car revs to around 4,000rpm and stays there. also i have noticed that when majority of the time when it does stick and i am able to free it up and stop, the car will idle at 1,200rpm and not go back to 800-900rpm. i have only noticed this happening once the engine has warmed up to operating temps. mods are in sig. i will be replacing all vacuum lines, o2 sensors, and spark plugs on friday unless i get asked to work overtime. was wondering if any of you have had a similar problem or an idea on what could be causing this because it almost caused me to rearend someone yesterday in town. sorry for writing a book but had to explain what was going on. thanks for any help.

Badazz 97 TA

iTrader: (18)

Have you cleaned the throttle body at all to see if its gunked up with carbon or debris? Is the return spring on the throttle body strong enough still to bring it back to idle. I would be looking at everything to do with the throttle body before anything else.

slow96ss

the throttle body is brand new just put it on a few weeks ago. i looked at it yesterday and it is still very clean. all the vacuum lines are connected but a few had some dry rotting so thats why they will be replaced. all sensors are connected also. ses light is not on which i dont trust anyway because it is always on and off and when it is on and codes are ran the only codes that ever come up are random misfire, and bank 2 too lean.

also does cruise control not work with the tb that i put on?

95mysticta

iTrader: (4)

Im willing to bet your IAC is gummed up. I really wouldnt think it would be the cable unless with the new tb your cable has a lot of slack in it or its too tight. If the IAC is dirty and gummed up it can stick and hold your rpm and then it will slowly push the iac valve back to lower the rpm when it un sticks itself. Id start there.

slow96ss

it wasnt dirty when i replaced the TB but i will check that after work today. one of the throttle cables does have some slack though but i didnt think it would cause this issue. is this problem usually connected to the IAC?

95mysticta

iTrader: (4)

Its simple to check... check the return spring area not just the tip. I had that issue with mine this year where it the return spring was all cakes up not the tip and it would case it to stick open/closed.

96capricemgr

iTrader: (1)

The Holley TB is WELL known for sticking issues, a search should reveal the fix now that you know the part is prone to it.

For 52mm you would have been VASTLY further ahead to go with a rebored stocker as all the aftermarket TBs have issues, the Holley are just more substantial issues than most. If spending the coin on an aftermarket TB then 58mm is the only way to go.

Was the LT4 manifold destroyed to fit the LT1 heads? The only thing that separates it from an LT1 intake is more material above the ports to seal to the taller LT4 head ports. That extra material will stop it from seating right on LT1 heads unless the intake is ruined as an LT4 manifold by milling the material off or the heads have some of the valve cover rail ground off to make room for the LT4 manifold, then after all that you just have a red intake that is internally the same as the later small port LT1 intakes just like your car came with.

If the heads or intake were modified to fit eachother than that work could also be suspect and a potential source for a vacuum leak.

slow96ss

95mysticta- thanks for that i will be sure to check that as i only checked the tip
96capricemgr- i got the holley tb for $80 from a friend that is getting out of the lt1 crowd and into ls1 i still have the stock tb sitting in the shop. the lt4 manifold was put on by previous owner along with different heads(not sure what kind and he didnt know either but said they were ported and on a 93 firebird that was a strip car before he bought them). i wish he would have had the lt1 intake and heads still when i bought the car cause i would have just ported both and been done with it. about 3-4 months ago i had a major vacuum leak in the back of the intake and had to replace the gaskets. i know for sure that there are no leaks from the intake manifold now