High Idle

[bluecamaroz28]

It is stock 1999 LS1 Camaro with headers only.

It started after taking it radiator shop for cleaning the radiator. Rad was removed out of the car and put back after cleaning.

When started, it idles fine below 1000 rpm. Once I give it gas, it climbs to about 1800 rpm and stays there unitl I switch it off and restart it, then it goes again once I step on the gas.

When I unpluged the IAC, it goes down to 1000 rpm. When I plug it again, it goes back to high idle.

I tried and reset the TPS by unplugging the connector while key is off, switched key on for seconds then key off and plugged it again and started the car but it did not resolve it.

I removed the IAC, cleaned it and put it back. Nothing changed.

It was idling fine untill I took it to radiator shop.

What could be the problem??? and how to resolve it?I done a scan using HP Tuners and found these codes: P0405, P0134, P0154, P1637. I reseted them but P0405, EGR, goes back right away.

Checked the target idle using HP Tuners editor and it is right at 500rpm when hot.

Tune file is attached.

[bluecamaroz28]

Anyone, please.

[bluecamaroz28]

Ok. Here is what I found out. TB sticks at partially open. It does not close 100%.

I foreced it by hand and it would idle perfect. Done this several times and it idles perfect when I force TB by hand. However, it does not go back to close by itself.

I think it is the spring or the TB blade shaft.

So, I took out the TB, removed the TPS and cleaned TB with WD40 and sprayed the shaft from both sides. Sprayed the spring. Cycled TB from close to open by hand several times.

I adjusted the TB screw out to make the blade close more.

Put it back and it did the same. When I give it gas, it idles at 1800rpm. It does not idle down until I force the TB back.

Do I need to replace TB or it could be the throttle cable???

[Highway21]

Ok. Here is what I found out. TB sticks at partially open. It does not close 100%.

I foreced it by hand and it would idle perfect. Done this several times and it idles perfect when I force TB by hand. However, it does not go back to close by itself.

I think it is the spring or the TB blade shaft.

So, I took out the TB, removed the TPS and cleaned TB with WD40 and sprayed the shaft from both sides. Sprayed the spring. Cycled TB from close to open by hand several times.

I adjusted the TB screw out to make the blade close more.

Put it back and it did the same. When I give it gas, it idles at 1800rpm. It does not idle down until I force the TB back.

Do I need to replace TB or it could be the throttle cable???

is your cruise control cable sticking maybe? .. i would check that whole unit to make sure its not binding.

[bluecamaroz28]

is your cruise control cable sticking maybe? .. i would check that whole unit to make sure its not binding.

You are right. With help from a member over LS1TECH, here is what I found.

I poped the U cover and watched as I open the throttle and it closes except a bit at the end. Forced it by hand to close and noticed a bottom gear under the open U cover stops before the TB goes to 100% closed. When I force the TB to close, this gear turns a little bit.

I sprayed it with WD40 and flipped the throttle several times by the gas pedal and I could hear the TB close 100%.

Put back the cover and started the car. Now it idles perfect even after pressing the gas and letting it idle. It's back to normal.

I did not adjust the cable at all.

It turned out there was dust under the gear prevent it to go back fully after depressing the gas pedal.

Thanks goes to edcmat-l1.

Some little thinking could help.

[Highway21]

You are right. With help from a member over LS1TECH, here is what I found.

I poped the U cover and watched as I open the throttle and it closes except a bit at the end. Forced it by hand to close and noticed a bottom gear under the open U cover stops before the TB goes to 100% closed. When I force the TB to close, this gear turns a little bit.

I sprayed it with WD40 and flipped the throttle several times by the gas pedal and I could hear the TB close 100%.

Put back the cover and started the car. Now it idles perfect even after pressing the gas and letting it idle. It's back to normal.

I did not adjust the cable at all.

It turned out there was dust under the gear prevent it to go back fully after depressing the gas pedal.

Thanks goes to edcmat-l1.

Some little thinking could help.

glad to hear its fixed! ya i have had a few customer cars have that very same problem.. one reason i have my throttle cable going directly to my TB.. not like i ever "cruise" around in it anyways lol..