I ported a 98 LS1 throttle body to use on my 02 WS6. I've ported a number of TB's before this being my first LS1 however. My problem is the damn thing idles all over the place, 800-1250 usually, never consistent.

I ported the front side of the TB, never going into or behind the blade area so I didn't think there were any problems with air getting by. After sometime I decided to tig the hole closed on the blade to eliminate any air getting by to see if that made a difference, nothing still idled like crap.

I changed the sensors with new ones and still nothing. The thing that doesn't make sense is one day it idles at around 800 and the other days at 1250. It also doesn't return to idle very fast, when I come to a light, depress the clutch the thing will idle up to 2000 and then down to 1250. I've changed the sensors, checked to make sure that little o ring on the IAC was in place and even put some dilectric grease on it to make sure it was sealing. Checked for vacuum leaks and made sure it was seating correctly and still nothing. If I snap the throttle at idle it just sits at 2000 grand for a few seconds then back to idle at 1250. I took readings with the Tech2 and the IAC is jumping all over the place at idle never consistent.

The only thing I can come up with is the cable arm itself, on my 02 this arm is bigger and not as elliptical where on the 98 it’s smaller and a perfect half moon. Would this make it idle crazy? My only hope now is to sell it to a friend with a 5.3 and buy a newer style TB, port it and see what it does. Unless somebody has any ideas.

 

Did you cover with epoxy/redrilled IAC and Air holes ?
If so, make IAC / AIr holes much bigger ! (at least 1/4" )
That should do the trick. I had the same problem.

 

Did you switch the throttle shafts? You need to do that if you haven't.

 

You definatly need the hole in the blade, your IAC motor is struggling right now because of it. You also should swap the shafts/cams so it operates right. Look up "idle relearn" and try that.

I would drill the hole out to stock size and work from there. There's also an idle screw on the TB itself for adjusting the blade. The IAC is going to make the car idle where it wants to, but the screw acn help. Check the TPS w/ blade closed (just plug it in w/out installing it) using your old TB and adjust the new one to match.

 

my did same on my 00 ss i resset pcm it solved it

 

Thanks guys, i did try the idle relearn but did nothing. I also never filled the IAC holes. Right now i've got the stock one back on. I didn't switch over the shafts, i was thinking of doing that but other than the cable cam what exactly is different about them? I'll try drilling out the hole and see what happens, it was idleing high before so i figured i was getting to much air, but probably now to little.

 

The 98-99 tb cams were smaller than the newer ones.

I'd drill it out to stock size, then install it and do an idle-relearn.

 

Thats what i've learned, given the smaller cam does it has a different calibration to read it?

 

The 98-99 cars will not be able to open a 00+ tb fully with the stock cable. The 00-02 cars might break the cable if you floored it because it doesn't need to move as far. A 98-99 tb would work and be driveable, but you might run into complications running the 00-02 cable.

The easiest thing to do is just swap out the TB cams/shafts.

 

Thats exactly what i was thinking except i'm getting full throttle (Via Tech2 readings) but i think its not closing completely. I'll keep looking for a 00-02 TB, i really don't want to disassemble the original on my car. Thanks for the help