L98 idle small problem
Thread Starter
Drifting
Joined: Jun 2005
Posts: 1,426
Likes: 1
From: brookville pa.
L98 idle small problem
ok guys hope you can help 1990 c4 L98 with a lt1 intake swap, when I start car[cold open loop] it wants to jump between 1000 and 600 rpm and mostly will stall out not always, but as soon as it goes closed loop no more surging idles around 1000 rpm[ around 800 in gear] any ideas welcome geo. ps not a vacuum leak that I am sure of
Advanced
Joined: Jun 2004
Posts: 56
Likes: 0
From: Fort Worth Texas
ok guys hope you can help 1990 c4 L98 with a lt1 intake swap, when I start car[cold open loop] it wants to jump between 1000 and 600 rpm and mostly will stall out not always, but as soon as it goes closed loop no more surging idles around 1000 rpm[ around 800 in gear] any ideas welcome geo. ps not a vacuum leak that I am sure of
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Any codes?
Take the TB apart and Idle Air Control solenoid (IAC) off clean it all up. Reassemble the TB assembly then do the IAC reset proceedure....You may also need to correct the throttle stop setting if you have messed with it in the past. Also check the TPS sensor voltages as mentioned above post then go from there.
Take the TB apart and Idle Air Control solenoid (IAC) off clean it all up. Reassemble the TB assembly then do the IAC reset proceedure....You may also need to correct the throttle stop setting if you have messed with it in the past. Also check the TPS sensor voltages as mentioned above post then go from there.
Melting Slicks
Joined: Jan 2001
Posts: 2,940
Likes: 5
From: Chesapeake VA
In addition to the good advice mentioned, I would also check the base idle (assuming your car has one, my 86' does).
After I cleaned my throttle body and IAC the first time my idle shot up to 1300 in neutral and 1100 in gear. The factory cap was still covering the idle adjustment screw, so I had to remove that and set the base idle. After that, all was well.
After I cleaned my throttle body and IAC the first time my idle shot up to 1300 in neutral and 1100 in gear. The factory cap was still covering the idle adjustment screw, so I had to remove that and set the base idle. After that, all was well.
Pro
Joined: Mar 2008
Posts: 579
Likes: 2
From: High Bridge New Jersey
It
ok guys hope you can help 1990 c4 L98 with a lt1 intake swap, when I start car[cold open loop] it wants to jump between 1000 and 600 rpm and mostly will stall out not always, but as soon as it goes closed loop no more surging idles around 1000 rpm[ around 800 in gear] any ideas welcome geo. ps not a vacuum leak that I am sure of
