Starting And Idle
Thread Starter
Supreme Member
iTrader: (2)
Joined: Jul 2001
Posts: 1,823
Likes: 1
From: San Antonio, TX
Car: 1988 IROC-Z
Engine: L98 (350 TPI)
Transmission: MD8 (700 R4) + 3.42 LS1 Rear
Starting And Idle
I have a Question for people with L98's. When the car is at operating temperture or any temp fro that matter. Ex 220* When i start mine the idle jumps to 1500-2000 RPM and take a Long Time (About 20Secs) To Get Down To 650-750RPM. Also When i'm driving down the road and try to stop the car i have to use excessive force to get the car to stop. What i have noticed that when i put the trans in Neutral (the rpms are at 2000RPM) the car stops much quicker then. When the car reaches a complete stop the rpm's slowly come down to about 650-750RPM. I would like to know is this normal? i have adjusted the tps voltage to .54VDC and adjusted minimum air rpm. I would like some advice from all the TPI guys. thanks in advance.
------------------
88' IROC-Z, 350 TPI, 700-R4
------------------
88' IROC-Z, 350 TPI, 700-R4
Moderator
Joined: Jan 2000
Posts: 19,655
Likes: 309
Mystik,
Have you cleaned and lubricated the IAC? Might help.
------------------
Later,
Vader
------------------
"Get UP - Drop the bombshell!"
Adobe Acrobat Reader
Have you cleaned and lubricated the IAC? Might help.
------------------
Later,
Vader
------------------
"Get UP - Drop the bombshell!"
Adobe Acrobat Reader
Thread Starter
Supreme Member
iTrader: (2)
Joined: Jul 2001
Posts: 1,823
Likes: 1
From: San Antonio, TX
Car: 1988 IROC-Z
Engine: L98 (350 TPI)
Transmission: MD8 (700 R4) + 3.42 LS1 Rear
Actually i haven't but, as my other problem persists, I think that wouldn't be such a bad idea. What should i use to lubricate the IAC valve? Since the vehicle cannot be driven anyways. hehe. 
------------------
88' IROC-Z, 350 TPI, 700-R4
[This message has been edited by mystikkal_69 (edited August 18, 2001).]
------------------
88' IROC-Z, 350 TPI, 700-R4
[This message has been edited by mystikkal_69 (edited August 18, 2001).]
Moderator
Joined: Jan 2000
Posts: 19,655
Likes: 309
Mystik,
It's really fairly easy, but DON'T do what I did the first time! I removed the IAC, plugged it back in to watch operation, then turned on the ignition. The IAC stepped the pintle out to full extended position until the spring took over and launched the pintle across the garage. A while later, after moving a couple of other cars and several pieces of equipment, I found all the parts I needed to reassemble the unit.
You can gently rock the pintle back and forth and allow the spring to extend it until it comes apart in your hands. Clean everything with lint-free cloths and a mild solvent. Harsh solvents can affect the insulation of the stepper motor coils. It's generally the dirt and buildup on this worm shaft that causes sluggish IAC operation.
When the worm gear on the pintle shaft is clean and dry, apply one drop of clean light oil to the shaft and work the pintle back into the rack gears of the motor by the same rocking motion. It takes a while to get the pintle back into the worm gears, but you'll get it. It is important to get the pintle fully retracted into the housing so that the pintle is not forced against the gears when reinstalling the IAC unit in the throttle body.
While the IAC is out, clean the air passages in the throttle body. The oriface in the TB where the IAC resides is the seat that the IAC valve closes against, and it can accumulate a lot of carbon, dirt, and debris. The easy way to do this is with carburetor cleaner and a small stiff brush.
When everything is clean and dry, replace the gasket if it is damaged, apply a little anti-seize to the threads, and torque the IAC to the proper specs. (13 ft/lb for '85-'89 , 30 in/lb for 1990-on.)
------------------
Later,
Vader
------------------
"Get UP - Drop the bombshell!"
Adobe Acrobat Reader
It's really fairly easy, but DON'T do what I did the first time! I removed the IAC, plugged it back in to watch operation, then turned on the ignition. The IAC stepped the pintle out to full extended position until the spring took over and launched the pintle across the garage. A while later, after moving a couple of other cars and several pieces of equipment, I found all the parts I needed to reassemble the unit.
You can gently rock the pintle back and forth and allow the spring to extend it until it comes apart in your hands. Clean everything with lint-free cloths and a mild solvent. Harsh solvents can affect the insulation of the stepper motor coils. It's generally the dirt and buildup on this worm shaft that causes sluggish IAC operation.
When the worm gear on the pintle shaft is clean and dry, apply one drop of clean light oil to the shaft and work the pintle back into the rack gears of the motor by the same rocking motion. It takes a while to get the pintle back into the worm gears, but you'll get it. It is important to get the pintle fully retracted into the housing so that the pintle is not forced against the gears when reinstalling the IAC unit in the throttle body.
While the IAC is out, clean the air passages in the throttle body. The oriface in the TB where the IAC resides is the seat that the IAC valve closes against, and it can accumulate a lot of carbon, dirt, and debris. The easy way to do this is with carburetor cleaner and a small stiff brush.
When everything is clean and dry, replace the gasket if it is damaged, apply a little anti-seize to the threads, and torque the IAC to the proper specs. (13 ft/lb for '85-'89 , 30 in/lb for 1990-on.)
------------------
Later,
Vader
------------------
"Get UP - Drop the bombshell!"
Adobe Acrobat Reader
Thread
Thread Starter
Forum
Replies
Last Post