what is the factory idle
Banned
Joined: Mar 2001
Posts: 203
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650 is what TPI cars are supposed to be at. But who cares ? Set it to what YOU like. Mine's set a 600 for example...
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92 Z28 5.7
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Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.
Click here to see pics of my car !
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92 Z28 5.7
------------------
Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.
Click here to see pics of my car !
Senior Member
Joined: Mar 2000
Posts: 597
Likes: 0
From: Michigan
Yeah, they manuals say 650 in park/neutral and 450 in gear but that is ridiculus. I have mine at 850 in park and 700 in gear.
bsa
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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 24# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter
bsa
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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 24# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter
Moderator
Joined: Jan 2000
Posts: 19,677
Likes: 314
C&K
Factory idle speed parameters are between 600-650 RPM in DRIVE for an automatic TPI depending on the year. This is controlled by the IAC on EFI cars. (NOTE: An aftermarket or custom PROM may have a different target idle.) It is important to realize that the idle RPM in neutral is not significant. The IAC will attempt to control the idle speed to the target idle specification regardless of other factors. The target idle speed changes at different CTS temperatures and when the AC compressor is on. The target idle speed is most easily controlled by the ECM when the throttle minimum air position is set correctly.
The procedure for setting the minimum air position is as follows:
Cut and form a paper clip into a "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' sockets. Turn on the ignition, but don't start the engine. This will force the ECM into its diagnostic mode. Wait 30 seconds to allow the IAC pintle to fully extend. Under the hood, remove the electrical connector from the IAC, then turn off the ignition and remove the paper clip jumper from the ALDL. With the IAC pintle fully extended (closed) all idle air will be controlled by the position of the throttle plates.
Locate the Torx screw on the left side of the throttle body. It may be equipped with a protective metal cap from the factory. This was intended to discourage adjustment. If the cap is present, use a small punch to knock it out. Once the screw is accessible, start the engine and place the transmission in DRIVE. Adjust the throttle stop to obtain 450-500 RPM with the transmission in "DRIVE", rotating the Torx screw clockwise to raise speed and counter-clockwise to lower speed. Once the idle RPM is set, place the transmission in PARK and turn off the engine.
Re-connect the electrical connector onto the IAC. Start engine. Idle speed should be governed by the ECM at approximately 650 rpm in "DRIVE" (for unmodified cars). Idle speed in NEUTRAL or PARK is less significant, and will be higher.
It is important to note that this and any other engine adjustments should only be done when the engine is at full operating temperature. It is also important to understand that the dash-mounted tachometers should NOT be used to set the RPM, since they are notoriously unreliable and inaccurate.
If you have attempted to "adjust" the factory hot idle without reprogramming the ECM PROM, you've just screwed up. You may have accomplished getting the curb idle higher, but do you have any idea what your IAC counts are? It's probably just sitting there, dead, and will eventually get varnished in that position. Good luck to you when the weather changes.
Carbureted vehicles are typically 550-600 RPM in DRIVE with all accessories on. The setting procedure is less involved, but must still be followed.
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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader
Factory idle speed parameters are between 600-650 RPM in DRIVE for an automatic TPI depending on the year. This is controlled by the IAC on EFI cars. (NOTE: An aftermarket or custom PROM may have a different target idle.) It is important to realize that the idle RPM in neutral is not significant. The IAC will attempt to control the idle speed to the target idle specification regardless of other factors. The target idle speed changes at different CTS temperatures and when the AC compressor is on. The target idle speed is most easily controlled by the ECM when the throttle minimum air position is set correctly.
The procedure for setting the minimum air position is as follows:
Cut and form a paper clip into a "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' sockets. Turn on the ignition, but don't start the engine. This will force the ECM into its diagnostic mode. Wait 30 seconds to allow the IAC pintle to fully extend. Under the hood, remove the electrical connector from the IAC, then turn off the ignition and remove the paper clip jumper from the ALDL. With the IAC pintle fully extended (closed) all idle air will be controlled by the position of the throttle plates.
Locate the Torx screw on the left side of the throttle body. It may be equipped with a protective metal cap from the factory. This was intended to discourage adjustment. If the cap is present, use a small punch to knock it out. Once the screw is accessible, start the engine and place the transmission in DRIVE. Adjust the throttle stop to obtain 450-500 RPM with the transmission in "DRIVE", rotating the Torx screw clockwise to raise speed and counter-clockwise to lower speed. Once the idle RPM is set, place the transmission in PARK and turn off the engine.
Re-connect the electrical connector onto the IAC. Start engine. Idle speed should be governed by the ECM at approximately 650 rpm in "DRIVE" (for unmodified cars). Idle speed in NEUTRAL or PARK is less significant, and will be higher.
It is important to note that this and any other engine adjustments should only be done when the engine is at full operating temperature. It is also important to understand that the dash-mounted tachometers should NOT be used to set the RPM, since they are notoriously unreliable and inaccurate.
If you have attempted to "adjust" the factory hot idle without reprogramming the ECM PROM, you've just screwed up. You may have accomplished getting the curb idle higher, but do you have any idea what your IAC counts are? It's probably just sitting there, dead, and will eventually get varnished in that position. Good luck to you when the weather changes.
Carbureted vehicles are typically 550-600 RPM in DRIVE with all accessories on. The setting procedure is less involved, but must still be followed.
------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader
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