TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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That doesnt really work, the ecm uses the IAC to attempt to set the idle at a speed thats programmed into the chip. The throttle plates are adjusted to set the IAC at a certain point so it can maintain the idle speed its looking for. Now if the throttle plate or TPS is out of adjustment, thats a different thing entirely. What are you trying to set the idle at?
Follow the tech article on this site. I'll outline it for you.
Run engine up to operating temperature.
Ground the A & B terminals on the ALDL
Wait 30 seconds. The ECM is opening the IAC now and you want to wait to make sure that it is open all the way.
Unplug the IAC connector.
Remove the ground from the ALDL terminal.
Start the car.
Adjust the minuimum air by means of the Torx screw on the driver's side of the throttle body.
Turn car off.
Reconnect IAC electrical connector.
Restart car.
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
<font face="Verdana, Arial" size="2">Originally posted by irocbsa: Follow the tech article on this site. I'll outline it for you.
Run engine up to operating temperature.
Ground the A & B terminals on the ALDL
Wait 30 seconds. The ECM is opening the IAC now and you want to wait to make sure that it is open all the way.
Unplug the IAC connector.
Remove the ground from the ALDL terminal.
Start the car.
Adjust the minuimum air by means of the Torx screw on the driver's side of the throttle body.
Turn car off.
Reconnect IAC electrical connector.
Restart car.
bsa
</font>
They wanted to know how to adjust idle, not mininum air. They are not the same. Idle is a set figure in the computer chip so you must modify that chip to really set idle speed.
For more information see the PROM board and do a search.
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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's. My Camaro Project
<font face="Verdana, Arial" size="2">Originally posted by John Millican: They wanted to know how to adjust idle, not mininum air. They are not the same. Idle is a set figure in the computer chip so you must modify that chip to really set idle speed.
For more information see the PROM board and do a search. </font>
Just what John said. There is a table that you set your Desired Idle Speed to based on certain coolant temperature settings. Then there are other parameters/tables that you may need to modify to make the engine STABLE at that RPM level.
Lastly, certain things (like engine in "Park or Neutral", A/C On/Off, etc) on certain ecms can adjust the "Desired Idle Speed" further. On SD, the eprom adds "extra" rpm if you are in "Park/Neutral" or "A/C is On". Other things too, that I forget off the top of my head.
