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Idle goes up to 3,000 RPM's

Old 03-26-2009, 03:41 PM
  #1  
mercedez
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Question Idle goes up to 3,000 RPM's

The ECT, ACT and the IAC have all been replaced and throttle body cleaned.
The idle is still high after car warms up. It goes from a low of 800 to 3,000 which is now worse after a new IAC has been installed?
What else could it be?
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Old 03-26-2009, 07:23 PM
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87foxgt
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3,000 is pretty high I was going to say check your vacuum lines but thats really high. check the idle speed adjustment screw. At 3000 my powerband kicks in lol
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Old 03-26-2009, 07:45 PM
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89musclestang
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does it surge up and down or does it stay steady at 3000? and is it speed density or MAF? it could be your TPS sensor or MAF sensor if you have it...
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Old 03-26-2009, 08:42 PM
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Originally Posted by 89musclestang
does it surge up and down or does it stay steady at 3000? and is it speed density or MAF? it could be your TPS sensor or MAF sensor if you have it...
It goes up and down from 1,000 to 3,000. It is MAF 1988 California 5.0
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Old 03-26-2009, 08:44 PM
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Originally Posted by 87foxgt
3,000 is pretty high I was going to say check your vacuum lines but thats really high. check the idle speed adjustment screw. At 3000 my powerband kicks in lol
It didn't do that with the old IAC. Then it would only go as high as 1,500 off and on erratically after the car was fully warmed up.
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Old 03-27-2009, 04:07 PM
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PJC Racing
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You need to do a base idle reset.

1. Clean TB with carb cleaner and nylon brush (toothbrush size). Engine off, fully open TB blade and spray/brush TB until all gunk and oil residue is cleaned.

2. Allow to dry, or close TB blade and start engine until it clears all carb cleaner fumes/liquid.

3. Let engine idle...if it doesn't, increase idle speed via TB stop screw until engine stays idling on its own.

4. Disconnect IAC valve, if engine dies repeat 3 with IAC disconnected.

5. Set idle speed to the lowest setting possible between 650-850 rpms with IAC disconnected. It is key to use the lowest possible to prevent idle surge, rolling, etc once the IAC is connected as follows.

6. Turn engine off, and reconnect IAC

7. With Ign On Eng Off, check TPS voltage output....if it's between .8vdc - 1.0vdc, it's OK. This voltage check should be done between the Green and Black wires at the TPS side connector as shown in the pic below....(-) terminal of the DVOM on the Black wire and (+) terminal on the Green wire.

8. Disconnect battery (-) for 3-4 minutes.

9. Reconnect battery, start engine, allow it to idle for 2-4 minutes to confirm setup,

10. If idle speed falls too low or stalls, increase idle speed via the TB set screw a little at a time.

11. Turn engine off for 20 seconds, re-start engine and repeat 9 - 11 if required.

12. Reconfirm TPS output is within the .8vdc - 1.0vdc range.......you're done!...

..no need to reset ECM KAM (reset computer) b/c the TPS minimum value used for idle control, is automatically reset by the EEC-IV every time the ign is cycled on-off for 20 seconds-on, and as explained in the next post

13. Allow a 10-20 minute "relearning" period under normal driving conditions (drive cycle).....now you're done.

Courtesy of Joel5.0
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Old 03-27-2009, 06:51 PM
  #7  
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Originally Posted by PJC Racing
You need to do a base idle reset.

1. Clean TB with carb cleaner and nylon brush (toothbrush size). Engine off, fully open TB blade and spray/brush TB until all gunk and oil residue is cleaned.

2. Allow to dry, or close TB blade and start engine until it clears all carb cleaner fumes/liquid.

3. Let engine idle...if it doesn't, increase idle speed via TB stop screw until engine stays idling on its own.

4. Disconnect IAC valve, if engine dies repeat 3 with IAC disconnected.

5. Set idle speed to the lowest setting possible between 650-850 rpms with IAC disconnected. It is key to use the lowest possible to prevent idle surge, rolling, etc once the IAC is connected as follows.

6. Turn engine off, and reconnect IAC

7. With Ign On Eng Off, check TPS voltage output....if it's between .8vdc - 1.0vdc, it's OK. This voltage check should be done between the Green and Black wires at the TPS side connector as shown in the pic below....(-) terminal of the DVOM on the Black wire and (+) terminal on the Green wire.

8. Disconnect battery (-) for 3-4 minutes.

9. Reconnect battery, start engine, allow it to idle for 2-4 minutes to confirm setup,

10. If idle speed falls too low or stalls, increase idle speed via the TB set screw a little at a time.

11. Turn engine off for 20 seconds, re-start engine and repeat 9 - 11 if required.

12. Reconfirm TPS output is within the .8vdc - 1.0vdc range.......you're done!...

..no need to reset ECM KAM (reset computer) b/c the TPS minimum value used for idle control, is automatically reset by the EEC-IV every time the ign is cycled on-off for 20 seconds-on, and as explained in the next post

13. Allow a 10-20 minute "relearning" period under normal driving conditions (drive cycle).....now you're done.

Courtesy of Joel5.0
Thanks for the info lots of it. Everything up to #4 was already done plus you can add a new IAC to it.
I don't know how the TPS reading/adjustment works or how to adjust idle.
The battery was disconnected also.
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Old 03-29-2009, 02:08 PM
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Do the reset and run KOEO/KOER tests.
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