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IAC Valve

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  #21  
Old 04-20-2012 | 03:37 PM
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Ive got the FSM in front of me, but cant copy individual pages & paste them . I would check your whole intake manifold out, especially if you have recently worked on it. Check for gasket leaks, check all the vacuum lines, check that your throttle body is tightened, & check that the valve in the TB is closed at idle. The IAC air assist hose runs from the intake manifold to the IAC valve, & sometimes this gets blocked.
Hope this helps
 
  #22  
Old 04-20-2012 | 03:42 PM
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I just put the intake on like an hour ago so i adjusted the idle after i did that now im waiting for it to cool down to check it. How can i check for gasket leaks?
 
  #23  
Old 04-20-2012 | 04:00 PM
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A smoke machine is the recommended way, but...if you spray carb clean around the gasket area & the idle increases, the gasket is leaking. Same for the vacuum hoses. Just be VERY carefull not to spray carb clean on your exhaust...& have a fire extinguisher handy !!!. You can be pretty precise in where you spray, if you use the plastic spray tube thingy that comes with the can.
 
  #24  
Old 04-20-2012 | 04:18 PM
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Okay what hoses should i check for vaccume leaks? cause theirs alot just do the ones attached to the throttle body? Cause ive been trying to adjust it all day and something keeps causing the iacv to close
 
  #25  
Old 04-20-2012 | 04:31 PM
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A leak in any of the vacuum hoses would mess with your idle. I know its tedious, but if you disconnect each one in turn & check if the idle changes you can isolate it.
First I would use the vacuum gauge to check your manifold vacuum. It should be a constant 17 - 20 kPa with no fluctuations. If it is low...you have a vacuum leak.
Also I would check the air assist tube which runs from the intake manifold to the IAC...read previous post...good luck.
 
  #26  
Old 04-20-2012 | 04:47 PM
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Okay im gonna go get a vaccume guage tonight. but i did start trying to disconnect hoses and i did find a hose when disconnected it brought my idleing back up good. Its the hose that runs from the TB to alittle green plastic round thing beside the egr control silinoid on the driverside fender. Its right on top. I can try to take some pics later but i cant get them to upload. I looked in my shop manual but cant find it
 
  #27  
Old 04-20-2012 | 05:44 PM
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Check your fuel trims. If your trims are lean & they come back to normal after pinching that hose, your Evap purge valve is faulty. Without the ability to do enhanced diagnostics, I'm afraid you must resort to trial & error. A FSM will give you diagnostic flow charts & sensor voltages for the components in question.
Start with the vacuum gauge & check manifold vacuum, then pull the vacuum hoses one by one. If the vacuum decreases that hose is OK. If the vacuum doesnt decrease, you have probably isolated it.
 

Last edited by kiwibilt; 04-21-2012 at 03:26 AM.
  #28  
Old 04-20-2012 | 09:10 PM
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What do u mean by fuel trims? and when i hook a vaccume guage up what reading should i get? im gonna get one tomorrow and do trial and error like you said
 
  #29  
Old 04-21-2012 | 03:09 AM
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1) Pull a hose on your intake manifold & connect the vacuum gauge
2) Start car...check hose you pulled to ensure its not sucking...if it is, pinch it or jam a small bolt in it...vacuum should hold steady at 17 - 20 kPa & not fluctuate.
3) While car is idling, spray carb clean or starter fluid around intake gasket, plenum gasket, throttle body gasket, vacuum hoses & IAC & listen for revs to increase. Check the hose into your Evap purge valve & from the Evap purge valve into the manifold. Isolate leak this way, & double check by watching vacuum gauge.
You can check your IAC by teeing into the air assist hose with your vacuum gauge & unplugging the IAC...if vacuum is more than 40 kPa, your IAC is faulty.
Your looking for damaged, pinched or kinked hoses, loose fittings etc.
I would re torque your intake manifold, plenum & throttle body (16 ft lbs).
Also check your throttle body valve is closed at idle.
When its idling, stick your finger over the lower bypass port...revs should decrease.
Your base idle should be achieved with the idle adjusting screw at 2 - 3 turns from fully closed (with evap purge valve electrical connector unplugged).
Thats about all you can do with a vacuum gauge & a can of carb clean LOL, but if the induction system has been messed around with you just need to check that its tight & not leaking first. Have a good look at the hose between the evap purge valve & the manifold (loose). Also take a good look at the air assist hose to the IAC (blocked/kinked).
If you can scan it for DTCs let me know & I'll try give you some more tips.

You can check the operation of your evap purge valve by checking your fuel trims prior to, & after pinching the hose. I would check your TP sensor voltages & your MAP sensor out as well, but you need access to a decent scanner.

BE CAREFUL...carb cleaner & especially starter fluid is EXTREMELY flammable. Have a fire extinguisher handy & don't spray anywhere near your exhaust manifold.

Have fun bro & tell me how you get on
 
  #30  
Old 04-21-2012 | 11:27 AM
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Thanks man ill try this tonight. I was gonna put a new head on my other car but it looks like i got my hands full with all this. I appriate all the help between everyone here ill hopefully find the problem.
 



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