idle air control valve

[jeepguy]

i replaced my idle air control valve and it said to adjust it to 1inch and 1/8th so i did and it seems like its doing the oppsite of what its supposed to do when i first start it it will go straight to about 700-800 RPM but once it warms up it will only idle at 1400-1600 does it just take time to wear in? or something

Topic

[college man]

whats the year, make,model and engine size? I also did not know a IAC was adjustable.

[jeepguy]

its a 1995 jeep wrangler with a 2.5 and yup its adjustable

[Venom Z28]

Ive never adjusted one out of the box even though it says to. I just install it, plug it in then start the vehicle. I let the computer adjust it to where it needs to be.

[Matt]

Your best bet is to get your hands on a copy of the factory service manual. I downloaded one for my Rav4 off Ebay for $8. It’s totally worth it.

[college man]

I would adjust the IAC back in. with it adjusted out it sounds like it can’t close off. try putting the adjustment back
and see if the idle gets better.C8-)

[jeepguy]

yea its not closing off but shouldnt it have a higher idle when cold and lower idle when warm?

[college man]

You are correct on the cold and warm idle. But with the IAC vavle adjusted out it bypassing to much air causing
high idle.the computer makes the decision of how much to open and close the valve. C8-)

[EricTheCarGuy]

Quoted From college man:

You are correct on the cold and warm idle. But with the IAC vavle adjusted out it bypassing to much air causing
high idle.the computer makes the decision of how much to open and close the valve. C8-)

Yea I agree you should have just installed it and not made any adjustments, I would recommend you try and get the adjustment back to where it was when you bought it and see if that gives you the result you’re looking for.

[jeepguy]

thats what i did at first i just installed it drove a couple days and still had the problem so i took it back out and read how to adjust it and now its slightly better but not much

[EricTheCarGuy]

Then it’s likely that was never the problem in the first place, perhaps look for vacuum leaks as they can often cause idle issues.
http://www.youtube.com/watch?v=9CPqbaSgcok+

[jeepguy]

ok well im still having the problem, which is once i drive it and bring it to temp then i shut it off if i try to start it right away it will start but if it sits about 15 mins it will not sart it will start for a sec then die and will not restart for about 20mins i have done a fuel pressure test during the no start condition and fuel pressure was good i also have a good spark during the no start condition ive checked for vacuum leaks and there is none ive replaced just about everything including
distributer cap
rotor
plugs
wires
the thing that sits under the cap (i cant remember the name) but it times the spark
fuel pressure regulator
Engine coolant temp sensor
crank shaft position sensor
mass air flow sensor
fuel injectors
idle air control valve

[Matt]

It sounds like you’ve replaced alot of parts that probably didn’t need changing. Here are some videos to get you steered in the right direction, because you need to actually figure out what is missing when the truck won’t start.

Vacuum leaks:
http://www.youtube.com/watch?v=9CPqbaSgcok

No start basics:
http://www.youtube.com/watch?v=FBUYs539cy4

Fuel pressure test:
http://www.youtube.com/watch?v=tJF5Lli4xq8

Watch those vids and see what you may have missed. Good luck.

[jeepguy]

ive done all those test and i have a good spark and good fuel pressure

[Trcustoms719]

So the idle never drops down to under 1,000rpms when it’s warm?
Only when cold? It sound like the IAC is working backwards lol…S:-o

[Matt]

How did you test for spark and fuel? Did you put a fuel pressure gage on the truck? Did you use a spark tester? I only ask because alot of folks post that they have tested for these neccessities when all the have done it pushed on the schrader valve to see that fuel comes out without actually verifying that the pressure is where it needs to be, etc. And honestly since you’ve replaced most everything else, but then monkey’d with the IACV, you might want to see if you can take it back for a new one, and don’t adjust it this time. Good luck.

[Author]

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