Hi Im new here Ive been into sports cars all my life. Due to the snow I traded into trucks and well jeeps are suppose to be killer in the snow. I bought my jeep 04 grand cherokee 4.0 HO it makes a ticking noise. I panicked I thought it was a knock I was so pissed at the dealer. I came online and listened to the knock videos didnt sound like mine. I finally narrowed it down when I looked under the hood its the AIC. My idle is not rough at all its smooth, the car doesnt stumble at long stops has no signs of stalling. Oil pressure is great just ticking at cold start ups. Any ideas on what to do? I can deal with the noise I just dont want my truck to die or blow up. Any input would be great thanks.

 

Make sure it's the IAC you are looking at and not the TPS. Unplug it and see if the ticking stops. If it does try cleaning the IAC or replace it. If it doesn't then the ticking is not the IAC.

 

The IAC, TPS, MAP, CTS, O2, or any other sensor will not cause a noise in the engine. The 4.0 is kind of a noisey engine anyway, they do make noise when they run, but they will run and make noise FOREVER. Take the serp belt off and see if the noise changes.

 

its def the iac i an feel the tapping when i put my hand on it. its a cold *** day type of thing once its above 30 its fine but we get a lot of 10 to 0 degree mornings so I just think it doesnt like the cold. Ill unplug it and see what happens but I dont think I will like the answer. In the spring Ill buy a new iac and replace it

 

A brand new IAC is only about 50 bucks at NAPA, why wait?

 

Looking at the bold points, he should wait because of you're original point

Feeling it does not mean anything. I can put my hand on the fender and feel things that are going on in the motor, does not mean i need to replace my fender. I'm betting if you disconnect the IAC the tapping will still be there. Really the only reason it might tap is if it is severely dirty (to an extent i have never seen before) and if that is the case the thing would be running TERRIBLE.

 

It is not your IAC. If your IAC was bad you would have high idle, you would stall out unless you foot is on the gas pedal. Your IAC is part of your throttle. The ticking you hear is more than likely the lifters, which is one thing that our 4.0 is known for. Trust me with the IAC, mine went in my xj and my wife's is going in her WJ. I know what I am talking about there.

 

ok i went out to the truck started it up and heard the ticking. Went to the hood opened it its the cyclinder thing above the air filter compartment I unplugged it ticking stopped pluged it in ticking started did this 3 times same result. Whatever that cyclinder thingy is thats the issue is that thing the IAC???

 

Ok I looked at another post the part is the evap soleniod and according to the ppl on that forum and thread they all say its normal. It ticks only when its cold out and when its above 30 degrees it doesnt tick. Common issue I guess. i appreciate all the help on this one I really do since I dont know anything about 4 wheel drive trucks and having small issues scares the shyt out of me these things can get expensive as hell. Thanks again guys and girls for all the help

 

would a bad IAC cause an idle in park/neutral to be around 1200 rpm?

 

it could. could also be the tps, a vac leak, etc. need more info

 

ive checked every vacuum line over and over again.

should there be a certain area of vacuum lines that im looking for.
ive cleaned the IAC twice to it may be time to replace along with the TPS.

*no intentions of thread jacking*

 

Test the IAC and the TPS