qcswlal

Well I took my 2006 HHR 2.4ltr to a mechanic ( recommended by a friend) while visiting Florida because my check engine light went on...codes showed cam shaft intake and exhaust sensors were bad and I had a mis-fire. Changed the sensors, installed all new coils and as a courtesy he cleaned the throttle body...the car has 291,000 miles on it...I bought it new and it's been well maintained..Now no matter what the mechanic does he can't get the idle to below 2000-2500 RPMs.. His shop has gone over the car twice for vacuum leaks, testing the throttle body sensor, air intake etc...He couldn't re-set the idle despite following the standard ECM re-set procedure..He recommended taking it to a GM dealer to re-flash the ECM...that didn't work and the dealer said it's mechanical.....so back to the original mechanic who spent an entire day, called in another mechanic to consult..but the car still will not return to a normal idle....when I start the car cold it idles fine, then if you start to drive and come to a stop the RPMs slowly but steadily rise to 2500 RPMs...I have done everything to try and re-set the ECM...let it idle for 3 minutes turn it off 60 seconds then idle again for 3minutes ....nothing. The mechanic did the disconnecting battery thing too...and still high idle. The car is a manual, otherwise runs fine..plenty of pep for it;s age..runs smooth at all speeds but at times it feels like the cruise control is on when it's not....Ideas?

donbrew

What codes led you to believe camshaft sensors were bad? Very rare for a passive coil of wire to go bad.

qcswlal

Can't remember the exact codes but had them checked by Advance Auto before I took it to the mechanic just to keep him honest. The ignition coils were the ones replaced.....I have read even on the Chevy Cobalt forum(s) that this is a common problem with the 2.4ltr engines when you go to clean the throttle body...BTW, I never "authorized" them to clean it....I have read in some forums, many people don't clean them on such an old engine like mine for this very reason...IDK, I am planning to take it to my mechanic in NY who my father used to use his father as a mechanic...so I have a relationship with him and trust him. I am not at all handy with fixing things so I'm really at a disadvantage..

Oldblue

sleeper

Welcome.......

guppy

I think if you just drive it, it will relearn. You need to put 45-60 minutes behind the wheel before it completely relearns. You might try turning the key in the "on" position for a couple minutes without starting the vehicle, then off for a minute, then on for a minute, then off. The throttle body needs to go through a learn procedure. Usually this solves it, worst case you reflash the pcm, but you said you already did that, so this kind of stumps me. Keep us posted. I would be interested to know what you find. Best of luck to you.

donbrew

If you indeed had the sensors replaced not the solenoids I suspect that a larger problem has been ignored involving the timing chain.
I suspect that the mechanics involved are cluless about the vehicle and may have broken the throttle body. You can get a new one for under $200/ used considerably less and installation involves 4 bolts and a couple of plugs. God only knows what they did with all of that ECM programming and resetting.

guppy

Yeah, I too was thinking about replacing the throttle body, seems like yours is under $50 on ebay. I think the 2006 throttlebody is different than all the rest of the HHR's.

donbrew

If there is a difference it is the electrical connector. There is a difference between 2.2L and 2.4L.

qcswlal

Well folks thank you for all your replies...and your warm welcome to the forum. My 2006 HHR LT, is now after 3-4 weeks of driving it almost every day in all conditions is idling normally....any where between 800-1200rpms...I am convinced especially after reading other posts, that it takes a long long time for the computer to re-learn where the idle should be...I'm still nervous about the idle, but yesterday and again today all seemed well....So my advice is to just wait it out if you have checked every possible other reason for a high idle like vacuum leaks etc...and the computer will eventually "re-learn" where the idle should be...THanks again!!