rough idle--o2 sensor??

[jstreet]

I'm new to this site and have read all the threads on the IAC valve sticking. It sounds like that could be my problem. My 03' expo idles rough usually sitting still and the whole truck seems really sluggish sometimes. I really have to give it some gas and then it will get down the road. My "service engine soon" light also came on yesterday. I took the truck to Auto Zone and they hooked up their scan tool and it said 02 sensor and then something about port1-bank1 or something close to that. I'm not sure if the o2 sensor is common. Or should I buy both, or should I buy both o2 sensors and the IAF. Also how hard are all three to change. If I tear up our family wagon my wife will kill me. But I'm pretty good with cars. Thanks

 

[dyurkosr]

jstreet, you need to find out what the codes are. If there are more than one code, you need to start with #1 first, clear the codes and then see if the check engine light comes back on. If it does, rinse and repeat. (you know what I mean) The IAC motor is located just behind the throttle body on the back of the intake manifold. It is held in place by 2 - 10mm bolts and one wire conected to it. Before removing the valve, pull the wire on the valve and see if the idle getts better. If not, remove it and clean it. Remove the valve and spray throttle body cleaner down iside it and move the valve stem back & forth. When your re-installing it, make sure you put the bolts in it first to hold the gasket in place. This may help. DO NOT replace the O2 sensors untillyou are sur ethe base idle is where it needs to be first. Also, you may want to remove the air cleaner and clean the MAF (mass air flow) sensor as well. If you need help on the MAF, drop me a note. Good Luck! Dan.

 

[jstreet]

Thanks alot for the info. There was only one code on the scanner. It read co2 sensor with some numbers behind it. I'll try cleaning the part you told me to first. I also wanted to know. Do I have to take it back and have the people delete the service engine light? Or when I pull the negative battery cable off will that do it? I don't know if it makes a difference but the truck will also act up just driving down the road doing 60mph. I was driving it yesterday on a highway and it would all of a sudden start to studder real bad and lose power. This would go on for a few minutes and then it would clear up all of a sudden and drive fine and smooth. Not sure if this helps. Thanks again for your help.

 

[jstreet]

I went home today and pulled the wire off the IAC motor. The truck cut off immediately. I don't know if this is good or bad. I also wiggled the wires on the o2 sensors and tapped on both. This was after I plugged the wire back in and restarted the vehicle. Nothing seemed to change. The truck wasn't running rough when I was wiggling the wires though. It did it for a few minutes when I started it up and then quite. Just figured I'd give you an update. Thanks

 

[dyurkosr]

jstret, how many miles are on your truck? Sounds like you have more than one issue going on. The truck should not have stalled when you pulled the IAC plug off. It should have dropped the idle real low, but not stalled. Ill have to do a little digging on this issue. You poor running at highway speeds sounds like coils - missfire. Diss the positive cable from your battery will clear your codes. Probably a good idea to do that and see how soon the check engine light comes back on. Have it scanned again and save teh code information. Ultimatly, your going to have to get it to a shop that can do a data stream reading on it to check fuel trim and long term fuel trim. They will also look at the o2's to make sure they are cycling off and on as well as any missfires on any cylinders. Get fresh coads first and ill see if I can go any further without datastream help. Dan

 

[jstreet]

My expo has 50,000 miles on it. I'm glad your helping me because I'm sure it's gonna cost an arm and a leg at the shop. Thanks and I'll wait to hear from you. I did pull the neg cable off for about five minutes and the check engine light went out. I haven't driven it yet to see if it comes back on.

 

[dyurkosr]

jstreet, have you had a chance to pull any new codes? If so, are they the same as the last time you pulled them? If so, your going to have to get it to a Fore dealer or someone with a datastream type scanner and waveform screen to pull more info.