6.0 Idle Issues And Seafoam

[vavtx]

I have been having idling issues with my 2001 GMC 6.0. It seems to have started after I seafoamed the engine through a vacuum line on the intake....it also got cold outside about the same time. Intermitently, the idle would hang aroud 1500 in park and 1000 in gear. I replaced the IAC and TPS. It seems better, but not right. When I come to a complete stop it take about 1-2 seconds for the idle to drop from 1000rpm to 750rpm. If I drift forward a little bit, the idle will jump back up to 1000rpm. After I stop, the idle will drop again. It is kind of weird. I am also getting code P0507(high idle). Any ideas or suggestions? I also thought of a vacuum leak, but this seems to intermittent.

[1999 Tahoe 4x4]

Could be debris in the seat of the IAC valve. Some bigger particle of debris could have been dislodged by seafoam and settled on the IAC seat. At startup/reset the IAC sets against the seat and then rertacts a little. If the seat is dirty the initial seating against the seat might not be right. Check the IAC Valve seat on the side of the throttle body.

 

Many people speak highly of seafoam. I don't think I would use it on my truck. The fact that some smoke comes out of the exhaust does not mean it cleaned anything. Also I have never heard of any cleaning agent that cleans quick while being not aggressive. You can always test seafoam on a some engine part that you have removed. Give it THE second or two cleaning time just like if it would have when it is introduced through the intake. I bet it won't clean anything. If it did, everybody shop would be using it as THE most effective parts washer.

 

Anyway, my truck runs great without it. But that's just me.

 

BTW: I don't think it is a good idea to pour any liquid into the intake. Also you should not expect anything (especially a liquid) that you inrtoduce through any vacum line to go evenly everywhere. Spray into the throttle body, maybe.