High Cold Idle After Tune-Up

[pengwin]

Hello All,

Last weekend I changed my O2 sensors to get rid of a CEL. A week prior to that, I seafoamed, knowing I was going to change my O2 sensors. In addition to the sensors, I changed my plugs, wires, and pcv valve. I also cleaned the MAF and throttle body. Ever since then, my cold idle is higher, and takes much longer to drop (1400+ down to around 1200 after 3-4 minutes in park). What could be causing this? I usually don't shift to drive untill it drops to around 1000 rpms, but that takes forever now. Before my sensors went bad, it used to drop to 1000 rpms much quicker. Please help... unless this is normal?

 

[PitbullRescuer]

Where did it idle before? Should idle well below 1000 rpm when warm, more like 700 or so. Did you do the elbow mod in your sig at the same time too?

 

[pengwin]

Yeah, i did the elbow mod at the same time. I guess i should have included that in the post also. It idles where it is supposed to when warm, which is why im not too concerned. But it idles about 200 rpms higher than it did before when cold.

 

[pengwin]

Maybe my mixture didn't reset? I pulled the fuse for a while and it was idling really high on my first start up so i decided to disconnect the battery instead and it dropped back down to what it is at now. Perhaps I should leave the battery unplugged longer?

 

[TheDurk]

Anytime you have the airbox off to do plugs, etc., and then have this problem, the first thing to do is recheck all those vacuum and electrical connections. And not just visually. Last December, I changed plugs, cleaned TB and MAF, etc. on the last decent day of the year. Idle would start at 1400 and then go back down to 1100 and stay there. Then the weather turned brutal and I just lived with it until late March. First warm day I decided to attack the problem. In two minutes I found that the vacuum hose to the throttle-opener thingy on the passenger side of the throttle body was sitting on the nipple, but not PUSHED on. It looked perfect, but was sucking air. Two seconds later problem solved. Spot on 700 after warming up.

Not saying this is your problem, but it is what I would check first.

 

[pengwin]

ahhhhhh ok. i hate vacuum leaks.

 

[Drcoffee]

I got my truck to idle again. I ended up pulling off the plastic intake tubing and gave a couple of squirts of MAF cleaner down the hole in front of the throttle plate. I left off the plastic intake tube and started the engine and it fired up and then died. I did that 3 times. What I was hoping is that the cleaner would dissolve the carbon and then suck it past the IAC valve letting it function again and close. I was right. After reconnecting the plastic intake tube it fired up and the idle dropped to 750. I didn't have to remove the IAC either. Don't flood the hole, just two quick shots of MAF cleaner should dissolve any crud.

The reason I used MAF cleaner is it doesn't leave a residue and is less aggressive than carb cleaner.

I hope this proves to be an easier fix for this problem than removing the throttle body.