In the last 2 weeks my idle has leaned out a bit, I'm reading it off of an aem wideband and it normally is solid at 14.6-15.2, however recently it has leaned out and is ranging from 16.3-17.2 and there is noticeable more lope in the idle. Any ideas on what could be causing this?

 

would also like to note, that when cruising, my a/f ratios are right were they should be.

 

An exhaust leak before the wideband sensor can cause that.

 

Yes but that wouldnt really account for the funny idle. I would say check for a leak in the intake or around the maf or in plumbing and see if you are sucking in any air from after the maf. Strange that it would be normal on cruise tho. BOV leak?

 

My IV had similar issue that destroyed an exhaust valve on cylinder 3. A new fuel pump and FPR sorted it.

 

vacuum/boost or exhaust leak

 

did a boost leak test and found that the turbo outlet pipe going to the lower intercooler pipe was leaking pretty bad at the seal, so I'm going to replace that and go from there, thanks for the help guys, will keep you posted

 

nice find, that should help tremendously.

 

went ahead and put in a new gasket and its not leaking nearly as much but is still a little bit, can't really get the bolts much tighter any suggestions? It is not that much and holds pressure a lot more steadily now though. Still haven't got it back together and checked the idle, but should be back together in 20 or so min. will post conclusions.

 

you might consider pulling the gasket and putting some of "the right stuff" on the gasket..it sounds like your surfaces aren't as flat as they should be or it's not tight enough.

 

Yeah that sounds like a good idea, should have done that before I put it back together, the car runs a lot better, but it still leaks and still has the lean idle problem. I'm going to go back and get some of "the right stuff" (assuming that it is some sort of silicon gasket maker or gasket sealant) and put it on the gasket. I am using a thicker gasket material that I cut myself, but the leak is still there.

Other than that I fixed all the other boost leaks and it runs stong. Any other ideas on why it is idling lean? The rev's also stay high in between shifts, like they won't really fall for a few seconds. Where should I look for vacuum leaks? I'm sure there is no exhaust leak, checked today, and as I said before there's only that one small boost leak, so now I'm onto looking for vacuum leaks, or some other problem. Once again thanks a bunch guys for the help!!

 

a boost leak is a vacuum leak...same thing

 

oh ok, never really knew that, I was just refering to a boost leak as more the lines associated with the turbo and vacuum as some of the vacuum lines comming off of the intake manifold, makes sense that they are the same thing though

 

Ok, I looked up "the right stuff", when I use that should I put it on the gasket itself, or toss the gasket all together and just use "the right stuff" in place of my gasket?

 

I've used it both ways but since you have the gasket, I would put on some rubber gloves and just slather the gasket in that stuff with a thin layer on both sides, that should help, it'll turn to rubber basically when it's dry