Knock at idle?

Did a search came up empty handed? 2007 LGT. Couple friends and I went to a drive-thru Christmas light show type deal which resulted in a lot of idling and stop n' go type driving. After about an hour of this I had a progressively more noticeable knock. At this point I was in the park with nowhere to go so I had to grit my teeth and stick it out. When I pulled out and got back to normal driving knock disappeared. Are these motors prone to windage issues or oil-starvation at idle? Anybody with a similar experience?

 

P.S. Car is bone stock. Occasionally throws the P0171. Other than a slight hesitation and occasional rough idle it's a happy car.

Occasional CEL???

 

Have you fixed the issue causing the CEL or just clear it and drive? That CEL means you're running lean with a possible faulty sensor or vac leak. The knock could be from the running lean. Clearing the CEL doesn't make the actual issue go away.

 

Do a pressure test since it's easy.

 

Plug the intake inlet with a paint can or mason jar. Pump up to 25-30psi into the thin vac line on top of the BPV/BOV and listen for any possible leaks.

 

Could also be o2 sensor causing CEL.

 

Go from there and see what happens

Occasional CEL???

 

Have you fixed the issue causing the CEL or just clear it and drive? That CEL means you're running lean with a possible faulty sensor or vac leak. The knock could be from the running lean. Clearing the CEL doesn't make the actual issue go away.

 

Do a pressure test since it's easy.

 

Plug the intake inlet with a paint can or mason jar. Pump up to 25-30psi into the thin vac line on top of the BPV/BOV and listen for any possible leaks.

 

Could also be o2 sensor causing CEL.

 

Go from there and see what happens

 

You are definitely right. I’ve been lazy about diagnosing the car. Trying to find enough time (and warm garage) to troubleshoot and build me a little home depot pressure tester. Was toying around with going to the dealer or a local Subie speed shop but, I don't feel like getting d**ked around at the same time.

http://legacygt.com/forums/showthread.php/trouble-codes-cels-26113.html

 

system too lean.

 

get it fixed before you burn a valve.

 

Do you have Cobb AP at stage 1 ? I tuner may be able to fix your lean condition.

 

Oh, I had my Tuner raise my idle rpm because I coast alot and wanted better oil pressure for my 142,000 mile engine. My 5mt wagon idles at 900rpm now.

 

"Couple friends and I went to a drive-thru Christmas light show"

 

Your not a girl, are you...

 

"Couple friends and I went to a drive-thru Christmas light show"

 

Your not a girl, are you...

 

I should clarify shouldn't I. Took the wife and another couple. Although I felt a little moist going through the park now that I think about it.

What mileage? Have you done simple maintenance like spark plugs?

I should clarify shouldn't I. Took the wife and another couple. Although I felt a little moist going through the park now that I think about it.

 

 

Thanks, you have restored my faith in mankind.

^haha. Car only had 36k!

Hmm, I know for fact my car idles mostly fine, but sometimes has a hick up. Ever replaced the intake manifold o rings? I know mine leak a bit especially when cold, and sometimes when i start up hot it will mis a bit.

Check for a turbo inlet pipe tear, leaking intercooler, detached vacuum line, or other source of leak. A boost pressure/leak test is a good first thing to do.

 

I know it sounds counter-intuitive (too lean vs. too rich), but the system cannot adjust the fuel scheduling any more to account for the leak.