engine noise, bad idle!

[2g_turtle]

Hey guys, so I have a problem with my gsx, my car idles like Crap and runs lean, idle is set for 850, on warm up the car idles fine and once its warm, but once you drive it and go to stop it will idle horrible and run lean around like 16-17 even goes --- sometimes, and the car is really hard to start all of a sudden, and if it leans out, it won't start right away and you have to let it sit, and there is a rubbing or knocking noise coming from the motor around 3000 rpm, its not loud buy you can hear it. I have no clue what it could be or what would cause the problem, motor only has around 7000 miles after a full build, thanks for the help

 

[andrew k]

a bad intake gasket will cause such symptoms. could also be maf related. or a bad piping connection.

 

[Russman1986]

Dose your isc click when you turn the key on? Could be a bad MAF sensor.

 

[2g_turtle]

The car is just hard to start after it leans out and stalls and I'm confused on what the noise from the motor could be. And if they could be related.

 

[RayBan GST]

did you check for boost leaks to start with ?

check also you spark plugs wires and also try to unplug the MASS wires when the car is on and check if the number changes or for different reaction

 

[andrew k]

if your getting a/f ratios of 16 to 17:1 plus its very possible your noise could be ping or knock from predetonation. otherwords the fuel mixture may be igniting to early in the compression stroke on the pistons. if severe enough you can melt down the pistons... they can also get little pic type marks on the top of them typically seen on the exhaust side. its a lean condition.