Luna

iTrader: (6)

Hey guys, I have been having a few issues with my formula lately, mostly it has been making really weirdass sounds which i have posted on the maintenance forums and gotten between little and no help.

But now I am having more problems, I have noticed a considerable dropoff in gas mileage, used to get 22-24 mpg avg, now i am averaging 17-18 and that is with conservative driving.

Now today I start my car and I notice the idle is about 300 RPMs higher than it was yesterday... WTF?! Sitting at about 1100 RPMS in Park and about 800 in Drive.

What is a normal Idle? Could it be adjusting because the weather has recently cooled off quite a bit ? What about the gas mileage ? Check o2s?

Also , I think one of the weird noises is piston slap because it only seems to happen when its cold, but I dont have any idea what piston slap sounds like anyone care to enlighten me on that sound?

Please dont move this to the general maintenance forum right away because i never seem to get any help in there!

RPM WS6

iTrader: (3)

Idle should be 550 in gear and 650 in park/neutral. If your tach is anything like mine though, it'll read 200rpm too high. Only way to really check idle speed is with a scanner.

But, regardless of what the tach reads, if it's higher than it was by 300rpm then there is an issue.

I've done tons of work/research on LS1s and idle issues. I was fighting an odd idle issue that took quite a while to pinpoint, I've posted quite a bit about tracking idle issues, maybe some of that info can help you.

Here are a few to get you started:

https://ls1tech.com/forums/showthrea...highlight=idle

https://ls1tech.com/forums/showthrea...highlight=idle

This one below was my own personal idle issue. Seems that it ended up being my EGR valve. I never posted a final reply because I wanted to make sure I had the issue solved and it's been problem free since June now so I guess it's ok:

https://ls1tech.com/forums/showthrea...highlight=idle

Hope that gives you some ideas to try checking.

Luna

iTrader: (6)

I think I need to start by replacing some general maintenance type of things, its got 82k miles on it and 7k are mine so I dont really know what kind of maintenance has / hasnt been done recently. So I should probably start with new plugs, wires, and fuel filter, the air filter has been replaced with a K&N along with my new airlid. Anything else I should replace?

Also my dad said he thought that one of the weird sounds was the vapor canister but he had no idea where it was or if this car even had one. Does it ? if so where is it ?

BLUE99T/A

iTrader: (2)

It should idle high until it reaches operating temp, then gradually fall. Mine was 1100 all the time and it turned out there was a hole in my pcv line.

Wyckedcamaro

iTrader: (2)

check your throttle position sensor. Jiggle it.. it may be fried or a broken or lose wire there.

RPM WS6

iTrader: (3)

Canister is in the back of the car near the fuel tank I beleive. The purge solenoid is under the hood though, runs along the driver's side of the intake and plugs in near the TB. I've heard of some people complaining of a ticking noise coming from that solenoid shortly after an engine start but it goes away quickly.