Hashish

iTrader: (1)

My car has a very hard time idling and I'm not sure why. Its a 2001 ls1 with a 98 cam in it with LT and an slp loudmouth. When I used a Snap On scanner and looked at my data I noticed that my ignition timing at idle was jumping around anywhere from 14* to 21*. Is this normal? This is a fresh motor with less than 300 miles if that helps. Thanks

jimmyblue

iTrader: (11)

That's the adaptive spark, busy trying to maintain
a fixed idle RPM. It's normal. Kind of low advance
though.

I would suspect that maybe idle mixture is bent
by mistrimming, making things "soggy" and giving
the idle control loop a hard time (if the motor is
too slow to respond, it gets unstable).

If you are in open loop, does it idle better, and
get into trouble once warmed up? Think about
what makes the idle, worst.

Hashish

iTrader: (1)

The idle stays pretty bad most of the time, there are really no events that make it worse other than trying to find idle. My Manifold absolute pressure is 16 hg if thats normal.

DaveX

If I understand correctly, you are running a factory 98 cam. Not sure what mods you have but the spark jumping around is normal, like Jimmy said. You can tweak this with tuning software, but if your running a factory cam you shouldn't have to. And this probably wouldn't help your idle problem. It should idle ok with the factory tune. I would look for a mechanical issue, though as far as power is concerned you would benefit from a tune with the headers.

Hashish

iTrader: (1)

ok thanks guys. I am going to check my cam timing one more time just to double check. When setting cam timing is there a specific side of the timing chain that needs the tension on it?

DaveX

There shouldn't be noticeable slack in the timing chain, so no. Dot to dot and you should be good. Before you go through all that, look for a vacuum leak.

DaveX

Or an exhaust leak upstream of the 02's or at the collectors if your running closed loop.

Hashish

iTrader: (1)

I have looked insanely hard for a vacuum leak, and I wouldn't be pulling 16hg of vacuum with a leak would I? And my LTFTs are reading at a -1.8 or so. I have a very small amount of slack in the chain but only on one side(only about 1/16th of an inch or less). I have entertained the idea of a leaky seal on the bottom of the intake??