Low Idle

[6gear]

I just installed an LS1 with an 02/03 LS6 cam and advanced the timing 2 deg. The truck idles around 900 rpm's untill it warms up and then the r's drop steady to around 400. I was told by street and performance that I shouldn't have advanced the timing because the cam and crank sensors would be out of sync. Anyone else know anything about this, or know how to idle it up?

[farmtruc]

I just sent you an email, but an editor can easily fix this, just bump the idle up to where it's supposed to be.

You may get away with adjusting the idle screw, but that is very sensitive and you may affect drivability, the pcm may think you are pressing the gas.
It's kind of a pita, but you could set the cam up in it's stock position and then advance the timing thru edit, also, since you put that cam in, what rpm are you shifting at, becuase the 4.8's i've tuned shift at about 5600 rpm, which is very low in my opinion and you can usually advance the timing 3-6 degs too, without any detonation. It's really wakes the engine up when you allow it to shift at 6100 rpms, especially with the ls cam.

where are you located? if you don't have edit and aren't too far maybe we can hook up and make that thing move a little faster.


allen

[6gear]

I am in north central arkansas, would advancing the cam timing like I did cause the idle problem or does it sound like something else? also I noticed a ses light on could the low idle be causing this? I had no ses lights before the swap.

[farmtruc]

In the old days, i used to advance my cams all the time, never had that problem, i wouldn't think what little your did would cause such a problem,
did you try disconnecting the battery and resetting the pcm? is the idle rough at those low rpms, or is it smooth, are all your sensors connected and seated? Maybe the ses light is the low rpms.

Are you able to read the ses code?

[6gear]

It idles fine but at 400 it wants to give it up, I haven't disconnected the battery yet and I don't have a way to check the codes, around 650 to 700 it has a good sound to it with a slight lope. I have gibson headers and flowmaster mufflers. So how does LS1 edit work or will you be giving out a trade secret

[farmtruc]

you can purchase ls1edit from carputing.com you need a pc/laptop and to compliment the editor you'll need a diag tool, to read stuff to make sure you're tuing right.

ls1edit is no secret, it just takes time and patience to get it right, there are enuff ppl out there to help you out, including me, the cost is like $550 and you get a cable and software. It's the best out so far.

Once you get it, you'll be able to set idle, fuel, timing, shifts, basically anything in the pcm, (well what they've discovered so far) if you're doing a swap, it's pretty much mandatory that you have edit or access to a shop with edit. It's the only way to reap the benefits from the install.

Did you keep the stock truck pcm? If so, the trucks come with less agressive timing and fuel tables, they are pretty much the same pcm, you'll just want to edit those things to make the ls1 run at least like it would in a vette.


if you have any specific questions, feel free to ask


allen

[6gear]

I am currently using the truck pcm, the people at street and performance said that the car pcm was pinned differently then the truck and I would probably burn it up if I used it.

[farmtruc]

hahaha, that's funny, i've come to a conclusion that if you really want to know something you just have to do it yourself.

I hope my pcm doesn't fry someday, i'm using a z28 pcm and truck harness, oh no, lol

I've called them a few times also and sure they look good on ads and shit , and i'm sure they are very good at somethings, but if they don't know the answer i really wish they would say " i don't know the answer to that" that drives me crazy when ppl do that.

The pin out is probably a little different, but i'm positive the power and ground wires are the same, and plus, all the sensors are the same, there may be a few wires that are labled differently, but they perform the same function, a lot of the camaro pinouts label the wires differently, maybe MASS wire and MAF wire, something like that.

There's no reason to switch to the z28 pcm, your truck pcm will be fine, but it may need tuning. You have a bigger bore and are probably flowing more air than the pcm thinks, when i did the 5.3L to LS1 swap, the pcm i guess was close enuff that is idled just fine and plus you installed the ls6 cam,

maybe i can borrow your truck for a while and get it tuned just right, i'll need it for about 6 months or so, hahahah, jk,

let me know if i can help,


allen

[6gear]

I agree with you if someone doesn't know something for sure they should say they just don't know. I appreciate you setting this straight, some of us are at the mercy of others untill we learn the hard way and I had just as soon avoid that. I have had thoughts of trying the car pcm after I am able to drive this thing, Will I have a vats problem with the car pcm? I will have to think about you borrowing the truck, you would probably end up slinging a driveshaft out of it.

[farmtruc]

Originally posted by Ron@Aug 13 2003, 02:24 PM
...a driveshaft out of it.

lol,

You're right, you'll have to delete vats, scale the shifts, check rpms, and tires

the maf will need to be scaled just slightly, at least on mine, as soon as you do get it running, get a diag tool and record your a/f and ltrims,
a/f should be about 12.5 NA, and ltrims should be about (at least i like that way) -7, that way in the winter, the cold will use a tad more gas and make them about -3 to -5


allen