Rough idle question...

[StuntmanMike]

My car has a rough idle, I've heard the LS1's idle a bit rough, but this seems a little too rough for me.

It usually runs pretty smooth when driving, but at idle, especially at a light with my foot on the brake in gear, I can feel it stumbling a bit. No SES light, and my mileage isn't bad, last tank was 22.7. It feels like it's gotten worse over time, as it didn't do it when I got the car.

Also, I can sometimes feel it when accelerating past 2k rpm on the highway, or if I just hit the gas to rev it when it's not in gear. But oddly enough, if I punch it from a stop, it seems pretty smooth. There's something about that 2k mark, I once left in out of OD on the highway to simulate a gear swap, and it seemd to be vibing pretty bad. Put it in OD, revs dropped, and it was smooth as glass.

Just hit 84k last week, and I've changed the plugs and wires (Delco iridiums & MSD wires), fuel filter, and cleaned the MAF.

This weekend I'm going to clean the IAC and see if that helps.

Anything else along those lines that I can do or check?

Thanks!

[1MileCrash]

mine seems to be idling a bit rougher this year as well. i changed the fuel filter before i put the car away last fall and i'm going to be doing plugs here in shortly when the weather cooperates and i have the free time. i'll be doing iridiums myself...consequently...what do you have yours gapped at? there is a service update for the iridium plugs to gap them at .040" not the originally stated .060"

[StuntmanMike]

Actually I forgot to check the gap with a guage before installing them. I'm pretty sure they come pre-gapped though, and IIRC the gap wasn't that big, so I'm pretty sure it wa the .040.

I may pull one of the driver's side plugs and verify it this weekend.

[BADASS2000SS]

No need to chech the plugs, AC Delco Iridiums come gapped at .40. You mentioned you cleaned your MAF. Depending on how you cleaned it, that could be you problem! How did you clean it?

[StuntmanMike]

No need to chech the plugs, AC Delco Iridiums come gapped at .40. You mentioned you cleaned your MAF. Depending on how you cleaned it, that could be you problem! How did you clean it?

Well, I cleaned the MAF because I thought it might have been the cause of the problem, but there was no change afterwards.

I used CRC MAF cleaner, it comes in a spraycan. I removed the MAF, and just sprayed it down like it says in the directions on the can. I didn't physically touch the wire or anything.

[sunsetorangess]

Go ahead and clean Your IAC motor and put some injector cleaner in the tank when it gets low, drive it a bit and then fill up at a different gas station than what you normaly use..
J

[astyles]

mine was running ruff too,so i sea foamed it and it has helped alot......

[1MileCrash]

No need to chech the plugs, AC Delco Iridiums come gapped at .40. You mentioned you cleaned your MAF. Depending on how you cleaned it, that could be you problem! How did you clean it?

i'd recommend checking them. the delco plugs that i bought are pre-gapped and i found them to be in a range anywhere from .037 - .045. needless to say they all got regapped to .040.

[BADASS2000SS]

Well, I cleaned the MAF because I thought it might have been the cause of the problem, but there was no change afterwards.

I used CRC MAF cleaner, it comes in a spraycan. I removed the MAF, and just sprayed it down like it says in the directions on the can. I didn't physically touch the wire or anything.

Good job, its not that then. You can check the plugs if you would like, I checked all 8 of mine and they were gapped at .40. I gapped them to .55 and my idle is nice and smooth. There was another thread about this and he found a few of his plugs to have some grease on the ends of them. He cleaned all his plugs and he was good to go! Good luck!

[StuntmanMike]

Good job, its not that then. You can check the plugs if you would like, I checked all 8 of mine and they were gapped at .40. I gapped them to .55 and my idle is nice and smooth. There was another thread about this and he found a few of his plugs to have some grease on the ends of them. He cleaned all his plugs and he was good to go! Good luck!

So are the plugs supposed to be gapped at .40, or .55?

I did a search, and saw both gaps mentioned.


Was your idle rough when they were gapped at .40?

[sunsetorangess]

They should be gapped at .40
There was a bulliten put out From Gm changing the spark plug gap to balance out the idle...
Thats when it changed to .40, use to be .60
J

[StuntmanMike]

They should be gapped at .40
There was a bulliten put out From Gm changing the spark plug gap to balance out the idle...
Thats when it changed to .40, use to be .60
J

Ok, thanks.

So today I replaced the PCV, cleaned the IAT and TB, and used some Seafoam Deep Creep spray in the intake.

It might be my imagination, but it seems to run a bit smoother now.

I also bought a can of the liquid Seafoam, I might give it a shot tomorrow, either that or dump it in the gas tank.

I looked at the MAF, it still looks nice and clean. It hasn't been that many miles since I cleaned it, so that doesn't surprise me.

I took it for a ride and did a few full throttle runs, it ran good and seemed to rev nice and smooth to 5k, so maybe it IS running normal.

I'll have to check out some other cars at the next club meet, see how everyone else's car runs.