I have changed the plugs and wires. I also changed out the O2's. The car is slightly rough at idle and while driving under 2000RPMS. There is no color in the exhaust (black or white) when flooring it. There is no lose of power (that I can tell). Any thoughts on what else I can check? I have a 99.

 

Might clean your MAF with some spray carb cleaner. I have to do it once in a while. I think I over oil my air filter sometimes

 

My car a long time ago was doing that. Eventually the MAF went bad. Be very careful when cleaning the MAF, if I remember don't touch the connectors where there is some grease or vasaline stuff. That will damage your MAF for sure.

Cheers!!

 

I have an SLP MAF laying around can I just change the stock MAF out for the SLP MAF without having to change the tune?
I do have HP tuners for the vett. I'd rather leave it stock till I get som other things put on the car.

 

You might want to check to see if you have any air leaks at air bridge duct and coupler. It also will cause rough idle.

 

Thanks, I'll look again but I just installed a Vara ram intake. It was doing it before and it's still doing it now.


What about a fuel filter?
What about having the fuel system cleaned? Or can i put in some fuel additive/cleaner from a bottle.

Any other suggestions that I can do or look at?

 

I don't believe you will harm anything by switching to the SLP MAF. The computer in the car will relearn itself. I can see that you changed air takes systems, sometimes that will cause it to idle rough until the computer relearns itself. Should be under 50 miles to relearn itself. If not switch it out, should be okay.

Cheers!!

 

I'm not sure if this will be much help, but here is my scenario: I have a 2000 vert that has had a rough idle since I bought it. The car was bone stock and had 90,000, mostly highway, miles on it when I bought it, but it is like brand new on the inside and had the oil change sticker on the windshield. It had belonged to the nephew of the owner of the dealership. With this info, I decided that it had been well maintained and figured the idle was carbon, plugs, etc.

Since then, I have ported the throttle body, ported the MAF, done the coolant bypass, Blackwing, long tube headers, cat removal, x-pipe, corsa pro series, TR 55 plugs, MSD 8.5 wires, and had about 5 reflashes (tunes). After porting the thottle body and the Blackwing (did them at the same time), the idle problem got a little better. I could still feel it, just not as bad.

After the header, exhuast install I went to get my first street tune (the first few were just generic tunes, as I told my tuner I would be installing headers). I had some knock retard in the 4800 to 5200 rpm range. After a little deducing, we attributed this to carbon since my miles were mostly highway (low rpm). We also thought this might fix the idle.

After the Seafoam, I took it back again and now the carbon removal has caused the passenger 02 sensor to go bad. I put a new 02 sensor in it and when I drove it, the idle problem had gotten worse, back to like it was when I bought it. It's kind of embarrassing when everyone asks you why it idles like that. My 65 year old mother even noticed.

This is where I am right now. If this rain outside will subside I am going back to the tuner today and try to get a decent tune in it. We have talked about the idle, but these other problems have overridden the idle thing for now.

I'll post up when I have something to add.

 

Just got back from the tuners. I had some really messed up timing at idle, 28 degrees when it should be 17 or 18. We figured that this must have come from a Hypertech or something from the previous owner. This made the idle sound better, but it didn't get rid of the rough idle. I have to drive it for 30 - 50 miles to let the computer acclimate itself. Going back next Saturday, we'll see..

 

Use a timing light to check the coils. We have found the coils can be bad/misfiring and still not throw codes... I had that problem for 8 months and finally fixed it with a coil replacement.

VR

 

I seafoamed it, Not a lot of smoke. I also had teh fuel filter changed. They said the filter was really clogged up. I put in some fuel cleaner. I'll run this for a couple of takes to see if it cleans up this idle.


Good point. I'll look at thisas well. Thanks.

 

Try another MAF Sensor. Borrow one from a friends car and see if it makes a difference. I went through a similar situation with my car. Changed everything I could think of and tried cleaning the original Maf Sensor. I was able to borrow one and it made all the difference in the world.

 

It has done it since I bought it and it was bone stock (wondering about that now, see below). Porting the MAF was the last thing I did and it didn't change anything. Do you think the MAF has been bad the whole time? (wouldn't there be a code?) I have a buddy with a '98 that will let me borrow his MAF. I'll try that and see what it does. Did you see an immediate difference or did it take the normal 50 miles or so, of driving first?

Like I said above, my timing was at 28 degrees at idle, so someone has been in the PCM at some point. I am wondering now, if maybe it had a cam in it at one time and he took it out when he bought his new car. All I know about the previous owner is, he was the nephew of the owner of the dealership and he traded this car on a new C-6. I assume the same cam for a LS1 will fit a LS2. I think it's time to invest in some tuning software and just see for myself what is going on in there.