KN AIR FILTER, Rough Idle

02-Z71-TX · February 20, 2003

I installed a new KN drop in Air Filter and it runs great, but at idle (warm or cold engine) it idles a bit rough. Anyone else have this problem? Any suggestions?

TROYROBO · February 20, 2003

smooth as silk with mine----might have other problem that has shone it's ugly head?????

lrymal · February 21, 2003

I installed a new KN drop in Air Filter and it runs great, but at idle (warm or cold engine) it idles a bit rough. Anyone else have this problem? Any suggestions?

Sounds to me that a vacuum line came undone during the install.

Y2K Silverado · February 21, 2003

Yep, I've experienced the same thing, I don't use a K&N or any other high flow filter any more. I don't believe they're all what they say they are, I actually loose low end when I install a high flow filter. My fastest 1/4 time was with a paper filter not a K&N and I had them at the track at the same time.

Jim

2001 HD · February 21, 2003

Try resetting your ECM by disconnecting battery or removing fuses. The ECM needs to "Re-learn" long term fuel trims.

Oh...and keep an eye on the intake tube for a white powdery substance that looks like fine silicone dust or baby powder.

CMNTMXR81 · February 21, 2003

An air filter won't make a significant enough difference to require an PCM "Idle-Re-learn" reset.

I dyno'd back to back on the dyno with the Z. First pull was a regular paper Fram, it registered 318rwhp. After that pull, I quickly got up, swapped them out putting my K&N in and making another pull. The K&N equaled 316rwhp. The torque numbers (which I don't recall off the top of my head) where the inverse. The paper Fram was 2-3 lbs-ft lower than the K&N. At the end of the day, the conclusion I came to was that the "advertised gain" K&N claims is negligible if at all nonexistent and mute. The only advantage I can conclude with a K&N is it's cleanability and re-usability.

Sounds like you have the possibility of a couple of things

1) Air is getting in somewhere after the MAF and before the TB. Is the connection from the airbox to the inlet tube (which the MAF is mounted on) to the TB sealed/tightened sufficiently?

2) Due to air intake blowing past the filter, sometimes the oil will atomize (kinda like fuel meeting air in a carb) and then get hung up on the MAF's electronic resistors/vanes and in the TB around the TB blade. Check the MAF and if need be, use some electronics cleaner (available at Radio Shack) to spray on and let it evaporate to clean it, and then check your TB and clean up any soot from that oil that may accumulate around the throttle blade.

I have a good notion to say that if you installed it and noticed this right away, it's probably just number 1.

SilveradoWV · February 21, 2003

Dont know if this applies or not but just wondering if you installed the foam gasket that came with your K&N?? I have a K&N Drop In and have been running it since I got my truck almost a year ago, no problems so far. And yes, the gains are not what K&N say, but then again they didnt test with a Silverado (Well, if they did thats not the gains they are advertising) I bought mine because it is cheaper than the paper filters.

cyrylyn · February 22, 2003

An air filter won't make a significant enough difference to require an PCM "Idle-Re-learn" reset.

I dyno'd back to back on the dyno with the Z. First pull was a regular paper Fram, it registered 318rwhp. After that pull, I quickly got up, swapped them out putting my K&N in and making another pull. The K&N equaled 316rwhp. The torque numbers (which I don't recall off the top of my head) where the inverse. The paper Fram was 2-3 lbs-ft lower than the K&N. At the end of the day, the conclusion I came to was that the "advertised gain" K&N claims is negligible if at all nonexistent and mute. The only advantage I can conclude with a K&N is it's cleanability and re-usability.

Sounds like you have the possibility of a couple of things

1) Air is getting in somewhere after the MAF and before the TB. Is the connection from the airbox to the inlet tube (which the MAF is mounted on) to the TB sealed/tightened sufficiently?

2) Due to air intake blowing past the filter, sometimes the oil will atomize (kinda like fuel meeting air in a carb) and then get hung up on the MAF's electronic resistors/vanes and in the TB around the TB blade. Check the MAF and if need be, use some electronics cleaner (available at Radio Shack) to spray on and let it evaporate to clean it, and then check your TB and clean up any soot from that oil that may accumulate around the throttle blade.

I have a good notion to say that if you installed it and noticed this right away, it's probably just number 1.

what kind of exhaust was the dyno'd vehicle running? There's no point in opening up the front of the air pump if the back isn't open as well. Even without headers, I noticed a big increase after installing the K&N FIPK and having a cat back already.

2000Plow4x4 · February 28, 2003

Yea my truck i just picked up has been idling rough, i dont have a KN yet but it idles rough around 500 rpm. maybe exhaust leak, have looked for vacuum leak but nuthin so far, plugs looked fine as well, truck only has 27k miles. anybody else had this problem. the cold NH mornins make it sound like a diesel. any help thanks

CMNTMXR81 · February 28, 2003

An air filter won't make a significant enough difference to require an PCM "Idle-Re-learn" reset.

I dyno'd back to back on the dyno with the Z. First pull was a regular paper Fram, it registered 318rwhp. After that pull, I quickly got up, swapped them out putting my K&N in and making another pull. The K&N equaled 316rwhp. The torque numbers (which I don't recall off the top of my head) where the inverse. The paper Fram was 2-3 lbs-ft lower than the K&N. At the end of the day, the conclusion I came to was that the "advertised gain" K&N claims is negligible if at all nonexistent and mute. The only advantage I can conclude with a K&N is it's cleanability and re-usability.

Sounds like you have the possibility of a couple of things

1) Air is getting in somewhere after the MAF and before the TB. Is the connection from the airbox to the inlet tube (which the MAF is mounted on) to the TB sealed/tightened sufficiently?

2) Due to air intake blowing past the filter, sometimes the oil will atomize (kinda like fuel meeting air in a carb) and then get hung up on the MAF's electronic resistors/vanes and in the TB around the TB blade. Check the MAF and if need be, use some electronics cleaner (available at Radio Shack) to spray on and let it evaporate to clean it, and then check your TB and clean up any soot from that oil that may accumulate around the throttle blade.

I have a good notion to say that if you installed it and noticed this right away, it's probably just number 1.

what kind of exhaust was the dyno'd vehicle running? There's no point in opening up the front of the air pump if the back isn't open as well. Even without headers, I noticed a big increase after installing the K&N FIPK and having a cat back already.

ATR Pit-Bull Cat-Back