I was driving today and noticed that either my valves had started making more noise or I had an exhaust leak. I was in the garage with a friend (another s2k owner) just now revving the motor a little to try and figure out if it was the valves or exhaust, and while the car was idling I noticed another weird noise coming from the back. If you stand at the back of the car so that the engine noise doesn't overpower it, there's a very faint puffing noise coming from the exhaust. It's not rhythmic at all and does it maybe 1 or 2 times per second. I know "puff" isn't the best description ever, but that's what it sounds like... sorta like pressure is building up and then letting out all at once. I've never noticed it before and my friend had never heard it from his car either.

The only thing we could come up with is the fact that it's spring and the temperatures are changing and the ECU could be relearning. Does anyone have any other ideas?

 

Lean misfires, sticky injectors. Description is good.
https://www.s2ki.com/forums/index.php?act=S...dpost&p=5592292

 

See if you can post a GOOD sound clip.

 

Check your plugs and stop driving it asap. Same shit happened to me and what happened was i was leaking throught the intake valves, an dbroke off a goddamn plug somehow and it was bouncing around in the combustion chamber of cyl 4.

The ECU relearning wouldnt really give you those kinda problems, something more deep is the culprit, any CELs to go with it?

 

Having same issues.... coming from rear drivers side.

sounds as though there a slight amount of back pressure for a sec then, 'puff'

 

If there was a broken spark plug I think the description would be different, and the engine would not be running smoothly.

 

If the "puff" as described in the original post is a lean misfire caused by sticky injectors it can be confirmed. This can be done by hooking up an OBDII reader with a laptop to capture and plot the O2 sensor and short term fuel trim (STFT) data.

A lean misfire has no fuel, so the engine shoots out a "puff" of air instead of a normal vent of exhaust. This causes the O2 sensor to glitch to which the STFT responds.

Here's an example of a misfire, O2 sensor (top) and STFT (bottom) graphs. The first two humps of O2 sensor are normal and the third shows a read when a misfire occurs. The STFT below responds accordingly.

 

Gotcha, this is what happened to me and I was getting that puffing sound

 

So any specific solution to cure this problem?

Since I picked up the car a few weeks ago, I put new spark plugs, changed the oil, fuel injector cleaner, the works.

I also took it into the Honda dealer 2x for alignment and fender lining replacement in the last 2 weeks and they did not notice anything.

 

I read through the entire 9-page thread posted earlier and the only similarites I have at the moment are the puffing noise, which another local owner told me his car has had since he bought it new. Granted he hasn't heard mine in person, but he says his car does almost the exact same thing I described. I need a valve inspection/adjustment no matter what, so I'm going to go ahead and take care of that now and quit being paranoid about this for a while. If the car starts running rough or I start getting CEL's then I'll start worrying again, but until then I'll just rely on the extended warranty that came with the car.