Hello,

93 Civic DX, d15b7 with 140k miles.

Ever since I had the catalytic converter + o2 sensor + muffler replaced a year ago, the idle feels like it's low and I've recently noticed a soft thumping sound from the exhaust pipe.

When the cat converter went bad, the car had very low power so I had to rev the engine pretty high to get up some hills. Wonder if I could have caused a gasket leak from the pressure (assuming the cat converter was blocked?)

Other info: no CEL, I bled the coolant recently, distributor and spark plugs replaced recently (~5k miles ago)

I wonder if anyone might have any suggestions of things to check?

http://youtu.be/sxr5Sxs30G0

Thanks!

 

well, since my last post I've done the following, but still hear the misfire (thumping) while at idle:

replaced valve cover gasket, adjusted valves
replaced coolant
checked ignition timing
replaced spark plug wires (with OEM wires)
replaced compressor, alternator belts
replaced brake master cylinder
checked for vacuum leaks - replaced IAC valve gaskets

Looking at the spark plugs, I do see a bit of white powdery marking on all 4 plugs, which sounds like it might indicate a lean fuel mixture. The fuel filter was replaced <2 yrs ago. Any suggestions of where to look next?

 

posting pics of my spark plugs, in order from 1 to 4, followed by all 4.

- like I mentioned above I do see some white powdery material on the electrodes.
- also see some deposits on the porcelain.

Does this give any clues to the misfire I'm hearing?

 

Curious as to whether you found a solution to this problem. Sorry to revamp an older thread but nobody seemed to post anything and an answer was never stated.

 

If you are having a similar issue, I'd sugguest checking your compression by doing both a dry and wet (put a few drops of oil into the spark plug hole) compression tests. I was having a similar issue where the exhaust note would burble every few seconds or so. No other issues or check engine lights.

Did the compression test and figured out I had leaky exhaust valves on cylinder #4. Could be the same issue here.

 

Thanks for the input! I'll have to try that when I get home today.

 

Thanks for reviving the post. No, I never did resolve the problem.

- dry compression (in Hg): 180, 175, 175, 185
- vacuum (in Hg): 21, but with A/C on goes down to 15. Little vibration but less than 1 inch.

I also had my injectors checked and cleaned by cruzinperformance, with no issues found.

 

Car is still running just fine though? That's all I'm really worried about at this point.

 

Sorry for the late reply, haven't been checking the posts often enough...

Yes it seems to be running ok, BUT my emissions seem to be getting worse and just barely passed last year.

Low speed emission results
2012 HC:197 CO:0.00
2011 HC:82 CO:0.45
2010 HC:13 CO:0.06

So I'd really like to figure out what is going on with it.

People seem to say Seafoam gives good results, might give that a try although I don't know exactly what it is supposed to fix.

 

my 92 eg4 with a d15b2 has some sort of problem like this. Thumps a bit with a hot engine, and shakes a tiny little bit when at idle. But never stalls, and drives pretty good. When the engine is cold, there is not a problem at all. But i haven't tried anything to fix it yet.

And sometimes it seems to run a little bit rich, when you release the throttle and then inmediately press it again it sputters (although it drives and feels normal, it only sounds like it does) a tiny little bit...