josephkuhr

Just replaced my catalytic converter ($$$$), as well as spark plugs. Doesnt bog anymore...although it still feels restricted at low rpms.

Anyways, now the exhaust shakes when i come to a stop. From the interior it sounds like the the resting of pipes in your house during the night time. I know that it is the exhaust shaking because i looked under the car after coming to a stop in my driveway to make sure. The mechanic who did the job said that the previous owner extended the piping at the point before the bend or the muffler and that i need to cut that out and reweld...Does that seem to make sense?

Does anyone have any idea what the problem is? Has this happened to anyone else before? Plss help me if you know.

P.s the guy who put in my spark plugs didnt gap them at all...and didnt use any special tool to torque them in...could this have any serious effect? They were NGK platinum or something like that.

Dareng

You shouldn't have to gap new spark plugs. You should always check but they should already come pre-gaped for you. Honda's generally run better in Iridium plugs. They are a little more expensive but you will get more millage out of them.

I know that then I replaced my cat with high flow, it took a little while for the engine to remap the settings for the idle. But after a couple of days, it went away.

The only reason that I can think of that the previous owner would extend the piping is becuase he had added on a smaller or aftermarket muffler adn the piping needed to be extended. So he could have extended it for that reason. It might be shaking becuase it is not hung properly on the car itself. What year civic and what frame (2D or 4D)?

MPR

Again, another reason I do all the work on my own car. Incompetent mechanics. Honestly, this is simple stuff that any mechanic should be able to do properly.

You should ALWAYS check the gap on new spark plugs before installing. You do not need a special tool to install new spark plugs. You tighten finger tight, then a 1/4 to 1/2 turn from there with a ratchet. The spark plugs you buy for your car are not JUST for your specific car. Many other vehicles can use the same plugs but may specify a different gap. Thus, they aren't always pre-gaped for your specific car.

The mechanic should have checked for rattles after installing the cat and should make sure nothing taps or rubs, even if another part of the exhaust has been changed before. Just because it wasn't 100% stock before the job was done doesn't mean he can leave it with a rattle instead of making a slight adjustment which is probably all it needs.

josephkuhr

2000 Civic Si 2D, and I'm pretty sure you are right that the previous owner extended it because it was a smaller aftermarket set up (magnaflow). I don't wanna cut the extended piece because then my exhaust would hang behind the bumper and build up soot all over it and possibly melt it depending on how hot the fumes get.

It must have to do with the install of the cat, because the vibration most definatly wasnt there before, so im going to talk to the mechanic. Hes a family friend, but if this is his quality of work...i may not be inclined to go back to him ever again. By the way, i paid $200 for the cat + install, sounds like a good deal to me, but im not afraid to admit that im new to the car world (in a practical sense) i.e inexeperienced, but reallly love cars. But ya, anyone have any price comparisons?

josephkuhr

Such a good point. The thoughts actually been rattling around in my head to take some mechanical courses next summer if i can find some kind of program. I would really love to learn how to work on cars so that i could do everything my self. Either way i still plan to gradually read/research and do whatever i can on my own.

MPR

$200 is a pretty good price for a cat install (cost of cat included).

Just to give you an idea...I built my entire 2.5" custom exhaust system from scratch all for less than $400 all said and done.

jdm itr (integra type R) 4-1 header with 2.5" collector, $100 used, in good shape, I re-welded the flange and port-matched it. Got a 2.5" flange coupling for about $25, got a 2.5" magnaflow high flow cat for $90, 2.5" magna flow resonator for $90, various 2.5" pipes, bends, straights etc.. for $? can't remember, and a used carbon fiber 2.5" megan racing muffler for $50. Pieced it all together first with clamps for fitting, then welded up all the joints and welded on the stock hangers from the old exhaust and thats that.

You can save yourself a HEAP of money by doing the work yourself. But not everyone can do it all. If you can't it's good to find a good shop you can trust that will give you a deal and not try to pull one over on you to get more money.

Good luck with your car, I hope you can get it fixed without too much hassle. I think the mechanic who did the install should fix the rattle imho.

josephkuhr

Awesome feedback and thanks for the warm wishes, i talked to my mechanic and he said he'd put it back up on the hoist again and take a look...hopefully everything works out well.

Its great hearing posts like yours. Reading play by play information like that really puts in to perspective whats involved with car building. I plan on learning how to weld someday, because i know how crucial it is to any gear head interested in doing their own work. Your set up sounds bad *** tho . You clearly know what your doing.

Thanks again for your input .

MPR

No problem.

It takes a bit of time to learn a lot of this stuff. I'm always reading and learning new things on a daily basis, and there is A LOT still to learn.

Start off by doing simple things like oil changes and brakes and work your way up from there. That's basically what I did. Having the right tools is also very important. And I can't stress enough, research research research before doing anything. Also helps to have someone there who's experienced in what ever procedure you're performing. Ask lot's of questions too.

Let us know how you make out at the shop.