I just put in a Megan Racing 4-1 header and there are a couple of problems. First of all it is extremely loud and I was wondering how I could quiet it down. Second, during idle the RPMs are really low to the point of almost stalling. How can I fix that?

 

All headers are pretty much giong to be loud. You are going to need a resonator welded into your midpipe (do a search on here and you should find all the info you need.)

Also - did you disconnect yuor battery when you were installing the header? Since you removed a CAT your ECU needs to readjust so disconnect the battery for a few minutes (or just step on the brake pedal a couple times after you disconnect..should drain the system quick) then reconnect the battery. Start the car and let it idle for a little while (5-10min should be all you need) and you should be fine after that.

 

It's loud (and probably raspy) because you added a header with another aftermarket exhaust. Only thing you could really do is add a large resonator to the mid pipe and hope it helps.

Not sure about the RPMs but did you reset your ECU at any point? You may want to if you haven't. Just disconnect the negative from the battery for a few seconds and connect again - then let the car idle for 10-15 min.

 

The ECU will never get used to not having the CAT. It wont run any different without it, but you will get and keep a CEL soon. You need to use an anitfouler (just search on here for that) or have the 2nd O2 moved behind the other CAT to get rid of the CEL issue that will come up.

For rough idle, like ack said, if you removed the bat cable then it will probably idle rough for a little bit. It will relearn and come back to normal. Driving it around for a bit will make it come back to normal sooner.

As for the nasty @$$ rasp... that is part of a header on this car. Start searching to see what huge resonator and exhaust people on here are running to help reduce that.

 

dis is why i dnt like headers

 

Header, one! The ECU needs a reset, after that you will be golden as long as you have the anitfoulers.

 

anitfoulers???

 

im saying Headers because im speaking about more than one header.

 

ok, anitfoulers are what trick the ecu to think that there is a Catalytic converter, when you take off the stock header you remove one cat. Thus making your car run lean, because it senses their is not cat. The deal you are looking for with the MMW header already has them it is just a bolt it up, let the ecu reset, the figure out how much you want to do about rasp.

 

oooooooooooo thanks 4 da info

 

no prob.

 

It wont run lean. The 2nd O2 is only used to see if the cat is doing its job. If it isnt, it sets a code to let you know that the cat is gone, not working properly, etc. When you remove the cat you have to trick that O2 into thinking there is one still in the system so it doesnt set the code. But no fuel trim is set off of the secondary O2, it is set of the primary O2.

 

I thought I herd somewhere that it would lean it out because it would scene the levels of oxygen yada yada yada. But I am not ashamed to be wrong, its how you learn. But with out the antifouler you will throw a "Check Engine Light" CEL. Thanks for the info.

 

Are there any manufacturers that offer some sort of a silencer for exhausts? If so will that even quiet down the raspy noises?

 

A resonator is really your only option. I don't think a silencer would make a worthwhile difference

 

maybe he meant Quite Freaking True?

 

^^ I think you are trying to reply to the stolen car thread beandip ? Pretty funny, cause I just finished reading the whole confusion the guy had about what QFT meant on there.

 

Wow, how did i do that? Damn why am i the king of fail lately? I swear I was on that page. lol maybe it was when the boss came in and had to hide it so I was not to get fired. I think I did a total of 30 min of work today, so there is my WIN!