Evo X Problem After Exhaust intall!!!

[PattonX]

Hey guys I have a stock 2008 Evo X and today I intsalled a 3 inch cat back straight pipe to axle then 2.5 out to the tips no muffler. Sounds great but when im getting on it at about 6k rpms pulling hard it makes a studder like its hitting fuel cut of or somthing just for a split second then gets write back into it! does car need to be tuned for exhaust? overboost? any ideas will help thanks

[blkside]

Is that all you installed was the catback?
Did you verify everything was tight ?
Why would you get a 3"/2.5" exhaust? Manufacturer?

[toku-one]

did you notice if it was doing this before the exhaust?
studdering up top seems like the original factory tune type stuff.

[mangoes]

Did you replace your fuel relay yet?

[Dubs46]

my 8 did that when i installed my dp. mine was at like 5500rpm though it would seem like i hit boost cut. but after a while it stopped doing it. it was weird. my car runs just fine now

[PattonX]

All i did was remove the old exhaust and build the new one. Everything was tight. I built the exhust my self and my exhaust bender would not bend the 3 inch tube to fit the passenger side outlet in the bumper! to much of a bend. I also was not sure if I would like the sound so beffore i buy the write 3 inch die for the bender i wanted to make sure i was good.

[SoCal_SS-396]

do you have a boost gauge ..?

[PattonX]

i didnt replace the fuel relay yet! are they a problem?

[PattonX]

no boost gauge yet... getting one tommarow now

[Mike W]

Your studdering is telling you that _your_ car with _your_ set up needs a tune or something looked at. Plug gap check, a boost gauge and some kind of datalogger that can see if you are knocking are all in your immediate future if you keep your current set up and mash WOT.

Yes fuel pump relays have been a problem for several people.

Mike W

[PattonX]

sweet thanks for the input

[PattonX]

I live In San Diego any ideas who i should have tune my car and around how much $ i should expect to pay?

[Mike W]

There is only one EVO tuner in the San Diego area and that is Reese. If you drive north there are a bunch. I am one of them. All are listed in the vendors forums here to choose from.

Fan boi contest to follow...


Mike W

[rl22]

pm sent

[jackfrog]

i have question, do you really feel power gain after catback installed? and do u need a tune for that too?

[Mike W]

With a cat back exhaust only you can feel better response. A little more top end too maybe depending on the system.

If you installed an exhaust only, you would not need a tune. If you did an intake only you also would not absolutely need a tune. The ECU can fix and trim for the most part with either mod alone. But when you start combining a high flow exhaust with an aftermarket intake, then you really should get the car tuned asap.

The OP's car is probably running rich at the high RPM range and that is what is causing it to break up a bit. Some kind of intake might lean it back out but then the car would have too much ignition advance.

Mike W

[big boss]

Good info MIKE!!!! O0 Just wondering could it be BOOST CUT??? :?

[Mike W]

Overboost on an EVO X would have the ECU cut boost to a very low level and leave it there until you cycled the ignition. Also would most likely give you an overboost SES code.


Mike W

[PattonX]

Thanks To Mike @ RRE and his Kick ass skills on the dyno problem is fixed and car runs better then ever! Pulls harder and runs smother! RRE gets a big O0 in my book!

[R33F]

Good to know! O0

[jaydeeway]

Did you change out the fuel relay too? Or all you did was have it dyno-tuned?

[kungfudevil]

More on the subject of fuel pump relays, would boost spikes be caused by a bad relay on the Xs? I've been starting to see boost spikes every now and then (I usually see around 25 psi on WOT but sometimes I see boost of almost 29 psi on my meter).