I just put in a Megan Racing cat back on my car and decided to test it out. Haven't topped out my car in a while so decided to try it out. I reach 105 mph and it's starting to top out already. I remember before when i was able to reach 120-125 without a problem. Don't know what the cause could be. I do have bad tires on my front wheels but don't know if that would have such a big effect. Any ideas?

 

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UH, maybe let the computer adjust to the new tuning before you try and go all out...

If the exhaust is any kind of one at all, the engine will now want to run leaner, so it will take some time for the computer to adjust A/F to cope. Just drive it and run a tank of gas through it, then you should be good to go.

 

EDIT: Oh yesh, don't top your car out on the street, it's stupid and illegal, and noone on this board has ever done it - EVAR!

 

A32's are typically a touch on the rich side from the factory.

Aside from that, I don't think much power is gained through cat backs on these things.

More so from the right header/y-pipe combos.

 

ok thanks, so this would be the cause of the car actually feeling a little slower than normal?

 

I've done it , just not on bad tires.

 

No it would not.

 

any possible answers then if this is not the problem?

 

Aside from the norm, (check engine codes etc) then no. Were you going uphill, what was the weather like, did you have a headwind, did you not isntall the catback correctly therefore creating an exhaust leak, which will hurt power output etc

 

Like I said, "If it is any kind of exhaust at all". By that I meant if there was any measurable performance to be had by it, then the computer would have to re-learn - just like it DOES when you put on a y-pipe...

But I didn't know how much power the cat-back would give, apparently none - so therefore - no re-learn.

 

And yes, haven't we all, and I would not do it on bad tires either. Sarcasm > yor azz

Then again, my car goes alot faster than 105, I have gone 105 on bad tires

 

Was there packing paper or something stuffed in the muffler that you didn't remove?

 

It will not do it with just a catback no matter cat-back it is.

And no, the MAF sees what it sees and does what it does when it sees what it sees, so no, there is no adjust adjustment time.

 

Meh, makes sense. His car is still slow though And as I said, I am not farmiliar with how much power is to be had w/ ANY cat-back on a Max, not just this one...

Seriously though, as mentioned above, differences in temp. would have the potential to really drag your car down, especially here in Fla where it can get 100% humidity and 100deg. outside. In the winter time when both are low, my Max is noticably quicker.

How long before you put on the cat-back did you do your origional "test"? If it was a while then maybe something else happened between then and when you put on the exhaust.

 

it has been a while since i tried to push it, and i'm pretty sure i would notice if there was packing paper stuffed in my muffler, i checked for leaks and didn't see any and i think if there was a leak that was small enough to get by me then it couldn't be cause for such a power difference, the only work done on my car before this was having the axles changed and i have two different tires on the front which is temporary due to a blowout i had

 

tried it out again, i try to keep O/D off but it only goes up to about 4500-5000 rpm and then if i put O/D on I don't feel the gears switching, i think the first time i had this problem i was on an empty highway and it was at 110 and climbing like normal and then all of a sudden i felt a power loss and although i was pushing the gas it was decelerating and would only stay around 90 to 100 and i'm guessing since then i've had the problem

 

If you have auto, you have to hold 3rd until you get to about 120mph, then let it go into OD. If you have 5spd, just redline every gear and you should be able to hit 130 no problem, but it may tkae you a minute or two to top out at 140mph.

If you have mods that will let your max work up a little higher in the powerband( read: y-pipe, intake, 00VI/MEVI), then you should be able to do better.

I know when I had my 95 auto w/ 120k it would do 140 all day long, and it was totally stock. My 1st 97 auto w/ 130k would too, and my 5sp will damn sure hit it.

Not that I have ever exceeded the speed limit of course...

 

yea sure.

 

same my 99 is totally stock, 120k and it reaches 120 mph no problem, ive never pushed it further than that because im not that of an experienced driver and don't want to do more than i can handle....

 

From what I remember, doesn't some Gxe Autos top out at 115. Cause I believe mine does. If so, couldn't I just swap out my ecu from an Se?

 

Only reason to do so would be for dynoing.

 

yea i've taken my max up to 137 before without a problem, but now it feels like something is holding it back, but i checked my ECU codes and i got a code for the front right heated O2 sensor, could this be the problem? (where is this O2 sensor located?)

 

Yup, it's in the stickies and only GXE's have it. But he said he's had his car up past that before, so I don't think that's his problem.

And yes, an O2 sensor will make you car run like azz. Get a new one.

 

yea anyone know where i can see a pic of the location of this sensor? I have a GLE and i did change my ECU a little while ago but i don't think it was from a GXE because i'm pretty sure the numbers on the ECUs don't match up

 

you dont have enough backpressure!!

 

God I hope you're joking

 

yeah my 98 gxe tops out at 117-118 mph...my 96 auto has seen 138 mph once... and my 95 5spd did 140 twice last week with an intake, warspeed y/hi flow cat. udp, and megan racing catback....it felt pretty good til 128mph then was having har time pushing it with total of three guyz and three 17" inch chrome rims with tires on them in trunk and one on seat with sh*t load of stuff in the car....did that in the tunnel on I-76 west in PA...

 

No, that sensor is not holding you back.

 

and i still got codes for my rear and bank 1 sensor 2 o2 sensors