Performance improvement after cat-back installation
 

Call me crazy, but replacing my rusted out OEM cat-back actually improved my car's performance considerably. For a while it would run fine when cold, but when it warmed up it would lose most of its low end and in general was sluggish. I thought that those symptoms were directly related to a malfunctioning knock sensor, which in fact I had a code for, but I knew that the knock sensor itself was ok because I had it replaced. I'm wondering whether the rusted out cat-back was somehow setting off the knock sensor. I wonder though, if the code is still there, is it possible that I got a sizable amount of torque back just from fixing exhaust leaks? I had three malfunctioning coil packs replaced a few weeks back but drove a considerable distance without noticing much of an improvement in torque. It did improve the sputtering that was plaguing the car as of late. Now, I go ahead and buy a new exhaust and it runs like new. Interesting to say the least...

FYI, my only performance mod is a budget Y-pipe

P.S. I hope I didn't just jinx myself. lol

Interesting - I have been meaing to replace my cat back as well. What did you replace it with?

Not to sound stupid but what is a budget y-pipe? And where did you purchase from?

1) I replaced my old OEM with a new OEM. It is not a performance cat-back, if that's what you're wondering.

2) Budget is the name of the company who makes the y-pipe. You can buy them online somewhere, just do a search for it on this forum.

I am going to run the codes sometime this week because I am curious to see whether the knock sensor code is still popping up. I wouldn't be entirely surprised if it is not because I can't imagine getting back this much power just from a new cat-back. This car continues to confuse me....

Can you get engine knock from having an exhaust leak though?

That's rediculous. No.

Directly? no. If the exhaust leak causes your air to fuel ratio to lean out, then yes it definitely is possible.

but thats only if the leak is before the 02 sensors - so the top of the y pipe basically.

a leak behind your cat (cat back....) wont affect anything.

very true. to be honest even if you were running lean, i dont think it would necessarly set off your knock sensor unless it really did knock or ping. your knock sensor only detects knocks or pings not if your running lean rich ect ect. its still possible to run lean and not ping or knock.

Budget is a brand name. I read somewhere on the org that Budget is no longer making Y-pipes for the 4th Gen. I also know their website is no longer up. I bought mine about 2 years ago--I believe they are/were located in a suburb of Toronto Ontario---- Oakville, Ontario? I think the remaining sources for 4th Gen Y-pipes are now Cattman and Warpspeed.

Update: I checked my codes today and to my surprise the KS code (P0325) is still present. This would mean that in fact the performance improvement is linked to the cat-back replacement alone. It was badly rusted and leaking, but I did not expect to see this type of improvement in low end torque. The car is actually fun to drive again. Before, the car would be very sluggish in the lower RPMS and would only start to pull around 3KRPM. Now, however, it pulls smoothly from the get go. Let's hope that this lasts.....lol

Update part 2: As I had originally feared, the car is back to running like crap. The same symptoms that had plagued it in the past are now back in full force. The car runs fine when it is cold but once it warms up, it loses all of its guts and the exhaust develops a weird buzzing sound. I'm pretty sure that the culprit here is the KS. It must have thrown something off when I changed exhausts, now it readjusted itself somehow. I could be completely wrong, but I seriously doubt it.

Is it possible to bypass the KS even if it hears knock? I'm so sick and tired of the way it runs, especially knowing how it COULD run. As I mentioned earlier, the KS itself has been replaced. Chances are that it is not the KS itself that is cause of this dilemma.

Thanks

470k ohm resistor and run on 93 octane...

If you still getting the KS code, have you checked the KS harness?

No, I have not. I was thinking about replacing it, but I am very strapped for cash right now and there is no guarantee it will fix the problem.

Will putting in the resistor take care of the KS code altogether? Also, what are the risks involved with putting in the resistor assuming I run 91+?

Check the KS harness first per the FSM specs. If out of wack, it's roughly < $20 IIRC to replace.

The problem is not the cost of the part, its the cost of installation.

If you pay to get a KS put on, there is something wrong...

the harness is gonna be fine.. just remember there is only 1 wire running to the ks..

Of the KS harness?? It's very easy to replace. Definitely a DIY job, if needed.

Thanks for all the advice guys. What are the risks associated with running the 470 ohm resistor?

I feel the need to wash out this myth (again) because frankly, I like Budget Exhaust. Just got a NEW polished SS mandrel bent y-pipe and b-pipe shipped to me from budget. They still have 4th gen pipes in stock, but will only make batches, not 1-offs for every order that comes in. So when a batch withers down, there might be a waiting period. SO in short, if people keep saying they don't make em anymore and orders fail to come in, it could become true. But in the meantime, its not.

My car is a '99 GXE and when i hit 3900RPM or higher the exhaust starts to make a rattling noise, a year ago there was a rusted spot which was patched, but now i am the owner of the car (parents gave me it) i need to upgrade some stuff. Car has 107K which isn't too bad, but my mother killed the tranny with her exelerate then let go in 3 secs driving technique, around 2 and third gear it sometimes shifts roughly, but overall i love the car. Anyways I wanted some better sound from the exaust and i hate fart cans, so i mind as well get the real deal, any suggestions? My budget is like $300. I was thinking of cutting the muffler and geting stragiht pipes with a nice looking stainless steel tip so it doesn't rust.

iv'e just put a sudo N1 on my car and it gave a performance boost, along with a high flow cat. KS is def. an easy enough job, just gotta fit your hand in there...

Replace the knock sensor yourself. Ive done it a few times on a couple of maximas.