So I decided to gut my pre cats yesterday (Monday) and today (Tuesday)...and well here is my input....don't waste your time and energy. I got this accomplished with the loose of 2 ratchets, 4 sockets, 1 pry bar, 2 cans of PB, driver side fog light, dent in the passenger side fender, $40 worth of drill bits, $30 worth of anti freeze and tranny fluid, 4 stripped bolts, and many many many cuts and bruises...and did I mention I started 11 am Monday....slept a total of five hours and finished Tuesday at 9. After all this I STILL have a mother%^&$ing exhaust leak and I never got to install my nofoulers and my car smells like a gas station, guess i'm going to the muffler shop tomorrow......and worst of all I cant tell a difference. So save your time and sanity and just buy some headers, I never want to do anything like this again.

 

Gutting the pre-cats is becoming more common. See my post here.

I paid my mechanic $100 to do just the rear pre-cat. Money well spent in my opinion.

 

Where I live mechanics wont do it because of emissions...so I had to do it myself...it made me hate life a little.

 

Ha! Just you try and put headers on with less issues! You will really hate yourself then...

 

I difinitely felt a difference when I did it on my 03, and yes it was a pain in the @$$, but not as much as yours, maybe cause in Cali, and didnt have to use no PB blaster on any of the nuts.....

 

Hot dog! 3 precat gut threads this week and counting. I do all my own work on my cars but for this job i went to my best friend which owns a mechanic shop. You see some jobs are worth paying for and to me this was one of them. He took 3 hours start to finish with air tools and torches.

 

As for the leak did you check where the rear manifold comes down and connects to the Y, you made sure the Ring gasket was in there and fully tight, where mind was once.....

 

I found pulling the headers off was easier than everything else, they didnt give me any problems...and I had to take them off cause I snapped like 4-7 bolts.

 

Thats all well and good but just you try and put some obx headers on dat bish and see what happens!you'll be slingin blood and snot everywhere trust me.

 

My car has 180k and originally came from Florida.

 

Already did that and swallowed about a shot class of anti freeze and also took a bath in it haha, but is it really that bad to put obx headers on?

 

The ring is there and two out of the three nuts are tight, the third refused to go on anymore, and I dont feel any significant difference...but that could be because im too pissed about the leak, the dent and the f%^&ing fog light!

 

After about 12 hours i gently took the obx headers smashed them on the ground guitar style and slung them across my driveway.literaly i dropped a new engine in my max and had it running by myself in less time!

 

Ok. I think the easiest method would be to cut off the y-pipe and lift the engine towards the front to the get the rear header on and drop it back in.

That's a fraction of the time of all this blood, sweat and tears that people are wasting

IM, axles, radiator, some wires and motor mounts are easy to remove vs what people are doing LOL

This is like taking candy from a baby compared to what I just got myself into...I just bought a Z32

 

NO! Read my install thread, if the link doesn't work I bumped it to the top of fifth gen page. Took me several hours but not days to do. I've had them installed for nearly a year now with no problems

http://forums.maxima.org/5th-generat...-comments.html

 

I will be doing this on my 5th Gen soon. On a lift. With a Nissan Master mechanic. Hopefully I won't have so much trouble...

 

With a lift and tools you will have no problems and a Nissan Master Mechanic, can it get any easier....

 

Yea, the complete absence of 10 years worth of rust and corrosion.

 

i removed the Y-pipe from a 2001 model that was heavily rusted (parts car) just to sell it with the pre-cats, it took me about an hour and a half to remove the Y pipe, however i had a garage, tools, and some socket swivels (definatly needed) and best of all, it was all on a lift! The car rusted apart, but the bolts didnt break, they came off, the manifolds were harder to remove than the y-pipe was.

matthew

 

I used a 3 ton jack , I wish I had a lift! My Y was so rusted I stripped a socket, bent a breaker bar, then I had to drive to a muffler shop so they could break loose the two bolts on the Y where it meets the third cat, they even had a hard time. Then I snapped four bolts on the radiator cat so the radiator had to come out resulting in a bath of anti freeze for me, then I spent minimum 5 hours trying to drill those bolts out and still only got one drilled out. By this point I was starting to go insane lol. Then on the rear manifold and cat I broke 3 more sockets and 2 socket wrenches and bent the breaker bar to near 90 degrees..after heating and pb blasting this one bolt..so I said **** it and gutted the cat while on the car which did I mention resulted in a broken nose. ONLY DO IT IF YOU ARE PREPARED!

 

DAMN! thats how I felt these past two days, what makes them so hard to install?

 

Seriously... in Tennessee? 62K people outside of Nashville, and you couldn't find one mechanic who would gut your precats? I find that highly implausible.

Gutting precats on a 5.5 Gen is a reasonable mod. There's a small gain in the butt-dyno, and a pleasant deepened tone to the exhaust.

Shame about your DIY problems. You've earned the right to vent.

 

All the shops around me said no, Id have to drive to another county because if they get caught they get like a 15,000 dollar fine or some bs like that, I tried offering them cash under the table no evidence receipt or anything like that but they said no, which I understand. I live in the middle of the county too and im not about to drive 35-40 min on open headers as fun as it may be haha. I live in Williamson county and our emissions is strict, obd2, mirrors and sniff and even if your throwing a code for something nothing emissions related they send you away.

 

I must have gotten lucky, all my bolts turned with no problem and I i needed for the cats were a small crowbar and a hammer

 

No, it is not that bad...it will be as hard of a job as you make it.

 

And worst of all my mpg took a steaming crap! Im now getting 13.1 mpg at idle........F^&*ING Idle! thats worse than....idk even know what!

 

This thread is absolutely hilarious! I thought I was the only idiot that does exhaust work in the driveway. Remember, heat is your friend!

 

Dude....never again, even if it is "direct bolt on" never ever again eff that ish...

 

But seriously guys any input on why im getting 13.1 mpg and im hearing some funky sounds from 1.5k up?

 

My first guess would be something's broke.

Codes?

 

besides the two 02 sensors no.

 

Sounds like the maf took a crap.

Lots of threads on here about ppl changing intakes and pop goes the maf. Exhaust would have a similar effect. Why it happens, idk.

 

but it still accelerates just fine wouldn't maf cause crappy accleration as well? The only time it wouldn't allow me to accelerate was when I was running hot because my dumb *** forgot to fill the radiator back up and it gave me the p1217 code.

 

The symptoms vary wildly. It can run very rich, but still attain decent performance. I had to replace my maf, b/c I was getting 19 mpg mostly hwy, but there wasn't a discernible difference in perf.

The best bet is to see if you can swap mafs with someone to be sure, so you don't spend 90 bucks if you don't have to. If it has high mileage on it (100k+) it may be worth it to just replace it anyway.

Semi-related tidbit: I started my car with open headers when replacing the y pipe gaskets and gutting the SS mesh in the failed flex section (cattman headers) and it instantly went into safe-mode the 1st time I started it. I didn't check the code, but I imagine it was a too lean one.
I reset the ecu and it started fine. The ECU and sensors do weird things. It's not always logical.

 

I have a 180k, I re used my old gaskets for the y and the front header manifold and I wasnt sure about to toque specs so me being tired and lazy at this point just tightend them till they were decently tight ( at this point I was afraid of snapping a stud on the head.) could this be caused by a bad exhaust leak? cause when I start moving my mpg goes up to 16-17 ish but at idle it goes to 13s. Also the front pre cat (which is gutted) only has 4 out of the 7 bolts holding it in place. And to add to your tidbit I drove over 15-20 miles on open headers, I even opened it up for someone in a civic who thought he was king of the road.....im about 90% sure he shat himself and half of Franklin tn now thinks I have an LS in my car....

 

I doubt it. Are you sure the comp reading is even close to correct? And what do you mean at idle?

 

I also gutted the rear cat while on the car, the nut rounded holding it in place.

 

At idle, sitting there in park and sitting there in drive with foot on the break. I had 2 different places read the codes only ones that were given were the rear o2 sensor downstream and the p1217 which is engine to hot ( forgot to put coolant back in the radiator.

 

If you're not rolling, then how can you have anything above 0

 

Touche. But tha'ts what the computer says I start rolling it works its way up from 13 to 16 or 17 then I stop and it goes back down, this only happened after gutting those damn cats before that I got near 19 city and id cruise at 85 at 2800 rpm getting 31 mpg. So something is jacked up and i'm not liking it. Like i'm really 100% regret doing it. I loved my car more than my family and now I want to get rid of it, don't think y'all realize how much this ruined the car for me. For god sakes I broke my EFFIN nose dealing with this pile of horse pucky!