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Discussion Starter · #1 ·
The frontier is not my first Nissan, but its shaping up to be the most expensive to repair. Whats the deal with the exhaust manifolds? 1000$ a piece seems a little much for a part you need for emission controls :surprise: (integrated Cats)

Went to 3 shops today all are telling me between 3500 and 4000$ :frown: to do a replacement exhaust. Two out of three looked at me like I had 2 heads when I said I needed manifolds, and yes after they looked it was deemed a replacement.

Maybe its just me being cheap but if it wasnt for emission laws (southern ontario) i would go for headers.

Is there something i'm missing or a cheaper way to go?
 

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Discussion Starter · #2 ·
So after calling around to parts suppliers, there are 2 different manifolds for the Frontier. Option A Integrated Cats or Option B manifold with no cats. Option A is $500+ Option B is 200$. Other then no cats with option B what is the difference?
 

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From 99-02ish the 3.3 Frontier had manifolds and primary catalytic converters that were separate parts and bolted together. This style was prone to the manifolds cracking. For 03 they went to a one piece design which (supposedly) fixed the cracking problem and increased flow to give 20 or 30 additional horsepower. Assuming you have an 03, this is probably what you have. I’m not sure exactly when the update happened but you should be able to physically see that the cat and manifold are separate parts, look on the passenger side, there is less crap.

I’ve never actually seen anyone mention that an updated one piece manifold cracked. Is this your problem? Or is the catalytic converter not working?
 

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Discussion Starter · #5 ·
From 99-02ish the 3.3 Frontier had manifolds and primary catalytic converters that were separate parts and bolted together. This style was prone to the manifolds cracking. For 03 they went to a one piece design which (supposedly) fixed the cracking problem and increased flow to give 20 or 30 additional horsepower. Assuming you have an 03, this is probably what you have. I’m not sure exactly when the update happened but you should be able to physically see that the cat and manifold are separate parts, look on the passenger side, there is less crap.

I’ve never actually seen anyone mention that an updated one piece manifold cracked. Is this your problem? Or is the catalytic converter not working?
I definitely have the updated one piece on my 03 (built in April i believe). The issue I have is the passenger side O2 sensor was "replaced" by an incompetent garage and I have the codes PO420 and PO430.

They broke/cut the manifold getting the 02 sensor out and welded in a bung for the 02 sensor with the manifold still attached. Needless to say the weld was garbage and has a huge exhaust leak. I can only assume they tried to remove the drivers side as well as it has a leak around the O2 sensor area as well.

That was when I first bought the truck a year ago, never could get a hold of anybody afterwards. Now I'm coming due for an etest, and don't want exhaust leaks with my son in the truck.
 

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For 03 they went to a one piece design which (supposedly) fixed the cracking problem and increased flow to give 20 or 30 additional horsepower.
If this would help the ultra-reliable, but weak and thirsty VG33 get another 20-30 HP, we'd be lining up around the block to get 'em.

But point taken on eliminating the cracked manifolds.
 

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That’s unfortunate, especially if the cats are still working. There just isn’t much room in there to make a proper repair to the bung. You could potentially have them taken out, fixed and have new sensors installed. Depending on your mileage it’s almost certainly better to just find 700 more dollars and replace them with new parts.
 

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For 03 they went to a one piece design which (supposedly) fixed the cracking problem and increased flow to give 20 or 30 additional horsepower.
If this would help the ultra-reliable, but weak and thirsty VG33 get another 20-30 HP, we'd be lining up around the block to get 'em.

But point taken on eliminating the cracked manifolds.
I could be wrong and I was definitely guessing on the actual number but I thought I remember there being some performance increase with the updated design.
 

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Might this combo be a 3.3 SC part?
 

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Discussion Starter · #10 ·
At just shy of 190,000 miles (Canadian truck with Imperial gauges go figure) I'll be replacing them with new. I've grown to love this truck and how easy it is to work on (for the most part) and plan on keeping it for a long time. Thanks for clearing up my confusion on the manifold styles.

The rock auto manifolds are the cheapest I've seen so far 424-461 CAD, even cheaper then the "eastern authorized dealer" quoted me. the only question about that would be the taxes and duty charges when they get delivered to my door. I think I'll probably get the cats from the parts supplier here for 512 + tax and pick them up.

As for the ultra reliable thirsty and weak VG33, damn its thirsty but i'm still getting better mileage then my old 98 sonoma 2wd and with the 5spd i'm not winning any races but i know i'm getting were i need to go "On time, every time."
 

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I have stainless short tube headers on mine with those 90° O2 simulators to eliminate the CEL. Seems to work well, and have yet to have any cracks or leaks

 

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Discussion Starter · #12 ·
I have stainless short tube headers on mine with those 90° O2 simulators to eliminate the CEL. Seems to work well, and have yet to have any cracks or leaks

I've thought about that route. I'm trying to keep the truck stock as possible as its my daily driver and I need to pass emissions testing without any potential issues (failing a visual inspection). If I was building an off road toy I'd be all for headers.
 

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I've got some cracking manifolds that gotta go and was hoping to go header for power, mpg, and just to avoid future cracks(lame). I've seen the short ss headers from a few companies that say they bolt onto the OEM exhaust system and include o2 sensor and egr ports. ($100-$150) Fortunately, I live in an area that does not have emissions tests but would still like the truck run clean. Other than these tests, why would anyone replace cracked manifolds with more manifolds? That are more expensive.. and will likely crack.. Is there any other downside to headers?
 

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The cracking issue was a design problem that they fixed in 03 and it seems as though the aftermarket manufacturers of manifolds have corrected as well. I’m not sure why you think just because it’s a manifold means it will crack OR that headers can’t crack.

I’d be MUCH more worried about fitment and premature failure from a set of no name 150 dollar Ebay headers than I would a set of Dorman aftermarket manifolds.
 

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From 99-02ish the 3.3 Frontier had manifolds and primary catalytic converters that were separate parts and bolted together. This style was prone to the manifolds cracking. For 03 they went to a one piece design which (supposedly) fixed the cracking problem and increased flow to give 20 or 30 additional horsepower. Assuming you have an 03, this is probably what you have. I’m not sure exactly when the update happened but you should be able to physically see that the cat and manifold are separate parts, look on the passenger side, there is less crap.

I’ve never actually seen anyone mention that an updated one piece manifold cracked. Is this your problem? Or is the catalytic converter not working?
Can replacement '03 and '04 integrated manifolds bolt right in on pre-2003 trucks? Seem like they would.
 

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I don’t know for sure that an 03-04 one piece manifold/cat would bolt up to an older truck with no issues. I’m sure the studs on the engine are in the same place, I just don’t know about the other end.
 

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They'll fit but those integrated manifolds are ridiculously expensive. As far as headers, don't waste your money on cheap ones. Spend a little more and get a quality brand like Doug Thorley. Stock type manifold kits are inexpensive from places like Rockauto.
 
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