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I've been doing quite a bit of reading about the pre-cat failure and all and i am very interested in replacing the exhaust manifold with new headers. Im looking to support MarkSpecV. Any1 recommend MarkSpecV's headers? Easy installs? still works? build quality?
Anyway here is the real question i had about replacing the headers...
I understand the point of the spacer on the 2nd o2 bung. It causes the o2 sensor to get less of a reading by recessing the second O2 sensor away from the exhaust stream. Which equals no light.
I guess my only question is wouldn't this mess with the air/fuel ratio because the ecm is no longer getting accurate readings? Decreased gas mileage? too rich? too lean?
"OBDII cars have two oxygen sensors to measure the amount of oxygen contained in the exhaust gas. The first sensor is located on the manifold or header and measures O2 content of the exhaust as it escapes from the cylinders. This sensor is used by the PCM/ECM to calculate fuel trims and look for combustion problems. The second oxygen sensor is located after the catalytic converter and is used only to measure catalytic?converter efficiency. The PCM/ECM does NOT use any data from the secondary O2 sensor for engine management. The PCM will set an CEL(check engine light)/SES (service engine soon) / MIL(Malfunction Indicator Lamp) light?if the catalytic converter is removed, the sensor is removed, or the sensor goes bad."
Can anyone confirm this? I am hesitant to get a header because i dont want to mess up my fuel economy, so i am weighing out all the options. If this is true then i have nothing to worry about, since the 2nd o2 sensor just detects the efficiency of the cat... Has anyone experience any drop in MPG since installing headers on their 2.5?
i really want to do this in the future with the same header, some people had fitment issues but Mark said it was a faulty batch or something along those lines, ALOT people bought from him with no issues so thats what i think it was a bad batch.
second 02 sensor isnt after the cat converter....well, technically it is but its after the pre cat thats in the header itself....
Mines are Nismo so that wouldn't void warranty, I don't know about the other headers out there. Mileage didn't suffer whatsoever....other then smashing the pedal when its first installed.
__________________ 2006 Nissan Altima 2.5S Special Edition
It might be a little modified
Quote:
Originally Posted by j_archer_69
I love women that are into cars. Unless they are ugly. Then I don't give a shit.
second 02 sensor isnt after the cat converter....well, technically it is but its after the pre cat thats in the header itself....
Mines are Nismo so that wouldn't void warranty, I don't know about the other headers out there. Mileage didn't suffer whatsoever....other then smashing the pedal when its first installed.
actually, any r-tune component is concidered off-road, so technically speaking you did void the warranty. you cant return r-tune products nor are they covered by any warranty, i dont know though, i got the info off a website that sell nismo/r-tune products
I've been doing quite a bit of reading about the pre-cat failure and all and i am very interested in replacing the exhaust manifold with new headers. Im looking to support MarkSpecV. Any1 recommend MarkSpecV's headers? Easy installs? still works? build quality?
Anyway here is the real question i had about replacing the headers...
I understand the point of the spacer on the 2nd o2 bung. It causes the o2 sensor to get less of a reading by recessing the second O2 sensor away from the exhaust stream. Which equals no light.
I guess my only question is wouldn't this mess with the air/fuel ratio because the ecm is no longer getting accurate readings? Decreased gas mileage? too rich? too lean?
I bought headers from Mark in December 07 and they were worth every penny. Install was pretty simple actually, took about 2 hours in my driveway. I've noticed a pretty good increase in gas mileage as well. The only thing I don't like is the sound, but all in all, its a great product and Mark is great guy to deal with.
I bought headers from Mark in December 07 and they were worth every penny. Install was pretty simple actually, took about 2 hours in my driveway. I've noticed a pretty good increase in gas mileage as well. The only thing I don't like is the sound, but all in all, its a great product and Mark is great guy to deal with.
What kinda sound u talkin bout??? U mean the beefier sound or r u talking about something else? I wouldn't think a header install would add that much sound, especially keeping the stock exhaust. can any1 confirm?
Here's the deal im debating between MarkSpecV's headers and megan's. Anyone have any recommendations. MarkSpecV doesnt have any in at the moment he said prob may sometime, id like to support forum vendors but i also want so good quality stuff. Thanks
The second o2 sensor just tells the ECM the pre-cat there and working. It won't affect your A/F ratio. It gets "tricked" into thinking it's still in place by being recessed further back.
If Mark is out and you can't wait and desire high quality, go w/ the Nismo. But your going to pay a pretty penny. A lot of my off forum friends support the Nismo header as they claim it has the best collector out of them all.
I think the XS header will suffice if your willing to wait.
I want to get headers as well ... if you can't find cheap ones for the alty try searching for the sentra se-r/spec-v ... same engine so.. good luck looking im waiting a lil bit to buy
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