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Discussion Starter #1
The reason I ask this question is because I have a BCRH installed now and around ~8000 rpms I get a backfiring/sputtering type of noise. I know that a header usually causes an engine to run a little bit leaner, but I thought that the computer adjusts for this. If it isn't a lean condition, what else do you guys think it might be? Also.....everything seems to be in order (install, condition of header, etc). No other mods, except a Tanabe axle-back.
 

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Isn't redline 7800? Do you have the reflash? If not then your bouncing off the rev limiter alot. Not a good idea. Your car is fine if you don't have the reflash.
No, its 8300RPM before you hit the limiter without the reflash. After its 8600RPM.
 

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i can go to like 8200 rpm before it bounces, the only way to know if its running too lean is to get a AFR gauge and keep an eye on it. check all your intake and intake manifold also.
 

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I get that backfiring too in between shifts in racing. Whether or not its a good or bad thing that's another story but it's alot more noticable when you're running open header.
 

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no... didn't do it when I ran open with the stock header and cat. Yeah, there's a cat on there but even with a entirely closed exhaust you can still somewhat hear it. And I don't think its related to the rev limiter because with the header the car backfires at all times. Worst is when you just started it in the morning on your way to work... sometimes I'll get a backfire loud enough on deceleration or in between shifting to make me think I shot a flame out.

dualdiagnosis, you have no other mods other than your catback? No intake or anything? I have a CAI and I think that might be making me run a bit rich or whatever. But alot of K20 owners have been saying that when they run open header they'll get excessive backfiring on deceleration and in between shifts. I'm not sure about the sputtering at redline though.
 

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Discussion Starter #9
Mine does that too but redline is 7800. the needle does bounce past 7800. It's not accurate at all. So you're not really redlining at 8300. It's just an inaccurate tach.
Why do you keep saying this!!! You are not accurate. Peak horsepower is 7800....NOT THE REDLINE.
 

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Discussion Starter #10
no... didn't do it when I ran open with the stock header and cat. Yeah, there's a cat on there but even with a entirely closed exhaust you can still somewhat hear it. And I don't think its related to the rev limiter because with the header the car backfires at all times. Worst is when you just started it in the morning on your way to work... sometimes I'll get a backfire loud enough on deceleration or in between shifting to make me think I shot a flame out.

dualdiagnosis, you have no other mods other than your catback? No intake or anything? I have a CAI and I think that might be making me run a bit rich or whatever. But alot of K20 owners have been saying that when they run open header they'll get excessive backfiring on deceleration and in between shifts. I'm not sure about the sputtering at redline though.
I guess saying the backfiring was a slight mis-representation of the problem. It is more like a sputtering or misfiring at around 8000 rpm. I am not bouncing off of the rev-limiter either because you can start to hear it at about 7500 rpm. Yes, other than a Tanabe axle-back, the header is my only other mod.
 

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Your probably just burning off excess fuel in your exhaust when you shift. Your running catless now thats the reason it would be doing it.
 

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there is no sensor that detects AFR on the header. the only sensor there is the o2 sensor for emissions. the MAF sensor up front does the AFR and so the header should not be causing the car to run lean.
 

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Does this noise happen while you are on the throttle or when you let off? If it happens when you let off it is just backfiring. It happens to me and I only have a HFC, not a race header. Its not to loud, but I do get the occasional loud pop. I dont see why you would be running lean. The RSX guys would run lean if they ran I/RH/E/Reflash. However we do not have this problem on the Si because of the MAF. I see no reason why you would be running lean.
 

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Discussion Starter #15
I figured it probably wasn't a lean condition, just being a lil paranoid ya know. :xyxnervou But, it does seem to happen right before I let off the throttle to shift gears.
 

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I've never had this problem with my BCRH equipped K20Z3 in my FA5. It just pulls nice & strong all the way till the red light flashes.
 

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i would dyno to get a an a/f reading just to be safe. race header w/ aftermarket exh. should make a/f slightly lean but nothing drastic to worry about. that shouldn't be causing ur issue. any sorts of sounds especially if it sounds like missfiring at or towards redline when ur WOT should be checked out.
 

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I've never had this problem with my BCRH equipped K20Z3 in my FA5. It just pulls nice & strong all the way till the red light flashes.


So does mine... never said any drivability problem was occuring. I'm sure everyone's cars with the BCRH pulls nice and plenty strong.

Reaper702, are you sure one of the 02 sensors aren't AFR? I'm pretty sure one of them is wideband. I think one is for emission but the other is wideband. I'm saying I think cause I'm too lazy to grab the service manual to check. I'm laying in bed with my wireless keyboard and it's cold :biggrin:
 

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So does mine... never said any drivability problem was occuring. I'm sure everyone's cars with the BCRH pulls nice and plenty strong.

Reaper702, are you sure one of the 02 sensors aren't AFR? I'm pretty sure one of them is wideband. I think one is for emission but the other is wideband. I'm saying I think cause I'm too lazy to grab the service manual to check. I'm laying in bed with my wireless keyboard and it's cold :biggrin:
haha yea, the primary O2 does some work with determining AFRs while the secondary is merely emissions.
 
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