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The Scratcher
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667 Posts
Discussion Starter · #1 ·
I deleted my cat (not my CATS, their still alive) about 3 month's ago, and i couldn't be happier, but recently my Exhausts been emitting loud pops on 6000~ish upshifts and revving in the lower rev range (1000~), it sounds bloody amazing but why the sudden change? it never did it before, why did it take 3-4 months to show this lovely change?

Hope its not bad for the car.

Some technical notes: Car's got a Takeda SRI and a custom magnaflow exhaust with no resonators.
 

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youtube.com/justahondaaccord
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1,325 Posts
Did you just delete the 3rd cat when you installed the exhaust or the precats as well? Exhaust backfires are typically caused from excess unburnt fuel getting burned off in the exhaust.
 

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The Scratcher
Joined
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667 Posts
Discussion Starter · #3 ·
Did you just delete the 3rd cat when you installed the exhaust or the precats as well? Exhaust backfires are typically caused from excess unburnt fuel getting burned off in the exhaust.
I deleted both resonators and the first and most visible cat (guessing its the 3rd cat).

Is this a problem tommypenguin? or is it just gonna affect my mileage slightly.

please respond soon :<.
 

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youtube.com/justahondaaccord
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1,325 Posts
Normally it's nothing to worry about, without logging its always hard to guess what your ar might be. Could be running rich from the intake given you have not had a tune to rescale your maf for the changes in flow from it. A quick way to find out would be putting your stock airbox on for a couple days and see if you are still backfiring, if not you know it's the intake causing the backfire.
 

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youtube.com/justahondaaccord
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1,325 Posts
I wouldn't say it's never anything to worry about, but most of the time it's not. A second cause for a backfire can be from a hose leak somewhere on the intake side introducing unmeasured air into the engine. Introducing unmeasured air would lead to a lean condition where too much air is going into the cylinder and not allowing for all fuel to combust resulting in unburnt fuel going into the exhaust causing the backfire.

I'm paranoid and given no one else I've read about on this forum is backfiring and the fact you only have one mod to point the finger at on the intake side that could cause the issue, I would look into it, it would take you 20 minutes to throw the stock inbox on.

Ps. Here is wikis definition of a backfire...

http://en.wikipedia.org/wiki/Back-fire
 

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The Scratcher
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667 Posts
Discussion Starter · #8 ·
Thanks for the replies folks, im less worried now, whenever possible ill reinstall the stock airbox and see if that was the culprit.

Once i reduce my exhaust size back to 2.5 inches instead of 3 inches that is. (3 inches loses me some low end power and places it somewhere illegal)
 

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youtube.com/justahondaaccord
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1,325 Posts
Who sells tunes for these cars? I've been searching the net and have not found anything.
No tuning solution currently exists. I'm considering looking into what it would take to unlock an ECU on my accord and an ecu table programmatically if and when I ever get the time away from school to do so. I'm hoping I could leverage the ecuflash/romraider opensource software which is built using JDK 6.0 and the Eclipse IDE but have no clue if that is a pipe dream or if there is a chance I could do it. I'm not currently ambitious enough to try and write an application from scratch to tune a honda ecu, at least at the moment.

As for current options, you can log several ecu parameters such as afr against rpms and throttle opening angle on your car if you have an android phone, blutooth dongle and the torque app. Based on the logs I previously took the Accord is using wideband o2 in the exhaust so you can see your afr while running in open loop driving. Most car manufacturers do not use wideband o2 and only are able to measure afr in closed loop driving(ie low rpms and low throttle opening angle). If the OP is worried about his afr when backfiring, an easy way to take a look would be to log.
 
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