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Old 04-17-2010, 08:35 PM   #1
dstan
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2000 BRP 2.5RS Coupe
Wow the 89 Civic is fast

Default Backfire in Intake?

I have a 2000 RS that here recently I have been having a strange POP coming from an unknown place, today it happened several times today at an autocross (it only happens at AX's) and my friend (very car knowledgeable) said it was coming from the intake or front of the car.

Details:
* 195 K on car and not sure if the valves have ever been adjusted(my guess)
* only happens at AX's
* sounds like a backfire
* Re-flashed ECU by I-Speed
* 1st run today it did it 2 time 4th run it did it 6 times
* has done this for the last 3 autocrosses
* 93 octane on a 91 octane flash
* I run Seafoam through tank monthly
* 25mm front bar with ALL poly bushings

Thanks in advance for your input
Dave
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Old 04-17-2010, 11:58 PM   #2
Patrick Olsen
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I presume this is happening off throttle / under engine braking? Is it right after you come off the gas, maybe going from WOT to engine braking? I very occasionally get a pop in engine braking situations, I just figure it's a bit of unburned gas popping in the hot exhaust. Could be wrong, but it's never happened regularly enough to trouble me.

Pat Olsen
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Old 04-18-2010, 01:00 AM   #3
dstan
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Wow the 89 Civic is fast

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actually just the opposite WOT and out of the intake,

I have had the exhaust pop every once in a while, this is new and happened alot today on course only, never heard anything on the 3.5 hour drive home.

Car still has all the power and is still very smooth even when it POP's
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Old 04-18-2010, 01:35 AM   #4
Ysidro
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if its out of the intake thats no good.You sure its out of the intake?
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Old 04-18-2010, 10:29 AM   #5
Bluefoton
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defective PCV valve? Its job is to prevent an intake backfire... IF it's that...
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Old 04-18-2010, 10:42 AM   #6
dstan
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Quote:
Originally Posted by Ysidro View Post
if its out of the intake thats no good.You sure its out of the intake?
not sure what it is, but all signs say so. I think (hope) it is the valves need adjusting.
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Old 04-19-2010, 06:54 PM   #7
dstan
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solution has been found,

all i can say is change your plugs often if you AX as much as I do
I love cheap fixes
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Old 04-19-2010, 08:33 PM   #8
Bluefoton
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How did they look like?
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Old 04-19-2010, 09:04 PM   #9
dstan
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Wow the 89 Civic is fast

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Quote:
Originally Posted by Bluefoton View Post
How did they look like?
they were nubs, I am surprised the car would even start
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Old 11-04-2012, 09:13 AM   #10
subidub
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I have a similar issue, when I get ready to launch and revving my engine (3-4k rpms), every now and then I'll get a backfire out of my intake and the engine will subsequently sputter for a few seconds while it recovers. I have similar mods to the OP,
I speed srs30
Gravelsport intake with k&n
Light weight crank pully
Delta cam 1500 regrinds

Changed my plugs about 35k miles ago with ngk coppers, figured they would still be ok. I'll check them regardless.
Does anyone else have any ideas?
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Old 11-04-2012, 07:20 PM   #11
dgurion
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Someone I know recently had similar issues. Turns out his ignition coils were badly corroded.
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Old 11-04-2012, 08:04 PM   #12
subidub
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Quote:
Originally Posted by dgurion
Someone I know recently had similar issues. Turns out his ignition coils were badly corroded.
good to know! I will check my entire ignition system and see if I can find anything.
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