Welcome to Ultimate Subaru Message Board, my lurker friend!
|Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.
We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!
Serving the Subaru Community since May 18th, 1998!
Slight backfiring after setting timing to "manual" specs
Posted 14 December 2005 - 02:42 PM
According to the book it should be 8* BTDC @ 800 RPM (or something like that).
My idle was already high (1100) so I turned it down to spec which is 800-900. Also, my timing was sitting at about 12* BTDC.
So now with my timing set to 8* (+/- 2*), I notice it backfires just slightly. Only happens when I "stab" the throttle and coast for a bit. Doesn't sound loud at all, in fact it's a really quiet, almost rattling tone; sounds a bit like when you kick up road sand and it bounces off your wheel well.
Regardless it's backfiring now and it didn't so much before.
Does it make sense that it'd backfire being 4 degrees advanced? Or is this now a carbeurator thing now that the timing is "correct".
160k mi (almost), I always thought you were allowed a few degrees advancement with higermileage vehicles to compensate for wear and timing belt stretch, things like that.
Posted 14 December 2005 - 04:28 PM
Posted 14 December 2005 - 04:34 PM
Posted 14 December 2005 - 05:18 PM
I run 4 degrees additional initial advance (12 BTDC) and I haven't had any backfiring issues. I agree that it's probably not related to timing.I have removed the AIR from my engine. You also should have an anti-backfire valve. Make sure the vacuum to it is connected. It's probably located on the passenger side in front of the wheel well.
Kay, bare with me, what's the AIR and what is it's primary purpose? Will I notice any positive affects if I plug it off? Also, as far as vacuum lines and anti-backfire valves; can you be a little more specific? If I were to stretch the vac lines from this car end to end, I could reach the Subaru Manufacturer from here (it's a rat nest).
Is the valve part of the manifold or connect to the manifold in anyway? You said pass side, in front of the wheel well. That's not the big black plasic canister next to the radiator with 3 or 4 hoses coming out the top is it?
Posted 14 December 2005 - 05:33 PM
The AIR system introduces fresh air into the exhaust ahead of the catalytic convertor to help it burn off hydrocarbons. On each head, next to the exhaust port, there is a tube that's about an inch in diameter. These run up to reed valves fed through the air cleaner. Sometimes those reed valves go bad.
On mine, I just blocked those ports off. I used a nickel (maybe it was a quarter) under the flange and bolted it tight. I cut off the tubing, because there was no where for it to go with my aftermarket carb, but you could try blocking it off that way and see if it fixes the problem. If not, just unbolt it and remove the coin.
Oh, and the canister is your evaporative canister. It takes vapors from the fuel system and recycles them into the intake. That's not going to have anything to do with backfiring.
Posted 16 December 2005 - 12:20 PM
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users