Skip to content
View in the app

A better way to browse. Learn more.

Ultimate Subaru Message Board

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

Back firing

Featured Replies

what cause back firing.. i got a 2 inch header's to a cat then from there a 2 inch all the way back to a chrome cannon. it happen's when changing gear's when letting the foot out and then pushing your foot in the cluch it goes pop pop.??

Any help would be greatfull

 

clint.

Kinda sounds like what mine was doing when I installed the duals. Do you still have the ASV system hooked up? If so, you need to pull the hoses off of the breather can, and plug them. Or, just remove the system, period. Couldn't figure that one out myself, had to ask here on the board......

  • Author
Originally posted by TomRhere

Kinda sounds like what mine was doing when I installed the duals. Do you still have the ASV system hooked up? If so, you need to pull the hoses off of the breather can, and plug them. Or, just remove the system, period. Couldn't figure that one out myself, had to ask here on the board......

 

Asv system is that the polloution system? whats the breater can? what you mean plug them block them?

 

clint.

ASV system- Part of the Catalytic Converter system. Adds air to the exhaust to assist the cat in doing it's job. If you remove the cat, and don't block off the ASV tubes, you have extra air in the exhaust. Which causes the back-firing.

Look at your exhaust where it bolts to the head. Follow those metal tubes up, and you will find the rest of the ASV system. Off of that, is 1, or 2 hoses that go to the breather can, AKA- air filter canister, on the carb. That's where I blocked mine off. Just pulled them from the breather, and stuck a plug in the hose, capped the tube on the breather also. Don't want dirt getting in there......

  • Author

And this fixed your problem? got any pics on the plugs and that? i'm noob at engine problems sry lol

 

clint.

hey man,

my 90L wagon with a weber pops like that too, exactly as you described. I have blocked the air injection valve with welder. the little injector pipe joins on the left hand bank just where the header joins the block. still pops on changes. sounds kinda cool.... :brow:

hey it makes your car sound like a rally car:brow: Thats like 50 horsepower right there man!!!

  • Author

50hp??? me car's more then that.. anyway i'll might try adding a turbo muffler before the rear axle then out ot my chrome muffler.. see if i gain any back pressure doing that..

 

clint.

You probably need a new EGR vavle (or maybe just clean it), and there should be an anti-backfire valve near the firewall on the drivers side. There's a big tube going to it from the EGR.....

 

either of these parts will cause backfireing on decel.

 

I've never heard of the AIS system causeing this, and I wouldn't think it would - why would adding a little more air to your exhaust cause backfireing? I need a more technical explanation of that one. Backfireing is usually the explosion of unburnt fuels in the exhaust..... I suppose the added oxygen from the AIS might help that along, but I'm not sure.

 

GD

  • Author

hmm i have a anti- back firign vavle on the passanger side of me car, it's a gold, Mine makes a spshhhh liek a blow off vavle when i let the accell off.

 

clint.

mine doesn't backfire, it just pops when I take the foot off the loud pedal and change gears. btw I have all of 60hp atw, last time I checked!!! :banana:

the abv wooshes on mine too. I assume yours connects to the back of the manifold on the right ruby? it is an ULP EA81 you've got in your brumbles?

  • Author

yes mines a unleaded only brumby, (I run Shall Optimax 98% octance) in it.

 

clint.

My 89 rx pops when shifting gears. its usually either 2nd or third and it makes the noist as the gear goes in. and it does sound like its comming from the exhaust. I have custom duals with no mufflers. LOUD!!!:moon:

Please sign in to comment

You will be able to leave a comment after signing in

Sign In Now

Account

Navigation

Search

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.