Okay I recently brought my car over to Tempe, AZ right by ASU here since I'm going to school there. It has backfired on 2 occasions since I brought it out and began running Chevron 91 Octane here. Both times were shotgun status backfires coming from just under the turbo area... Never had this problem before. Now after the second really bad backfire, I now have a noise when i blip the throttle in neutral of a rattling right when it comes down to the 1,000 rpm range, doesn't happen every time but I can reproduce it several times, seems to becoming from just above the tranny area behind the inter cooler. I'm running a full catless stromung turbo back, with dual tip muffler, cobb stage 2 91 octane mapping, car is otherwise stock. The engine was replaced with a new shortblock and all the goodies and gaskets at 18,000 miles by the dealership, the engine now has 11,000 miles (9,000 miles on stage 2). Running Motul 10w-40 6100 Semi-Syn up to 1,500 miles ago, when i switch to Motul 5w-40 8100 Full Syn all oil changes have been done at 3,000 miles with K&N oil filters. I don't think it his heat shield rattle as i have held the heat shield and reved it and sitll produced the noise... The car has full power, runs like a bat out of hell still and does not knock other then when it comes down to idle from being blipped, at its a clanking/rattling sound more like. I would rait noise level at a 5/10.. Don't know what to think, if it was knocking it would be consistent and all the time, this is only when the motor is free falling at that low RPM... confused, it still runs perfect, no CE lights no oil pressure lights nothing.. Anyone have any suggestions?

 

Welcome to i-Club.
I think you either got a bad tank of gasoline or
your spark plugs are fouled and need to be replaced.
Backfiring is not normal.

 

this is the reason it 'backfired', actually afterfired, but we won't get into that. A catless exhaust is the reason it afterfired.

 

Afterfire doesn't sound like a shotgun.

 

mine does on occasion, normally just a small pop...

 

do you have a BOV?

 

testes1010

Do you know the difference between afterfire and backfire?

blueby

Have you checked the uppipe heatshield?

 

Good question.

 

MOREX:
I am not 100% on what the difference is. I am thinking where the "explosion" actually occurs. Is that correct.

 

Wow, I never got a notification about your post.

AFAIK afterfire is gas igniting in the exhaust and backfire is in the intake. I'm not 100% positive and that is why I asked.

I only know what I've read and you know how misinformation gets spread around on the boards.

 

No blow off valve, just stage 2 cobb, the stromung and panel filter. I guess it afterfired but it was loud as hell and I've never heard it from the turbo region like that before. I'm going into kingpin for the second time this week because the rattle is getting worse its now progressed from 2,000 rpm down.. so 2 motors in 33k miles, I think its time to sell this car and move on.

 

what kind of car is it? I know its a suby, but what year?

 

05 Wrx

 

lmao, read the title? Well no insight from any subaru forum thus far, so i'm trading the car tommorow most likely, I'm tired of the issues. These cars are damn fun, but break down more then old used cars.

 

How do you get 33K miles on an '06?... 2 motors?

What are you doing to that poor car?