I'm running out of ideas to correct some backfiring I'm getting from my car. I bought a 2003 Baja with 46k miles. I'm playing with modifying the vehicle to get a little more HP but after just one change, removing the muffler, it's been backfiring.
I took the car back to the shop and they added a resonator which they said would solve any possible backpressure issues.
It's still backfiring so the next step I can think of is to get the car tuned.
I'm kind of wondering if the car always had the problem but the muffler was cutting out the noise or if it was removing the muffler that caused the issue.
Has anyone else run into backfiring issues with their Baja or is my car just 'special'?
I don't have the issue, but perhaps I can offer some things that will help you decide where to look.
Unless fuel is completely cut off by the ECU on deceleration, all engines will "backfire." I do not know whether Baja ECUs are supposed to completely cut fuel above a certain RPM or not. I know my '91 XT-6 ECU did not cut fuel (though most people claimed it was supposed to until a few of us took the exhaust off to check). Normally, you will not hear the backfiring through the stock exhaust. If you change to straight pipes or just a glasspack, you'll hear it but probably as a burbly sound on deceleration. If you're getting nothing and then all of a sudden a hugely loud BANG! like a gunshot, then you have a big air leak somewhere between the head/exhaust manifold junction and the end of the pipe. Anything between the burbly sound and the loud BANG! is a lesser degree of air leaking into the exhaust system.
Now, if it's truly backfiring (i.e. exploding backwards through the intake) rather than the pop/bang through the exhaust that we all call backfiring, then I think you have a timing issue. Not spark timing, mechanical timing as in timing belt. Or, something even worse. I SERIOUSLY doubt this is what's happening, though.
EDIT: The condition of nothing and then a gigantic BANG! should not happen on a fuel injected car that's running properly. That's something that normally would only happen on a carbureted car.
Thanks for the infomation.
The sound isn't too bad. It's not a deafening loud gunfire pop, but it is noticable pop.
I guess it would actually be called an afterlight...if I have the word right. It sounds like it's back where the muffler used to be. hehe
It will be fine and then it will give this single 'pop', then be fine again for a bit.
I might have the guys who removed my muffler take another look to ensure there's no air leaking anywhere from the pipe they installed.
I think bulwnkl is dead on. you probably shouldn't have cut off the muffler. you are experiencing all of the sounds that the muffler is there to quiet down. This is normal behavior of a mufflerless vehicle.
Ahh..if the backfiring is normal on mufflerless cars then there's no problem then. As long as it's not hurting anything in the car. Last thing I want to do is to cause any damage in the engine somewhere.
After the resonater <sp> was installed the backfire/after light doesn't happen as often. I'm still going to get it tuned just in case. I'm not sure what kind of care this car had with the previous owner.
I just got my car back. They did say it was a lack of backpressure...so yes, air was going in. You guys were right!
The big problem is that I asked if I could use a high performance muffler but they suggested I go stock since the high performance still does not provide enough backpressure.
So, my ideas of trying to get more horsepower have gone by the wayside but I have found a company close by, (Max RPM), that has worked on non-turbo Subaru Baja's before and have some ideas to up the HP. They're into car and motorcycle modifications.
I had the same issue....I took the original muffler off and changed out to a flow master 40 series, then did dual out lets, with quad pipes but the H4 sound could not hang or sound good. I changed like you did to resonated dual tips, and smaller diameter in the tips so as not to have the echo effect. Baja beauty sounds as good as it can now considering it is a sautered on flow master. I do not have any kick back sound now whatsoever that I notice now. Mine had about 15,000 miles on it at the time I did it and they told me my engine really hasn't tuned itself in thru wear yet to give it a few thousand more miles....they were right. In your case I'd say tune your baby. If you could hear mine, I think you would be impressed it is not the ugly sound, but after all 4cyl has its limits.
Thanks for the ideas. I'm going to try all that out once I get some money back up. As soon as I get a nice paycheck from work it disappears on something. lol This last one my dog had to go in for surgery so that put me back in the hole money wise. =)
As long as it's not hurting anything in the car. Last thing I want to do is to cause any damage in the engine somewhere. 