47 replies to this topic

[Delete This Account]

Lol, i read crackle, i give crackle.

lol

I love my backfire/crackle. When I have my straight through exhaust on I get get back fire on demand. Rev it up to 4000, blip the throttle again and BANG.
Works 60% of the time, every time.

[Jimmy88]

Mate I had the exact same noise start to occur about 3-4 months after I did my exhaust on the old RX. I had borla replica extractors with standard middle and 2.25 diff back with a redback muffler and 3" oval tip. I took it back to the place that I had it done and they said that it was a fault inside the muffler, so they changed it over and it was good as gold.

Im not saying that anyone else is wrong however it may be something to consider.


James

[AN1MAL rx liberty]

Cheers guys, I'll take everything into account, hopefully get it running with a Better note

[Soop]

Exhaust crackle is caused by unburnt fuel going down the exhaust and igniting spontaniously on hot spots in the exhaust as well as when it comes in contact with air. Changing the muffler/tips simply just changes the way you would hear the afterfire. Depending on how a good condition all your sensors are (O2, Knock ect), they can cause the engine to be running lean or rich which either can result in backfire. If you had a slight intake leak, you computer would run rich as a defense mechanism and throw buckets of fuel down the exhuast. Also ignition timing can affect it aswell. If the ignition timing is out for any reason, the mixture could be igniting while the exhaust valve is starting to open ect

There are a myriad of reasons why cars backfire and crackle. Mine makes a loud bang between full boost shifting when your giving it the welly, this is from the car running rich between gearchanges. Works both up the gears and down, if i heel and toe my exhaust sounds like the 4th of July

100% correct.
That video quality is so poor its nigh impossible to tell whats going on anyway.
Sounds like the gas flow slowing down as the RPM settles. It could also be a form of DFCO (Deceleration fuel cut off) to stop physical backfires.

There is next to no chance that a tip is going to alter anything about the operation of the vehicle or the sound it produces.

[AN1MAL rx liberty]

I'll take another better quality video when i get a chance, i had a service the other week, there was a pretty reasonable exhaust leak which was welded up. It's sounding a bit better now.

[Soop]

That would cause some funny sounds. Can sometimes cause backfiring as you're adding more o2 to the exhaust. If the leak is downstream from the o2sensor then you can sometimes see a rich fueling situation, because the oxygen sensor obviously picks up the extra o2 which in turn causes the ECU to think the engine is too lean.
This wont fix the faux lean situation though, as it will get to a point where the fuel can't be burnt in the cylinder due to a lack of actual o2 for the molecules to attach to. So in a worst case scenario, you're going to run into misfire problems and so on. Not always noticeable, but it plays havoc with the long term and short term fuel trims, which will show as shite fuel economy.

[AN1MAL rx liberty]

the leak was before the o2 sensor... fuel economy is pretty crappy at the moment, what may be the cause of this?
sorry im pretty mechanically incompetent.

[Soop]

Reset the long and short term fuel trims (pull the battery cable off over night or something). And the ECU will relearn them. If the leak is fixed the economy should improve over the next tank of fuel.

The cause will be exactly as I explained in my last post.

[AN1MAL rx liberty]

ok cheers for the help mate

[Soop]

No worries.

[AussieTemplar]

I think the noise he's trying to make note of is that little like.. flapping/clapping noise as the engine revolutions drop.. I get it too on my car and you can only hear it when you are right next to the tip.

[Soop]

Yes, its an echo. You might want to look for a leak your self.

[Josh.]

my car makes that borrible noise as well except a lot louder and when accelerating as well as decelerating. does this mean i must have a massive leak or could it be a dodgy muffler?

[Soop]

Could be a dodgy muffler or the exhaust diameter.

If its doing it at 0% throttle with load on the motor, it could be a result of DFCO, which is a fuel saving module within the ECU.

[Josh.]

im probably going to get a new muffler in the next few weeks so hopefully that fixes it.
if not, how would i fix the ecu problem? just reset it?

[AussieTemplar]

It's not an exhaust leak.. its something to do with the tip or how the exhaust gases escape.. I had it on my old muffler too, but with my new tip.. like Walts said, the non-round edge gives less of a slapping noise then my old rolled tip.

[Soop]

It's not an exhaust leak.. its something to do with the tip or how the exhaust gases escape.. I had it on my old muffler too, but with my new tip.. like Walts said, the non-round edge gives less of a slapping noise then my old rolled tip.

lol, ohh jesus.

It's not the tip buddy.

If the DFCO in the tune was deactivated then you would get a bang bang bang instead of the fluffy sound you do have. Its perfectly normal.

[Delete This Account]

lol, ohh jesus.

It's not the tip buddy.

Yes it is mate. It's either the tip or the muffler.

Remember he's not talking about exhaust crackle or backfire as such. He's talking about the weird air rushing noise when the revs drop.

[AussieTemplar]

Yeah, the OP described it so badly.

I know what a backfire is or exhaust crackle, I get that, and I love it.. but once the revs drop and they hit the tip or something it gives off a weird fluttery noise.

[Josh.]

i hope its not my tip, that thing cost me $110 haha

thanks for the help though, ill get a new muffler and see how that changes things