My MS3 doing some kinda ''back fire'' noices...

[carbosam]

My car started doing some ''Pup-Pup-Pup''' intermitently in the last fews day, sound like a back fire but its not loud at all. Its doing it at idle and when driving. I hear it mostly in low RPM since its not loud. Its louder when its cold outside and i start the car though.

Gonna get that checked out by my dealer since its still under warranty but s*** this car always have something, just got my turbo replaced 2 weeks ago.

Anyone know what could it be?

 

[bykeryder4life]

If your car does well on a leakdown test and the valves are sealing properly, dont worry. Turbo cars make some gurgle/popping noises. Unburnt fuel in the exhaust is firing and popping making that noise. Called afterfire. A true backfire would be through the intake valve and its very loud, and indicates a valve isnt sealing so when the cylinder fires or unburnt fuel fires its going back through the intake tract.

 

[lavoiespeed3]

My car started doing some ''Pup-Pup-Pup''' intermitently in the last fews day, sound like a back fire but its not loud at all. Its doing it at idle and when driving. I hear it mostly in low RPM since its not loud. Its louder when its cold outside and i start the car though.

Gonna get that checked out by my dealer since its still under warranty but s*** this car always have something, just got my turbo replaced 2 weeks ago.

Anyone know what could it be?

Do you have a Catalytic converter? If you remove this part it's normal

 

[carbosam]

If your car does well on a leakdown test and the valves are sealing properly, dont worry. Turbo cars make some gurgle/popping noises. Unburnt fuel in the exhaust is firing and popping making that noise. Called afterfire. A true backfire would be through the intake valve and its very loud, and indicates a valve isnt sealing so when the cylinder fires or unburnt fuel fires its going back through the intake tract.

Its not loud at all so its not a back fire but my car wasnt doing that at all before so something changed...

 

[carbosam]

Do you have a Catalytic converter? If you remove this part it's normal

Non, my car is bone stock

 

[79535]

Did you visit the dealership? Did they find a fix? I am curious because I am having the same issue.

2007 MS3 - P0302 - Cylinder 2 misfire
It seems to happen randomly, either at idle or under light load cruising.

The CEL seems to appear randomly and the car sounds like it is missing at idle. I am starting to get aggravated. I replaced the coil for cylinder 2 (2nd from the passenger side) today and it did not fix my problem. The spark plugs appear to be fine as well.

Mods include:
CP-E turbo back exhaust
Cobb intake
HKS SSQV recirculated

 

[noobinacan]

Its your exhaust and it pop's...that's all.
and is to be expected really..since our car's run rich from factory.

Unless it happens when you are on the gas...nothing to worry about.

 

[79535]

I don't think my exhaust would be causing a cylinder 2 misfire.

 

[Nokkers3]

I get this as well, but I've been told that it's normal.

 

[79535]

I hope you guys are referring to the pop of the exhaust and not the CEL.

 

[SRTie4k]

Did you visit the dealership? Did they find a fix? I am curious because I am having the same issue.

2007 MS3 - P0302 - Cylinder 2 misfire
It seems to happen randomly, either at idle or under light load cruising.

The CEL seems to appear randomly and the car sounds like it is missing at idle. I am starting to get aggravated. I replaced the coil for cylinder 2 (2nd from the passenger side) today and it did not fix my problem. The spark plugs appear to be fine as well.

Mods include:
CP-E turbo back exhaust
Cobb intake
HKS SSQV recirculated

You should try moving the spark plug to another cylinder and see if the problem follows the plug. That'd be a good starting point.

 

[justanothermp5]

^+1
if it moves to the other cylinder its the plug if not its the coil

 

[79535]

I should have mentioned that I had already moved the sparks plugs 1 cylinder over. Oddly enough, it had no effect. Cylinder 2 was still misfiring.

Oddly enough, I had a set of denso itv122's kicking around. I installed them and I haven't thrown a CEL is a couple of days.

You would think that swapping the stock plugs around would have caused the misfire to jump cylinders if a set of new plugs was going to fix the misfire.

I'm almost wondering if I had a loose harness or something that I may have inadvertently tightened somehow.

I also reset my ecu when I put the new plugs in.

Thanks for the input guys.

 

[matsuda]

Its your exhaust and it pop's...that's all.
and is to be expected really..since our car's run rich from factory.

The OP said that it happens at idle (it's not rich).

 

[79535]

So the misfire returned. From what I can tell, my wiring seems to be in order. I can't find any cracks/insulation breaks that would cause issues.

It would appear that:

1) I'm having compression issues and the engine will need an overhaul (engine has only 13 000km on it since it was replaced under warranty )
2) I have a bad injector

I am grasping at straws right now. If the engine needs an overhaul, it may be likely I will be back with forged internals or a new BMW 135i. Just kidding about the BMW.

Wish me luck. The car will be visiting the dealership within a week.

 

[Tim25]

Good luck, I'm interested to hear what the problem is.

TIM

 

[SBSPEED3]

The OP said that it happens at idle (it's not rich).

he also said it does it more when he first starts it. mine will pop and gurgle at idle in the mornings when its cold, because it will run extra rich at start-up. this is pretty normal.
to the OP has anything else changed that would cause you to just now notice it?
example: mine will do it alot more, when its colder outside

i should mention that i have no resonators or muffler, this doesnt have any effect on the burble, except make it louder.

 

[blh_wakeboard]

They shoot flames too ,

http://www.youtube.com/watch?v=AacxGefRDfY

It's always popped quite a bit for me, especially when its cold. No CELs so far at 30k miles. Although it was popping like crazy 2 weeks ago even while just under cruise. Took the TMIC off to look at the plugs and discovered the cold side piping was sliding off the throttle body causing a vac leak. I have never removed or messed with that piping and the worm gear that holds it on the throttle body before, it was pretty loose so I slid it back on and tightened it down. The excessive popping went away, probably not your fix but thought I'd share...

 

[SBSPEED3]

They shoot flames too ,

the cold side piping was sliding off the throttle body causing a vac leak. .

i think thats a fairly common problem with these cars, i know the stock turbo inlet was pretty loose on mine when i did the intake. its like the guy that was responsible for tightening everything down was asleep on the production line... japanese efficiency my ass!!! lol

 

[79535]

I may have fixed my problem.

I reinstalled my stock intake. In doing so, I (yet again) removed all boost hoses/intake parts, cleaned all connections and tightened everything down. Unfortunately, I did this at the same time that I reinstalled the stock intake/bpv so I cannot conclude that this fixed my issue.

I ran it like this (on stock tune with only TBE installed) for a week and it hasn't thrown an engine code.

Last night, I installed my newly acquired AP with a stage2 map. Everything seems to be alright and I have not thrown a cylinder 2 misfire yet.