[guru_method]

Usually the car backfired every once in a while, usually quick WOT 4-5 shifts and flat foot. Now it does it every single shift while WOT and not even flat footing. It cracks hard like a rifle and shoots a nasty flame.

Today It happened on 2-3, 3-4, and 4-5 while racing with another tuned 135i. He got the fireworks.

Don't get me wrong I enjoy the hell out of it but since it's a new thing, I'm worried that there's something goin' on or that there's a problem with the tune. I also scared an old dude so bad the other day that I might have shortened his life expectancy.

What do you guys think, should I be worried?

I wasn't able to connect my tablet to get some logs, will try a new cable and see.

UPDATED: LOGS

Got the tablet working with new cable. Took the opportunity and updated MHD Backend and JB4 to latest firmware. Did about 6 3/4 gear pulls on map 5 before logging. Pops and flames every single gear change. Clutch is slipping a little bit in 2nd gear so couldn't really capture a good log in that gear.

LOG 1

LOG 2

[1Spec]

You're running very rich

naw dogg, YOLO!

My only suggestion is that you record a video of it next time so that the rest of us can enjoy.

[Jeff@TopGearSolutions]

Only thing you can do is log it. We are blind over here. In for, "I want my car to do that too"

[Velocity26]

I will put on my psychic hat and give this a whirl ... You are getting some post shift throttle closures, causing the mix to become instantaneously lean, and then the ECU corrects and clears it all back up.

Now run some logs and we can find the real reason.

[PNWN54]

What tune are you running? Post a log with video.

[jjbmuu]

Originally Posted by Jeff@TopGearSolutions

Only thing you can do is log it. We are blind over here. In for, "I want my car to do that too"

I want my car to do that too

[guru_method]

A friend took a little vid from his phone, no flame but you can hear it when I let off the gas

Originally Posted by Jeff@TopGearSolutions

Only thing you can do is log it. We are blind over here. In for, "I want my car to do that too"

Gonna get a new otg cable to see if the tablet cooperates and will do some pulls in Mexico asap

Some will be in that boat for sure. I wouldn't be in a hurry to get rid of it if it's not an issue.

[jjbmuu]

Holy sh*t that's pretty loud! You don't see n54's doing that every day.. Reminds me of when I was running with autotuning enabled and meth, the mixture was so rich I could make the exhaust pop almost on demand like a cable tv movie, that's on another level though.

[Izero]

Originally Posted by guru_method

A friend took a little vid from his phone, no flame but you can hear it when I let off the gas

Gonna get a new otg cable to see if the tablet cooperates and will do some pulls in Mexico asap

Some will be in that boat for sure. I wouldn't be in a hurry to get rid of it if it's not an issue.

I'm gonna bet that you're getting an extreme rich condition when you let off the throttle after WOT which causes an "afterfire"....

Worse things that can happen with an afterfire are:

1) Bore Wash - excessive fuel and rich condition can "wash" the oil on the cylinder bores away and cause the piston/rings to begin to prematurely wear the cylinder

2) If you have CATs you can melt them along with the O2 sensors [doubtful that it will harm the Lambda (aka Air/Fuel) Sensors]

3) Cops...Tickets... and worst is if the cop is familiar with catless vehicles and he tickets you for a clean air act violation [$5,000-$10,000 ticket I believe?]

If it truly is a backfire then you've likely got some problems with the tune or a valve problem.

A backfire is when fuel/unburnt hydrocarbon ignites... for instance if the Cam overlap is set too long... or if your valves aren't sealing properly. This can cause major problems for your turbo, intake, and other sensors along the way.

I'm banking on it being a afterfire, but you'll need a real good log to get it figured out for sure.

[Jeff@TopGearSolutions]

Originally Posted by guru_method

A friend took a little vid from his phone, no flame but you can hear it when I let off the gas

Gonna get a new otg cable to see if the tablet cooperates and will do some pulls in Mexico asap

Some will be in that boat for sure. I wouldn't be in a hurry to get rid of it if it's not an issue.

Depending on what's happening it's probably not "good", especially if it's happening out of nowhere. Is it so bad that you need to stop driving the car, probably not.

Although people think the noises are cool it does actually mean that your car is not running optimally. If this was a rally car with anti lag, different story.

A pop in a 3-4 or 4-5 shift is reasonable but from a 1-2 its definitely a rich condition. One of my other cars used to shoot a 3-4 foot flame on a 1-2 shift and it's cause I was running dumb rich. I didn't really get the back fire noise though, just huge flames haha. Sounds and looks cool but it wasn't tuned optimally.

I'm about to sway heavily towards a hardware issue, like fuel injectors or pumps, assuming nothing has changed in the tune.

[MachWon]

I'm having the same issue, gunshots and fireballs. It happened on my old motor and it's happening on the new motor also. I never got ANY pops until I installed my 2-step relay. I'm going to take it out soon and see if it stops. It's gotten really old.

[techwhiz]

Originally Posted by 1Spec

You're running very rich

Yes. Unburnt fuel igniting.

[guru_method]

Originally Posted by MachWon

I'm having the same issue, gunshots and fireballs. It happened on my old motor and it's happening on the new motor also. I never got ANY pops until I installed my 2-step relay. I'm going to take it out soon and see if it stops. It's gotten really old.

The relay is something I must look into as well now that you mention it that is when they first started happening in 4-5 shifts last year. I'm gonna check if deactivating it by setting it to 0 rpm makes any difference.

Why did you have to replace your engine? If it popped what was the reason? (If you don't mind mind me asking)

[guru_method]

Originally Posted by Jeff@TopGearSolutions

I'm about to sway heavily towards a hardware issue, like fuel injectors or pumps, assuming nothing has changed in the tune.

Tune is the same from about early January. I hope it's not hardware related the Stage 2 fuel pump is less that 1000 miles from Fuel-It although it's been in there for about 6 months, the injectors are original 43k on odo.

I'm gonna update the JB4 to the latest version and do some logs tonight.

[Antetokounmpo]

http://www.e90post.com/forums/showthread.php?t=946649

[Whiteout335i]

This use to happen to me when I had bad injectors.

[guru_method]

Updated 1st post with the links for tonight's logs and comments. Let me know what you think. Thanks

LOG 1

LOG 2

[Izero]

rich condition followed by lean right after the shift [which is normal]

You aren't flat foot shifting in the first log though... and I believe that's a 3-4 Shift right?

It does look like a bit of knock on cylinders 1, 2, 4, & 5 right after the afterfire though...

What plugs are you using?

The log are also in JB4 Map 5, try taking a log in Map 1 and see if the problem carries... if it doesn't then try Map 2......

[guru_method]

Originally Posted by Izero

rich condition followed by lean right after the shift [which is normal]

You aren't flat foot shifting in the first log though... and I believe that's a 3-4 Shift right?

It does look like a bit of knock on cylinders 1, 2, 4, & 5 right after the afterfire though...

What plugs are you using?

The log are also in JB4 Map 5, try taking a log in Map 1 and see if the problem carries... if it doesn't then try Map 2......

No falt foot shifting in either, just shifting as quickly as I can. 3-4 shifts, correct.

Oem plugs, oem gap replaced last year.

Will try other maps. Usually do Map 5 because I don't know exactly how much ethanol is in the fuel. Should be ~e60 from the mix but do not have an analyzer to be certain.

Thanks

[3000GT MR]

Ever since I've been running the correct AFR's on my ST, my car has done this pretty excessively. Its not loud in the car but apparently people behind me feel the percussion and say it sounds like a shot guns going off. It does this on e40 alone, e85, e85 w/pi, and with my meth (which is dependent on injectors so it won't run if the fuel isn't). Here's a few videos of it. It does it NLS and with out.

[DR-JEKL]

That sounds and looks fkn awesome