[adventr]

So I know i've got a lot of threads going on here, but since there isn't a lot to search from, I figure maybe these threads will help out the next person with this issue...




So I'm running Full Bolt Ons (FBO):

2011 E90 RWD 6AT

BMS Intake
VRSF Catless DP
FMIC
Stett CP
Cobb V3



Just put the Cobb on today. See my other threads for those issues...

Running Stage 2 + FMIC Aggressive tune.
Running 91octane + E85 for a total mixture of E30 (Been running this every tank for the past month, no problems).

Ran at the track 2 weeks ago (exactly) with only FMIC and BMS Intake. Car ran GREAT for the weather conditions, and I pulled off several LOW 13sec passes.
Car has been running GREAT up until today, when I installed the Cobb.


Cobb driving experience notes:

- Driving around town feels good
- LOW RPM boost feels good
- Mid RPM with low boost feels good
- High RPM with low boost feels good

Here's where the problem lies:

Went to do some datalogging - Full Throttle Mid to Upper RPMs results in MASSIVE FIREBALLS out the exhaust. Like, light up the ground behind me so I can see it in my rearview mirror massive.
Sounds like a Full Auto Rifle going off behind. It's breaking up BAD.



So what in the world could be causing this?? I datalogged it happening 3 different times, and I hope that it shows it (uploading now).

I was live monitoring Timing Cyl 1, Timing Correction Cyl 1, Boost, and AFR. Saw nothing out of the norm at the time (high/low recordings)!!



My car does have 42k on it, and I'm supposed to replace the Spark Plugs at 45k. Would that cause this?

Oh, and the car threw out NO CODES while this was happening. Damnedest thing....



Logs coming next.

[adventr]

Log 1:


http://www.datazap.me/u/adventr/prob...0&data=1-6-8-9



Log 2:


http://www.datazap.me/u/adventr/prob...15-16-17-18-19

[adventr]

Can anyone look at those for me and see what you think??

[adventr]

This was the very first log that I took. It was a 2nd gear run, and it only made 1 "backfire" and then ran OK up from that. Shows it shifting into 3rd gear as well.


http://www.datazap.me/u/adventr/prob...15-16-17-18-19

[Johnny Boost]

I would stop running e85 until you get a pro tune. You shouldn't be using an aggressive map if you're running 91 octane. Also when you are logging, go WOT for at least a full gear because that will give a fuller picture of what is going on. Just to be clear, what map and what mods were you running when you saw backfires?

Edit: Your AFR ratios look really low in that 3rd log you posted. You're dropping into 10s especially after post-shift which means you could be having throttle closures like my car was having before the pro tune. I'm not sure how that would cause backfires though.

[adventr]

Originally Posted by Johnny Boost

I would stop running e85 until you get a pro tune. Also when you are logging, go WOT for at least a full gear because that will give a fuller picture of what is going on.

Have never had any issues at all mixing 3 gal in with a full tank of 91. Not a single one. Was running the BMW PPK tune as well.


And there was no way that I could do a full gear at WOT in 3rd or 4th. When it's backfiring like that, it doesn't accelerate at all.... just pops and blows fire.

[adventr]

Originally Posted by adventr

Log 1:


http://www.datazap.me/u/adventr/prob...0&data=1-6-8-9



Log 2:


http://www.datazap.me/u/adventr/prob...15-16-17-18-19

Have been studying these logs. Looks like I was hitting 19.5+ PSI boost before the throttle plate closed?
That seems a little high with the Actual TPS @ 100%. Does it not?

[weehe126]

If you are on the stock spark plugs still I would change them right away. It is also suggested to decrease the gap to 0.022-0.028". If you are getting missfires or spark blow out could cause the fireballs.

[adventr]

Originally Posted by weehe126

If you are on the stock spark plugs still I would change them right away. It is also suggested to decrease the gap to 0.022-0.028". If you are getting missfires or spark blow out could cause the fireballs.

Yeah, I'm sure they are the stock spark plugs. Currently trying to locate some online.

My car is CPO with Maintenance, but I sure don't feel like putting it all back to stock just to have them change the plugs....


Question though, wouldn't a misfire cause a SES light or show up in the logs as something?

[Johnny Boost]

Originally Posted by adventr

Have never had any issues at all mixing 3 gal in with a full tank of 91. Not a single one. Was running the BMW PPK tune as well.


And there was no way that I could do a full gear at WOT in 3rd or 4th. When it's backfiring like that, it doesn't accelerate at all.... just pops and blows fire.

Have you tried switching from aggressive to the sport map? Cobb requires at least 93 octane for aggressive mapping. Is it worth doing damage to your car?

[Johnny Boost]

Originally Posted by adventr

Have been studying these logs. Looks like I was hitting 19.5+ PSI boost before the throttle plate closed?
That seems a little high with the Actual TPS @ 100%. Does it not?

I don't see anything wrong with your boost. Your boost should max out in the 4k rpm range then start to taper down because the N55 turbo cannot handle high boost up top. But again, you're running the most aggressive map and you're not using the proper fueling. You could be causing damage to your engine.

[adventr]

Originally Posted by Johnny Boost

Have you tried switching from aggressive to the sport map? Cobb requires at least 93 octane for aggressive mapping. Is it worth doing damage to your car?

I've not tried switching maps yet. Just curious if you've looked at the logs?

It doesn't appear to be pulling timing due to fuel quality.

[Johnny Boost]

Originally Posted by adventr

I've not tried switching maps yet. Just curious if you've looked at the logs?

It doesn't appear to be pulling timing due to fuel quality.

Just as a general rule of thumb, you should always start with the most mild map first then work your way up after you've logged. Especially if you're going to ignore the recommendations of the manufacturer of the tune. Yes I've looked at them. I would flash to sport then re-log but log properly this time. Go into 3rd gear and go WOT from about 3k to 6k rpms. Or just start at a low RPM in 2nd gear and go WOT through 2nd and 3rd gear. Regardless of what's going on, I think a pro tune would be very beneficial to you as it was to me.

[adventr]

Originally Posted by Johnny Boost

Just as a general rule of thumb, you should always start with the most mild map first then work your way up after you've logged. Especially if you're going to ignore the recommendations of the manufacturer of the tune. Yes I've looked at them. I would flash to sport then re-log but log properly this time. Go into 3rd gear and go WOT from about 3k to 6k rpms. Or just start at a low RPM in 2nd gear and go WOT through 2nd and 3rd gear. Regardless of what's going on, I think a pro tune would be very beneficial to you as it was to me.

Definitely agree on the pro-tune. Just installed this thing today though, so figured I would try the OTS maps first.

I can dump some 98 octane (only thing we have available higher than 91) in it tomorrow and see if that fixes the problems. I was told to look for timing corrections across the board if fuel quality was a problem though.

[Johnny Boost]

Originally Posted by adventr

Definitely agree on the pro-tune. Just installed this thing today though, so figured I would try the OTS maps first.

I can dump some 98 octane (only thing we have available higher than 91) in it tomorrow and see if that fixes the problems. I was told to look for timing corrections across the board if fuel quality was a problem though.

To answer your question from earlier, misfires typically do throw codes in your ECU. But I wouldn't rule out your spark plugs as someone else mentioned. Try running a tank of straight 91 octane. Also try going down a map and see if you are still getting backfires. Whether you do or not, send the logs into Cobb and/or PTF. They will both review your logs for free and make suggestions.

Here is one of the only threads I could find about violent backfires and I'm not sure how useful it will be to you

http://www.1addicts.com/forums/showthread.php?t=556212

[Sidewinderpb]

I'm no tuning expert, but that seems more like after fire than backfire to me. Maybe running rich with an improper tune? If it was actually backfiring, there'd be some crazy shit going on. Backfires begin in the cylinder from what I understand.

As a disclaimer, I only read the original post.

[adventr]

Originally Posted by Johnny Boost

To answer your question from earlier, misfires typically do throw codes in your ECU. But I wouldn't rule out your spark plugs as someone else mentioned. Try running a tank of straight 91 octane. Also try going down a map and see if you are still getting backfires. Whether you do or not, send the logs into Cobb and/or PTF. They will both review your logs for free and make suggestions.

Here is one of the only threads I could find about violent backfires and I'm not sure how useful it will be to you

http://www.1addicts.com/forums/showthread.php?t=556212

Going to try switching tunes this morning and see what that does for me first. I'll post up results and a new log.
Thanks for your help!

[adventr]

Originally Posted by Sidewinderpb

I'm no tuning expert, but that seems more like after fire than backfire to me. Maybe running rich with an improper tune? If it was actually backfiring, there'd be some crazy shit going on. Backfires begin in the cylinder from what I understand.

As a disclaimer, I only read the original post.

Ya know, that makes sense. I don't think it's actually backfiring, but after firing. Whenever it would happen, I could look in my mirror as I was driving away and see a big "cloud" of dark color right where it did it.

But that may also be from weak plugs. I'll try changing those out too.


Will keep this post updated.

[turbo_chris]

I had the same issue on my 37k mile e90 yesterday when making a custom 18psi map on my jb4. It was spark blowout. Install new plugs and do some logs. You will be amazed at how much power it picks up.

[Dark_Knight_335]

Sounds like a fuel air mixture issue producing severe backfires- in any case, I would love to see a video of that!

[Jeff@TopGearSolutions]

Pull the plugs and see if they are fouled with fuel.

10 AFR is super rich, that's too much fuel on this car. You need that number closer to high 11's.

[Andrewe92]

from my understanding any time there is back fire it is due to being too rich... not the best afr ratio. I would adjust tune by getting protuned or getting a jb4..