[themyst]

OK guys, I tested Cobb Stage 2 on meth the other day, and it seems what Cobb has said in regards to meth actually slowing down performance appears to be true.

Based on my observations:

AFRs are now in 11.4-11.6 range across the board dropping as low as 11.17, as the DME does not seem to be pulling fuel as needed to hit the 12.x AFR target.

HPFP/LPFP actual movement is extremely volatile, although not plotted on this graph.

The car pulled noticeably slower according to the butt dyno.

IMO, meth is a waste on this map. I could be wrong; this is why I created this thread for discussion.

[tibra1]

In comparison to your previous logs did running meth on this map improve w the timing drops...these logs seem a bit cleaner..although a little richer AFRs

[themyst]

Well, give me 50 degree ambient temps to run in again, and I'll show you a really noisy engine. When it's warm outside, i rarely see timing dropouts or too much noise; meth or not.

[tibra1]

That is just bizarre!!..so the tune runs better in hot weather..these guys in Texas must tune for their local climate....jking..as always appreciate your feedback..

[themyst]

I could be wrong, but I think the tune has less authority to increase/decrease boost on stage 2 vs stage 1.

When it was 50 degrees outside, stage 2+FMIC no meth pulled ridiculously hard. As hard or harder than my piggyback+meth setup.

[SIKH335]

Any Dyno's to compare these results? Perception is an interesting thing. Also I'm assuming this is a pps Meth kit how is Meth metered

[themyst]

if someone wants to put my log through virtual dyno, I'll be happy to e-mail the log to whoever wants to do it. E90 6AT, stock tire size.

This is a basic "PPS" kit on a CM10 nozzle. Was spraying 900-950ml/min, from when I ran this exact same setup on the Procede/JB4.

[rader1]

IIRC, clap's dyno sim indicated an increase of power when on meth and rob@cobb said the dme would be able to react quickly enough to keep the AFRs where they need to be to make more power. But you're logs seem to indicate otherwise

[themyst]

those virtual dyno runs aren't quite useful unless run multiple times and taken from an average. The one log I got put through virtual dyno states I have 360whp and 380tq.

And that is correct, the DME should be able to pull fuel to achieve the requested AFR target, but doesn't seem to have occurred in this log. On pump gas only, I see 12.0 - 12.2 AFRs virtually across the board and HPFP/LPFP actual activity all over the place.

[tibra1]

Originally Posted by themyst

Well, give me 50 degree ambient temps to run in again, and I'll show you a really noisy engine. When it's warm outside, i rarely see timing dropouts or too much noise; meth or not.

Originally Posted by themyst

I could be wrong, but I think the tune has less authority to increase/decrease boost on stage 2 vs stage 1.

When it was 50 degrees outside, stage 2+FMIC no meth pulled ridiculously hard. As hard or harder than my piggyback+meth setup.

Wait im confused so the tune pulls harder and less drops..in colder or warmer weather??

[themyst]

Originally Posted by tibra1

Wait im confused so the tune pulls harder in colder or warmer weather??

Based on my personal experience, the tune will pull much harder in colder weather, albeit with a somewhat noisier motor.

[OpenFlash]

Originally Posted by themyst

those virtual dyno runs aren't quite useful unless run multiple times and taken from an average. The one log I got put through virtual dyno states I have 360whp and 380tq.

And that is correct, the DME should be able to pull fuel to achieve the requested AFR target, but doesn't seem to have occurred in this log. On pump gas only, I see 12.0 - 12.2 AFRs virtually across the board and HPFP/LPFP actual activity all over the place.

Log fuel trims and see if they are stuck at -34% when meth is enabled. That would explain the issue. I've seen some cars require very different fuel tables to achieve the same fuel trims. I suspect this variance is hardware related given all the different injector/pump revisions we've had. Could easily be a situation were your trims are lower than others running the same mods, same tune, in the same conditions.

[SIKH335]

Should in colder weather!

[tibra1]

Originally Posted by themyst

Based on my personal experience, the tune will pull much harder in colder weather, albeit with a somewhat noisier motor.

And timing drops improve in colder or hotter weather??

[themyst]

Originally Posted by SIKH335

Should in colder weather!

In theory, a tune that targets load should output similar performance regardless of weather conditions; this isn't like the Procede/JB4 where boost targets are absolute.

Which is why I am led to believe the stage 2 has less authority over boost than stage 1, as stated previously.

[themyst]

Originally Posted by tibra1

And timing drops improve in colder or hotter weather??

you've seen my logs. timing drops are far worse in the cold weather, but look pretty much perfect in the warmer temps.

[tibra1]

Originally Posted by themyst

you've seen my logs. timing drops are far worse in the cold weather, but look pretty much perfect in the warmer temps.

Yes but things are changing from day to day...just want to see what the most current news is..there is also a member who reported these timing drops as well... his ambient temp was 60 .. he had FBO n runs stage 2+ aggresive FMIC

http://www.e90post.com/forums/showth...ght=Cobb+stage

[themyst]

Originally Posted by shiv@vishnu

Log fuel trims and see if they are stuck at -34% when meth is enabled. That would explain the issue. I've seen some cars require very different fuel tables to achieve the same fuel trims. I suspect this variance is hardware related given all the different injector/pump revisions we've had. Could easily be a situation were your trims are lower than others running the same mods, same tune, in the same conditions.

Haven't logged STFTs during the meth run, but I just took a look at the LTFTs and they are at 10.2%.

[themyst]

Originally Posted by tibra1

Yes but things are changing from day to day...just want to see what the most current news is..there is also a member who reported these timing drops as well... his ambient temp was 60 .. he had FBO n runs stage 2+ aggresive FMIC

http://www.e90post.com/forums/showth...ght=Cobb+stage

You should log your GIAC stage 2 pump with BT cable and show us where you stand

[tibra1]

Originally Posted by themyst

You should log your GIAC stage 2 pump with BT cable and show us where you stand

HAHA..according to you I can only do cylinder 1 w BT so that would be pointless..I actually saw many timing logs of GIAC stg 2..when GIAC was the "buzz" tune 2yrs ago..and none had any timing drop issues..I will look for some and e-mail em to you..

Keeping this all about COBB...i think this tune def has the potential to be the best..so if my questions are critical its only b/c i want to learn as much as i can.

[themyst]

Yep, BT cable is only capable of doing cylinder 1 timing.

I am definitely looking forward to ATR and a OTS meth map from them so I can get cracking. Stage 2 + FMIC is a nice stopgap though.

[AU335i]

so, do you think this will happen with any flash tune? if I had a way of logging, I'd love to see how spraying meth on top of my flash tune effects my performance and compare...