[scottro]

Hi all,

Just got my AP in the mail and it's my first mod to the 335! Been having a lot of fun with the increased power, just wanted to post up some graphs and ask a few questions.

First, a rolling start from ~20mph in second gear through 2nd and most of 3rd:



Any idea why it doesn't appear to make boost until ~3200rpm's? I'm surprised it takes that long to get to a state of positive pressure.

Second, can anyone confirm if the COBB tune starts to pull back boost at ~6000, so the dip in boost from 6-7K RPM is expected? Actually looks like it's pulling the boost starting at about 5800rpms...

Other than that, it appears to hold the boost pretty stable for the time I was in 3rd gear.

Then I just happen to be playing around on a night where we actually got some rain in Arizona, so temps were good and the ground was wet! Here is a graph of some tire spinning at slow speeds (quick take off from stop lights, flooring it coming out of a turn, etc.):



Again it surprises me a bit that for most of this, I'm not actually boosting! For very few parts of that graph does the pressure actually become positive.

Maybe I'm misunderstanding how to read it, but my assumption is that negative values indicate a vacuum exists in the intake manifold, while positive numbers mean there is negative vacuum (or boosting).

Anyways, all in all a pretty good experience with Cobb so far! Some times I'm a little uneasy about running it as it seems like the engine falls on its face occasionally, but I'm not seeing much ignition correction so I'm not sure what's causing that. Maybe what I'm feeling is the affect of DTC kicking in? Not sure...

[scottro]

Wow, sorry about the large graphs! Kind of thought the forum software would auto resize those.. They appear huge on my screen.

[enrita]

when you log you should ALWAYS disable all nannies to prevent intervention. best is to roll in 3rd and shift to 4th .

[scottro]

Originally Posted by enrita

when you log you should ALWAYS disable all nannies to prevent intervention. best is to roll in 3rd and shift to 4th .

Thanks I'll give that a shot next time I'm logging

[slowSwede]

Another tip is to log more parameters, usually the pre-selected ones are good to give a complete picture.

[scottro]

Originally Posted by slowSwede

Another tip is to log more parameters, usually the pre-selected ones are good to give a complete picture.

I did log a bunch more but only included rpm & psi in the graphs as I don't know how to have more than 2 y-axis. I saw a post here about making advanced graphs, I'll have to follow that some time to include more of the data.

I modified the default data log options a little, but in general I have requested / actual load, rpm, boost, boost delta, wastegate duty cycle for bank1 and bank2, and the ignition correction for all cylinders. Generally the ignition correction is typically 0's, at least during full load. Occasionally it pulls up to 3-5* of timing under easy acceleration around 1500-2500rpms, kind of odd.

Maybe i'll switch to the actual timing advance for each cylinder so I can graph that and see if there are any dips.

What parameters do you recommend?

[Bmwguy11]

the 2nd graph looks like the graph is not adjusting properly to accurately display boost pressure.

That said, over 5000rpm, the boost pressure is somewhat inaccurate on the cobb AP datalogs it seems.

And yes, it's normal for boost to drop as you get closer to redline.

[derrick603]

How is your car liking the Sport map on Arizona gas?

[scottro]

Originally Posted by derrick603

How is your car liking the Sport map on Arizona gas?

Not too sure yet.. I was a bit concerned about that cause I know AZ has bad gas, not to mention most stations don't even carry anything above 91.

That being said, occasionally when pressing the pedal and getting into boost it feels like there is some hesitation, not sure yet what the cause of this is. Looking at requested load vs actual load, they are typically pretty close. Also I don't notice any timing being pulled when under full throttle conditions up to ~14psi.

But as I stated earlier, let me try logging the actua lignition timing instead of just the correction fields and see where we're at.

[slowSwede]

Originally Posted by scottro

I did log a bunch more but only included rpm & psi in the graphs as I don't know how to have more than 2 y-axis. I saw a post here about making advanced graphs, I'll have to follow that some time to include more of the data.

I modified the default data log options a little, but in general I have requested / actual load, rpm, boost, boost delta, wastegate duty cycle for bank1 and bank2, and the ignition correction for all cylinders. Generally the ignition correction is typically 0's, at least during full load. Occasionally it pulls up to 3-5* of timing under easy acceleration around 1500-2500rpms, kind of odd.

Maybe i'll switch to the actual timing advance for each cylinder so I can graph that and see if there are any dips.

What parameters do you recommend?

I just go with the defaults and ignition correction (or is it actual?). It's sort of a pain to plot the logs...but as you mentioned there is a post around here somewhere that points you in the correct direction. For me timing correction has always been zero, but I only look at the logs when the right foot is working hard...I'll have to check some logs to see if I have the same symptoms as you on low loads.
Usually I don't graph the logs, since you can just read them straight away in Excel and understand what's going on.

[scottro]

Originally Posted by slowSwede

I just go with the defaults and ignition correction (or is it actual?). It's sort of a pain to plot the logs...but as you mentioned there is a post around here somewhere that points you in the correct direction. For me timing correction has always been zero, but I only look at the logs when the right foot is working hard...I'll have to check some logs to see if I have the same symptoms as you on low loads.
Usually I don't graph the logs, since you can just read them straight away in Excel and understand what's going on.

Yeah if you could check your logs for that timing pull under low load that would be great. You running a Cobb Stage 1 "Drive" as well?

[Jeff@TopGearSolutions]

Originally Posted by enrita

when you log you should ALWAYS disable all nannies to prevent intervention. best is to roll in 3rd and shift to 4th .

[slowSwede]

Originally Posted by scottro

Yeah if you could check your logs for that timing pull under low load that would be great. You running a Cobb Stage 1 "Drive" as well?

Checked my old logs and there's pretty much no difference between high/low loads, correction of 0 on all cylinders. In one log I had minor corrections on cylinder 5 and 6.
Running Cobb stage 1 aggressive with 94 octane.

[enrita]

Originally Posted by slowSwede

Checked my old logs and there's pretty much no difference between high/low loads, correction of 0 on all cylinders. In one log I had minor corrections on cylinder 5 and 6.
Running Cobb stage 1 aggressive with 94 octane.

you should go FBO and run stage 2+

[scottro]

Originally Posted by slowSwede

Checked my old logs and there's pretty much no difference between high/low loads, correction of 0 on all cylinders. In one log I had minor corrections on cylinder 5 and 6.
Running Cobb stage 1 aggressive with 94 octane.

Thanks for checking and getting back to me! Guess I may have a problem to chase down as these timing pulls on low loads are actually pretty consistent on each log I've taken.

[slowSwede]

Originally Posted by enrita

you should go FBO and run stage 2+

Will do that early next spring if I still have the car...recently she has been running strong without problems so I don't have any plans on starting a new affair

Wintertires spins all over, but next spring...I'll hide out in the garage for a day or two...

[slowSwede]

Originally Posted by scottro

Thanks for checking and getting back to me! Guess I may have a problem to chase down as these timing pulls on low loads are actually pretty consistent on each log I've taken.

Could be due to hardware or Gas, try getting some good quality fuel and log some more.
As for me looking at my logs, glad I can help out in some way.