[Rob@Cobb]

Originally Posted by themyst

Not concerned with a specific load limit, just the theory that the piggybacks are limited by the stock load target. Some more clarification would be appreciated!

Quite honestly I have not tuned a piggieback or attempted to trick the ECU. It's a feat they can push the motors as hard as they do while telling the ECU life is peachy. They have my respect for the number of hours spend modeling what the ECU needs to hear.

I'm am not 100% sure what their limitations are. The bulk of my time is spend looking for ways to properly tune a motor using the factory ECU. We hit limitations electronic or mechanical and look for proper solutions that retain a very OEM level of quality and smoothness.

Cheers,
Rob

[Joshboody]

I had some questions before, but not sure if they were answered in the many pages on the other threads.

Do the flashes have to follow the same torque/load targeting logic in increasing boost in hotter weather and reducing in cold? i've seen about a 2.5psi swing from summer to winter when stock. The piggies of course target the boost you want.

Also I would love to see some of the changes in timing tables due to weather. When stock in the summer I'm bouncing off the knock threshold, but in the winter... smooth. the dme doesn't really seem to learn in the summer when i can't get much beyond 5-7deg advance.

The tunable version will have tables for different weather conditions, or you adjust general timing and a correction for weather is added automatically?

sorry if this has been answered or i haven't read everything thoroughly enough to understand.

[Rob@Cobb]

Originally Posted by biz77

Would you be willing to share how the ECU calculates "Load?"

Load is usualy a mass of air in a certain number of cylinders per a rotation of the motor. Different ECUs have different load calculations, but it's generally a mass of air from which the ECU can calculate how much fuel is needed to make x.xxx lambda in a particular cylinder.

As lance mentioned the load curve looks very similar to the torque output of the motor.

Cheers,
Rob

[Rob@Cobb]

Originally Posted by Joshboody

I had some questions before, but not sure if they were answered in the many pages on the other threads.

Do the flashes have to follow the same torque/load targeting logic in increasing boost in hotter weather and reducing in cold? i've seen about a 2.5psi swing from summer to winter when stock. The piggies of course target the boost you want.

Also I would love to see some of the changes in timing tables due to weather. When stock in the summer I'm bouncing off the knock threshold, but in the winter... smooth. the dme doesn't really seem to learn in the summer when i can't get much beyond 5-7deg advance.

The tunable version will have tables for different weather conditions, or you adjust general timing and a correction for weather is added automatically?

sorry if this has been answered or i haven't read everything thoroughly enough to understand.

Hi Josh,

The ECU is concerned with the mass of air in the motor which is dictated by the temperature and pressure of the gases entering the motor. Given the ECU wants a certain mass of air in the motor, and it really can't change the temperature of the air, so it uses pressure to make sure it gets mass of air requested.

As you touched on timing and load changes in the different weather conditions, the ECU uses what it has control of to run as efficiently as possible. The factory has spent a great deal of time determining what they think is the optimal Minimum Best Timing for power, efficiency, and emissions. When the temperature of the air rises, it pushes closer to the detonation threshold. They can remove timing, lower load, and add fuel at a basic level. Adding fuel and lowering timing can lower efficiency and hurt emissions. The next recourse is to lower load, yet keep the lambda and timing where it's efficient. When you lower load, timing can generally go up which is what I believe you are describing. As you have also seen with super high temps the ECU has to remove load and timing to keep the motor from destroying itself. However the goal is to get back to a point where the motor is most efficient and it will try to get back to that point when it can.

Which brings me to my next topic of the knock control system. From what I have seen so far, it's incredibly sensitive where your car is likely not hurting itself trying to get back to running efficiently with factory mapping. I tend to simply lay off the car in the heat being safe.

In the end we leave the factories ability to save the motor, but continue trying to get back to what it thinks is efficient and safe. What we can offer is lower powered maps for the climates which see super high temps in the summer. I usually resort to adding some sort of water injection or octane booster for the months which are super hot allowing my driving habits to go unchanged unless I'm just laying off the go peddle. No matter what turbo car you run, they suffer power loss in the heat.

Hope this helps,
Rob

PS, it's pretty late and I might need to go back for editing in the morning. Hacking == yes. Writing == no.

[shockin330i]

subscribing. I really like that I don't have to drive across the country to stop by your door.

[mithiral67]

Originally Posted by Rob@Cobb

What we can offer is lower powered maps for the climates which see super high temps in the summer. I usually resort to adding some sort of water injection or octane booster for the months which are super hot allowing my driving habits to go unchanged unless I'm just laying off the go peddle. No matter what turbo car you run, they suffer power loss in the heat.

So if its really hot out and you normally run the 93 map, drop it to the 91 map? What would you define as really hot, cause a Texas heat is very different then a lot of heats accross the US.

[Joshboody]

Originally Posted by Rob@Cobb

Hi Josh,

The ECU is concerned with the mass of air in the motor which is dictated by the temperature and pressure of the gases entering the motor. Given the ECU wants a certain mass of air in the motor, and it really can't change the temperature of the air, so it uses pressure to make sure it gets mass of air requested.

As you touched on timing and load changes in the different weather conditions, the ECU uses what it has control of to run as efficiently as possible. The factory has spent a great deal of time determining what they think is the optimal Minimum Best Timing for power, efficiency, and emissions. When the temperature of the air rises, it pushes closer to the detonation threshold. They can remove timing, lower load, and add fuel at a basic level. Adding fuel and lowering timing can lower efficiency and hurt emissions. The next recourse is to lower load, yet keep the lambda and timing where it's efficient. When you lower load, timing can generally go up which is what I believe you are describing. As you have also seen with super high temps the ECU has to remove load and timing to keep the motor from destroying itself. However the goal is to get back to a point where the motor is most efficient and it will try to get back to that point when it can.

Which brings me to my next topic of the knock control system. From what I have seen so far, it's incredibly sensitive where your car is likely not hurting itself trying to get back to running efficiently with factory mapping. I tend to simply lay off the car in the heat being safe.

In the end we leave the factories ability to save the motor, but continue trying to get back to what it thinks is efficient and safe. What we can offer is lower powered maps for the climates which see super high temps in the summer. I usually resort to adding some sort of water injection or octane booster for the months which are super hot allowing my driving habits to go unchanged unless I'm just laying off the go peddle. No matter what turbo car you run, they suffer power loss in the heat.

Hope this helps,
Rob

PS, it's pretty late and I might need to go back for editing in the morning. Hacking == yes. Writing == no.

Thanks for the feedback. So I am understanding that the dme doesn't necessarily have different maps for different temps... it's calculating load from mass of air and adding MBT, which if based on a load table, would not really account for increase in cylinder pressure and cylinder temps from hotter air. so adjust timing proactively by trial and error. And a flash has to follow this logic of course, but we would have the option to change maps in the summer and winter changing the load target... basically what we are doing with piggies either by autotuning or changing maps.

[denial]

Originally Posted by mithiral67

So if its really hot out and you normally run the 93 map, drop it to the 91 map? What would you define as really hot, cause a Texas heat is very different then a lot of heats accross the US.

+1

Specifically, any special recommendations for Texas like heat? Would it be ok to run the regular OTS maps (93) in Texas heat without the need for additives or higher octane fuel, etc?

[BQTuning]

Originally Posted by COBB Tuning

...It is interesting to note the scaling used by BMW -- the factory load targets for the ECU are in the 130-140 range but they included resolution all of the way up to 180. Normally, the factory X-axis scaling is inadequate for airflow levels larger than stock (Subaru being a good example) and we have to rescale these axes almost immediately during the tuning process. We have the ability to do this on BMW but Stage1 power levels do not require it (yet!?). ...

So pretty much the N54 has far more "open" capabilites than expected. When you mentioned "airflow levels" are you talking in general ie intake, boost, exaust, or or just one of these ?

Originally Posted by COBB Tuning

It's probably a fairly safe assumption to say that BMW has tested and run these ECU/engine configurations at a much higher power level than the final delivered product :-P From my experience, I would say that these cars come pretty well tuned from the factory for the stock power levels…and thankfully, VERY conservatively!

So in essence the N54 is pretty much factory underrated, in other words, BMW has echoed to its recognized tuner(s) that the red line on boost is 15-16 psi I suppose. Dinan S3 and even the 335is boost caps are in the 14's. So based on your experience with the ECU and stock Turbos red line does not start at 15 psi ? If yes, what do you speculate that red line occures with stock ?

Originally Posted by COBB Tuning

With this knowledge, I then worked on reducing ignition timing as necessary through the problem areas while smoothing in some of the large jumps that exist in the OEM mapping without reinventing the unaffected areas of the table.

So your map build is based off of the OEM Map ?

[BQTuning]

Originally Posted by Clap135

In theory this makes no sesnse, one would think this the ecu would pull back load and drop timing, not pull back load and raise timing only to possibly knock again.

If the ECU pulled back both load and timing wouldnt that be a major decrease in output power vs. decreasing load and increasing timing will have less power output loss ?

I am just learning

[Clap135]

Originally Posted by BuraQ

If the ECU pulled back both load and timing wouldnt that be a major decrease in output power vs. decreasing load and increasing timing will have less power output loss ?

I am just learning

yes it would have a major decrease in outpower, however that is what you want when the engine is knocking due to fuel quality or heat ect.

Bmw's calculation appartly found a way to lower load and keep igntion up to achieve the desired knock free effect. This works on a stock car, not so sure about a car running double the boost, but we'll find out

[COBB Tuning]

Originally Posted by mithiral67

So if its really hot out and you normally run the 93 map, drop it to the 91 map? What would you define as really hot, cause a Texas heat is very different then a lot of heats accross the US.

That's definitely not a bad idea; the 91 mapping is more conservative and may provide some peace of mind on the most burtal of summer days

Regards,
Lance

[COBB Tuning]

Originally Posted by BuraQ

So pretty much the N54 has far more "open" capabilites than expected. When you mentioned "airflow levels" are you talking in general ie intake, boost, exaust, or or just one of these ?

Total mass of air being displaced by the engine. Many factors go into this...density, pressure, temperature, etc.

Originally Posted by BuraQ

So in essence the N54 is pretty much factory underrated, in other words, BMW has echoed to its recognized tuner(s) that the red line on boost is 15-16 psi I suppose. Dinan S3 and even the 335is boost caps are in the 14's. So based on your experience with the ECU and stock Turbos red line does not start at 15 psi ? If yes, what do you speculate that red line occures with stock ?

Can you elaborate on what you mean by "red line on boost"? Without upgraded cooling (more efficient FMIC, water/meth injection, etc.) it's likely that the load/boost levels being run on our 93 map is the most that we'll run for our Stage 1 OTS offerings.

Originally Posted by BuraQ

So your map build is based off of the OEM Map ?

In a sense. We begin tuning the relevant cells/tables starting from the factory's default values.

Thank you for your questions and please let me know if I can be of assistance in any other way.

Best regards,
Lance

[Smitty1]

What about the use of a larger intercooler?

Admittedly I don't have a great understanding of the art of tuning turbos like the 335I but the stock intercooler seems to be a weak link when it comes to running more boost. Since the idea is to lower the temp of the air getting compressed by the turbos the cooler the air the better.

I think you guys already said that running a car with a larger intercooler would should be fine with the current maps, is that correct?

In my mind a larger intercooler is the first step to take when you start pushing this cars for more boost. Sure you get a power gain, but it also allows the turbo's to breathe easier with out roasting them. When you are talking about a sensitive auto like the BMW 335I it pays to be cautious on how you approach HP.

Down pipes are another matter. They create more flow and help increase the flow of the turbos and exhaust, but doing that first with out lowering the temp. of the air coming in is not the way to go.

[Clap135]

Speaking of modifications. I am under that assumption that the stock ecu has AF targets which you guys alter. Why would adding a full catless system change the way stage 1 reacts. The ecu still has that target and will simply adjust trim to achieve the af ratio, would it not?

[BQTuning]

Originally Posted by COBB Tuning

Can you elaborate on what you mean by "red line on boost"? Without upgraded cooling (more efficient FMIC, water/meth injection, etc.) it's likely that the load/boost levels being run on our 93 map is the most that we'll run for our Stage 1 OTS offerings.

Red Line = critically unsafe conditions capable of distroying your stock turbos and or engine.

In other words what is the max boost the engine and stock turbos can handle before they reach that -red line- with Cold Air Intake, Oil Cooler, Intercooler, DP's, high flow cat and free flow exaust upgrades ?

[Sniz]

one of the best threads I have seen on this forum in quite some time, keep it up guys.

[iwanna335]

Originally Posted by shockin330i

subscribing. I really like that I don't have to drive across the country to stop by your door.

TX is half the country.....

[bulldog_yyc]

Originally Posted by Clap135

Speaking of modifications. I am under that assumption that the stock ecu has AF targets which you guys alter. Why would adding a full catless system change the way stage 1 reacts. The ecu still has that target and will simply adjust trim to achieve the af ratio, would it not?

good question - I was also somewhat puzzled as to why S1 is not recommended on a full bolt on car, since larger IC and catless DP's would add to the safety margin (vs. stock car) rather than reduce it. Perhaps it has something to do with the O2 sensor (and A/F) behavior under catless conditions?

[Bagelfast]

So on a hot day, the COBB tune sometimes cant handle the heat and going down a map would be best? Arent piggies able to auto-tune themselves now to compensate for this?

[Clap135]

Well adding flow mods will increase flow obviously. More flow, requires more fuel, so you will run lean untill the ecu adds fuel. Maybe cobb thinks you will run to lean? I highly doubt that, either way it will adjust trim to hit the target.

Another concern with TBE exhaust is their effects on boost response. Depending on how Cobb address spool up, this might cause overshoots and cause throttle closures. But ill let them comment on that.

[COBB Tuning]

Originally Posted by Smitty1

What about the use of a larger intercooler?

Admittedly I don't have a great understanding of the art of tuning turbos like the 335I but the stock intercooler seems to be a weak link when it comes to running more boost. Since the idea is to lower the temp of the air getting compressed by the turbos the cooler the air the better.

I think you guys already said that running a car with a larger intercooler would should be fine with the current maps, is that correct?

Yes, there should be no ill effects caused by running an upgraded intercooler. Spool may be slowed down slightly by the increase in volume, but this is usually an acceptable trade-off for people.

Regards,
Lance