BDEL (boost desired engine load) isn't the controlling map, it's more like the target map. BWGDC (base wastegate duty cycle) is the table the ECU will follow initially to know what WGDC to use at a given RPM and gear. If BEC (boost error correction) is enabled, then it will adjust WGDC to follow the values in BDEL + boost adder

 

Raptord, thanks for the clarification about the BDEL. So with the BEC zeroed out I can start with a low number (say 20%) on the WGDC (as that is the only map the controls boost at that point). Then log the boost error and edit till I get the boost curve I'm looking for in different gears. Then activate the BEC for consistency of targeted values.

I am going to do some more reading on the WGDC map and stock boost control as the only difference is that the error correcting based off of PSI targeted values instead load values.

Thank you for answering my questions.

 

Exactly.

As another note, I would only use BEC with PSI-based boost control, not with load-based. The reason for that is that, let's say your tuned for 22 psi, which usually corresponds to 240 load on your car. So your ecu will target 240 load. If the engine gets heavily heat-soaked, the engine will need more than 22 psi to reach that same 240 load, so you risk over-boosting even though you're using error correction.

 

I use BEC with load based boost, however I just set upward correction to much lower % than downward correction (0.5 - 3%), and have the WGDC very close to perfectly flat boost without correction at all. I have correction interval set to 200ms. I find this does not cause any overboost conditions. The only way it could was if it was very heatsoaked, and I was doing an extended load hold and over a longer period the smaller increments of boost increase would increase boost beyond desired levels. However that said I tune a few PSI above where I set the boost, so even at 5-6psi higher there's still no knock and the AFR's are safe (slightly richer than normal top end) for additional thermal and knock management.

Having BEC enabled allows me to tune flat boost to about +/- 0.5psi accuracy. Wouldn't do it any other way. I dont like PSI based since it's always trying to hit a particular pressure and I find this method much more susceptible to environmental changes like temperature, humidity, elevation etc.

 

I almost have my WGDC dialed in, but my boost error just reads 3.0585 constantly in my logs. Any ideas?

 

Post up your BDEL and boost adder maps. PSI or load-based boost control?

 

I set it up for PSI based boost, correction zeroed out.

3rd gear log file: here

 

double check your boost error MUT request in rom, as well as your evoscan settings connected to it...

 

Anybody know what the MUT request is for WGDC Correction? I haven't been able to get mine to log properly for quite some time and I wonder if that's my problem.

 

does anyone have the GM 3-bar scalings for BoostErrorPSI please?

cheers

 

Have a look at the Tephra V7 ROMs for JDM cars, the settings should be in there.

 

I disagree with not using BEC on either boost control option. I actually stopped using PSI based boost control because its irrelevant to tuning on the stock ECU IMO. We tune for a desired LOAD curve, a path in which we want the ECU to follow every single time. With the same boost under different air temps and other climate conditions will yield different load curves. Using load based boost control ensures you are riding on the same curve at all times.

I use the IAT vs Timing Trim to adjust my timing appropriately for varying air temp conditions. It hasn't failed me yet

In New England, we see DRASTIC climate changes, even on the same day. I have had days where it was below 10*F (-12*C) in the morning and 80*F (26*C) in the afternoon.

-Jamie

 

I was going to comment on that as well. I've used BEC + temp/baro compensated load for 5+ years in the Pacific NW (which has temp swings year round) and it does its job once you are willing to invest the time to get it right. BEC can be zero'd out during initial tuning but for any true road car it needs to be turned back on and properly dialed.

 

Sorry to bump my own qeustion but I still haven't found the answer to this^^

I'm using Teprhas V7 94170715 ROM if that helps. Thanks!!

 

burgers22: thanks mate, got the info i need as you advised, appreciate it

Ian0611: 8A is Boost Error (PSI or LOAD) and 8B is WGDCCorr. If you are referring to the addresses needed, sorry cant help there.

cheers