how-to: ECU-based direct boost control
Mar 10, 2012, 06:12 PM
#1021
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
Mar 10, 2012, 06:49 PM
#1022
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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
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.
Mar 10, 2012, 07:00 PM
#1023
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.
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.
Mar 10, 2012, 08:36 PM
#1024
Evolved Member
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.
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.
Last edited by EvocentriK; Mar 10, 2012 at 08:39 PM.
Mar 15, 2012, 01:29 AM
#1028
May 24, 2012, 04:18 PM
#1032
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.
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 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
Last edited by Dynotech Tuning; May 24, 2012 at 04:21 PM.
May 25, 2012, 12:07 AM
#1033
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.
May 25, 2012, 03:27 AM
#1035
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
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