I do understand that WGDC % is not how much the wastegate is open but how much air is vented by the BCS. I was just thinking that say at 4000 rpm's there's enough exhaust velocity to start opening the WG if WGDC is less than 100. But I'm sure you're right and it's a non factor.

 

You need to have the right top box on the error correction table to be zero'd out.

 

My thinking on TBEC using load values has evolved since I started doing this. I started off running these load based values:

0
0
0
0
0
0
1
0.5
0
-0.5
-1
-1.5
-2
-2
-5
-7
-10

But with these values the ECU kept adding WGDC of about 1-3% when load error was negative between 2 and 8 points. Why would I want the ECU to add boost? So I added 1 to 3% WGDC and ran this TBEC:

0
0
0
0
0
0
0
0
0
0
0
-1.5
-2
-4
-8
-10
-12

Now the boost is rock solid and the only time the ECU steps in is when the load is above target by 7.5 points or more. When that happens the ECU opens the WGDC to protect the engine.

I have tested this multiple times and it gave me consistent boost regardless of gear and weather.

 

Naji,

Are you going to implement that setup on Andrea's Evo next Saturday?

Justin

 

Yes...And here is the 3rd and 4th gear boost on Evos that I have used this on:


January 22 2008



December 23 2007



November 10th 2007

 

It was doing what you told it to do . By not zeroing out the negative ("underboost") correction in that range the ECU saw it was under and added. If it still sees its under in the particular zone it will add again.

The small danger of zeroing that out completely occurs if the positive (overboost) correction is too aggressive and then you'll get a dip.

 

Agreed...I just did not want the ECU to add any boost when it sees slightly lower than expected load numbers. I just want the ECU to protect the engine in case there is an over boost (higher than expected load numbers) condition. This table that I am using now did the trick.

 

What you guys doing is pretty much WGDC boost tuning with protection from overboost. It probably works well if you tune it in summer or live in a place with mild season temp changes.

What happens if you tune in winter and in summer boost drops and you never hit your goal? That's what TBEC would be for.
Same with changing mods, if your boost drops, you would have to retune WGDC all over again.

 

why not change the interval from 10 (0xA) to 1, this will mean the error correction algorithm will process more often, and will result in a flat'r boost curve.

of course you will need to put fairly realistic numbers into your wgdc table as well...

 

Yep, that's how I have it. I got the wgdc table as close as possible then implemented correction. The top 3 are zero, in fact it doesn't start correcting until about -1 psi. The error correction table still needs a final tweaking, as there is a slight dip after peak boost, but has proven to be stable & predictable in various temps.

 

I haven't tried 1 yet...but I am on 2 and I think this is the most valuable bit of data that Mr fred found associated with the stock BCS. By having that interval shorter with a good TBEC table the boost can be a lot more stable.

 

Here in SoCal we do not get a lot of extreme temp variation. I have tested in the summer and in our so-called winter and still got the same boost in 3rd and 4th gear.

 

I have tried 1 in the WGDC correction interval #1 and it is fantastic. I will not tune boost any other way. The load based boost control has come a long way thanks to mrfred's fine tuning of the boost load method.

Personally, I would zero all the negative side of the TBEC table as well as the first two of the positive side. This has given me consistent boost as the tables that I have posted show. The tables are multiple back-to-back runs in 3rd gear and in 4th gear and are not one run only from each gear.

 

I set my wgdc in the fall when it was about 65 deg. It gets to be in the 20's here in the winter & over 100 in the summer. We'll have to see what happens in summer...until then it's been good.

 

I'm sorry i actually meant nj1266 in my post, he does not use upward boost correction (his negative boost error correction is zeroed out.) You and I do. So you should be good in summer i would imagine.