Wastegate duty cycle % values

[2QUIK6]

Does a higher value for wastegate duty cycle percent cause the wastegate to open the puck further or close it more for higher boost?
There are 2 tables, one vs. RPM the other vs. TPS. In the TPS table, I have all 99.6%.
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Reason I ask, is I see values of 0% at 1600 and 2000 rpms which I would think you would want the puck closed as much as possible for better spooling at low rpms. Then at higher rpms I see values like 99%, maybe because the higher rpms would generate a lot more boost if the puck was not fully open????
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I always figured before that higher values meant more boost but after noticing the 0 values, maybe not.
Thanks

 

[BoostKillsStres]

The values of 0 mean the solenoid isn't bleeding any boost off thus all the pressure is going to the WG which isn't what you want in the low RPM's IMHO. I have always set the first couple of cells to 100% so that the sol is bleeding all it can so that minimal boost gets to the WG thus not moving the puck and promoting faster spool. Obviously you have to be careful how far you go with this as you may get to the point of causing a boost spike.

HTH

 

[2QUIK6]

Thanks Mark, that's what I originally thought when I saw the 0's in the table. Interestingly enough, my TTA stock chip has a value of 17% at 2000rpms, yet the GN had 0%, but the GN spools much faster..probably because of the THDP. Both were 0% at 1600rpms.
Guess I'll go experiment...

 

[TurboDave]

You must remember, that the original ECM and chip had built in safety valves so-to-speak to actually slow spool up. Thus limiting that fast boost build up was safer becaue initial tire spin was minimized.

That's why you see the wastegate solenoid voltage with a big slow ramp on it's build up in most chips, and the zero early values the the boost table.
There's a filter value in the chip that causes that slow WG solenoid voltage ramp up. Again, safety was the idea. Kept us maniacs from killing ourselves leaving the dealership lot

 

[BoostKillsStres]

Very well put TurboDave gotta love that WG ramp fix

 

[2QUIK6]

Thanks Mark and Dave. How about this thought, leave the 1600 rpm setting at 0% since at below 2k you're not building boost anyway and you're not burning up the solenoid having it pulsed at 100% setting at idle or light cruise.

That's probably another good reason GM had 0% in the first 2 slots at 1600 and 2000 rpms so they wouldn't be swapping solenoids while under warranty.

 

[BoostKillsStres]

Actually the WG sol won't get any DC control signal until the ecm thinks your in boost or pe, not sure which, so its not doing anything at cruise.

And if you leave a value 0 close to when you start building boost aka 1800-2000 then your introducing a ramp if the next value is 100 just like the factory ramp which is built in which will slow spool as the sol DC will slowly ramp up from 0 to 100 as it interpolates values for the rpm range inbetween the rpm dc values that you set.

 

[ijames]

There's a MAF threshold to tell when you are in BOOST mode, set at 76 gps in the stock chips. You can see it in DS when the boost flag gets highlighted at that maf value. The ecm only runs the wastegate solenoid when the boost flag is lit. Realistically, wgdc at rpms less than about 2500 really don't matter because 1), most chipmakers set the ramp filter constant to $FF so the ramp is instantaeous, and 2) with any kind of converter the motor is going to be over 2500 rpms before the maf gets over about 40 gps - again, watch some directscan data if you have it and you can see all this clearly.

 

[TurboGeezer]

MAF Threshold

So, does it, therefore, make sense to adjust this threshold in order to begin the "bleed" a little sooner??

TG

 

[ijames]

I don't think you will see any significant difference. Watch your boost gauge and direct scan and see how your boost and maf compare (and of course, watch the road ).