juyanith

iTrader: (7)

Can someone explain how the Wastegate Solenoid Activation RPM table works?

From a stock 94170008 ROM:

The left column is labeled "Condition" and the right "Units". Are the "Units" RPM values? If not, what are they? I'm trying to understand when the BCS will be activated and deactivated, but the table isn't making any sense to me. Maybe it's just the terms reactivate and deactivate that I'm confused about as I don't understand why you'd deactivate the solenoid at 3250 RPM.

lemmonhead

just make things simple and get a ebc or mbc, no need for the tables nore the solenoid

mrfred

iTrader: (50)

Don't take this as bashing, but if we all had that attitude, we'd be nowhere with the Evo ECU understanding.

I've been fairly curious about the WG solenoid for a while, but haven't taken time to look into it. My only experience thus far is that the WGDC activates shortly after I go WOT.

mchuang

iTrader: (11)

Wouldnt the boost solenoid be considered the wastegate solenoid? I know we call it boost solenoid, but as far as I know there is no wastegate solenoid

lemmonhead

the turbo nipple is t-ed to the wastegate actuator and wastegate solenoid which bleeds off from turbo nipple to intake duct until the ECU decides its time to cut boost then its flows from nipple to actuator. Is that what your asking?
and mrfred no harm but I was trying to help him out with controling boost. Why try to figure some algorithm out when you can control it GREAT with a simpler means. I know that is what I do in my job as a control engineer. Power company's want a switchover to a new system and they old system has these wierd algorithm schemes to control boilers, i dont waste time to try and figure out the complicated way of controling it, I just use a simpler but EFFECTIVE way to control it. See my point?

RazorLab

iTrader: (8)

You don't even need to touch those tables to get great closed-loop boost control with the stock ecu for alot cheaper than a EBC or MBC.

jcsbanks

The on/off are hysteresis on the enable-disable RPM range.

I would raise the disable to 100 RPM before the rev limiter to give a bit more power up to 7500 RPM.

I don't know why the 3250 RPM value is there on this ROM, others seem to be at 7000-7500.

juyanith

iTrader: (7)

Thanks for the input. I actually had to look up "hysteresis" which seems to be the "lag" between a cause and effect. I'm not sure how that applies to the values in the table, although there may be lag in the logged results.

I set my "max wastegate..." table to 50% and did some logging. When I first start the engine WGDC is 0% until coolant temp rises to about 131* at which point it will shoot to 100%. I am assuming that 100% is its "disabled" state. When driving, it will go back down to 50% when I'm just cruising and come back up to 100% as I come to a stop (idle).

When I try a WOT run, the WGDC is 100% at the start then drops to 50% within a couple tenths of a second (even though RPMs are below 3250). It then tries to adjust the load based on the error correction table, which give a max positive increse of 8%. It will stay at 58% for a little bit, then corrects again to 60% and I don't know where this additional 2% comes from. It will stay at 60% for the rest of the run. When I let off the throttle, it drops back down to 50% and will stay there for a while.

I keep trying to find ways that the table below matches (or at least approximates) the logged data, but it doesn't. My basic observation is the the BCS functions as follows (with max set to 50%):
I don't see any evidence that the BCS is adjusted differently after 7188 RPM.

Lemmonhead, I'm actually pretty pleased with how the ECU is controlling boost. What I'm really doing is trying to understand how all the tables interact and this one confuses me. Being a computer nerd I actually *like* trying to figure out the algorithms, but thanks for the bump.

RazorLab

iTrader: (8)

Nice data juyanith

mrfred

iTrader: (50)

Check out my notes on this page:

https://www.evolutionm.net/forums/sh...=259494&page=6

juyanith

iTrader: (7)

Oh yes, I've read through that thread more than a couple of times. What you are doing there is what I was basically trying to follow. On my base tune, WGDC never moves from 100% and boost is mechanically limitted. It works well, spiking to 23.5 PSI then dropping to around 18 PSI at 7500 RPM. However, when it gets cold again I expect to see those number increase so I started trying to figure out how to get the ECU to adjust.

What I never saw in your data was the 100% WGDC before the WOT run. In fact, it looked like it was 0% based on the graphs so that was the behavior I expected. (Of course, I don't know what you've got the 500 RPM "baseline" WGDC set to nor if you have modified the pill(s) in any way.) Right now I'm planning to try changing the pill closest to the wastegate as shown here: https://www.evolutionm.net/forums/sh...d.php?t=227006 and see how that works for me. The only current modification I have is the removal of the pill closest to the BCS.

jcsbanks

I've not looked in enough detail because I had an AVC-R so I fitted it.

I would expect 0% duty when off the throttle.

With a quick try to log WGDC it made no sense with the published request IDs on my twin solenoid IX, and I didn't go further.

What I mean by hysteresis, is like the speed limiter, IC spray coolant temp etc there is a dead zone where the value doesn't switch, this stops oscillation when you're near the trigger value. So as the revs increase it won't turn on until it reaches the higher value, and then it won't turn off going down the revs until it is below the lower value.

mrfred

iTrader: (50)

My 500 rpm BWGDC value is set the same as my 2000 rpm value which is about 70%. Yeah, I always see 0% logged WGDC until I step on the gas. And it will go to 0% again when I lift the throttle. I'm curious about what load/throttle/rpm or whatever controls this. No time for me to look at it right now though. Still hammering away at trying to understand the code where the MAP sensor is used to judge EGR performance. :-)

juyanith

iTrader: (7)

Yeah, I expected 0% too and at first thought I wasn't logging the WGDC correctly. I thought about min activation/deactivation ranges also, but the table still doesn't make sense to me. "Reactivate on" 2000 RPM until it drops to 1906 would make sense but then what are the 3250 "deactivate on" and 7188 "deactivate off" values? If it's active above 2000 RPM they would be meaningless (and deactivating between 3250 and 7188 doesn't make sense anyway). I then thought that one was "low" load (cruising, idle, etc) and the other "high" but the logs don't support it. I've tried various other combinations but still haven't found something that matches the data and there's still the issue of the added 2% (where did that come from?)

juyanith

iTrader: (7)

Hmm, it just occured to me that maybe the reason for two values are for a dual solenoid setup. Solenoid 1 activates at 2000 and doesn't deactivate until 1906. Solenoid 2 (which my VIII doesn't have) activates at 3250 and deactivates at 7188 (although what happens if you never hit 7188?). That does seem closer to what I'm seeing.