EBC and MBC together?
 

I got sick of the EBC so I built a manual controller from home depot parts.

I like the ability to switch between a boost target and the wastegate, so I'd like to keep that functionality.

Below is what I have tried so far, with the DC for the EBC set to 100% across the board, and a regular switch wired in line to the solenoid.

Attachment 209210

The configuration on the left was a failure because when the solenoid was powered, it just dumped the boost signal out to the atmosphere, so it would just crash into the overboost fuel cut.

The configuration on the right hasn't worked so far, but it doesn't overboost anymore, so I would say it is an improvement. I just end up with wastegate pressure regardless of whether the EBC is active or not. I don't know if there is a problem with the configuration, the solenoid, or if the spring in my MBC is just too weak.

So here is my question: Does this idea hold merit, or is it doomed to failure for some reason I haven't noticed?

run it in series, not parallel.

oh wait, you want to run the MBC...but use the solenoid to allow to run wastegate?

I'm thinking the configuration on the left should work. When fully closed (100% DC) the solenoid shouldn't leak boost, so all the air will go into the MBC and would as if the solenoid isn't there. When fully opened (0% DC) the air should flow freely into the wastegate actuator.




why don't you like the EBC function?

edit:

disregard original post. the config on the right should work as long as the MBC is tight enough.

incidentally, dont hook the solenoid to the ECU. just wire in a +12 and GND with a switch.

it overshoots and changes a lot depending on ambient temperature. See this thread for more thoughts.

try a pressure regulator after the solenoid.

Post resurrection, with a good reason. See below:

I'll be trying the method that Deliverator linked to on NASIOC. I think it is brilliant. The EBC and MBC are hooked up in parallel.

1. The MBC acts as a max allowable boost controller. No matter what the EBC is doing, the MBC has ultimate control over the maximum allowable boost level. This is HUGE.
2. One could use this with an on-off switch on the EBC to switch between MBC control and straight-up wastegate control. Or...
3. One could use this with the EBC duty cycle control to regulate part-throttle boost levels with the MS throttle-based duty cycle function. This allows for better part throttle modulation. I like this personally as I have done it with the EBC.
4. Even if you do not use the part-throttle modulation, you can still set up the EBC to spool to a lower pressure than the MBC, and reduce the boost lag from running off of the wastegate only. But, ultimately, the MBC will clamp the upper boost level if the EBC overshoots ( due to cold weather, tuning, whatever).

So I have a question, hence the thread resurrection. Bear with me. If one wanted to, a 5th way to use this would be to have a switchable system. Stage one is regulated by the EBC, and Stage 2 is regulated by the MBC. If another power line was connected to the EBC solenoid, in parallel with the MS, then one could lock it to 100% by sending it a continuous voltage signal. This means the EBC would be shut, and the MBC would be in control. One could use this to have settable boost levels, but without the wastegate lag (that comes from just turning off the EBC). Or with a button on the shifter or steering wheel, have a two-stage boost system, for lower boost in 1st gear for example.

Question: Is it OK with the MS-I EBC driver circuit to have a parallel circuit (to the EBC) that is just a switched 12V signal, or will it damage the MS circuit?

The EBC output, like most of the other outputs, is a closure to ground. The EBC solenoid has +12 applied to one side of it, and the other connects to the MS, which provides a PWM'ed ground to drive it.

If you want to operate the EBC solenoid manually, provide a switched closure to ground between the EBC and the MS.


Is it possible that you are making this needlessly complex?

That's what i do. A simple $0.50 switch from radio shack on the ground line between the valve and MS.

Attachment 208140

Ahh OK right. I knew that actually, but forgot. So all it would take is a switched, parallel path to ground to lock the EBC at 100%, with no harm to the MS. Thanks.

No I don't think it is needlessly complex, in that it is potentially full of win compared to the standard approaches.


Method 1: Wastegate control only
Pros:
- Cheapest and simplest of all.
Cons:
- Slower spool
- More difficult to adjust target boost level
- Limited adjustment range


Method 2: MBC only
Pros:
- Simple and effective
- Easiest to tune (just turn a knob)
- Wide range of target boost settings.
Cons:
- Not switchable electrically.
- No part-throttle boost (wastegate) modulation.


Method 3: EBC only
Pros:
- Electrically switchable (between wastegate and EBC target boost)
- Wide range of target boost settings, part-throttle boost modulation,
- Already available on MS
Cons:
- For MS (open-loop control) overboosting with ambient temp drops is a problem
- Takes more time to tune than the MBC
- Slow spool when EBC is off (wastegate mode)


Method 4: MBC and EBC in parallel, power interrupt to EBC (0% duty cycle)
Pros:
- MBC acts as a max boost clamp (greatly reduced overboosting with ambient temp drops)
- Part-throttle boost modulation
- Electrically switchable boost levels (between MBC and wastegate)
Cons:
- Slow spool when EBC is off (wastegate mode).


Method 5:
- MBC and EBC in parallel, Power interrupt to EBC (0% duty cycle), Ground bypass to EBC (100% duty cycle)
Pros:
- Same as Method 4
- Electrically switchable boost level with three states (EBC, MBC, wastegate)
- Electrically switchable between two boost levels without wastegate lag
Cons:
- Most complex of the above methods to tune and implement.

Pick your poison! I'll be trying Method #4 at least, if not Method #5

I might would try 5 maybe. Like you said, it should fail to MBC pressure if (when) temps change several degrees and EBC has a heart attack. I would like some boost by TPS control. Feathering second gear is hard as hell right now.

Exactly!

With the small turbos, the wastegate spool 'lag' might be OK, though I noticed a definite improvement with the 2560 after adding EBC. With the 2871 I am going to now, I would think improving the wastegate only spool would be even more dramatic.

Well damn you, I might have to try this over the weekend. I bought the shit to build EBC stuff, but never did the mod. Actually, I need to redo how my supErior Waste Gate is controlled first to help with boost response, then do this mod. Maybe next weekend. :)

You will be trying it out before I then, since I am still building the new motor. Please post up when you have some results.

You know, there are some other options here if one gets creative.

For example, WI fault protection. It would work with any of the EBC methods above. Interrupting power to the EBC as we know causes it to go to 0% duty cycle, and thus the boost defaults to the wastegate level. This is presumably the lowest boost level of all, since the EBC and MBC can only raise boost from the wastegate level.

So, if one were using WI, then one could put a normally-open pressure switch in the water feed line to the mist nozzle. The power to the EBC would be run through this. That way, if there is a WI failure (anything short of a clogged nozzle), then the EBC goes to 0% duty cycle, and boost does not go above the wastegate pressure. No WI, no high boost. There is a potential Catch-22 here though if one wants to set WI to come on above the wastegate pressure.


EDIT: Attached is a PDF of the vacuum diagram and electrical diagram of what I am talking about for Method 5 as described above. There are three modes: wastegate control, EBC control, and MBC control. I am not sure what to call the switch, but it could be thought of as two, three-position rotary switches that move in tandem.

Just to update, the original drawing never did work. It would just keep building boost until I hit the overboost protection, even with absolutely not tension on the ball in the MBC. I could flip the switch and run wastegate just fine, but the "high boost" never worked. I removed the EBC and just ran the MBC, and it works just like it's supposed to.

Here is another way to do it with two simple SPST on-off toggle switches which are easy to find, like at Radio Shack. The first switch 'arms' the system. The second switch selects EBC or MBC.

Check me on my math here :)

Are you using the GM EBC valve? If so I do not understand why it did not work so maybe I am missing something. The guy on the NASIOC site that did this successfully had the vacuum lines connected like I have in my diagrams, and like you have yours shown in the left diagram. And judging from the picture he is using the GM (Delco) valve.

Today I checked the way the EBC valve works with a power supply to be sure I have it right. No power (0%) air flows from the inlet to the wastegate connection. Power (100%) air flows from the wastegate connection to the vent (where the foam filter is located). I was concerned at first that at 100% the EBC would just vent the boost signal to ambient, and keep any pressure from actuating the MBC valve. But, when at 100% EBC, there is a lot of resistance to flow between the wastegate port and the vent. So it would seem like since there is so much available flow from the turbo, that the flow would overpower the vent, and still allow pressure to build and actuate the MBC. In other words, the vent would not bleed off boost fast enough to prevent the MBC from actuating the wastegate. This would have to be true for it to work for the NASIOC guy.

But like you said, it did not work for you, so something here is amiss.

I am using the GM valve, and I don't understand why it does not work. Everything on paper indicates that it should work great, but actual execution proves otherwise.

Interesting. Hmmm... You know it occurrs to me that I could play around with this on the workbench using an air compressor (while the car is offline). A regulated shop compressor will make a decent air source to simulate the boost signal.