Guys,
I'm about to pull the trigger on this thing, but the only thing that's holding me back is that from what I hear, the XEDE can't control a stepper motor (like the HKS EVC V uses) to control boost. Has anyone worked out a solution to this? I'd rather not use the stock solenoid, and it seems like it's just a matter of getting the proper electrical signal, no?

Joe

 

Joe,

Never thought of that? But the Xede can control another solenoid.

So you would need two controls for a stepping motor. One for gain another for % duty cycle. Sure you can do it. But why use the Xede with the stock solenoid or just run a MBC or EBC if you don't like the stock Solenoid.

Eric

 

Eric,

The whole idea behind going for the XEDE is to retain some margin of safety that I'm lacking with an SAFC and AVC-R, in that if the ECU detects knock, boost will be dialed back and fuel and ignition curves will revert to a safer "knock" map. Whereas, with the little blue boxes, kock occurs, 20+psi is still requested and the engine internals have a tendency of becoming externals, especially when running the car hard for 30 minutes or more at WOT most of the time on the track.

I'd rather have something complete and comprehensive than a bunch of hack boxes, especially in the situation where we might get a bad tank of gas and the SAFC and AVC-R both try to seek outputs based upon better gas, which may lead to detonation.

 

Hmm good ideas Jimmy the xede will offer the protection that your looking for for serious road racing but as you know (and hence the post about the stepping motor) the xede will ask for the same peak boost also even if the secondary less aggressive maps are in use. The xede TMK doesnt have a knock count timing scaling but the secondary maps do seem to be a conservative enough trim in timing and fuel to accomidate for all current vishnu stages. The Xede only offers as much protection thats built into the factory ecm- a stepping motor that lowers duty cycle when knock is detected or when sensing the lower maps would increase safety a factory of ten very cleverly and very cheap! Good job!

 

With Xede the ECU contorls timing retard. I would use the Xede's boost control with the stock solenoid. I don't know of any after markect boost control that will pull boost out if it knocks. They just don't work like that.

 

It seems simple enough to integrate into the circuitry, anyone here good with a soldering iron?

Shiv and Brett, you listening?

Regards,
Joe, not Jimmy.

 

Eric I dont see why this is not possible with some homebrew setup based off knock sensor activity- such as a V of the KS stepps the FBC down a percentage or a granger attached to the solenoid to bleed boost. It might or might not be too complicated to use the solenoid output on the xede (I havent toyed with it PC in the seat remember )

 

Thought about it for a while why not uset use a the FBC in series with a granger soleniod (like two mbcs side by side able to switch with a current) triggered by either a knock link (or when one of the lights light up of your choosing) tapped into the Factory knock sensor. ~150. Or the granger in series with the FBC and borrow a logger to see what V real knock occurs (by monitoring pulled timing) and put a resistor inline to switch the granger low boost setting (when the correct V of knock sensor activity occurs). ~30

 

Stepper motors don't use duty cycle.

If it knocks at WOT, you will feel it. Your foot is the boost controller at that point.

 

Its too late at that point. Besides the EVO timing maps dont seen to be too dramatic

 

If it is too late for your foot to do any good, why do you think a boost controller would do better?

DSMs have this functionality to pull back boost if too much knock occurs, but I've never seen it happen on a 2G. It does happen often on 1Gs. Most people disable it on both cars.

Oh yeah, stepper motors usually require 4 signals to run. Each time you pulse a wire, the motor steps by x degrees. The XEDE won't be able to control a stepper.

Besides a single solenoid is good enough at controlling boost. You just need the XEDE to pay attention to knock and pull back the boost if it XEDEs (har har) your set knock limit. Timing pullback is a much better method of quelling knock quickly, though. It is much more direct and quick.

 

I'm XEDE illiterate, does the XEDE have the function of pulling timing when knock occurs or will it keep requesting it?

 

No Xede maps are all slightly negative from what Ive seen. It will fall back on the factory secondary maps retarding them even more. The reason why your idea is tasty is we can get even more aggressive with the "optimal" tune and have lower boost as well as the secondary maps for safety. With basemaps there is no need though as the xede and factory ECM do the job quite perfectly- frankly

 

If you chose to run boost control in "OFFSET" mode instead of "ABSOLUTE" mode, then any knock activated boost cuts/trims will still be intact with the XEDE. The only thing is that I have never seen any such knock-triggered boost trims with the EVO. Hence, the reason why we like running in Absolute mode which, IMHO, works better than Offset mode which "rides" on top of a boost map which is inconsistent and less-than-ideal as far as boost response goes.

As for knock, the an XEDE'd system response to it the same way the stock ECU'd system responses to it. By pulling timing. When this happens, however, you will see a slight and quick drop/flicker in boost pressure caused by the sudden loss of exhaust velocity. This is more effective than dropping boost as ShapeGSX mentioned.

Regards,
Shiv