ECU control of exhaust valves

[Merlin]

Hello,


I'm curious if the purpose of the ECU controlling the exhaust valves is purely to lower emissions or if there is performance aspect to it???

Also, on what conditions/inputs does the ECU base it's control of the valves(I.E. engine RPM, T.P., coolant temp., whatever,etc.)???


I'm thinking it would be nice to plug the ports on the exhaust valve housings & end the mess without have to re-route the solenoid vent hose & also to eliminate the possiblity of a faulty solenoid or electrical circuit not allowing the exhaust valves to open.............


Thoughts???

 

[Danbot]

I messed with my exhaust valves on my 900RMK extensively, and in my opinion it's there for sound suppression, and air pollution control. There is probably a rare case or 2 that the solenoid got gummed up and stuck open but I don't think it's a problem to worry about, it would be easy to plug the hose if it failed,

I beleive the ECU's only decision on what to do with the solenoid valve is based purely on RPM. Anywhere above the rpm# set in the ECU and the solenoid closes which allows pressure to build under the bellows to open the VES valves. I don't know for sure, but I think it's still the same system used today. I found that this system makes the valves operate in a light switch fashion. For the most part... either open or closed, nowhere in between.

Plugging the VES hoses is nothing new, it was popular on the 900cfi engines. Some, like me had good luck using the stock VES springs, others found other combo's with lighter or (usually) stiffer springs.
I eventually even went so far as to oversize drill the pressure ports from the cylinder, and in the VES valve bodies.

On my 900cfi, plugging off the VES hoses I felt a boost to midrange throttle response, and quicker RPM build-up from idle. I could also tell by the sound of the exhaust note that the valves were now operating in a true variable fashion... able to be half open for quick midrange blips, or steady 1/4 throttle in the trees. The quicker RPM build-up tells me that, at least on the 900cfi, the stock solenoid controlled system was holding back the engine in some lower to midrange RPM situations.

This year I will start experimenting on my 13 Pro. Step 1 will be to install an inline style shut-off valve in the hose just on the vent side of the solenoid. This way I'll be able to try it both stock, plugged, or with restricted venting. Time will tell if the stock VES springs in the 800cfi2 are suited to plugged solenoid or not.

 

[Merlin]

Thanks for the reply,


Good idea on installing the manual shut-off valve, I may just have to try that as well - A needle valve with 1/8 NPT ports ought to do the trick..............

I appreciate the info...........


Thanks again,


Glen

 

[gman086]

I'm curious if the purpose of the ECU controlling the exhaust valves is purely to lower emissions or if there is performance aspect to it???

Also, on what conditions/inputs does the ECU base it's control of the valves(I.E. engine RPM, T.P., coolant temp., whatever,etc.)???

The ECU keeps them close longer initially than if they were controlled via gas only. By doing so they build more backpressure and give more pop off of idle and better fuel economy. So yeah, there is a big reason they are there. MOst aftermarket guys delete the solenoid control so as to open the valves sooner and reduce the chance of deto due to overly hot exhaust ports. I know for fact that even on stock Doo motors this translates into a performance gain so this is a common mod. By doing so, you may experience a bog when whacking throttle because they open too soon which is why you MAY need stiffer exhaust valve springs (you would NEVER need weaker when doing the mod). The guys at Carl's tell me there is no benefit to doing this on a stock Pro RMK but I continue to ponder this if for nothing more than to reduce exhaust port temps and prolong the life of my exhaust side cylinder skirts at the expense of some fuel economy. If you have any exhaust mods at all then you darn well BETTER be doing the solenoid block-off IMHO because they almost always raise the temps at the exhaust ports! The one major thing Poo needs to do for this motor is IMPROVE the cooling around the exhaust ports (ARE YOU LISTENING POLARIS???)!!!

Have FUN!

G MAN

 

[PaulAnd]

My d8 definitely got that low end bog after plugging the hose last year, go to the next harder spring and test? Or do you guys have a spring in mind? I only had a chance to ride it out west last year 6-10k, I ride 0-3k also.
Thanks!

 

[Mentzel]

There has been many long posts about this. The solenoid controls opening and closing of the exhaust valves based on a signal from the ecu. Plugging the hose will only cause problems in timing of the valve opening. It will create a bog or pop in the mid range unless you adjust the fuel map to compensate. The biggest problem is the pressure ports for the valves will get plugged in the cylinders. The hole is too small. (1/16") Constant venting through this port will carbon up over time, then slow the reaction time of the valves opening. Some find plugging the ports adds performance because it builds the pressure needed to open the valves when the pressure ports plug.

 

[geo]

A few questions to those in the know.

Does the ECU sent a fault code if the solenoid is not there?
Is the timing of the valve opening more than just rpm related? Cat's mechanical system had 3 stages (in 2011 only 2 in 2012) that were rpm AND elevation related. Pol seems to have a more complex engine management program with more checks and balances for deto.
I see something that says orfice size on the soleniod. Is that variable in there?
What is the stock spring rates and is there a place to find a listing of different rate springs (higher and lower spring rates).
A question for someone with an SLP stage 4 kit. Does SLP eliminate the soleniod activation with this level kit and let the motor dictate VES opening?

I always had good results (more mid power allowing a lower clicker no.) with the older Doos at my elevation, by letting the valves open sooner using either spring preload or or rate.
Added fuel would be needed, but that's why the make PCV's right?

One more question lol. Has someone made or already tried reverse flow cooling (coolant enters on the exhaust side of the head first)? Is this not possible in the liberty 800?

 

[gman086]

Does the ECU sent a fault code if the solenoid is not there?

What is the stock spring rates and is there a place to find a listing of different rate springs (higher and lower spring rates).
A question for someone with an SLP stage 4 kit. Does SLP eliminate the soleniod activation with this level kit and let the motor dictate VES opening?

The ECU thinks everything is normal when the vacuum line is plugged so there is NO fault code generated! Also plug off the inlets at the exhaust valves with carb vacuum plugs.

Stock Polaris springs listed here:
SPRING COLOR LOAD @ 1 INCH(LBS.) LOAD @ .630INCHES (LBS.)
7041704-01 Blue 4.0 6.0
7041704-02 Orange 5.5 8.3
7041704-03 Pink 4.7 7.1
7041704-04 Purple 3.1 4.7
7041704-05 Yellow 2.4 3.6
7041704-06 White 1.6 2.8

So the ORANGE springs are the way to go if you have bog problems with the mod.

Have FUN!

G MAN

 

[richracer1]

The ECU thinks everything is normal when the vacuum line is plugged so there is NO fault code generated! Also plug off the inlets at the exhaust valves with carb vacuum plugs.

As for springs, SLP has their own versions:
http://www.startinglineproducts.com/catalog.cfm?pageID=detail&catalogID=3&catID=18&productID=155

Stock Polaris springs listed here:
SPRING COLOR LOAD @ 1 INCH(LBS.) LOAD @ .630INCHES (LBS.)
7041704-01 Blue 4.0 6.0
7041704-02 Orange 5.5 8.3
7041704-03 Pink 4.7 7.1
7041704-04 Purple 3.1 4.7
7041704-05 Yellow 2.4 3.6
7041704-06 White 1.6 2.8

I'll also add that the solenoid must remain connected to the wire harness or you will get a code, regardless of what you do with the hoses.

 

[geo]

Thanx

 

[Merlin]

The biggest problem is the pressure ports for the valves will get plugged in the cylinders. The hole is too small. (1/16") Constant venting through this port will carbon up over time, then slow the reaction time of the valves opening. QUOTE]


Thanks for the reply,


I'm not sure I understand your post completely, can you please clarify???

The ports in the cylinder & in the exhaust valve housing don't appear to be any smaller than those in the "big block 800" & to my recollection those didn't plug off if regular maintenance was performed???

Also, it would appear that on a machine equipped with solenoid controlled valves, exhaust is constantly venting through the solenoid, albeit a small amount, until it closes at the command of the ECU.............


Glen

 

[Merlin]

TTT


Anymore input on this???

 

[Mentzel]

Pull the exhaust valves and look at the small hole into the cylinders. I drilled the hole out to 7/64 on my CFI -4 motors increasing pressure to the bellows and solenoid. This will increase the response time when the ecu tells the solenoid to close. Also note how only one side of the valve mount transfers pressure to the bellows. It is very easy to plug because of constant combustion products flowing through it. If nothing else clean out the ports with a 1/16 drill bit. The old style "non solenoid" exhaust valves never plugged because they were not constantly venting. (a good design)

If you plug the vent line off the solenoid you are complicating the problem. Also check the springs under the caps frequently. Polaris did not use stainless steel springs so they will corrode and break. Took me forever to figure out one of my exhaust valve springs was broken.

Solenoid controlled EVs are clearly better but only if the pressure ports allow the valves to open and close exactly when the ECU tells them too. Any delay will cause midrange issues.

 

[Mentzel]

I also drilled a 1/2" hole near the shock tower and vented the hose out of the tub. That way I could see a constant very small puff of smoke. I always know the valves have adequate pressure. It only iced up once but a quick flick and problem solved.

 

[Vi-PEC Powersports]

the powervalves are there for a lot of reasons majorly to to hold back pressure at low rpm and to keep fuel in the combustion chamber longer(low rpm) and avoid throwing to much unburnt fuel by the exhaust. when they open, it is to release(balance) cylinder pressure (high rpm) to avois det,port exhaust heat etc.

with our ECU you can control the powervalves praticaly limitless here are a few snapshot from the the ECU settings(powervalves) and logs to show when they open. factory opening is at 6250 rpm based only. you can control the powervalves to your riding style with the ECU, factory setting accomodate the masses, may not be good for all of us, especialy turbo applications and big bore.

 

[powerfuldodge]

the powervalves are there for a lot of reasons majorly to to hold back pressure at low rpm and to keep fuel in the combustion chamber longer(low rpm) and avoid throwing to much unburnt fuel by the exhaust. when they open, it is to release(balance) cylinder pressure (high rpm) to avois det,port exhaust heat etc.

with our ECU you can control the powervalves praticaly limitless here are a few snapshot from the the ECU settings(powervalves) and logs to show when they open. factory opening is at 6250 rpm based only. you can control the powervalves to your riding style with the ECU, factory setting accomodate the masses, may not be good for all of us, especialy turbo applications and big bore.

YOu almost have me sold on this ECU. Pretty sure my next turbo will have the ECU.

 

[Merlin]

Thanks for the info.!

It all makes sense now - With the EV solenoid open most of the time, exhaust is constantly venting through the signal ports allowing carbon build up................Fortunately, the ports on my cylinders & EV housings were clear with next to no build up of carbon evident but then again, my machine only has 800 miles on it!

My springs were terribly corroded too which I attributed to the design of the plastic cover that has the hole in center - The hole allows water to fill the spring side of the chamber so the spring is(or may be) sitting in water much of the time................I was thinking of drilling a small hole at the bottom of the plastic cover to allow the water to drain out of the chamber - might work???

Pull the exhaust valves and look at the small hole into the cylinders. I drilled the hole out to 7/64 on my CFI -4 motors increasing pressure to the bellows and solenoid. This will increase the response time when the ecu tells the solenoid to close. Also note how only one side of the valve mount transfers pressure to the bellows. It is very easy to plug because of constant combustion products flowing through it. If nothing else clean out the ports with a 1/16 drill bit. The old style "non solenoid" exhaust valves never plugged because they were not constantly venting. (a good design)

If you plug the vent line off the solenoid you are complicating the problem. Also check the springs under the caps frequently. Polaris did not use stainless steel springs so they will corrode and break. Took me forever to figure out one of my exhaust valve springs was broken.

Solenoid controlled EVs are clearly better but only if the pressure ports allow the valves to open and close exactly when the ECU tells them too. Any delay will cause midrange issues.

 

[gman086]

My springs were terribly corroded too which I attributed to the design of the plastic cover that has the hole in center - The hole allows water to fill the spring side of the chamber so the spring is(or may be) sitting in water much of the time................I was thinking of drilling a small hole at the bottom of the plastic cover to allow the water to drain out of the chamber - might work???

Absolutely. The cover is only to hold the spring in place (bellows are what need to be in good shape and sealed, not the covers). In fact many Doo owners drill big holes in the covers so they can see if the valves are sticking.

Have FUN!

G MAN

 

[black swan]

need help.....EV solenoid??

'11 pro.....EV solenoid is bad. Has 12vdc in plug, but it will not open. No codes.
Tried actuating the solenoid w/ a 12v source, nothing. Tried 12v on each post, switching opposite to ground, nothing.

Here's the killer.....if the EV solenoid is inline, the EV valves blow open right off throttle and the sled DETOs bad, every time. If i remove the EV, and plug off the hoses, DETOs exactly the same.

If I run, the hoses unplugged, the engine case pressure vents obviously...and the valves never opening fully, more like barely at all...

Great lowend torque, but run flat while missing 600rs too...


Any experience this? And am I right on with my assumptions?

Bellows, springs, are brand new.

And can you put in the EV upside down?? The cut-out window faces up, right?

 

[skibreeze]

Ray, you made me actually get off my *** and go test this on my sled for you. The valves cannot be installed upside down (says so in the manual).

The solenoid is normally closed, if you apply 12vdc and a ground, you should hear a pretty loud click as the solenoid opens.

I put my mighty vac on the hose (the end you stick out by the A arms) to draw a vacuum, and it holds a vacuum for a few seconds closed, as soon as you apply voltage and ground it opens and will not hold it.

If yours does not do this, the solenoid is bad.