ECU control of exhaust valves

[black swan]

update: It is simply a spring-loaded plunger that is closed by a spring.

The tunneling thru the valve body will not allow gas pressure to open this orifice. When voltage is applied plus ground the plunger should slide to allow flow.

When ground is removed the spring should close the orifice.

 

[skibreeze]

So, does yours friggen work or not? We know how it is supposed to work.

 

[black swan]

NADDA!!.......back to the CAT this weekend. Thnx Dave, I knew you'd know....

So do we agree, that thing is closed at idle, then opens at 1/4 throttle....then closes.....when?? Cause if it doesnt close during during the REV, it will never have the pressure to fully open the EV.....


Conclusion: The EV solenoid is mandatory. Bypassed, the sled will never hit max rpm. Plug the lines w/out the unit..the case pressure will blow the valves open at 1/4 throttle and DETO some sleds.

If you hoses are broke and your sled runs like dog-chiatt....your valves aren't opening..






There's a sequence to it, close, open, close at 3/4 throttle...any thoughts..

 

[Vi-PEC Powersports]

There's a sequence to it, close, open, close at 3/4 throttle...any thoughts..

there is no sequence to it, it is rpm based only and when you reach 6250 rpm, the solenoid discharge and fully open the powervalves....it is 100% open or 100% close. Arctic cat is a total different setup, two powervalves opening stages by a servo motor

 

[geo]

Hearsay, but I was told by another respected source that the valve opening is not just rpm related ( I thought that would be too simple).

Elevation with barometric pressure and throttle position (like Cat and Doo) is a factor here also. The signal from the ecu to open these valves works in harmony with the equally instant fuel and timing changes built into the program.

I'm leaving the ECU to control the valves and I'll keep them clean until I can fit some Lectrons lol.

 

[Merlin]

Conclusion: The EV solenoid is mandatory. Bypassed, the sled will never hit max rpm. Plug the lines w/out the unit..the case pressure will blow the valves open at 1/4 throttle and DETO some sleds.

Thanks for the info.!

I suppose by experimenting with different springs & altering the internal porting a person may be able to get rid of the detonation & have the EVs operate more like the non-solenoid controlled systems but there doesn't seem to be really any benifit in doing so.............Seems like the factory system does the job just fine.............Just gotta route the vent hose to a place where it doesn't make a mess.............



Once again, thanks for sharing some first hand info.!

 

[black swan]

Anyone else have a bad EV solenoid? ..and what were the symptoms?

 

[skibreeze]

Ray, if you applied 12vdc and a ground to the solenoid and it didn't click, ie open and close as power applied and taken away, the solenoid is bad, Why are you asking about symptoms?

 

[black swan]

Relax Dave. A forum is an opportunity for everyone to learn.
We are simply having a conversation here.

 

[Mentzel]

The solenoid is normally open (venting) until 6250 rpm. The ECU then closes the solenoid and inflates the exhaust valve bellows using cylinder pressure. Pressure is transferred from the combustion chamber through 1/16" ports located under the exhaust valve base. The inflating bellows lifts the guillotine slide valve out of the exhaust port. When rpms drop below 6250 the ecu opens the solenoid and deflates the bellows venting to atmosphere once again. No venting occurs above 6250 rpm.

 

[Mentzel]

If solenoid is bad your valves will simply not open. Unless of course your vent line is plugged.

Neither will cause detonation.

 

[PaulAnd]

Should be a trouble code associated with a solenoid failure, no matter how it fails. Valve stuck in it's natural state of open/venting = loss of peak rpm, valve stuck closed/not venting = bog off the line. Black swan, why would you say the sled is detonating? What's the symptom in your words?

 

[black swan]

Great info guys!......My issues started last spring, 1600miles started losing rpms fast. Appears now, the valves were not opening at all...broken hoses at EV.

Since then, i have rebuilt my topend and went thru the valves completely 3x. New gaskets,springs, bellows.

The det issue might be a combination of the 15:1 head and plugging the EV vents which builds pressure to fast and blows the valves open prematurely=lean spot. Which is the same as using my bad solenoid that doesn't open, ever. (same condition, plugged venting.)

Right now the sled goes into limp mode, DET on dash. Everytime. But only at 1/4-1/2 throttle.
Run the sled, EV unplugged....sled pulls hard, no DET, no topend..missing 600rpm. Total of 60-70 breakin miles this way. 25% race fuel @ 10k.

 

[Mentzel]

If you are running a 15:1 head and no remap of the ECU. That is your detonation problem. It most likely has nothing to do with your power valves. The stock ECU fuel mapping is very very lean in the midrange for emissions reasons. To lean IMO, especially if you are running at low elevation. If you are holding it wide open for a long pull then back off to 1/2-3/4 that's when it will seize. Top end stock fuel mapping is too rich for max performance.

Get a programmer such as Vipec or power commander and add fuel too the midrange.

 

[Mentzel]

Also read plugs closely.
Coffee brown is rich, hot cocoa brown is great. Snow White or gray is lean. Powder black is detonation.

If powder black..

Add octane or reduce compression. Adding fuel will help marginally.