Will the EJK work properly with the pair valve in place?
Are there any other disadvantages to leaving it in place?
Have a 2009 UK efi model so assuming no other de-smog stuff.

 

Yes it will still work. You can take the hose that goes into the valve and plug it up. I used electrical tape up until I orders a pair valve eliminator kit off eBay.

 

Here is the link for the one I ordered for my 2018 FI

https://www.ebay.com/itm/PAIR-AIS-Va...-/253773615151

 

Thanks for both posts. Have ordered the same.

 

Guys, this is an interesting situation. The system allows fresh air into the exhaust under certain conditions. It has always been my understanding, from my research on the subject, that the system can only do so during deceleration. If the system were to inject air during other operations, it would radically change the makeup of gasses in the exhaust and render the O2 sensor readings unusable during closed loop operations. While injecting air during open loop (high performance) operations, where the O2 sensor data is not used for fueling, would not affect the fueling scheme, it would cause severe exhaust system heating - I'm talking about way more heating than what is reported in here..

Assuming that, EJK or stock, the EFI KLX 250 operates perfectly fine with the system removed and capped, then the only reason to keep the air injection system (PAIR) is so that one can enjoy an extra hot exhaust system and glorious decel popping ... (lol)

Get rid of it !

 

Klxster
If possible please can you explain closed loop and open loop to a thicko.
Doubtless I will have more of these if/when attempting the mcm.
For one, how do I 'lock down the engine'?
Thanks.

 

Open loop is first utilized during initial start up. It is a preset of particular fuel settings that is utilizeded until the engine reaches operating temperature. Basically it ignores the sensors as if the path is "opened". Once at operating temperature the ECU switches to close loop and take readings from the O2 sensor, TPS, temp sensor, air sensors, exct. to adjust the air to fuel ratio for the best fuel efficiency (usually 14:1 but differs). The EJK uses a O2 simulator that sends the same readings to the ECU and acts as if the bike is in open loop. This is an absolute must since the EJK is a piggy back unit. The EJK then adds fuel to those preset settings.

 

RB is correct regarding engine warmup being fueled by open loop. And he is correct about closed loop becoming "operational" once the engine is warm. But once the engine is warm, there is more -

Closed loop fueling only occurs within an "operational envelope", open loop fueling occurs within its' "operational envelope". Obviously these two operation envelopes "sit next to each other"... The breath and width of each envelope is determined by settings within the programming of the ECM. For the sake of trying to convey a very complex subject in simple terms, I will have to "dumb down" the subject WHILE STILL making statements that are 100% correct.

Closed loop fueling (as set up by OEM's) uses all the sensors to create maximum fuel mileage and open loop (no sensors, just preset fueling tables) is for high performance operations where fuel mileage is not a concern.

So, in general:
When you are putt putting around, driving normally, you are operating mostly or wholly within the closed loop operational envelope ( getting great gas mileage with low emissions..)

When you are terrorizing the hood, doing high speed highway runs, popping wheelies (if your mod combo has wheelie power) , you are operating within the open loop operational envelope.

Whenever you disconnect the O2 sensor, you have "killed" all closed loop fueling capability. The fueling for the bikes' "closed loop operational envelope" will now have to be provided by a piggy back fueler that is designed to take over that fueling (enter the EJK). Piggy back fuelers can fuel the missing fueling for the closed loop fueling envelope as well as modify the bikes' open loop fueling....

With a well designed fueler - you have total fueling control over your entire operating range. The knowledge and skills for perfecting a fueling curve are well beyond most all - so you generally have "preset" schemes available from the manufacturer to get you going and perhaps get you very close to perfect if you bike is modded exactly like the preset was designed for..

 

Lock down the engine means to take whatever measures are needed to make sure the crankshaft cannot rotate once set to Top Dead Center on the power stroke (power stroke means that both valves are closed). You do this once you have removed the obscured cam gear bolts (there is ONLY one obscured cam gear bolt per cam).

The only way a peep can totally screw the pooch during MCM is if the engine is allowed to rotate during the session - and this rotation goes unnoticed..

However, you can never destroy your engine because you will be rotating it by hand, then by starter, then installing the spark plug for a start to just idle, etc etc... Any issue should be found before engine damage can occur..

 

Thanks again Klxster.
How do you actually lock down the engine? Would sticking it in first gear do the trick?
Am on p 26 of mcm mod.