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Discussion Starter #1
The linear control valve (LCV) is sort of like a choke but for fuel injected engines.
The linear control valve supplies air to the throttle bodies when starting or during engine warm up and causes higher idle Rpm's.
The intake air volume determines the basic injection duration. As the intake air increases through the linear control valve, the intake air volume corrects the basic injection duration.
The correction volume changes according to the position of the valve at starting and when the valve position changes to accommodate the engine temperature and engine oil temperature as the intake air volume increases.
When the engine oil temperature reaches 80 °C (176 °F) or higher, the linear control valve fully closes to stop the air volume from increasing and control returns to basic injection control.

Now, this part can cause some issues if the pintle seat (see pic) or the tapered pintle (see pic) develops build up to prevent the valve to fully close and let surfaces to seal.





It can also possibly develop a vac leak between the O-ring on the valve motor and the passage housing(see pic).



The motor can also fail all together and not function or properly function.

Either way these can cause a vac leak that can cause some issues you will chase and chase and may not find.
Some symptoms are Loss in power, Poor throttle responce, Excessive popping, Chugging lower Rpm's, Stumbling with throttle, Erratic idle, dying.



A way to quickly eliminate the LCV being the issue to vac leak symptoms is to remove the 2 smaller hoses off the LCV and plug them good making sure no air gets past. Make sure you see no cracks in the 2 hoses going to your throttle bodies before running the motor. (See pic)



If your symptoms go away or reduce you have a few options.
If you do not get a diag code-

1. Leave the LCV blocked off as testing by plugging the 2 hoses from the LCV.
2. Pull the 2 hoses off the throttle bodies and cap the nipples(with time the caps can crack and you'll develop a vac leak. (See pic)



If you have a vac leak issue through the LCV go to the cleaning process or block/remove the LCV.

NOTE FOR THE 2 OPTIONS ABOVE.(For testing and permanent)
You will now have to give some throttle while starting especially in colder weather and you'll have to hold the throttle to warm the engine up to keep it running.
Keep in mind that if you keep thw LCV this way as of Blocked, Capped and you go and try to sell your bike this new starting prosses may sway potential buyers away as it will look like the bike has issues.


To clean the LCV-
1. Set the hoses back on the LCV as normal set up and spray throttle body cleaner or Spray Seafoam through the Bigger inlet hose to the LCV while first start/starting for a few seconds. Have The bike run for a 5-10 seconds after you stop spraying. The valve closes quick so you will have to repeat that starting/spraying process over and over. The engine may be hard to run at first as that's what the cleaner will do so give it some throttle to keep it running. This may/may not help.
2. Remove the LCV and clean by hand with throttle body cleaner. Make sure you clean The pintle and pintle seat.
The O-ring may need a bit of silicon to help seal a vac leak so apply a thin coat and let dry while assembled.(may not be necessary)

If this cleaning does not fix the LCV vac leak the valve motor may have failed.

You can test the LCV pintle for movement (I WILL ADD THE INFO LATER AS I WANT TO TEST THE ON BIKE TEST FIRST)

((If anyone has anything to add or any input feel free to mention it and I'll adjust the posting))















 

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Great write-up! The only thing I'd suggest is maybe pointing out where exactly it is on the bike.



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Good write up on the LCV cages call it IAC (Idle Air Control)

I absolutely hated that friggin thing from the get go the higher rpm to base idle rpm hot engine restarts were really annoying. Shelved it in 2002 its still on the shelf.

Use a fat "O" ring of the correct inside diameter that fits snugly between the throttle grip flange & switch box. Loop a small zip tie loosely through the "O" ring that's your "handle". Insert for cold start up you can adjust the throttle as desired when inserted it will stay where you put it..
Beside cold start & warm up you now have an easily adjustable cruise control without levers / clamps etc. Grab the zip tie to pop it out & leave it on the grip. If you need to buy this stuff the cost may be about .25 can't say for sure I had the stuff in my shop.
 

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A month ago, went with friends, we closed the motorcycle season. We thought we will so. It was cold, about 3-5 degrees Celsius. My motorcycle behaved strangely when it speeded up to the about 120 km/h and twitched. It looked like I was briefly and abruptly twisting the throttle grip to maximum. Upon arrival at the intermediate point, I checked the contacts of the ignition coils. I thought it was because of them. At the same time, I recorded the readings in the diagnostic mode and the parameter d1: 10 showed 165 degrees Fahrenheit. This means that the valve was hesitated close to complete closure and its operation was felt on the go. Another version to that trip.

PS
I rode on the previous Warrior without this LCV for a couple of months. You can live without him. Only in the cold do you need to hold the gas handle ajar at the start.
 

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Discussion Starter #8
Good write up on the LCV cages call it IAC (Idle Air Control)

I absolutely hated that friggin thing from the get go the higher rpm to base idle rpm hot engine restarts were really annoying. Shelved it in 2002 its still on the shelf.

Use a fat "O" ring of the correct inside diameter that fits snugly between the throttle grip flange & switch box. Loop a small zip tie loosely through the "O" ring that's your "handle". Insert for cold start up you can adjust the throttle as desired when inserted it will stay where you put it..
Beside cold start & warm up you now have an easily adjustable cruise control without levers / clamps etc. Grab the zip tie to pop it out & leave it on the grip. If you need to buy this stuff the cost may be about .25 can't say for sure I had the stuff in my shop.
I hate that high idle also haha. Probably half of us all do ha.
But I remember that little trick as I did it for a while. Pretty cool.


A month ago, went with friends, we closed the motorcycle season. We thought we will so. It was cold, about 3-5 degrees Celsius. My motorcycle behaved strangely when it speeded up to the about 120 km/h and twitched. It looked like I was briefly and abruptly twisting the throttle grip to maximum. Upon arrival at the intermediate point, I checked the contacts of the ignition coils. I thought it was because of them. At the same time, I recorded the readings in the diagnostic mode and the parameter d1: 10 showed 165 degrees Fahrenheit. This means that the valve was hesitated close to complete closure and its operation was felt on the go. Another version to that trip.

PS
I rode on the previous Warrior without this LCV for a couple of months. You can live without him. Only in the cold do you need to hold the gas handle ajar at the start.
Sound like it didn't know what to do with that low temperature haha. Atleast you knew what to check out before pulling things apart trying to fine the issue haha.


I took mine of my Raider, it was acting up and I’d get the dreaded hi idle low idle syndrome. I just use my go cruise to set the idle when it’s cold.
Wow, you actually removed it. I wanted to but didn't wanna dig up into the frame neck. I ended up using the seafoam spray to clean mine out and it smooth down the idle fluctuation pretty good.
How's your idle now and at Start up?
 

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I hate that high idle also haha. Probably half of us all do ha.
But I remember that little trick as I did it for a while. Pretty cool.




Sound like it didn't know what to do with that low temperature haha. Atleast you knew what to check out before pulling things apart trying to fine the issue haha.




Wow, you actually removed it. I wanted to but didn't wanna dig up into the frame neck. I ended up using the seafoam spray to clean mine out and it smooth down the idle fluctuation pretty good.
How's your idle now and at Start up?
It’s low on a cold day. It won’t stay running unless I give it some throttle. But that’s only for about 30 seconds or less. I’m not sure the D&D style forced intake stacks would look good with it still under the neck. I didn’t know about cleaning it, and I was just tired of it alternating hi and low idles.
 

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Mine's long gone also. Just takes a little crack of the throttle to start and then 10 to 60 Seconds holding minimal throttle while it warms up with 15 being on a warm day and 60 being on a very cold day.
Here it is on a day of about 50. I don't normally have to rev it so hard to get it to stay running, I made that video mostly for the exhaust sound but it captures the behavior without the lcv also

https://youtu.be/6DrHfzWlJPQ

With the coils relocated under the tank and the LCV gone it really opens up the view of the front rocker cover.

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When I start the bike, I can hear the sucking noise from the LCV filter quite well and when the RPM goes down to idle I can hear the LCV valve almost close but it is still sucking some air. Should it close completely right away or does it close off in stages?
 

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Discussion Starter #12
When I start the bike, I can hear the sucking noise from the LCV filter quite well and when the RPM goes down to idle I can hear the LCV valve almost close but it is still sucking some air. Should it close completely right away or does it close off in stages?
It closes off in stages as the oil temp increases.
 

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Discussion Starter #14
Ok, thanks Rudy, good to know. When warmed up, it´s completely closed then?
Yep, 80 °C (176 °F) or up.
You'd most likely know if it was stuck open when it's needed to be closed as the bike would give possible symptoms of a tps issue with stumbling and or excessive popping with throttle, fluctuating idle.
 

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Rudy, did you remove the LCV altogether and just deal with throttling up a little bit on cold starts? Did you have to fool any sensors at all to make the bike think it was still connected and working? Any check engine lights on without the LCV on. I know one of your posts said you just cleaned it but some of your pictures and the youtube video I found of you when I searched "LCV roadstar" looks like you just capped in at the throttle body and left it like that...
 

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Rudy, did you remove the LCV altogether and just deal with throttling up a little bit on cold starts? Did you have to fool any sensors at all to make the bike think it was still connected and working? Any check engine lights on without the LCV on. I know one of your posts said you just cleaned it but some of your pictures and the youtube video I found of you when I searched "LCV roadstar" looks like you just capped in at the throttle body and left it like that...
Mine is still connected on the bike except for the hoses which are plugged as in the pics. The pics with caps on the TB's are from a friend's and I have that pic showing that's the other option to plugging the hoses as in the other pic.I just don't like the high start up idle with every start so id rather have to throtyle a bit at cold starts and hold the idle up some.
As for removing the LCV completely you do get a code from the wiring not being connected to the LCV. I have though I've seen some state that the code goes away but mine didn't hence why it's still on my bike.
 

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Mine is still connected on the bike except for the hoses which are plugged as in the pics. The pics with caps on the TB's are from a friend's and I have that pic showing that's the other option to plugging the hoses as in the other pic.I just don't like the high start up idle with every start so id rather have to throtyle a bit at cold starts and hold the idle up some.

As for removing the LCV completely you do get a code from the wiring not being connected to the LCV. I have though I've seen some state that the code goes away but mine didn't hence why it's still on my bike.


Cool, I was interested in removing it altogether for appearance reasons and to unclutter a bit more underneath the tank but I’d rather n out have to deal with engine codes and such as a result.


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Cool, I was interested in removing it altogether for appearance reasons and to unclutter a bit more underneath the tank but I’d rather n out have to deal with engine codes and such as a result.


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I have had mine disconnected and removed for many years and never had a code pop up or any affects what so ever, except low idle at start up. I hated that darn thing, glad it's gone.:)
 

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Discussion Starter #20
I have had mine disconnected and removed for many years and never had a code pop up or any affects what so ever, except low idle at start up. I hated that darn thing, glad it's gone.:)
Hmm, maybe I got a code from something else. I never went into diag to check so I just assumed it was from disconnection the lcv. Good to know and I'll edit the post.
 
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