FI Bikes, Over-fueling, and Thermostats

Rush44 · Dec 20, 2012

Just wanted to share some information I gathered from a ride this week.

We all know about the problems FI bikes have with over fueling and adding fuel to the oil. Nobody has really been able to determine how bad the problem was, but we know there is a problem. The thermostat addition has gone a long way towards helping the bike reach a more desirable operating temperature thus doing a better job of allowing the rings to seal and not allow so much blow-by into the crankcase.

I'm testing a Gen4 fuel controller from Dobeck Performance that uses the stock ECU, stock wiring harness, and utilizes an wideband O2 sensor in the exhaust and a clip that attaches to the stock injector. Installation takes about 5 minutes (seriously). Along with a programming gauge Dobeck also supplied me with a "status" gauge that reads AFR live in the system and does not try to change anything. Our reason behind using this gauge was to determine exactly how the bikes run stock before we try to adjust and achieve 13 AFR. The stock run 2 days ago blew me away... the needle was buried into 10 AFR (the richest reading on the gauge) for over half the ride and only rose to 11.5 AFR during the bike warmup process. The more throttle I gave, the more load the motor was under, the richer the bike got. This represents a stock over-fueling of an estimated 25%-40% under our cold conditions due to the temperature sensor in the airbox. No wonder these stock bikes add fuel and have worse economy than other fuel controlled bikes I've rode with.

By cleaning up the AFR issue we would be able to extend range fairly dramatically and stop the fueling of the oil issue that many experience. This will help prevent engine oil breakdown and better protect the motor. I will be adding the programming gauge and moving to 13 AFR for this weekend and will be doing an oil change at the end of my ride to verify that gas has not been added to the oil.

Wheel House Motorsports · Dec 20, 2012

Cant wait for the full report after a ride in the deep with the closed loop gauge on it. I cant believe the bikes dont start stumbling and miss firing at that AFR, its SOOOO rich

Cat Bandit · Dec 21, 2012

very interesting, My friend has a 13 kx 450, and so far hasnt had fueling issues, but we're not running in really low temps. It'll be very interesting if you get better economy with the correct afr!

TeamOrange · Dec 21, 2012

I would want to know the coolant temps during the test. If your at say 175* what is the AFR at that point? What sensor and where determines the AFR?
I only got to ride my FI Berg once last year but it sure seemed like my carbed KTM525 got WAY better fuel economy.

Oz

EDIT: Rush, sorry i missed where the temp sensor in airbox determines AFR. I am assuming for calculation of air density.

Wheel House Motorsports · Dec 21, 2012

I have scoped the injector signal on a cr450f that was sitting outside in 25* weather and there was no discernable change in injector pulse from cold to 200* coolant temp. we did a plot of coolant temp sensor voltage vs injector signal and it changes the mapping VERY little. If i had a bike to play with i could feed the ecu a voltage for air temp and we could see how the mapping is affected by air temp.

I do know the piped 450 my coworker has we monitored the afr all summer and the thing runs in the 11's all the time even in the middle of summer in the hills to down low in the winter. only leans out into the 13's a little on a long WOT pull in 5th.

retired motoman · Dec 21, 2012

Please correct me if this is incorect.

Once the correct F/A mapping is achieved, the mapping could be loaded into another bikes Fi box. As long as it is the same make and model.
Would you be willing to sell or share the mapping?

Wheel House Motorsports · Dec 21, 2012

retired motoman said:
Once the correct F/A mapping is achieved, the mapping could be loaded into another bikes Fi box. As long as it is the same make and model.
Would you be willing to sell or share the mapping?

the unit doesnt have a "map" like your thinking of. aside from injector harness could plug into all of the 450's mx style bikes as they have similar HP and rpm ranges for the program that is setup in the gauge. This is not a TPS vs RPM table of trims and adds, its a true closed loop fuel controller.

The way the one Rush has is setup as so, the green mode(low speed cruise) is just a +/- a percentage of fuel. The yellow(cruise) and red(High load, WOT) modes are closed loop off the wideband O2 sensor, you select the afr you want to run in either mode and the controller live tunes it whenever your in that mode, then there is also a digital accel pump feature to help when stabbing the throttle. then the last 2 modes are just adjustments for when the transition for green-yellow and yellow-red happen.

there is no maps for this or that location, or whatever, its live all the time making adjustments between every single injector pulse. making sure you have the proper air/fuel ratio.

KAWGRN · Dec 21, 2012

Ski-Dooin it said:
I have scoped the injector signal on a cr450f that was sitting outside in 25* weather and there was no discernable change in injector pulse from cold to 200* coolant temp. we did a plot of coolant temp sensor voltage vs injector signal and it changes the mapping VERY little. If i had a bike to play with i could feed the ecu a voltage for air temp and we could see how the mapping is affected by air temp.

I do know the piped 450 my coworker has we monitored the afr all summer and the thing runs in the 11's all the time even in the middle of summer in the hills to down low in the winter. only leans out into the 13's a little on a long WOT pull in 5th.

so if the AFR is the same at 90 and 20 then the afr should be leaner just cuz of the cold air ,,,NO?if the air box air temp sensor is not doing any thing and not adjusting then its weird that the injection is even working

Wheel House Motorsports · Dec 21, 2012

KAWGRN said:
so if the AFR is the same at 90 and 20 then the afr should be leaner just cuz of the cold air ,,,NO?if the air box air temp sensor is not doing any thing and not adjusting then its weird that the injection is even working

The bikes seem to run very fat stock all over the place warm, cold, up or down. Its a big single cylinder four stroke and they can eat up a LOT of fuel and run just fine. because of the constant throttle chopping I assume they are mapped this way so when you chop it it doesnt lean out as there is the instant you let the air in from a idle to WOT snap, there is a delay before the ecu can see and add fuel for it so you get the lean pop that poorly tuned accel pump carbs suffer from. Now add less then ideal compensation tables for elevation and temps and they get VERY fat up high.

I would love to do more testing on it, but we only have 1 FI bike around the shop and its got knobies on it still, so hard to take it outside and test in the packed snow roads safely! so if anyone has a FI bike and a horse in SW montana and is willing to help out further development, let me know!

KAWGRN · Dec 21, 2012

I know on my berg if I ride it like a 2 st and chop the throttle it will backfire through the throttle body and out under the seat and BURN my NUTS LOL!!But my wife tells me Im hot!!! so its OK !LOL

Wheel House Motorsports · Dec 24, 2012

any more info? i know you were out riding

Rush44 · Dec 25, 2012

Ski-Dooin it said:
any more info? i know you were out riding

Hahah yes we were out riding! However, I didn't run the programming controller yet since the weather was a lot warmer and I wanted to see just how much the ambient temperature changed the AFRs. A 10 degree change is actually pretty big... the bike hovered around 10.5-11.5 (didn't bury the needle into the 10-) and ran much closer to 12 AFR when chopping the throttle. Still, it's over fueling and we WILL be running the programming gauge this Saturday.

On the first day the temp was around 18 degrees... the second day it was closer to 30 degrees.

Edit: One thing to note, I added a LOT of fuel to the oil on that first 18 degree day.... the oil level is now above my sight window when before it barely came into view

Revv Up · Dec 25, 2012

Rush44 said:
I added a LOT of fuel to the oil on that first 18 degree day.... the oil level is now above my sight window when before it barely came into view

So whats that equate to 1/4 of a liter? I'd be a tad nervous about running diluted oil through a new motor for sure.

TeamOrange · Dec 25, 2012

Rode Saturday on my Berg570. Temps around 20. Alt up to 2500'. Cooling system stock. 1.5' of 2 day old snow over good base. Did oil change after ride and found no signs of fuel in oil. Happy bout that.

Oz

Rush44 · Dec 25, 2012

anonny said:
So whats that equate to 1/4 of a liter? I'd be a tad nervous about running diluted oil through a new motor for sure.

I agree... this is why I feel the controller is so important.

Orange, glad to hear the Berg didn't overfuel on your ride. My ride was cold and the type of wind that chills you to the bone. I spent the majority of the ride full WOT with near handlebar deep heavy powder. I think the engine load really increases the issue.

KAWGRN · Dec 25, 2012

So im wondering if you just moved your air box sensor to a warmer location?on the berg its right above the engine I wonder if I slid it down about a half inch and let it draw engine heat around it into the airbox? How much it would lean it down?

Ryanexcr · Dec 25, 2012

I have a 2012 KTM 500 EXC and am having the same issues with over fueling, I also think it is more noticeable when in deep powder WOT for sure. I only have the JD Power Surge 6X and I am going to try and lean it as much as possible to see if that helps. But I don't think it will be enough. I thought I read a post awhile back about swapping out the temp sensor before the throttle body that actually tells the ECU that it is a constant 70 degrees. But I can't seem to find this post or part.

swedenturbo · Dec 25, 2012

Ryanexcr said:
I thought I read a post awhile back about swapping out the temp sensor before the throttle body that actually tells the ECU that it is a constant 70 degrees. But I can't seem to find this post or part.

Wouldn't that be a problem when starting with cold engine?

On my turbo build I put the sensor outside the plenum under the throtle body. The temp reading would be like the ambient temperature.

Rush44 · Dec 30, 2012

Results of the controller can be found in a new thread here:

http://www.snowestonline.com/forum/showthread.php?t=331687

Ryanexcr · Dec 31, 2012

Blocking off the radiator seems to have helped very much and I also re routed my case vent to under the motor instead of in the air box. I still need to get it out in the same conditions as the times I had issues being handle bar deep POW all day but it was a god test this weekend for sure.

FI Bikes, Over-fueling, and Thermostats

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Similar threads