(800) 853-2651
SHOP NOW

Adjusting fuel mix with a resistor.

Geo-TH,In

Geo-TH,In

Well-known Member
The past 50 hrs my 2012 Kawasaki mule 4010 has had only idling issues. Nail the gas and runs as
it should. I even bought a service manual from dealer. Same manual the service techs use. You
name it, I've done it. EVERYTHING is within factory specs. No codes on computer. It has clean air
filter, new plugs, cleaned fuel filter, fuel flow and fuel pressure is at specs. The throttle
body has two throttle plates, one is manual the other is computer controlled. Both have a tps. I
even replaced the manual tps. Bought a camera to look inside throttle plate, cleaned it with sea
foam. There are two temp sensors, one is air the other is engine temp. Both sensors have the same
resistance with the same temp. Resistance changes as they should with temp.

So this morning I decided to play a trick on computer. I replaced air temp sensor with a 1600 ohm
fixed precision resistor. After I took the pic, I covered the resistor with electrical tape so it
wouldn't short out. The computer now thinks it's 98 degrees when the actual air temp is 62. At 62
degrees the air temp and water temp resistance readings were the same this morning, 2300 ohms,
well within factor specs.

Today, it idled as it did when new. Be interesting to see what happens when the air temp changes.
If needed, I may install a fixed resistor in series with variable resistor to have the ability to
safely dial in a range of resistance values of the thermal resistor. Hope this works. I'm about
to give up. Been thinking I made a mistake buying a UTV with fuel injection. Carburetors are not
that hard to work on.

Who has tricked a computer using resistors?
a200650.jpg
 
Geo........welp my eyeballs are playin' tricks on me, but it looks like yer usin' one of yer wife's hair curlers. (grin) Yeah, 2-resistors in series could work. May haffta 'speriment with the FIXED resistor......electrical Dell
 
Boss took it for test drive. Said it's perfect. She uses it all the time. I'll figure it out some day. See what I need when it gets colder. May even put a resistor in parallel with thermal resistor to reduce it's resistance and variable with temp. Just have to experiment.
 
(quoted from post at 12:56:41 09/11/15) The past 50 hrs my 2012 Kawasaki mule 4010 has had only idling issues. Nail the gas and runs as
it should. I even bought a service manual from dealer. Same manual the service techs use. You
name it, I've done it. EVERYTHING is within factory specs. No codes on computer. It has clean air
filter, new plugs, cleaned fuel filter, fuel flow and fuel pressure is at specs. The throttle
body has two throttle plates, one is manual the other is computer controlled. Both have a tps. I
even replaced the manual tps. Bought a camera to look inside throttle plate, cleaned it with sea
foam. There are two temp sensors, one is air the other is engine temp. Both sensors have the same
resistance with the same temp. Resistance changes as they should with temp.

So this morning I decided to play a trick on computer. I replaced air temp sensor with a 1600 ohm
fixed precision resistor. After I took the pic, I covered the resistor with electrical tape so it
wouldn't short out. The computer now thinks it's 98 degrees when the actual air temp is 62. At 62
degrees the air temp and water temp resistance readings were the same this morning, 2300 ohms,
well within factor specs.

Today, it idled as it did when new. Be interesting to see what happens when the air temp changes.
If needed, I may install a fixed resistor in series with variable resistor to have the ability to
safely dial in a range of resistance values of the thermal resistor. Hope this works. I'm about
to give up. Been thinking I made a mistake buying a UTV with fuel injection. Carburetors are not
that hard to work on.

Who has tricked a computer using resistors?
Click to expand...

Why not keep the factory thermal resistor in the circuit and place the extra resistance in series with the factory resistor. Now the ECM input signal will still have a 'warm" bias and will track with ambient temperature.
 

Is it even possible any more to buy a utv with a carburetor?

In my opinion, we have gone way beyond what is necessary with all this electronic gobbledy gook.
 
This reminds me of a snake oil product for motorcycles called "BoosterPlug" that plugs in place of the thermistor and fools the ECU to give a richer than normal mixture for the current conditions. But you're doing the opposite.

By fooling the ECU into thinking it's warmer than it actually is, you're tricking it into running LEANER. (Air is less dense the hotter it is.) At idle, that's no big deal; but you're fooling it across the entire map, including when it's under load. Running too lean COULD cause serious problems, such as detonation and preignition. It's your machine and you can do as you like, but I sure wouldn't make it run lean if it was mine.
 
George,
I like following your posts.
This is the kind of stuff I like tinkering with... when I understand it.
You are tricking it to run leaner at idle, as others have stated. If you knew what resistance was across the temperature range you could bias the resistance accordingly. Do you have an O2 sensor to monitor?

Thats the 617cc engine you and I discussed a while ago. From all the forums I poke around on that engine is known to run rich at idle. I have seen guys complaining about it in Mules, Gators and zero turns. More than one complaint of the crankcase being full of fuel at 8 hours. (first oil change interval)
Finally for 2015, they supposedly have a new fuel mapping for it to correct the rich idle. But I couldnt get true confirmation on that, so I ordered the bigger engine.
 
About an hour and 10 minutes after I get on the road. Shooting for around 10:30. Send you a text when I'm on the road. Looking forward to some good ham and beans.
 
No O2. Computer looks at two TPS, two thermo resistors, one map. There is a crankshaft sensor computer looks at for idle speed and max rpms.
 
I need to go the other direction, less resistance, so series won't work. At 62 degrees I have 2300
ohms. Works great at 1600 ohms. The warmer, the less the resistance will be. I even measures what
the ohms of thermal resistor is at 98 and it was 1600 ohms. I figured the less the ohms, computer
will lean out a little and that's what happened.

If my calculations are right, if I put a 5250 ohm resistor in parallel with the thermal
resistor,2300 ohm at 62 degrees, I would have gotten 1600 ohms.

Going to tinker around and record data with different temps.
This is the best it's ran in a very long time. So I may not be there, but on the right track.
 
Kawasaki makes a bare bones 610 mule, single cylinder and carb. Google the 4010 mule. Many nice
bells and whistles.
 
I have 250 hrs on engine and no gas in oil. Nice clean burning engine. Very easy on gas. About a gallon in 2 hrs. Runs great at any speed other than an idle. The fuel pump operates for only 3 seconds when key is on. Then computer has to see engine pulses before it turns pump on again. That might have eliminated fuel leaking past the injectors. If I remove gas line from pump in tank there won't be any gas pressure if the key has been off for a few seconds. Gas pressure is a tick over 40 psi and there is a pressure relief valve .

I've been thinking I was running rich at an idle. Using a resistor and tricking the computer was my last option. Nice to know I'm not the only one with an idling issue. If needed, I'll come up with a way to make this mule work as it should at different temps.

I know a guy who's van wasn't running right. So he bought a new water temp sensor and just left it hanging near engine. He claims he improved his fuel mileage and engine ran better.
 
Put a resistor in fuel temp sensor on a Cat diesel engine, C12, C15, etc, good for about 30-35 HP, cleanly. Put a resistor in boost pressure sensor on same engine, good for additional about 40-45 HP, although smoky on takeoff until turbo is spooled, that is, if you mash on it. Forget what value the resistor are, 150 and 1500 ohm, can't remember off the top of my head.

Ross
 
Years ago I had a similar problem with a 1985 goldwing aspencade efi. I used a variable
resistor in series with the air temp sensor. I needed more resistance. The mule is the opposite,
I needed to have less resistance. So tricking computers isn't something I haven't done before.

I still think I'm still running a little rich. If I have too, I will put the air temp sensor in
freezer and measure it's resistance. Then subject it to about 110 degrees then measure the
resistance again. 110 degrees is about the max temp in pole barn in the summer. Lets say 110
degrees is 300 ohms and subzero is 3k. I put a 300 ohm fixed resistor and put it in series with a
3k variable. I'll locate the variable on dash and dial in the resistance I need to make it idle
right depending on temp.

Keep in mind both temp sensors check out good according to the service manual, but for some
reason it's running rich at an idle and there are no computer codes saying there is a problem. So
computer thinks all is well when it's not.
 
You may find this very interesting. This bloke has done some amazing work in Australia.
Theres a link on his website to a thread on it as well.
Enjoy
Rx
http://ozbushelectronics.com.au/page1.php
 
My goal was to lean out engine. I think I'm still a tick rich. That said, you have a good point about pre- detonation. After reading the service manual, I learned the engine is a 10.3:1 and no ultra sonic sensor. So I may use 93 octane instead of 87 in an attempt to prevent per-detonation.

Keep in mind, I had no choice, the resistor was my last option to make the engine idle as it should. If I went too far, I would still have a problem with the idle. There is a tiny window to make the engine idle right between 950-1050 rpms. A tick too fast and the clutch kicks in and then there is a conflict between clutch and engine because the clutch will engage, pull engine speed down, computer takes a moment to respond. At that point things go sideways, rpms decrease. then increase too much resulting in a contest between clutch and computer.
 
Update: It's 10 degrees cooler, 52, this morning. It started like it did when it was new.

For those who think I may be too lean, think about this. No gas engine likes to start when it's cold without choking it. So computer is still providing a rich enough mix to start a cold engine based on the cold water temp sensor. The air temp sensor, which was replaced with 1600 ohms, is telling the computer the air temp is 98 degrees.

When it gets colder, I may need to replace the 1600 ohm resistor with a larger resistor if I have a starting or idling issue.
 
>For those who think I may be too lean, think about this. No gas engine likes to start when it's cold without choking it. So computer is still providing a rich enough mix to start a cold engine based on the cold water temp sensor. The air temp sensor, which was replaced with 1600 ohms, is telling the computer the air temp is 98 degrees.

George, all that doesn't refute the point that you're almost certainly forcing the engine to run lean under load. Apparently smooth idle is a higher priority for you than long engine life. It isn't for me. Your engine, you can do with it what you want. It may outlast both of us, or it may burn a hole in a piston next year.
 
Try this:

http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c152801dba32
 
The real risk is MRS. Geo-TH, In running that thing wide open all day long! :roll:
 
(quoted from post at 17:41:40 09/11/15) I need to go the other direction, less resistance, so series won't work. At 62 degrees I have 2300
ohms. Works great at 1600 ohms. The warmer, the less the resistance will be. I even measures what
the ohms of thermal resistor is at 98 and it was 1600 ohms. I figured the less the ohms, computer
will lean out a little
,if I put a 5250 ohm resistor in parallel with the thermal
resistor,2300 ohm at 62 degrees, I would have gotten 1600 ohms.
Click to expand...

Quote " replaced air temp sensor with a 1600 ohm
fixed precision resistor. The computer now thinks it's 98 degrees when the actual air temp is 62. At 62
degrees the air temp and water temp resistance readings were the same this morning, 2300 ohms, " Unquote.

It is unusual for the resistance to decrease with higher temperatures and resistance to increase as the temperature drops. Do you have the numbers swapped around ?
 
I'll let you know if I pop a hole in piston. I'm not as concerned as you. The way it was running before I used a resistor I was ready to make a hole in the mule with a gun. So tell me how can a cold engine run if it lean of peak at high speeds and not fall on it's face?

It's paid for and you are right, I can and will do with it as I see fit. I look at it from a positive view point, it's running great. If I blow it up, you can rest assured, I'll not buy anything with a computer.

I would like to find a place to buy a temp sensor the resistance values I want at any given temp or I'll make one.
 
Jessie, the mule isn't ran hard or for a long time. For the most part, it's used for yard work
and idles around. Never put away hot and wet. Lucky to run much over 2000 rpms and 180 degree
water temp.

The nice thing is it's water cooled. I'll keep an eye on plugs. My farmall is definately running
lean, plugs have no carbon deposits, white as snow. It gets run hard for about 45 minutes when we
mow. I have to let it cool down for a few minutes before I turn it off. Mules plugs are not as
clean as Farmall C.

Do you know where I can buy a thermosister that will give me the resistance I want at a given
temperature?
 
Jameco Electronics sells a variety of thermistors. <a href="http://www.jameco.com">http://www.jameco.com</a> Sounds like you need one with a negative temperature coefficient ("NTC").

It's common for ECU maps to run a bit rich at high power settings. So, by running leaner than the map says, you could be running the engine at a stoichiometric mixture. So this would not be LEAN of peak EGT, but rather simply peak EGT.
 
(quoted from post at 12:25:50 09/12/15) He is correct, resistance goes up as temp goes down.
Click to expand...

Weird RTD's then. Industrial units increase resistance with temperature . Iirc the RTD's on my GM products are traditional and raise resistance with increasing temperature .
 

If there is 250 hours on it and it started to run rich the last 50 hours....then the question is what changed. Kawasaki has a tech hot line (at least they used to) for all the dealers to use. The hot line is for dealers and the dealer number must be provided before being connected to a technician. If your dealer has not called the hot line ask them to do so - better yet ask to be included on the call with them. If this is a common problem as another poster has stated they should have a ready fix. At one time engine ran fine - it should not need a work around at idle.

However, if you desire to fix it yourself I would offer several ideas for consideration.

1) The fixed resistor can fix the rich idle as you have demostrated. however it will stay in the system and affect the entire fuel curve. If you add a switch which is activated only when the throttle is at idle the resistor bias can be removed as the throttle is advanced away from idle.

2) In a simliar manner you could consider adding a parallel air path by drilling a small hole in the throttle butterfly. This would result in the throttle butterfly being more closed to maintain the same idle speed. The TPS would call for less fuel and the small hole would become insignificant as the throttle is advanced from idle.

3) Using similar reasoning as in 2) try adjusting the TPS to a more closed position. If this works...then why does the throttle position have to be more open to maintain idle speed then perhaps it was 50 hours ago. Has the timing become retarded...?
 
Thermistors differ from resistance temperature detectors (RTDs) in that the material used in a
thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response
is also different; RTDs are useful over larger temperature ranges, while thermistors typically
achieve a greater precision within a limited temperature range, typically &#8722;90 °C to 130 °C.

I always remember it this way, super conductors decrease resistance as you lower the temp while
thermisters are the opposite, lower temps raise resistance.

The service manual shows what the resistance should be at different temps, confirming lower temps
higher resistance. I'm looking for a thermsister with a different temp/resistance curve.
 
Mark, Before I purchase a thermsister, I need to look at the RT curve like the ones I found on ebay, http://www.taydaelectronics.com/datasheets/A-410.pdf. The RT curves are the bottom of the page. I know what the OEM values from service manual, so I would like to find something with a few hundred ohms less ranging from 0 to 40 degrees C.
George
 
If you poke into the details for the Jameco devices, you'll find data sheets that describe them in detail. They have a table rather than a graph, but the information you need is there.
 
>Weird RTD's then. Industrial units increase resistance with temperature . Iirc the RTD's on my GM products are traditional and raise resistance with increasing temperature .

Thermistors are available with either positive or negative temperature coefficients ("PTC" vs "NTC").
 
Mark,
I found better data sheet on ebay. Couldn't get the one I thought would work best, so I ordered an assortment of 100, 1k and 10k thermistor. I'll consult Bubba's electrical hand book and wire them in series and if needed make up a series/parallel combo to come up with the resistance that works best for different temps. This morning was 42, and the 1600 ohm fixed worked even better. It fired right up, ran fast for a few seconds like it did when new, then idled the best so far. No hesitation when I stepped on gas.

I'll drain the tank and fill it with 93 octane. Then I'll do my best to pop a hole in the piston, run it wide open on the road for an hour. Take cell and call for help if I blow it up.

What I can't figure out is why is it running rich when everything checks out, within factory specs and no computer codes identifying the problem?

My problems started with only 30 hrs on machine. It was idling too slow and oil light came on. I took it to the dealer because it was still under warranty. At 200 hrs the idling issue went from bad to worse. It took me 50 hrs of tinkering before I came up with the idea of removing the air temp sensor and using a resistor. One would think there shouldn't be anything wrong with a 2012 mule. I was ready to put mule down with a deer slug.
 
You must log in or register to reply here.

Similar threads

J
JMOR, A resistor question.
2
Replies
35
Views
1K
JMOR
J
C
1030 info
Replies
6
Views
265
cumminstinkerer
C
C
weak spark on a ford 4000 forklift
Replies
4
Views
369
Charlie M
C
A
long 2610 fuel problem
Replies
4
Views
195
Hemmjo
Hemmjo
P
Continental y112
Replies
11
Views
369
Clarkbug
C
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top