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TRX500 - 2006 -Running bad

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I have a 2006 TRX500 footshift  that belongs to my buddy , it is running bad , will not rev up like it should , it won't idle , it will stay running as long as you hold the thumb lever wide open ----

 

Drained and flushed the tank , which was not dirty at all , cleaned the carb which was also clean , ( did not remove the throttle position device ) have heard you should not remove it as it is calibrated / set  , cleaned the carb with aerosoil cleaner  and compressed air , feel it is clean and that is not the problem ---  new spark plug , air filter , oil change 

 

 

 I heard that even though this engine is carbureted , the throttle position device / gizmo on the carb can be a problem , and may have to be flashed or something from Honda ???  it  looks like and I have heard his Dad changed the carb with a new OEM Honda carb a couple of years back and it looks to be true 

 

I made a short video of how it runs , but I can't seem to get it  upload it ,  it is over 6 seconds ( which seems to be the limit of max ) , I have trimmed a video before here on this site and got it to work , but for some reason this video , isn;t working with me , maybe be the format 

 

 

 you can see the throttle position harness on top the carb 

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A video of the 500 starting and running 

 

Fixed it for ya Fishfiles

Edited by retro
Converted to .MP4

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The question is : What is that pigtail harness  between the carb throttle position sensor and the main harness of the atv ? 

 

The pigtail ( that has the orange tie strap on it )  is not shown on Partzilla finche under " carb " or the " wiring  harness " . ----- Is that a relay or resistor in the harness 

 

 

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I just found a thread from Honda Foreman and @jeep and @toodeep both were in it , sounds about what I am dealing with ,   first post went like this  

 

 

2006 Foreman 500 Running Issues, Misfire, Rev Limit

Hello All,

I am working on a 2006 Foreman 500 ES for my neighbor. He said it was misfiring so I thought the typical carb cleaning. Well I cleaned the carb and didn't find much in there. The jets were clean and no real varnish or anything. However I cleaned it thoroughly and then checked the TPS sensor. It had very erratic readings so I purchased new TPS sensor and installed it per the factory manual at 500 ohms at idle position. I installed everything again and tried test riding it and it still ran the same way.

It acts like the rev limiter is coming on too early. I can get the machine to go about 35 MPH but that is it. In every gear it feels like it hits the rev limiter way to early. It it feels like it is RPM related and not throttle position related. I reset the codes in the ECM as it was displaying a code 13 for the TPS. It now displays the "N" for 2 seconds and no other engine codes at the 1/4 second interval as shown in the manual. It does display code 5 for the 4x4 Front Final Clutch System. I completed all the steps in the manual to test this and all the measurements were good and the manual says "Faulty ECM". Will this code 5 for the 4x4 put the computer into some sorta "safe mode?"

Here are the steps I have completed so far without any success on getting it to run correctly:
1. Cleaned carb
2. New TPS set to 500 ohms at the idle position
3. Cleared codes in ECM - still have code 5 for 4x4
4. Checked all brake switches to make sure they cycle. The start in gear override works on the RH brake and it is not hanging up.
5. Check a bunch of the wires and connectors (not all of them, but a good portion of them).
6. Battery voltage is good and charging voltage is 14.3 volts.
7. Adjusted valves - intake was 0.014" and exhaust was 0.012". Both set to 0.006" now.
8. I tried to check timing through the plug on the RH side but it is spitting some oil out of it and didn't feel like getting oil all over myself.
9. It starts instantly and runs really good until the "rev" limit kicks in. It misfires, pops, and just will not let it REV anymore. I don't have an exact RPM number but I can get it if it helps at all.
10. No intake cracks.
11. It has a K&N air filter, which is clean.
12. Carb jetting was stock: 162 main, 45 pilot, needle clip in the middle. VE6DAA carb.
13. The machine has 400 some hrs on it and 4300 miles.
14. New spark plug - NGK BKR5E @ 0.040" gap.
15. Tried known good fuel.

Also, the owner said this happened all of a sudden. I doesn't sound like it was ever intermittent. Can't think of anything else right now. Any advice would be much appreciated and I don't want to spend $300 on a ECM if it is truely not the problem. I cannot think of any other machines in the area to try to swap parts with either.

 

 

Link to the rest of thread 

 

https://www.hondaforeman.com/threads/2006-foreman-500-running-issues.127322/

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That pigtail harness was an add on on the Rubicon’s because there was an issue with water running down that wire and into the TPS sensor and freezing (I think).

 

anyhow, it was definitely something Honda did as a recall on some machines.

 

I had one machine that was throwing error codes and when I looked at the ends on that harness there were signs of arcing so I removed the pigtail and plugged the main harness directly into the TPS and all of the problems with that machine magically went away

 

So try that.

 

I would unplug all the brake switches up on the handlebars for now as well. They can make those machines act funny if one of them goes bad

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36 minutes ago, jeepwm69 said:

That pigtail harness was an add on on the Rubicon’s because there was an issue with water running down that wire and into the TPS sensor and freezing (I think).

 

anyhow, it was definitely something Honda did as a recall on some machines.

 

I had one machine that was throwing error codes and when I looked at the ends on that harness there were signs of arcing so I removed the pigtail and plugged the main harness directly into the TPS and all of the problems with that machine magically went away

 

So try that.

 

I would unplug all the brake switches up on the handlebars for now as well. They can make those machines act funny if one of them goes bad

 

 

Thanks for the reply >>

 

 I just did  the things you said :

 

1) removed the jumper wiring harness and connected the wiring harness direct to the throttle sensor = no difference 

2) unplugged the left hand brake switch , the switch is cracked up , thought for sure that was it = no difference 

3) unplugged two switches on the right brake lever = no difference 

4) unplugged the foot brake switch = no difference

 

I can say now  ,  that what it sounds like when  running , could be  a rev limiter problem , spitting and sputtering 

 

 

 You mentioned something about codes , I don't see anything strange going on the neter . display = Where would I see that code , if there is any ? 

 

 

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That sub harness was part of a recall like jeep said. When they was installed a "drain" was also cut in the main harness so there would be no chance of moisture getting to the TPS and it freezing the throttle in cold climates. The TPS is just set by ohms so if it's a new oem carb that should not be an issue.

 

Any idea on what they was doing or when/how the problem started? Have you tried running it with the airbox lid removed? Does the exhaust feel like it has normal pressure coming out of it?

 

I'm guessing this isn't a mud machine (stock snorkel) but with enough miles and heavy use jumping time is another possibility.

 

How does the throttle plunger look in it and did you look to make sure the seat for the throttle needle didn't accidentally fall out at some point?

 

I'll keep thinking as I'm sure I have had one do this in the past but the file data base in my head is very disorganized so it might take a while to find it. lol

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1 hour ago, toodeep said:

That sub harness was part of a recall like jeep said. When they was installed a "drain" was also cut in the main harness so there would be no chance of moisture getting to the TPS and it freezing the throttle in cold climates. The TPS is just set by ohms so if it's a new oem carb that should not be an issue.

 

Any idea on what they was doing or when/how the problem started? Have you tried running it with the airbox lid removed? Does the exhaust feel like it has normal pressure coming out of it?

 

I'm guessing this isn't a mud machine (stock snorkel) but with enough miles and heavy use jumping time is another possibility.

 

How does the throttle plunger look in it and did you look to make sure the seat for the throttle needle didn't accidentally fall out at some point?

 

I'll keep thinking as I'm sure I have had one do this in the past but the file data base in my head is very disorganized so it might take a while to find it. lol

Wow , great info , thank you , this thread had been very helpful to me !!!! 

 

It is an OEM carb and the numbers match up 

 

I just went and ran it with the airbox lid off , no difference 

 

The adjustment of the TPS has not been messed with you can see the paint on the screws from the factory  in the pic 

 

The fuel is clean / the plug was new , but I better pull it and look at it again 

 

When someone comes over I will try and feel the exhaust 

 

 I have all the brake switches unplugged and removed the extension harness to the TPS 

 

When the problem  started  ----  A little history , it has 1885 miles and 486 hours , I know the original owner , it was a hunting only atv , he quit hunting and it sat for a few years , another guy I know bought it , cleaned the tank , changed the carb with a new OEM , he used it on his farm lightly for a couple of years with no problems , gave it to his son , my friend , he took it to his hunting land in Mississippi , it was there for 2 years with no problem , it has never been 4wheeling , from what he says and I have seen too  , this atv will run great , then malfunction , I have found mouse damage already , trying to look and feel up in there , my have to take all the plastics off 

 

When you say throttle plunger>>>?  image.png

  

 

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Man I wish I could chime in.. but reading about the gizmos & crap on this carb I have nothing…. A regular cab I’d say ur main is fine if she holds revs but either pilot & needle would be other issue for not running… those easier to address over all the crap they added..

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8 hours ago, Fishfiles said:

 

 

Thanks for the reply >>

 

 I just did  the things you said :

 

1) removed the jumper wiring harness and connected the wiring harness direct to the throttle sensor = no difference 

2) unplugged the left hand brake switch , the switch is cracked up , thought for sure that was it = no difference 

3) unplugged two switches on the right brake lever = no difference 

4) unplugged the foot brake switch = no difference

 

I can say now  ,  that what it sounds like when  running , could be  a rev limiter problem , spitting and sputtering 

 

 

 You mentioned something about codes , I don't see anything strange going on the neter . display = Where would I see that code , if there is any ? 

 

 

Gear position on 4wd light will blink for error codes thrown by the ECU.

 

I’d be looking for mouse chewed wires.  
 

Worse comes to worst I have an extra ECU I can send you to try.  I think you have an electrical issue that is dropping it into limp mode, unless it’s jumped time.  Would be unusual to jump time with less than 2k miles on it.

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4 minutes ago, jeepwm69 said:

Gear position on 4wd light will blink for error codes thrown by the ECU.

 

I’d be looking for mouse chewed wires.  
 

Worse comes to worst I have an extra ECU I can send you to try.  I think you have an electrical issue that is dropping it into limp mode, unless it’s jumped time.  Would be unusual to jump time with less than 2k miles on it.

depends on how it was treated during those 2k miles ?.

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10 hours ago, jeepwm69 said:

 Would be unusual to jump time with less than 2k miles on it.

 

 I have seen the problem come and go ,  if it were timing , i think  it would be messed up all the time ------ I rode this bike around and everything was great , stopped it , started it again and it went back to running bad , seen that happen at least three times now ------  you mentioned  " Limp Mode " ,  that would be a good way to explain the way it runs , sounds like a rev limiter not allowing it to go high speed , it is spitting and  sputtering ---

 

Here is something different  that happened yesterday , I was trying it without the air box lid off  as per Toodeep's advice , and it lightly  backfired once while reving it hard and letting off ,  it won't  that with the lid on --- I know a backfire makes you think timing 

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1 hour ago, Fishfiles said:

 

 I have seen the problem come and go ,  if it were timing , i think  it would be messed up all the time ------ I rode this bike around and everything was great , stopped it , started it again and it went back to running bad , seen that happen at least three times now ------  you mentioned  " Limp Mode " ,  that would be a good way to explain the way it runs , sounds like a rev limiter not allowing it to go high speed , it is spitting and  sputtering ---

 

Here is something different  that happened yesterday , I was trying it without the air box lid off  as per Toodeep's advice , and it lightly  backfired once while reving it hard and letting off ,  it won't  that with the lid on --- I know a backfire makes you think timing 

yep..back firing means the timing is off ?, or the c.d.i. is messing up ?. i would check the timing before you go buying parts.

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1 hour ago, shadetree said:

yep..back firing means the timing is off ?, or the c.d.i. is messing up ?. i would check the timing before you go buying parts.

 Maybe if I change the terminology  from a backfire to a misfire -------  in this case I am about 99.9% sure it is not a  timing problem  , cause  like I have said  , the problem comes and goes , it will run perfect for a few minutes >>>>  as far as I know timing doesn't do that , it is either out of time or in time  , it can't fluctuate for long periods ----   

 

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Hi: What is the voltage on the Ign. coil when it's acting up?

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They don't by chance still have the original carb on a shelf one could clean and swap out for testing? If this was an EFI machine I would suggest trying the TPS/MAP sensor but I have never had one go bad on a carb model to know if they can give the same issues.

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2 hours ago, Melatv said:

Hi: What is the voltage on the Ign. coil when it's acting up?

Hi Mel !! Help me out here , where to hook the meter up and how to perform this voltage test 

 

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1 hour ago, toodeep said:

They don't by chance still have the original carb on a shelf one could clean and swap out for testing? If this was an EFI machine I would suggest trying the TPS/MAP sensor but I have never had one go bad on a carb model to know if they can give the same issues.

 

 

Don't know where the old carb is , likely thrown away 

 

The fuel gauge and the  clock / time are both  flashing  if that means anything 

 

 I think I need to take the plastics off , cause I do see some chew marks under the front fender , on a green wire going to the power outlet    >>>>  I think I am going charge up my camera /  scope and try to look before pulling it apart 

 

 

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Fuel gauge and clock won’t matter.  
 

i think you have a wire somewhere not making a good connection.  The fact that it runs good sometimes is indicative of an electrical issue 

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42 minutes ago, jeepwm69 said:

Fuel gauge and clock won’t matter.  
 

i think you have a wire somewhere not making a good connection.  The fact that it runs good sometimes is indicative of an electrical issue 

I agree , I think it is wiring or an electrical component ----  I was really busy today , but I did charge up my camera / scope , tomorrow , I hope to try and stick it around the wiring and see if I can see any damage without pulling plastics , this is a favor job ---  he said  no hurry ,     I got to hunting season , LOL

 

 

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@retro thanks for fixing that video above ^^^^^ 

 

 

Today I thought I could examine the wiring harness for mice damage with a inspection camera , that did not work too well , in fact I think it was a waste of time , seen a little but nothing helpful , to check one area is ok 

 

 

fullsizeoutput_110c.jpeg

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Have another buddy's 500 over , his carb was overflowing , so after cleaning it and sticking a kit in it , I stuck that carb  in the red 500 that was acting like a rev limiter , runs perfect , it could be the throttle sensor or the carb itself , either way , a whole OEM carb is $450+ , that comes wiith the sender/ sensor  , or $160 for just the sender/sensor , an aftermarket is $52 , free shipping and comes with the sensor / sender  --- bet you know which what he wants to go 

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