erratic idle-- no codes
 

I have an 07 sportsman 800 efi with about 45 hrs on it. I purchased it new as a dealer carryover, but since I purchased it, the idle has been a bit erratic.. almost like a carb does when it is cold.

I took it to the dealer and they tell me it runs "normal." Now that I've had it about a year.. the warranty is out and I've tried adjusting the existing TPS & then replaced the TPS. The old TPS had a cracked sheathe on it, but never threw any codes.

Right now I've installed the new TPS and it acts the same way-- almost worse. It sputters and dies if you gently push on the throttle (idle-2500rpms). Setting the TPS at 0.710Vdc put the idle at 950 rpms. I did follow the service manual procedure to check & set the voltage with the butterfly all the way "out."

I unplugged just the T-BAP and it performed the same way & threw the famous 45 code, as expected.

The harness on both the T-BAP and TPS look fine & feel tight. I unplugged just the TPS and it idles well and has the low end response without sputter or stalling. But it falls on it's face (sputters and coughs) if you turn it wide open.


Any thoughts? ideas? No codes are thrown with everything plugged in .. it still sputters and dies if you gently push the throttle or try to drive steadily at 10mph on flat pavement. Most certainly stalls/dies going up a slight incline (makes it creative loading in the truck).


Thanks!



ps-- if there is already a thread on this, please direct me to it. I couldn't find anything searching that was this unique.

maybe the fuel pump is getting ready to die. your sure it's not the override kicking in by any chance? just a thought.

Thanks for the quick response.

I do not think it is the fuel pump because it does idle well & "putts" around 0-20mph like it should when the TPS is unplugged. Also-- it hardly has any hours on it. Do you know what the fuel pressure should be at idle?

It does it in forward & reverse so I don't think it is the override. Is there any way it could be in forward?

Thanks again.

sounds like the fuel pump. also fuel psi is 39

Thanks for the replies..I think i fixed it:

I adjusted the idle speed to 1150rpm, then adjusted the TPS to .800V instead of 0.710V. I understand this will make it run rich, but it has more bottom end and power than it ever has.. idles well, and does not sputter at any rpm or load range.

So... can you think of any harm letting it run rich will do? No codes... just a higher setting than what the manual has.

Thanks again for your help.

it actaully runs rich right from the factory so no it wouldn't hurt it and glad you got it straighten out.

How are you adjusting the TPS?

The first round, I set the TPS by the book-- I backed out the idle adjust screw, set the TPS at 0.528V (I think that was the #, the book isn't in front of me), then adjusted the screw to 0.710V (sure of that #). This made it sputter and idle erratically.

The fix was simple to turn the idle screw until the rpm was 1150, which was a TPS setting of ~0.800V. Now it runs like a raped ape. It has more bottom end than it has ever had (i've had this problem since it was new).

When I tried this before replacing the TPS, it did not work. I want to assume the originally TPS was faulty. I did check the wiring harness on both the T-BAP and TPS before replacing it.

You really got my attention now. I have an '08 800 and when I start it, it will bearily idle, (at about 750-800) if I touch the throttle, it dies. After a couple minutes the RPM starts to climb and when it reaches about 950> I can touch the throttle and it will go. After it's warm, the problem is gone, and it will idle at about 1150. I recently had it at the dealer and the whole motor was replaced and it still does it. (different issue) They told me it's just cold blooded. I'm not buying that as it didin't do this before. It's really annoying as I have to wait about two minutes before I can drive it. Does this sound like the same thing?

you shouldn't have to wait very long before its rerady. i never had to on mine.