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Discussion Starter #1 (Edited)
07 sportsman 800 efi idle issue and shutting off

still fighting the low speed hesitation and shutting off on this machine. when you gi start 1st thing of the day it idles around 1250 rpm. as the day goes on the idle continues to drop untill it gets to 950 rpm then the machine will randomly just shut off. it always starts right back up and anything above 1/4 throttle is fine. i have replace throttle body, tps, tps harness, tbap, tbap harness, installed new plugs,plug wires, battery. i got the tbap and tps sensors and harness from otb. i had a terrible time adjusting the tps. if i backed the idle screw all the way out,unhooked throttle cable i could not achieve the base voltage required in the service manual. i open the hole on the tps so i could get voltages in spec and the machine still did the same thing. i emailed otb and was told i shouldn't have touched the idle screw. he said he never does it that way because he could never get it to work. he said to bolt the tps on and adjust until it idles good. so i bought another tps and a used throttle body the still had the yellow glue blocking the idle screw so i knew it had never been turned. installed a new tps which still could not achieve the proper voltage , but adjusted untill it idled good and locked it down. still same issue. i dont know if a oem polaris tps would yeld different results. fuel pressure is at 40psi. compleatly stumped. i have chased all tbap and tps wires all the way to pcm and have no problems. i have to be over looking somthing but can figure it out. any ideas. PLEASE HELP
 

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Wow!!! So me I would be interested in two things. DC voltage at the battery with the machine running at 3,000rpm. Also the condition of the stator wires, both leads the one from the wire harness and the ones attached to the stator directly.
 

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Voltage sounds good. I know it may sound a little if course but with all you have done I'm leaning toward a wiring/voltage issue. If those check out it may be time to swap ECM's with a known good one. But I'm really leaning toward bad wires somewhere!!!
 

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Discussion Starter #5
One thing I noticed is the rpm reading on the dash doesn't seem to match the motor. I can watch the tach Jump 200 to 300 rpm with no notice in the sound of the engine. Possibly a crank sensor issue? Here is a you tube link

https://youtu.be/_nswJXu4m2M
 

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Interesting point, there are no codes for a bad CS not are there any electrical readings that can be done to them.
 

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Ok was that jump on warm up??? Because it looks like at the end of the vid it settled at 1170/80. That's were it wants to be, idling between 1150-1250. Of course in that range but at a constant idle rpm.
 

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Discussion Starter #8
No, right after the video it dropped back down 950 to 850. Is it just me or is the engine really not changing rpm. I have a timing pick up for my multi meter which will allow it to read rpm, I'll have to grab that from work tomorrow and check to see if it matches the tax
 

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Discussion Starter #9
So i played around with ityesterday and couldnt get it to act up. the tach still started off at 1250 rpms then would start reading 950 but it never did the rough idle and shutting off. seems like it only does it when it is hot outside. this thing is killing me
 

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My 2010 HO has the RPM all over the place. With headlights off i get one rpm reading that, although the engine speed increases, the tach does not, past 1450 rpm. With low beams i get a better number but gauge to engine speed is still off a bit but close. Hi Beams seems to be the best reading up and down the rpm scale. I have yet to figure it out so, i am watching this one. If i find a solution first i will post too
 

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Discussion Starter #11
So i found that procom makes a direct replacement ecu for my machine. Part number pe-e-ap800-a. I spoke to them on the phone and they said with a laptop i can change idle rpm, igntion timing, and other factors. They also stated i would still be able to retreive trouble codes and see live data and change fuel maps.. I ordered one to see if it will solve or at least help me trace down this problem.
 

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OP, you said originally that it does fine when cool and then acts up when heated. What kind of fuel you using and have you done anything to mitigate heat under the tank and on the sensors?
That model 800 has severe tank heating and boiling gas problems unless you use heat shielding under the tank extensively and wrapping the exhaust helps too. I even added a small exhaust fan under mine to pull heat out from around the tank and body work.
 

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Discussion Starter #13
I purchased a 09 heat sheild for the side frame and installed that and also heat taped the under side of fuel tank. Hoping that should be good.
 

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Sounds like you should be ok heat-wise then. One other thing about setting the TPS by hand for good idle though, its difficult but it must be set to idle speed when HOT to be right. It should idle around 1250-1300 after first being started and while cool and gradually settle to around 1150+/- 50 rpm when it gets to operating temp. If you set it to 1150 while cool it'll be too low when it gets hot.
 

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Discussion Starter #16
thanks for your help, this thing is driving me nuts. ive been an auto tech for 22 years and it kills me i cant figure this one out. when i 1st start it it does go up to 1250 rpm but then as it cools it settles at 890- to 950 rpm. the quitting part only happens when it is hot outside(at least thats how it seems because when its cool i cant getit to do it). when it does do the quiting, i havent been able to check fuel pressure but it always starts right back up and it doesnt act like its running out of fuel, it just shuts off. i have had my pressure guage on it and driven the snot out of it and pressure is always at 40 psi. the funny thing is when you see the rpm decressing on the guage you cant hear the motor idleing down. im really leaning towards a bad computer but now that i have ordered the procom, i see all kinds of bad reviews about them. i guess we will see.
 

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If you put an inductive timing light on it can you see it missing or ignition breaking down? Pickup coils don’t usually break down intermittently but, it’s not outside the realm. My tach goes wonky after a few mins of warming up but then comes back if I turn on the headlights. But last night after dielectric greasing all the connectors it didn’t seem to be as bad. Was there moisture in the connector? Not sure but after greasing it all up it ran well. Carbed 500 so my only computer is in the speedometer.


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Discussion Starter #18
Just got off the phone with procom again, and apparently they forgot to mention with their ecu the quad will be in 4wd all the time. I thought the 4wd was controlled by the speedo not the ecu?
 

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Discussion Starter #19
Ok, so i got a chance to mess around with it again today. I checked the tach with my multi meter and when the tach rpms drop down to 850 the engine is still actually ideling at 1150. So the tach is reading off. I tried what willshire said and sure as anything i turn the headlights on and the tach starts reading correctly. At the same time i couldnt get the quad to quit like it has been. Again seems like this never wwants to act up when i have to to trace it, yet i take it to use it and it quits all the time. Could a bad tach be causing the quiting problem? Does the tac tie in to the ecu at all?
 

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That’s a tough one because my 2010 carb HO only has the speedo and no ECU. I tried to see where it got it’s reference from and it looks like it’s from the pickup coil which I think it gets from an out put from the cdi but dang! I can’t remember and I’m gone for a week. I will be watching this because maybe we have the same issue but, since mine is carb it doesn’t effect an ecu it doesn’t have


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