Dragon det and low idle issues

sledmanhof · Jan 28, 2018

I have an 09 dragon 800 and just took the first trip out this season and I had noticed when I went to start it on the mountain it wouldnt hold an idle. Well got it warmed up and took off and had the check engine light come on once I’d hit roughly 6500 rpm and would kick it to limp mode with the det code. Checked the plugs and they were way to lean.

I talked to the nearest dealer and they told me to change the fuel filter which I did. Tried it the next day and it still had that issue. I did have trouble starting it before the trip but drained the gas and put new in and it fixed that problem. It idles fine at 1500 ft back home.

On the last trip last year I had replaced the voltage reg and capacitor but rode a full day running great after.

I also did notice a couple hornet nests that had formed over the summer behind my dash but looked in my air box and didn’t see anything. I’m at a loss at what could be causing this as it ran perfect last season

XCaSSAULT · Jan 28, 2018

As far as I know the only thing that could effect the way the motor runs at different elevations would be the air box/barometric senor.

I’m sure some good googling could turn up a way to test this sensor. And triple checking all wires for rub throughs and corrosion would be a good start.

Otherwise completely going over the exhaust valves is always good practice. Checking for cracked bellows, smoke from solenoid tube, spring condition, carbon build-up and clogged cylinder holes.

Might as well look in there with a good flashlight and check pistons/ cylinder walls.

Compression check too

sledmanhof · Jan 28, 2018

Thanks for the reply. I’m gonna tear into it this week hopefully. I’ve been reading to make it that lean it’s not getting enough fuel compared to the air it’s pulling in. I’ve never had the issue with the 2000 miles ive put on it. It got a new top end 400 miles ago. What else could also be related to the fuel? Aside from changing fuel filter which I did, is there an easy way to check the injectors without taking it to a dealer? I know the fuel mapping with the ecu was an issue a while ago but I’m assuming since I’ve never had an issue before it wouldn’t suddenly start now. I don’t believe the fuel had ethanol mixed in but if there was trace amounts could that have an affect on it too?

XCaSSAULT · Jan 28, 2018

I have very little experience dealing with injectors but I do know they are expensive. Really damn expensive! Like $210/piece and there is 4 of them! So i would dive into all other aspects that can cause lack of fuel. And there is many.

Such as weak fuel pump, faulty sensor or possible air leak from cracked intake boots or crank seal.

The problem at elevation really feels like barometric sensor but in all I’ve read on these sleds I haven’t come across the symptoms that that senor being faulty would show. Probably because it’s a bosh sensor and they seem to know how to make good products. But that doesn’t rule it out.

The throttle position sensor seems to be a common randomly failing part on these things and will effect fuel delivery especially at idle, so that’s should be on the list.

I’ve heard there are places that can flow test the injectors. I’d look into that before replacing them but only after ruling everything else out.

sledmanhof · Feb 11, 2018

So I finally got to tear it apart and the only thing I have come across is one of my exhaust valve springs was disinigrated. What could that have had to do with this problem if at all?

KJ800 · Feb 13, 2018

I've been having a similar problem on my 2010 800 Dragon. Bought it used with ~1500 miles and before I did any riding put the durability kit in it. Ever since the rebuild it has had a hesitation (or dead spot) right around mid throttle or 6500rpm roughly. If I go slowly through the throttle generally the check engine light will come on. If I let off it will go off and not come back on right away. If I don't let off it will flash and retard the motor.

What I have done with no change in performance:
-New fuel filter
-Fresh gas, have ran several fresh tanks through
-New crank position sensor
-New water temp sensor

I've been reading a lot on throttle position sensors, and tonight I tested mine using a rough homemade tester. Found that at about half throttle (but not where I was noticing while riding) it would get a 0 reading then come back to a normal voltage. I'll be buying a new TPS tomorrow and dialing that in. Starting to run out of options, but it makes sense that this is the problem. I'm hoping there is a dead spot in the TPS causing it to lean out and hesitate/throw crank position sensor code.

I'll update with my findings.

sledmanhof · Feb 14, 2018

That’s exactly the same symptoms I have. Hopefully that can be the culprit and is an easy fix.

KJ800 · Feb 18, 2018

So yesterday I put in the new TPS and went through the setup process. I was optimistic, but I tested the TPS again after calibration and there was the same "dead spot" in the throttle where the multimeter goes to zero. So... I may have not had a bad TPS after all, $169 well spent.

Anyway, took it down the length of the field probably 15-20 times. It still has the hesitation, although maybe half as much as the last time I rode. And, no check engine lights. I went through the throttle slow, fast, in-between, let off and went right back on it. Seems to run a little smoother. Maybe it just needed the throttle body adjusted along with the TPS. Supposed to be going to the UP on Thursday to ride for the long weekend. So we'll see how it runs.

peaceofwork · Feb 21, 2018

Be sure and report back, I watch this with great interest

sledmanhof · Feb 22, 2018

I took mine into the dealer and they were finding a code for water in the gas along with the detonation. I had them scope the motor and one piston moved around 2 mm so I had them tear it apart. Just got off the phone with them and they found the cylinders scored to the point of needing to be replaced or replated. Definitely not the news I wanted to hear about. I’m not sure how close their number is but they are saying roughly 2200 for them to rebuild it all. Considering I had totaled it out in a trailer rollover last spring I don’t think it’s wortg fixing anymore like that. Hopefully your guys aren’t worse case like this one is

XCaSSAULT · Feb 23, 2018

sledmanhof said:
I took mine into the dealer and they were finding a code for water in the gas along with the detonation. I had them scope the motor and one piston moved around 2 mm so I had them tear it apart. Just got off the phone with them and they found the cylinders scored to the point of needing to be replaced or replated. Definitely not the news I wanted to hear about. I’m not sure how close their number is but they are saying roughly 2200 for them to rebuild it all. Considering I had totaled it out in a trailer rollover last spring I don’t think it’s wortg fixing anymore like that. Hopefully your guys aren’t worse case like this one is

$2,200 to rebuild! American coin? Wow that’s rape. Assuming all u need is new mono block and piston u could do it for yourself for around $600. Of course best to be sure why it needed the rebuild before rebuilding.

sledmanhof · Feb 24, 2018

Yeah I forgot to ask them that the other day but will call them Monday about it. I had put a new top end in it about 400 miles ago Because it would occasionally go to limp mode if I hammered on it after starting up. That fixed it then but I should have done more investigating into it before that. Maybe that was the same issue. The cylinders looked perfect when I did that

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Dragon det and low idle issues

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