I have a 17 axys 800 with a Mtntek kit and I have a bog that I’m trying to chase down. When I first installed the kit, it ran perfect around my shop with no bog from just off idle to straight wide open. It was a used kit and the fuel lines had some wear spots so before the first ride I replaced the rubber fuel lines. I’m pretty sure it was just a coincidence but from then on it’s had a bog if I go from low throttle to wide open. It only does it after being at low throttle for a little bit then going onto boost. It seems to be running rich under boost then when I get on it again it takes a second to clear out and run right again. I’ve checked tps, new plugs, new maf sensor and new relays. My egt probe connection was a little loose so I crimped it back together and that made it a little better but still there. Also, the people at Mtntek have been awesome to deal with and the quality of all the parts is great. Sean has been great about trying to help me sort it out, but I was hoping someone here had ran into a similar issue and figured out what it was. I might change out my coil packs next and see if that helps. Gremlins suck, especially when it ran perfect, then after changing something so simple it starts doing this.
2017 Axys 800 turbo bog
- Thread starter S7even
- Start date
I have had spark plug caps wear out and give me strange symptoms, cheaper than a coil pack to try, and probably needs it anyway...
I have actually already replaced the caps with oem ones and new plug wires. The problem worsened last weekend and I think I’ve finally found the problem. I pulled my power valve cable and found it was broken. As soon as I receive the new one I will report back if it fixed it or if it was a separate issue that just happened. Judging by the fact that it sounded rich right around where the power valves were supposed to open, I’m guessing that the cable was stretched and causing the issue until it finally broke. Fingers crossed
Here is another thing to look at, I worked on a Silber turbo sled recently that had similar issues as you are describing. I used an ohm meter check resistance of the wiring harness between the MAP sensor and the ECM. Found one of the wires had a break inside the insulation. The wires should have very low resistance ~ .1-.3 ohms. On one of the pins saw 300 - 500 ohms. When I moved the wires the resistance would change. Need a good quality Fluke 87V meter and some stick pins to access the connectors. Polaris sells a connector kit for $100+ but you can go on Amazon and find them for $12 - 15. Here is the descripton: MOTOALL T-Map Sensor Pigtail Harness Wire Lead Wiring Connector Plug Cable Repair Kit. You can also just search for a Bosch MAP sensor connector.
This problem seems to be a fairly common failure and I suspect it is the cause of a bunch of the turbo bogging gremlin issues people struggle to solve.
This problem seems to be a fairly common failure and I suspect it is the cause of a bunch of the turbo bogging gremlin issues people struggle to solve.
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I hadn’t thought to check that so that’s good intormation to know. I’ve got a good fluke meter and stick pins for it so if this broken ev cable doesn’t fix my issue, I’ll check that next. Thanks!
Ok, replaced the ev cable and it made a big difference but there is still a rich spot in the mid range. Somewhere around 4800-5500rpm you can here it and if yum cruising down the trail at that rpm and go to give it throttle it feels loaded up and takes a second to clear out and run like it should. When I’m actually riding it in the trees and in and out of the throttle a bunch, I don’t notice it as much. @RMK900Tractor I’m going to take your recommendation and resistance test my map sensor. Did you just unplug the harness from the ecm to probe that side? And which wires were for the map, if you remember?
We just followed the wire colors back to the ECM plugs. I have a wiring diagram if that would be helpful. Just unplug both ends and use a good quality meter to check resistance. The good wires will have a very small resistance. I think we measured .1 - .3 ohms. The bad wire was 400 - 500 ohms and was very unstable as the wire was moved around. In our case, the gray wire was bad. Only 2 of the wires go to the ECM. The other two are ground and voltage.
If you wouldn’t mind sending me that wiring diagram, I would appreciate it. I’m sure I’ll need to look at something besides this at some point anyways. I’ll report back with what I find after I get a chance to test that.
PM sent
I went through and tested the harness map wires as well as all the wires in the map sensor extension that comes with the kit. All the harness wires read .3 ohms and all the extension wires read .5 ohms. I’m going to try and swap a known good egt sensor next I think. Maybe mine just isn’t reading right and makes the ecu think the pipe is still cold. It doesn’t throw any codes though.
Have you checked your compression? I just rebuilt an 850 that was bogging and we found low compression on one cylinder. Turns out it had detonation which broke off a chunk of piston.
I haven’t had a chance to check my compression yet but I will in the next couple days and report back. I checked it last year when this started and it was 115 each side at 4800 ft. I’m really thinking I have a sensor going out or wire broken somewhere forcing it rich all the time. I’ll also check my reeds again as soon as I can. Thanks again for everyone’s suggestions.
Ok guys, I finally had a chance to check compression and I have 120 on each side at 4800 ft. I haven’t had a chance to check my reeds again but when this started last year, I checked them and they were good. Any other suggestions on what to look for would be greatly appreciated.
Did you ever replace the EGT? There is a Ford part number that crosses over from the Polaris one for 2017 IIRC, so you can try it cheaper than what Polaris wants. Also switching out the MAP sensor is a relatively easy thing to try. In the "old days" of TPS sensors, I recall sometimes they would get erratic when moving between full closed and full open, giving runability fits, don't know if that is still an issue.
I haven’t replaced the egt yet. I’m working on getting a resistor to try before I replace the egt sensor itself. Do you know what that ford part number is? I replaced the map sensor last year with no difference to the issue. I have not swapped tps sensors either. I’m used to riding around the problem now, but in the next couple weeks I’m going to try and swap coils and a few sensors from a known good sled and see if I can get it to improve.
Here is the part numbers I saved:
08-10 FORD 6.4 / 6.4L POWERSTROKE DIESEL EXHAUST GAS TEMPERATURE SENSOR - 231047 NAPA Interchange Part Number:ALLIANT POWER P/N - AP63471, 1888560C1 MAXXFORCE 7 / 5S9328 / SU10790, 8C3Z-12B591-B, Echlin - 231047
