Any Turbo experts in here? Need help!

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This is a novel, but I want to accurately convey the problem and the trouble shooting I have done.


This is a 2012 Proclimb 800 with push turbo tial race gas kit on it with 4 injectors.

The sled has always had this problem below since the turbo kit was installed.


Between 4500rpm and 6000rpm, if I hold a steady light throttle, say 1/4 throttle, the sled cruises for a second or two, then dies almost like someone hit the kill switch. During this time, the AFR goes very lean. Before it completely dies, it picks back up, runs normal for a second, and then dies again. This cycle of AFR going normal (14.5:1) and then very lean keeps repeating itself until I give it more gas or let off the throttle. The sled idles fine, and anything outside of that 1/4 throttle, 4500 to 6000rpm range, it runs perfectly.


Things I have done:


1. It was doing this with the old fuel controller (power commander V, with the aux injector powercommander box). I could not tune this lean/rich steady cruise out.
2. I changed the fuel controller to a 3D race gas boondocker box. Sled runs 100% better everywhere else (than it did with the powercommander), but still dies suddenly at cruise and goes very lean, then going into the cycle described above.
3. I have replaced the TPS, thinking that the old TPS may have a "dead" spot.
4. I have set the new TPS to .69V at idle. I have tried other TPS settings, as low as .5v and as high as .8V and it did not have any affect on the issue, just made the sled run crappy everywhere else.
5. I have disconnected the throttle microswitch, thinking at light throttle, the switch may have been flickering between on and off, causing it to have the issues it is having. This made no difference.
6. Fuel pressure is 39psi at idle. It is the factory push electronic fuel pressure box. The fuel pressure gauge is under the hood, so I cannot see what the fuel is doing when the sled is having this issue.
7. I did a Compression ratio test and both cylinders are identical and well within factory specs.
8. I was told that an overly rich situation with tons of unburned fuel could cause the AFR to read lean, so I tried leaning out the midrange on the boondocker box. It ran much worse.
9. I currently have the 5000rpm and the 6800rpm settings on the boondocker box for the low and mid throttle positions set at +15. It makes the situation a bit better, but it is still very much there. Plus, I can tell it is rich as it gets boggy in the midrange with these settings.
10. I have tried removing the waste gate spring so no boost is being produced to see if turbo influence is a problem. It made no difference.
11. Tried adding fuel to the PSIL (up to 5psi) and the low column (up to 1/3 throttle position) thinking that the sled may be transitioning from vacuum to boost. This made no difference.
12. I confirmed that the exhaust valves are opening properly. They open to the mid point under mid throttle and full open under heavy throttle. It cycles once under startup and does not throw any codes.
13. Fuel pressure holds steady at 40psi when this problem is occuring.
14. I put the boondocker box in monitor mode, so you can see all the parameters. Commanded duty cycle is 12 and 13 and adjusted duty cycle is about 1 cycle higher. The big thing here is that the commanded duty cycle stays constant, even though the sled is going normal afr and lean afr. This should not be happening under a constant duty cycle, it should be getting an even amount of fuel and not going lean. Boondocker box shows it is always in vacuum when this is happening.


Here are videos so you can see what it is doing. One is of the AFR gauge and dash showing RPM and the other is over the boondocker box in stats mode. The videos are shot with a constant maybe 1/8th throttle, since there is no load on the engine to achieve the 5000rpm problem area. Although you can hear the sled cycling in RPM, I am holding a constant throttle. The cycling is due to the sled going normal AFR/lean AFR/normal AFR.


AFR gauge/Dash RPM:


M8 lean AFR - YouTube


Boondocker box in Stats Mode:


M8 lean boondocker box - YouTube


I am at a complete loss, trying everything and replacing everything that I could think of that could cause this problem.


The only other thing I am noticing is that my brake light flickers at idle and so does the gauge backlight. Would any kind of voltage regulator problem cause this? The manual says if more than 4.5A of DC load is added to the sled, the exhaust valve would detect low voltage and throw a code. This does not happen. The only DC load added is the wideband, that only takes 1.8A at worst case.


Anyone every see anything like this before? Anyone have any other suggestions?
 

moto5151

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How does it act on on the snow? Does it seem to surge? I'm wondering if that rpm range is a switch point within the fuel controller system. I think there is a point where mid range fuel settings take over from the low end setting. Then again in another point where it switches from mid to top end. Wonder if blending the fuel at that point will help. Kinda make the two ranges blend rather then have a fine line. Just a suggestion, as I've had to do this on other types of fuel controllers like the dobec box.
 
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It is worse in the snow. When it goes lean, you hit the handle bars.

I has thought about a transition point where one setting is right and the other is lean, but that does not appear to be the case. The boondocker box only transitions for three reasons: rpm, throttle position, and boost pressure. Throttle positions transfers low: 0 to 1/3 throttle, mid 1/3 to 3/4 throttle, and high 3/4 to WOT. Throttle is constant when this is occurring so no transition there. Boost pressure fuelling transitions when you first hit boost and then above 5psi. This is happening in vacuum, so no transition issue there. This is happening between 5000rpm and 6000rpm, picking back up in the 4000rpm range. So it could be transitioning between fuelling corrections there. However, I have the fuelling compensation set the same for the 3000rpm and 5000rpm settings and also, as the stats mode shows, commanded and adjusted injector pulse widths stay the same, so fuelling is not changing due to RPM. Therefore, I do not believe it is a transitioning issue.
 
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Sled runs fine wide open throttle. Will have to try without Boondocker box and see what happens.
 

Deano670

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How are you referencing boost signal to that bd box?? Are you using the bd boost pressure sensor?? Are you running ebc with it??

Deano

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BD pressure sensor in the charge pipe is being used. No ebc, 10lb spring in waste gate. Have manual boost bleed valve as well, but just running waste gate right now.
 

Deano670

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Im confused as to why your bd box is seeing a vacuum at idle??? -4.3????
 

wannaturbo

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looks like to me you are just to lean in that range give it more fuel and see if it helps.if you are only running a fuel controler these sleds can not usually be held at a steady throttle postion at those RPM and throttle position the factory computer advances timing and leans down mixture. to compinsate give more fuel and get used to burping throttle while driving at those speeds.good luck
 
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It is not just a tuning issue. I can add 40 counts of fuel in the rpm range this is happening at low throttle position and it makes no difference, it still goes lean. Also, I know of the Ecu issue. This is not it. It goes so lean the engine shuts down and does not pick up again until the rpms drop. I've got friends with 800 turbos and they go lean under constant low load cruise, but only to the point of high exhaust temps, not to the point of the engine shutting down and it being unrideable. This is a different thing all together.
 

HotShotHarry

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After 2 seasons, He's probably got it figured out.... I hope. It sure would be nice to know what the solution was though. To many of these threads end without the OP coming back and reporting what the fix was.
 
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