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05 900 alititude issues...still

C

ckspeed

Member
Okay well I asked about this a while back, got some good ideas, but I haven't found anything definite yet.

Still working on my 05 900 RMK 166 with a loss of power/bog at anything over approx. 6500 ft. I was told it was running really rich, but I don't know for sure. Very poor if any power, flat, barely pull itself on the trailer.

Below approx. 6500ft, runs awesome, no problems at all, like a switch turned on and off.

Swapped ECU for new, no improvement. No codes.

I was thinking that maybe the TPS was off, the intake boots cracked, or something similar was causing a lean mixture which the ECU was handling by adding more fuel but when the alitude increased beyond what the ECU could compensate for, it went lean and the DET sensor retarded the timing and fattened up the mixture. This is all pretty much a guess at this point.

The boots looked cracked, so I pulled them and checked the TPS at the same time. Idle voltage was .908 and WOT was 4.9 and the analog meter showed smooth movement. The boots don't look cracked all the way through, and the reeds are dirty and kinda crappy looking but I just haven't found the smoking gun yet....

What do you think of the boots? (I'll replace them anyway)
What about the reeds? Is that much dirt normal?

Anyone have ideas?

I need to do a bunch of other stuff to this sled but don't want to waste the money if I can't get it running right. I'm at 1200 feet now, so this doesn't help my troubleshooting.

Thanks a bunch in advance...:D:beer;

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Those TB boots are bad.... get rid of 'em.

Reeds look good though, use a q-tip or paper towel and some paint thinner to get the gunk off 'em. Be gentle, they're delicate.

Cleaned your exhaust valves?
 
Those TB boots are bad.... get rid of 'em.

Reeds look good though, use a q-tip or paper towel and some paint thinner to get the gunk off 'em. Be gentle, they're delicate.

Cleaned your exhaust valves?


Nope, nothing to the valves. What needs to be done other than replace the bellows and maybe springs? Could dirty valves cause my probs?

The boots are looking pretty bad, but I was hoping to be able to see a little light through them or something :mad:
 
Exhaust valves

If they get too dirty the valves will stick and not open all the way or not at the right time they're supposed to and engine will bog. Might even have a bellow with a tear in it. Just take the 4 bolts off holding on the black cap and the spring and bellow are right under it. Then take the nut off the end of the valve and the bellow will come off. Then take an allen wrench and loosen the 4 bolts holding the exhaust valve in slide them out and clean with a wire brush on a grinder or buy one and attach it to your drill and clean the carbon off them. Coat them with a coat of oil and reinstall.

Cracked throttle body boots will cause a lean condition and could cause the engine to burned down.
 
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Those boots have seen better days!
Agree on the exhaust valves also. Mine looked like a slough
 
looking at the reeds it looks like you have a lot of oil on them also. do you have a lot of oil coming out of the exhast to? my have a pump cable stuck. The other thing to do is when it starts acting up when you are up above 6500 ft pull the springs in the valves cap off the tubes coming out of the exuhast valves give it a try. 05 run better that way
 
looking at the reeds it looks like you have a lot of oil on them also. do you have a lot of oil coming out of the exhast to? my have a pump cable stuck.

Yeah, it was pretty oily and I did have a fair amount of oil in the exhaust.

The other thing to do is when it starts acting up when you are up above 6500 ft pull the springs in the valves cap off the tubes coming out of the exuhast valves give it a try.

Huh? :confused: Pull the springs out is all?
 
if you pull the springs out and plug the lines coming out put the tops back on you can rev engine up to engagment speed and see the valves come up all the way if they do make a run and see what happens if not you know you have a problem in the exhaust valves ( gumed up,rubber, or plugged orface) i have 3 05 900rmk with springs out and they run great that way
 
Another thing to look at is the exhaust valve solenoid. I have seen these get plugged with oil.

To clean it just take it off and clean with brake clean and compressed air.
 
I'm sure you already checked the oil cable, they break and go wide open.

The other thing you might consider is a fastrax fuel controller. Those sleds run very dry and I'm going to try a controller on my 975 so I can add the max fuel at different altitudes and see how it works.
 
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