kinger
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I am at 1000' check out my settings in my sig. Dont use them but compare to yours. At stage 2 your at whole lot different then mine.
bklynantnee
Veteran
Still has a real bad stumble just off vacumm transistion to boost. goes way rich and wants to stall. impossible to drive slow on the trail or around the house. bucking and pukking. nothing on the gems seems to help. ANY IDEAS??? Season really getting shorter...
thanks.
thanks.
shawnmcgr
Pro
What mode is your GEMS in when you see the stumbling? I'm assuming Green? Is the boost light on (blue) as well? What's your AFR doing? Have you checked your TPS? Post up your GEMS settings, maybe someone can spot an issue.
If your stumbling is occuring as the blue light goes on and off then maybe your boost setting is too high? When your GEMS senses boost the boost fuel circuit is triggered and additional fuel is added....this might be causing your rich condition. You've gotta get all of these GEMS settings to work together to get proper AFR at all loads/RPMs/Throttle positions.
If that's not it I'd try backing the altitude setting way off as well, see if that helps, then inch it up 0.5 at a time. This setting changes the fuel map and changes the pressure applied to the MAP sensor as well. If the comp sees a MAP reading higher than atmospheric then I believe it defaults to 85kPa and should throw a code.
Here's a description of what this setting does from Mac @ MPI:
"Another thought about this jumping from 14:1 to 10:1 as the sled goes from green to red. To explain this, I need to explain what altitude comp is and how it works. Below a certain pressure reading on the OEM yamaha MAP sensor, the GEMS box reads the yamaha map sensor and relays the same reading to the yamaha computer. Here's the catch, If you show the yamaha computer a map reading higher than atmospheric pressure, it gets upset and jerks and jumps for a minute. This happens when Blue-red is set too high. On the other extreme, id the Blue red setting is too low, the Yamaha computer will never actually see o inches of vacuum (which it expects to see at WOT). Basically the GEMS is passing all the high vacuum data to the yamaha computer, but not the low vacuum data. If this happens, we see 2 or 3 major things happen. 1- Bad mileage, 2- Too much timing since it thinks it not really at WOT, 3- Lean cruising conditions. It seems entirely possible that this could be adding to this lean cruise issue. Try turning Blue-Red up higher. The sled may jump a little when it gets into one of those special places , but there is not danger. If would be interesting to see if this didn't also help the 14:1 top 10:1 issue on top of adding Blue-green and removing some red."
If your stumbling is occuring as the blue light goes on and off then maybe your boost setting is too high? When your GEMS senses boost the boost fuel circuit is triggered and additional fuel is added....this might be causing your rich condition. You've gotta get all of these GEMS settings to work together to get proper AFR at all loads/RPMs/Throttle positions.
If that's not it I'd try backing the altitude setting way off as well, see if that helps, then inch it up 0.5 at a time. This setting changes the fuel map and changes the pressure applied to the MAP sensor as well. If the comp sees a MAP reading higher than atmospheric then I believe it defaults to 85kPa and should throw a code.
Here's a description of what this setting does from Mac @ MPI:
"Another thought about this jumping from 14:1 to 10:1 as the sled goes from green to red. To explain this, I need to explain what altitude comp is and how it works. Below a certain pressure reading on the OEM yamaha MAP sensor, the GEMS box reads the yamaha map sensor and relays the same reading to the yamaha computer. Here's the catch, If you show the yamaha computer a map reading higher than atmospheric pressure, it gets upset and jerks and jumps for a minute. This happens when Blue-red is set too high. On the other extreme, id the Blue red setting is too low, the Yamaha computer will never actually see o inches of vacuum (which it expects to see at WOT). Basically the GEMS is passing all the high vacuum data to the yamaha computer, but not the low vacuum data. If this happens, we see 2 or 3 major things happen. 1- Bad mileage, 2- Too much timing since it thinks it not really at WOT, 3- Lean cruising conditions. It seems entirely possible that this could be adding to this lean cruise issue. Try turning Blue-Red up higher. The sled may jump a little when it gets into one of those special places , but there is not danger. If would be interesting to see if this didn't also help the 14:1 top 10:1 issue on top of adding Blue-green and removing some red."
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