MPI Apex Stage 1 Dead Spot 7K RPM's

[mmaman207]

MPI stage 1 on my 07 attak. Has over 7K problem free miles (this kit has been awesome from Day 1) on it, until now. Last trip right off the trailer sled was falling on its face with no power and registering only 4ish psi boost. Brought it into the garage and found the sensing line from the intake to the GEMS was dry rotted, cracked, and leaking. My bad for not seeing it sooner. No big deal. Fixed that issue.
Since then its registering 10-10.5psi boost on my gauge, most I've ever seen before is 8.5-9psi in all these years of running it?? AFR's are still good all the way through and WOT AFR's are still spot on, no issue. And it still pulls like a freight train!
Problem is it now has a dead spot right at 7000-7300RPM's. Sled falls directly on its face, almost acts like its shutting off for a split second. Will do it repeatedly only at this RPM when pulling through it at trail riding speeds. Runs smooth as silk below it and above it, with AFR's where they always have been. No codes thrown, or any other funny business... just dies for a second then takes off again right at that RPM!
If I squeeze it WOT it runs right past the dead spot and never misses, or if it does it so fast I cant feel it, and subsequently still sucks up all my buddies and leaves them
Anyone seen a miss like this before?? Any ideas where to start??

 

[givemeaboost]

I've never messed with an Apex but it sounds like a dead spot on the throttle positioning sensor.

Ken........

 

[mmaman207]

Copy that... u have something similar happen on a different sled?

 

[givemeaboost]

It will happen on a fuel injected car so why not on a snowmobile ?


Ken...............

 

[YamerHammer]

Ya it did it on mine apex as well. I had to put a voltage clamp on the tps. hurricane sells them. I thought by changing the fuel controller to PCV to iron things out. Didn't work. Put the clamp on and BOOM powerband just like a stocker.

 

[mmaman207]

Alright... Ill check it out. Thanks!

 

[mmaman207]

I spoke to Hurricane, he says that its not the problem.... and to look elsewhere.

Any other ideas??

 

[YamerHammer]

Boost leak?

Sent from my Pixel XL using Tapatalk

 

[mmaman207]

I dont think so.... Its actually reading more boost than before. Makes me think lean miss.... but begs the question how is a belt driven supercharger suddenly making more boost than it has for the last 7 years?? All i did was get rid of the leak in the boost sensing line back to the GEMS....

 

[YamerHammer]

My guess you have a leak between the intercooler and motor. One of the throttle bodies is leaking causing false boost readings.

Sent from my Pixel XL using Tapatalk

 

[thor452]

maybe that line was no good from the start and leaked a little all along now the gems is reading more boost and your fuel measures are off. what pulleys are you running? I would attempt to adjust the mid range settings on the gems up a little. if all your afr readings are still good but have changed you may just be able to change the elevation setting I played with that on mine a few times and it worked. I had the issue you are speaking of on mine when I was tuning in the gems but my afr's would spike too. by playing with settings in gems I was able to work it out. 10 lbs is too much boost unless you are running race fuel or have a head shim. something is not right there too.