A lot of boost, but little power

[Stigapex]

Hello

I need some help here.
The sled is a APEX XTX 2011, with MCX 290
Earlier this winter I had no problems driving with 19 PSI for very short runs 500-660ft with premium fuel.
I never use to run any longer with full throttle. The sled worked all god and no error codes.

For a couple of weeks I have drived with 14 psi, everything ok.
I have a boost controller so its easy to change when I want.

Now I wanted to drive again with 19 psi, but all of a sudden the sled want give any power at 19 psi.
At 14-15 psi, no problem.
The sled is clutch-setup for 19 psi, so it will not hit the rev-limiter.
But when I hit full throttle with 19 psi, I miss a lot of rpm, and a lot of power.
The boost reader says 19 psi, and the af-reading is ok.
Earlier this winter 10800 RPM, and runed very well, now 9200 RPM, and feels like a 150 hp is missing.

I get no error-codes.
I have changed the spark-plugs CR9E, gaped to 0,018.

I can't hear anything wrong, but it's just no power.
Could the fuel be bad?, wouldn't that give me a code 65 if the knock-sensor is retarding timing.

I just can't figure it out, if someone have an idea, please help

 

[Riceburner]

Go back to 14 psi and see if it still works ok.

If not, check the rod that holds the air to air inter cooler in place.
This may have broken and the inter cooler may have come off the throttle bodies

This happened to a fell on with the same kit on a 2012.

 

[Stigapex]

Work ok at 14 psi.

The intercooloer is in place
I can't think that I have any leaks, because I get the boost I should have. I have 19 psi, but I don't have the power.

The only place I could think there would be leaks, is beetween throttlebodies and engine.

Where the vacuum/boost-read lines is connected I have the boost I should have, but if one of the rubbers is leaking, would I read 19 psi boost, but stil miss boost at one or more cylinder.

What if some of the injectors are bad, how will the engine then react?

 

[mbarryracing]

What is your AFR / Air Fuel Ratio when at 19 psi boost and full throttle?

 

[sleddog66]

i am not at all fimiliar with these turbo systems, but it seems to me that you may be on to something with the knock sensor. I can tell you that when it activates, it can leave a pile of power on the table. Maybe try some fresh fuel/high enough octane.

 

[machzrobbie]

Hello

I need some help here.
The sled is a APEX XTX 2011, with MCX 290
Earlier this winter I had no problems driving with 19 PSI for very short runs 500-660ft with premium fuel.
I never use to run any longer with full throttle. The sled worked all god and no error codes.

For a couple of weeks I have drived with 14 psi, everything ok.
I have a boost controller so its easy to change when I want.

Now I wanted to drive again with 19 psi, but all of a sudden the sled want give any power at 19 psi.
At 14-15 psi, no problem.
The sled is clutch-setup for 19 psi, so it will not hit the rev-limiter.
But when I hit full throttle with 19 psi, I miss a lot of rpm, and a lot of power.
The boost reader says 19 psi, and the af-reading is ok.
Earlier this winter 10800 RPM, and runed very well, now 9200 RPM, and feels like a 150 hp is missing.

I get no error-codes.
I have changed the spark-plugs CR9E, gaped to 0,018.

I can't hear anything wrong, but it's just no power.
Could the fuel be bad?, wouldn't that give me a code 65 if the knock-sensor is retarding timing.

I just can't figure it out, if someone have an idea, please help

When you say premium fuel - what octane are you running?? You need octane for that much boost or it will set knock sensor and reduce power, and it will not set a code. I took a headgasket out running 20 psi on 50/50 c-12 this winter because I was too lazy to drain the tank and fill it. Becareful running more then 18 psi with stock rods, we ran the asphalt all summer and a couple times at radar runs this winter and one of our motors threw a rod at 19lbs on striaght c-12 - no signs of deto, just a broken rod.

 

[Stigapex]

Thanks for the help
but it was the throttlebody that was loosened, so that problem was solved.

I'm running 98 oct european, I think that will say 93-94 oct in US.
I know I'm playing with the fire, when I'm driving that kind of boost with that octan but no problems with that so far.
I never hold full throttle for more then 7-8 seconds with that boost.

From 2011 the Apex have a knock-sensor, and I can't understand why it want give a code if its activated.

From what I understand with the Arctic Cat Turbos, they use the code from knock-sensor to adjust how much boost the sled can handle.
I lot of 2-stroke sleds have knock-sensor, and they give a code if its activated. Why wouldn't Apex give a code if its activated ?

 

[machzrobbie]

Thanks for the help
but it was the throttlebody that was loosened, so that problem was solved.

I'm running 98 oct european, I think that will say 93-94 oct in US.
I know I'm playing with the fire, when I'm driving that kind of boost with that octan but no problems with that so far.
I never hold full throttle for more then 7-8 seconds with that boost.

From 2011 the Apex have a knock-sensor, and I can't understand why it want give a code if its activated.

From what I understand with the Arctic Cat Turbos, they use the code from knock-sensor to adjust how much boost the sled can handle.
I lot of 2-stroke sleds have knock-sensor, and they give a code if its activated. Why wouldn't Apex give a code if its activated ?

I have a 2012 with a 290 MCX kit on it and I know the knock sensor has saved my motor a couple of times as you can feel a reduction in power and rpms drop when running close to the edge - but never a code. I think that because the apex was not designed for boost it just adjusts timing for the knock it senses and carries on just like cars do - I know what you mean about running without problems - so far - my sleds been good but - but this is what will happen eventually.

 

[yamaha1973]

Ouch! ^^^

 

[jabber800]

That's ugly! Is it Ernies sled?

 

[Stubbs]

Yup!