MPI turbo backfire

[Joey P]

If the gems was not changed then its most likely set in the middle...

where should i have it set to then

 

[Joey P]

If the gems was not changed then its most likely set in the middle...

and if it was set in the middle would that cause it to backfire

 

[Yamadog]

You are a bit rich at 9.7 and dumping raw fuel. Most of us are at 10.4 to 10.9. I know it sucks, $$$ but I would not trust the Koso gauge.

 

[Joey P]

would 11 to 12 be in the ball park

 

[Yamadog]

would 11 to 12 be in the ball park

I think that is a bit high. I melted one down last year. Everything I have gained on this subject from Matt at MPI, Allen Ulmer and othre motor guys is this motor likes to be sub 11 at WOT. Allen tuned mine and I am consistently seeing 10.5 at wot.

 

[matt@mpi]

When you hit the rev limiter it cuts ignition but still is dumping fuel. So all that un-burnt fuel collects in the muffler and gets hot enough to combust. That's were the back fire is coming from.

 

[Joey P]

When you hit the rev limiter it cuts ignition but still is dumping fuel. So all that un-burnt fuel collects in the muffler and gets hot enough to combust. That's were the back fire is coming from.

Thanks I'll be sure to lean it out a bit more

 

[Kerrdog569]

You need to add some weight to your primary clutch weights to keep it off the rev limiter also

 

[MrSled]

Here are my setting at 6 lbs of boost on the first gen turbo.
Green:3
Yellow:4
Green blue:4
Red:3

 

[matt@mpi]

Here are my setting at 6 lbs
Green:3
Yellow:4
Green blue:4
Red:3

This WON'T apply to any of the Yamaha kits that shipped this year!!! The controllers used last year has a different base setting and those numbers could be a problem. I know your trying to be helpful but the fuel maps are too different.

Please don't make adjustments without a QUALITY AFR gauge. Don't make any adjustments until your clutching is dialed in.

 

[MrSled]

This WON'T apply to any of the Yamaha kits that shipped this year!!! The controllers used last year has a different base setting and those numbers could be a problem. I know your trying to be helpful but the fuel maps are too different.

Please don't make adjustments without a QUALITY AFR gauge. Don't make any adjustments until your clutching is dialed in.

Well thats good to know and I guess I will leave it all up to you... scratch any help from me.

 

[matt@mpi]

Well thats good to know and I guess I will leave it all up to you... scratch any help from me.

Your just trying to help!

 

[Joey P]

the afr gauge is working right it set up the right way and iv hadn't had any problems with it my boost is at a steady 5psi and we used a another afr gauge it was saying the same as the koso

 

[WootTootViper]

Hey I’m new to the turbo game as well and completely confused lol and my sled backfires when I let off after a good long haul or if I’m getting a little brappy with the throttle how do I find my AFR and my local dealers aren’t much help.