MOTEC M150, DODGE VIPER

Procharged Viper, we’re running M150 loud pops and burble on decel. Can’t seem to find out why it’s doing this. Also in the transient zones, it’s fluctuating fuel trims. On decel it’s really rich and on acceleration, after a shift, it’s lean causing detonation on tip in. Hopefully you guys can help me out. Thanks in advance.

Do you have Engine Overrun Mode enabled (this will enable what is typically referred to a Deceleration Fuel Cut Off - DFCO). Most package have this available for setup in M1 Tune Workbook: Engine Systems->Engine Overrun

I would think your shifting issues would probably be addressed with tuning the Fuel Film system. Workbook:Tuning->Fuel Film Primary For starters just play with the Scale to see if you can see a difference -- I have cars that like 75%, and some that like 250%. There are also a couple of methods for the complete calibration. See the help for "Fuel Film Primary" for details.

Is your Intake Manifold Pressure Sensor located post throttle? I could see some of your issues happening if the sensor was incorrectly measuring between the Procharger and the throttle plate.

Jonah,

As long as the main VE table is well dialed in, fuel film adjustment will likely take care of the transient concerns you have. That's Motec's means of accel/decel enrichment as well as wall film management. It definitely takes some time to dial in just right, but then the engines stay on target really well in transients.

As David mentioned, you can disabled fuel on decel, but you can also run fueling and not have it popping and burbling with adjustment.

Edit: I forgot to mention, if you happen to be dealing with a fuel system that isn't maintaining stable differential fuel pressure and there isn't a sensor to account for it, or you're working with injectors that aren't fully and accurately characterized, that can be a factor in the transients issues you're running into as well.

I will adjust the fuel film and see if it makes a difference. We disabled over run a while ago but the popping is still there. We will be removing the procharger and going to turbos soon in the future. I will keep you updated on how things turn out.

David,

The MAP sensor is located in the intake manifold, post throttle body

Enabling the Overrun System is what disables the fuel (and should help the situation). Of course, you can also tune the VE table to not provide any fuel and correctly advance the ignition in the overrun area.

Mike,

The fuel system is controlled via PWM by the MoTec. We have a fuel pressure sensor on the regulator to monitor fuel pressure as well. It also is ran into the MoTec.

David that’s very true. I will try that next!