Hey I just recently bought a 2007.5 6.7L dodge cummins. I just bought efi live csp5 which is give me about an extra 225hp..... Everything else is stock ..... I was on i20 heading to work and usually I can get to 90 mph really easy well it was luging really bad like it didn't wana shift into 6 gear ... So I slowed down and it shifted just fine but it's still soooo slow and I was getting about 22 mpg now I'm getting around 8 mpg ... Please help me I don't wana hurt my truck any more I have to keep driving it and wana find the problem thanks!

 

Get a reading on fuel pressure

 

ok how would i do that??

 

Plumb in a fuel pressure gauge.