Engine Performance problem
1994 GMC C2500 V8 Two Wheel Drive Automatic
I have a '94 GMC 2500, 6.5l turbo diesel. With stock equipment, when traveling at 70 mph, it was turning 2100 rpm's. The average fuel economy was 15 mpg. I installed a k& n filter and 3" custom straight pipe exhaust. Now, when traveling at 70 mph, it is turning 2500 rpm's. What would cause this increase? If anything, I would have expected lower rpm's at cruising speeds. Also, the fuel economy has not changed, or possibly decreased slightly. Of everyone I have spoken to, nobody has any idea as to what is happening. Thank you for any help you may offer.
Thursday, April 22nd, 2010 AT 8:47 AM