Successfully solved a low RPM acceleration sputter a few weeks ago but now I’ve been getting significantly lower gas mileage. Normal MPG is about 15-16 monitored for years, but it has dropped to 13 tops.
here’s a timeline of the issues and troubleshooting:
while stuck in a traffic jam I started to notice some sputtering at low rpm acceleration. It seemed to only show up after driving for awhile. No CEL or codes. Rich smelling exhaust.
After reading about probable causes I decided to take a shot in the dark and replace the upstream O2 (went with NGK). Unfortunately this didn’t solve the issue. So I started working though other possible causes.
Cleaned the throttle body along with the associated 3 sensors (TPS, MAP and IAC). It was pretty dirty but nothing outside the norm. No change in symptoms. Also checked TPS voltage (.96-3.9vdc).
Checked for vacuum leaks. Found a a few crusty vacuum 90°s and couplers so I replaced everything that looked suspect. Still no change. Figured a quick tuneup wouldn’t hurt.
Changed out ignition parts one at a time. Cap and rotor no change. Popped a new coil in and boom! All the sputtering is gone. Continued with the remaining ignition parts (APP985 .035 gap plugs, united Motor wires, cap, rotor and coil)
the jeep is running well but my mileage has really dropped off. Could it be the ignition parts? Or maybe some other issue? Any quick checks to rule out some of the pricy sensors?
Appreciate any advice.
Ben
99 TJ 4.0 manual 3” sus lift 32s stock gears
here’s a timeline of the issues and troubleshooting:
while stuck in a traffic jam I started to notice some sputtering at low rpm acceleration. It seemed to only show up after driving for awhile. No CEL or codes. Rich smelling exhaust.
After reading about probable causes I decided to take a shot in the dark and replace the upstream O2 (went with NGK). Unfortunately this didn’t solve the issue. So I started working though other possible causes.
Cleaned the throttle body along with the associated 3 sensors (TPS, MAP and IAC). It was pretty dirty but nothing outside the norm. No change in symptoms. Also checked TPS voltage (.96-3.9vdc).
Checked for vacuum leaks. Found a a few crusty vacuum 90°s and couplers so I replaced everything that looked suspect. Still no change. Figured a quick tuneup wouldn’t hurt.
Changed out ignition parts one at a time. Cap and rotor no change. Popped a new coil in and boom! All the sputtering is gone. Continued with the remaining ignition parts (APP985 .035 gap plugs, united Motor wires, cap, rotor and coil)
the jeep is running well but my mileage has really dropped off. Could it be the ignition parts? Or maybe some other issue? Any quick checks to rule out some of the pricy sensors?
Appreciate any advice.
Ben
99 TJ 4.0 manual 3” sus lift 32s stock gears