SoHK_alumni
Well-Known Member
- Joined
- July 29, 2014
- Messages
- 462
- Reaction score
- 12
- City, State
- Tampa, FL
- Year, Model & Trim Level
- 5.0 V8 2002 Ranger
I have a 1996 Explorer 5.0 tucked into the nose of my 2002 Ranger. Went through the 5.0 before installing but had to have missed something. Getting very poor fuel economy and I can't figure out why.
Hoping a fresh set of eyes and minds might turn up an idea or two cause I'm surely out of ideas and know I've missed something somewhere.
Symptoms:
13.5 – 14.0 mpg average fuel economy over 3K miles
Noticable miss, particularly at 35/40 mph – 1500/1800 rpm but idles smoothly at 700 rpm
Perfect cold but poor/long/stumbling hot starts. (inline fuel check valve seems to have resolved the hot start issue)
No CEL/Fault codes
Fuel economy same driven gently , or enthusiastically.
No change to engine behavior when CPS taken out of time.
Test data:
130 – 135 psi dry/cold compression across all 8 cylinders (perhaps a bit low?)
Both short and long term fuel trims hover around 0%
Engine temp sensor reports 195° – 205°
Idles w/23” vacuum
Correctly toggles between open and closed loop fuel management
Speedometer accurate to within 1.5 mph at 70. (vss vs gps)
0 PSI exhaust back pressure at front 02 ports at 50 mph.
Specifics:
02 Ranger w/’96 Explorer 5.0, 4R70W box, rebuild Ford 8.8 TracLoc w/3.27 gears, TM headers, original Cats, 3” exhaust after cats. Stock cam, pistons, GT40 heads.
145K mile engine refreshed with rings, bearings, valve springs, t-stat, pcv etc. Block, cam and crank mic'd well within spec.
New plugs, air filter, front O2 sensors
Std copper and platinum plugs are clean, gapped to .054” – still look new
2 sets ignition wires
Original and “rebuilt” set of fuel injectors
Original and replacement FPR
Original and Accel ignition coil packs.
Original and replacement CPS, timed with OTC alignment tool while timing cover off the engine
Original and replacement Crank Position Sensor
Original MAF, TPS and IAC
Found harmonic balancer was 10° off, replaced with new, no change (of course found the new is 5° off!)
Original and replacement PCM.
Very strong spark at all 8 coil towers.
Verified fuel pressures, both with and without vacuum to the FPR.
The offending lump:
Hoping a fresh set of eyes and minds might turn up an idea or two cause I'm surely out of ideas and know I've missed something somewhere.
Symptoms:
13.5 – 14.0 mpg average fuel economy over 3K miles
Noticable miss, particularly at 35/40 mph – 1500/1800 rpm but idles smoothly at 700 rpm
Perfect cold but poor/long/stumbling hot starts. (inline fuel check valve seems to have resolved the hot start issue)
No CEL/Fault codes
Fuel economy same driven gently , or enthusiastically.
No change to engine behavior when CPS taken out of time.
Test data:
130 – 135 psi dry/cold compression across all 8 cylinders (perhaps a bit low?)
Both short and long term fuel trims hover around 0%
Engine temp sensor reports 195° – 205°
Idles w/23” vacuum
Correctly toggles between open and closed loop fuel management
Speedometer accurate to within 1.5 mph at 70. (vss vs gps)
0 PSI exhaust back pressure at front 02 ports at 50 mph.
Specifics:
02 Ranger w/’96 Explorer 5.0, 4R70W box, rebuild Ford 8.8 TracLoc w/3.27 gears, TM headers, original Cats, 3” exhaust after cats. Stock cam, pistons, GT40 heads.
145K mile engine refreshed with rings, bearings, valve springs, t-stat, pcv etc. Block, cam and crank mic'd well within spec.
New plugs, air filter, front O2 sensors
Std copper and platinum plugs are clean, gapped to .054” – still look new
2 sets ignition wires
Original and “rebuilt” set of fuel injectors
Original and replacement FPR
Original and Accel ignition coil packs.
Original and replacement CPS, timed with OTC alignment tool while timing cover off the engine
Original and replacement Crank Position Sensor
Original MAF, TPS and IAC
Found harmonic balancer was 10° off, replaced with new, no change (of course found the new is 5° off!)
Original and replacement PCM.
Very strong spark at all 8 coil towers.
Verified fuel pressures, both with and without vacuum to the FPR.
The offending lump: