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I got a 1996 f150 with a 4.9l from a friend with 98k miles on it. it now has 113k. I'm the third owner, and it sat for at least 10 years before I bought it.
The check engine light was on when I got it, and I unloaded the parts cannon multiple times on this truck.
Items replaced: (Motocraft where possible)
Vacuum Lines
EGR valve
EGR solenoid
DPFE Sensor
TPS
IAC
All o2 sensors
Coil
Plugs
Wires
Complete Distributer
MAF
Vapor Canister Purge Valve / Solenoid
Speed sensor
Temp Sensor
Knock Sensor
Ignition module (had the incorrect one)
Air filter
front and rear tanks with pumps (45 psi)
fan clutch
Front transmission seal
Valve in transmission valve body that was sticking. not allow upshift past second gear.
Secondary air system checks out ok.
15 of vacuum at intake
No exhaust back pressure
I've been driving, researching, and trying things that have no effect.
I've owned Fords all my life and I know this truck should be able to maintain speed with minimal throttle input. I can be doing 60 and on a 1/4 mile incline I'll have the peddle on the rug and be doing 45-50 when I crest the hill. Gas milage is atrocious at 8mpg.
The truck idles a little rough, but still quite.
One winter I was going to start the truck to let it warm up and it fired to soon which broke the nose off the starter. I've checked the timing so many times it's sickening. 10 degrees tdc.. Even did the piston stop tool method to make sure the timing marks were ok. It still hits hard on the starter on occasion.
Short and Long term fuel trims look ok to me.
One time I was driving to work, and out of the blue it decided to feel like someone tossed in another few cylinders worth of power! it Drove like I thought it should. Plenty of power, held it's own with minimal throttle input! I was so happy! Then I had to drive it home that evening, and it was a dog again.
I'm at my wits end, and any help would be greatly appreciated! I know I can get this turd polished! Onto fixing this ABS light for now..
Sounds like a intermittent stuck open injector, loosen the plug wires so they are just making contact on the plugs, fire it up and pull one wire at a time with insulated pliers, which cylinder doesn't make a rpm change?
I've thought about this, and experimented with this procedure. I changed out the injectors, and flow tested the originals. The injectors were good. I was thinking that there may be a short in the injector harness some place, but I can't figure out a way to get a node light on the injector connectors without pulling the intake off. Waiting for it to dry off outside. I'll pull the intake and harness. Replace the connectors and check out the harness.
What did the test show? Any one cylinder contributing less than others? What about a fuel pressure leak down test? The starter breaking makes me think of hydraulic lock
Each cylinder dropped out like expected. I just scoped the injector wires at the ECM and all the traces look normal. Running the cylinder contribution test on the scan tool has no major changes.
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