hey guys im new here ive owned my 2000 3.0 flexfuel 4x4 automatic ranger for about 2 years now it was a Wisconsin farm truck before that but has ran fine with only minor work needed up until recently first problem was a ruff idle and shaking under heavy acceleration, ran the codes and found a misfire on 5 and lean fuel bank1 sensor 1, replaced the o2 sensor, plugs, and wires. this got rid of the lean fuel issue but still had the misfire upon advice from a friend and fellow ranger owner i proceeded to change the injector on 5 as well as the coil pack but still have the misfire ive checked spark and it seems to be good i also did a compression test and seem to be holding 125psi steady im at a loss here and any help would be great im about to just scrap the 3.0 and swap in a 4.0 im getting tired of this thanks

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2005 FX4 4.0 SOHC L/S 4.10 Automatic Transmission k&n drop-in air filter, filter box mod, LED tag and back up lights

thank you for the reply but the misfire is not random it is confirmed on cylinder 5 only and everything in that video is fairly common practice ive already tried all of that stuff with no results looking for some more in depth or complicated tests/repairs the common joe knows already thanks

When you find out let us know. Actually I'm curious what it could be.

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2005 FX4 4.0 SOHC L/S 4.10 Automatic Transmission k&n drop-in air filter, filter box mod, LED tag and back up lights

Does anyone have an answer or lead on this? I have the same problem. Low RPM misfire, and then better when it gets above 2k. I replaced 1 and 5 injectors but my #1 cylinder is running 200 degrees cooler than the others. I unplug the injector and the misfire doesn't change. Has anyone's injector driver gone bad on the computer? I tried wiggling the wires and checking for broken ones, but to no avail.

I had a similar issue awhile ago, swapped out the coil packs and the issue disappeared.

i had some similar issues.. the rough shaking was from worn out camshaft synchronizer and i was getting a random misfire with misfire #5 sometimes... it would cruise low rpms fine but couldnt accelerate without misfiring and was getting worse and worse.. after pulling and cleaning the injectors, replacing fuel and air filter, cam synch, new plugs and wires..
it ended up to be a plugged up cat.. cat 1 on bank 2 fell apart and plugged up cat 2 bank 2... i checked by pulling the Y section of exhaust from the manifolds to the 3 bolt flange at the cat.. blew some compressed in one side and my hand covering around the air gun and i could feel air pushing my hand on one side but not the other.. i just smashed out the guts of the 2 cats on bank 2 and put it back in.. running fine so far.. well see how smog goes

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2003 Sonic Blue Ranger Edge Plus 2WD 4dr, Rebuilt FFV 3.0 v6, ported heads/intake, throttle body halfshaft mod, Flowmaster, 250amp alt, 2 - 15" sundowns with BAMF 5500w amp

When was the fuel filter last changed? How many miles does the fuel pump have on it? Have you run a fuel pressure test at both rails? Have you checked for leaky intake manifold gaskets?

An engine needs:
1) compression
2) fuel and air at close to the ideal ratio
3) spark (and at the proper time)

Youve verified you have spark and compression. This means either you have an issue where the spark is off time only for that cylinder (ive never actually heard of a pcm going bad in this way- this was more common when cars used distributors and the cap would go bad), no fuel in that cylinder (unlikely with a new injector) or your fuel to air ratio is off.

How many miles have you put on it since changing the o2 sensor? You may still have a lean condition and it just hasnt got done testing. Usually takes 80-100 miles with city/hwy for the pcm to finish all its testing and trip the CEL

Heres what you could try:

1) Rent a fuel pressure tester and check fuel pressure at both rails. Should be in the 50's psi range AT LEAST, and preferably in the 60s.

2) Rent or borrow an OBD2 scanner and check your Long Term Fuel Trim (LTFT) values for both banks. High positive values (truck runs lean and pcm must increase the injector open time by X percent) usually indicate a plugged filter, weak pump, or vacuum leaks (leaky intake manifold gasket leaking at cylinder 5 seems possible). High negative values (truck runs rich and pcm must decrease injector open time by X percent) are usually a bad fuel pressure regulator or sticky injector.

3) If 2 shows high positive values, use an unlit propane torch/carb cleaner/starter fluid (carefully!) to find where your vacuum leak is. Youll notice idle speed increase when youve hit the leak. I would DEFINITELY be checking all around the intake manifold at cylinder 5.

4) Disconnect the battery and turn the headlight switch on overnight. This resets the pcm and forces it to relearn all its fuel tables based on MAF and o2 sensor data.

Good luck

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s

Never heard of turning the headlight switch on. What does that do ?

For your situation you might want to pick up an OBDII wifi adapter and the dash command app to help you watch and diagnose your truck. It sure helped me when I had engine trouble. Tells you everything in real time off sensors and helps you make an informed conclusion. Even checks and clears engine codes.

Here's an example of one small portion of the app

Attached Images

image-88662053.jpg (50.8 KB, 2 views)

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Ford ranger 2001 edge, 3.0 vulcan, manual transmission, 3.73 open diff., 29" tires, 1.8 ratio Harland Sharp roller rockers, fender pod filter intake, MSD ignition wires, thrush glasspack, last catalytic comb delete, Electric fan, Nitrous Express wet kit 50 shot atm (soon to be supercharged, eaton m90, custom designed supercharger adapter intake by me )

I'm parroting the advice of others. Most people suggest turning it on for a period of time when the cable is disconnected; i would surmise it is either a signal to the pcm to clear fuel maps (and codes, etc), or somehow drains residual current stored in the vehicles electrical system. I would think however outside of possibly a few small capacitors in the pcm, there wouldnt be enough stored to require the headlights as a drain..

As long as the OP makes sure his fuel trims start from scratch, that's what matters.

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s

Just need to disconnect ground cable from battery for 20 minutes. That's it.

Good to see a direct answer on it. Bad google-fu I guess. I guess they built that in so that changing a battery would erase what the pcm had stored?

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2002 Ford Ranger XLT Supercab, 2.3L Duratec I4, 5-speed manual, 4.10 gears, ~100,000 miles
Power nothing with air conditioning; crank windows for life!
Throttle cable mod, retained accessory power mod, 2006 thermostat w/resistor mod
Headlight relay harness, Philips xtreme-vision bulbs
P235/75R15 Michelin LTX M/S2s

IDK. It's what I've always been told. I've always just disconnected mine before bed the night before I plan on doing whatever to the truck.

Do a leak down on # 5

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There is a way that seems right to a man, But its end is the way of destruction