Previously on "This Old Truck":

https://www.ford-trucks.com/forums/1...s-showing.html

Mileage now 298,5xx. Done since last report: Oil change and filter. Trans oil change (merconIII, no leaks apparent). Tires. Front brake pads. Clutch safety switch (was interfering with cruise control operation) Coolant replacement. (see below)


Rat damage related overheat (near total coolant loss, but no MIL) at 288k. (Rat suffered acute lead poisoning later that night) No sign of rodents since.

Fuel filter change (after onset of symptoms).

NO MIL/CEL, no pending codes. CEL/MIL operates on KOST.

Temps normal (190F +/-2 deg during steady-state cruise operation, fuel flows and fuel mileage have not changed significantly. (fuel mileage has IMPROVED approx 5%, possibly due to gentler/slower driving)

M5OD with Limited slip 3.73/ payload pkg II (1650lbs)

I'm trying to collect troubleshooting ideas.


Symptoms:

Intermittent misfire on startup, seems to get better as the truck warms up. (intermittent= some days it do, some days it don't.)

Truck starts and idles well, even with misfire.

Intermittent loss of power, usually worse on days when no- or minor- misfire at startup/cold idle. From the driver seat it feels like accelerating over painted lines on a rainy day. . . a couple revs of no power, then it pulls hard for a second or two, then misses a couple of shots, lather, rinse, repeat.

Usually worse in higher gears; (not noticeable in first or 2nd, bad in 3rd at high power settings, now almost constant in 5th, to the point that truck will not accelerate below 3000rpm in 5th even on flat ground.)

Fuel flows above 4GPH/ OBDII "LOD" (engine load) reported above 75% are typical during malfunction. (Fuel flows have been as high as 9GPH with no problems on other days.)

Symptoms started at approx 292k and have been slowly getting worse over the past few months. . . . usually worse at beginning of trip, fading to very occasional after 50 miles of high-speed driving. Some days/trips no noticeable malfunction.

Thoughts:

1) Ignition wires tired? (did visual inspection, no obvious damage, but no water spray test performed, but seems likely given that the problem is most evident in conditions that would lead to high cylinder pressures.)

2) Fuel pressure? (not measured yet. . . original pump but possibility discounted due to intermittent nature of malfunction.)

3) O2 sensors tired/rat damage? (Original units still installed/ no obvious damage on cursory visual inspection under truck)

4) Injector going bad or injector wiring rat damage?

5) Plugged catalytic converters? (no sound of blown exhaust gaskets, exhaust flows well at tailpipe, with puffs at misfire.)

6) Cam sensor? (never been replaced; known issue with this model engine. Had intermittent mystery squeak that came and went at approx 250k-260k)

7) Clutch slipping? (never had one do that; always lose the throw-out first)

8) LSD problem? (fluid level/ appearance ok, last changed 150k; would expect worse in LOW gears)

9) Blown head gasket/s?

10) Cracked heads/ block? (Oil and coolant levels and appearance normal)

So: That's the plan of attack. What am I missing?

(Clutch last done approx 170k; burned throw-out, did disk, flywheel, pressure plate, slave cylinder while the trans was down. I did not open the hydraulics or disturb the pedal linkage when I replaced the safety switch. )



Thanks in advance!

 

I agree, it being a 3.0L with a intermittent squeak, with that many miles on it, with the original cam sensor assy, suggests it belongs high up on the need to replace list, along with the original O2 sensors, as they've lived almost 3 lifetimes & the same for the plugs & wires if they have a lot of unknown miles on them.

I also agree with the problem getting better with a longer drive cycle, moisture some where in the secondary ignition seems to be a clue, so doing the spray bottle wet down test & do it at night & at the temp when the engine like to act out, so your more likely to see a arcs & sparks light show, or get an off idle indication.

The specified Motorcraft, or BWD cam sensor assy ignition parts are recommended, as members have reported they have good reliability.
The new specified fine wire plug design, along with OEM plug wires, both of which are designed to take the Double work load of my waste spark ignition systems, have given my family fleet quicker year round starts & the plug spark gap is staying in spec Way longer, which my coil pack & ground switching drivers appreciate, as they don't have to work as hard to make a nice hot spark kernel to get us going in cold weather.

The coil pack is known to crack out of sight underneath & cause random misfire, so if the wet down test doesn't show anything, unbolt & raise it to spritz it underneath, to see if you can induce any break down.

If the vehicle has been driven a long time with the misfire, the cat converter could be clogged from over heating & that exhaust restriction could cause wimpy power at higher rpm, so with your vacuum gauge perform the restricted exhaust scenario 14 here http://www.secondchancegarage.com/public/186.cfm.

Those are the things from your list I'd consider doing first.

 

oooh, good tip on the under-the-coil-pack arcing. I have a spare, so that's easy to check.

I replaced the plugs with Autozone cheepies at about 285k, trying to fix the last misfire. But I have new motorcraft plugs that I was going to go to at this upcoming oil change. . . . I'll do the wire check, then plugs.

I'll likely do the wet-down check tonight, with maybe the fuel pressure if I go down to my shop (50 miles one way-- not eager to try that with the power loss getting worse.) Maybe I can borrow the wife's car. . . get the timing lite, vac guage, fuel gage etc back to the truck. . .

After that, looks like targeted parts swapping is the order of the day. (*SIGH*)

Any tips on whose 02 sensors hold up well?

 

Nothing wrong with Motorcraft O2 sensors. I replaced the OEM O2 sensors on my 94 3.8L Taurus with the specified Bosch & they fit just like the OEM & have been doing just fine for 7-8 years now.

 

UPDATE:

Turns out that you need both the VIN and the actual sensors (there's a version number or some such on the originals) to order O2 sensors from Ford for the 3.0 Flex-Fuel. Something about ECM calibrations and emissions control numbers. Not sure I believe it, but the parts guys at two different dealers both said so. . . .

Also, there are 3 wire and 2 wire versions of the CPS, and none of the components interchange. (grrrr) Make DOUBLE SURE that your parts person uses the correct part number for both the rotor AND the stator.

SO. . .Parts still on order.

In the mean time I found a crazed/age-hardened hose between the PCV line and the intake snorkus. Replacing that has improved drivability drastically-- there may be other age-related intake tract leaks that I will check when it's not 110F in the shade here.

Lesson learned so far: intake leaks on the 3.0 FF will affect drivability without setting codes on older trucks with really old O2 sensors.

The good news? because it's probably been a too-lean situation, my Cats are probably fine.

 

Yup the Flex Fuel 3.0L has some one of a kind parts requirements, like special heat range spark plugs, delivery rate fuel injectors, Maf sensor, sensor that detects the % ethanol in the fuel being used, so it can have the computer adjust fuel injector squirt time & spark & the computer has special programming to control all of that. So its best to buy parts based on the VIN # & keep the vehicle up to date on TSB's, to prevent drive ability problems.
Sounds like your slowly getting a good grip on bringing the vehicle up to date on past due scheduled maintenance replacement parts & on this Flex Fuel puppy probably best to stay with OEM parts as your doing, but it'll likely relieve you of a good size wad of your gold doing it, so don't be surprised at the sticker shock!!!!

 

Go here & scroll down to scenario 14, to use your vacuum gauge to do a quick check for exhaust restriction. How to Use and Interpret a Vacuum Gauge

 

Finally got my internet sorted. . . I think.

Engine now performs 'ok' (after PCV hose replacement) at WOT, but cruise is problematic still (though better than before)

Still no vacuum numbers (is there a version of the site PAWPAW linked that doesn't use flash/video? I'm on 56K still. . . The price I pay for a view. THIS site takes about 5 min to load a page. not sure why-- seems to be a lot of stuff loaded in the background (like 1/2 MB)).

Compression: Coolant temp 110F; crank 10 sec/hole; Throttle wide open: all cyls 165+/-7 lb dry, #4 lowest at 158, #2 and #5 highest at 172.

That tells me that mechanically the engine is fine (better than the cold numbers a few months ago. . .)

#2 plug looks a little lean but not seriously so. (that's the one that I replaced an injector in 8 months ago.)

Old plug gaps about 0.050-0.055 at approx 10k miles from new. old plugs were Champion 7963 Finewire platinums (I do NOT recommend based on durability shown; they also have smooth-side bodies, which are not as resistant to flash-over in hot-dirty-wet conditions.)

Plugs replaced with Motorcraft AGSSF22FM finewire platinum, gapped 0.043-0.044, threads touched with lead-free dry-lube before installation.

Fresh high-tension wires installed.

O2 sensors still on order.

Drive test tomorrow; will get back on results.

What does the braintrust think of the idea that the TPS might have a bad spot in the potentiometer? I seem to remember a Yamaha I had that did weird power-excursion things in cruise that turned out to be under a recall for at TPS issue ( a bad throttle pot). . . .?

 

I'd not do anything else on making running parts replacement decisions until those old O2 sensors are replaced, the computer corrupt fuel trim tables are erased & the cold & warm idle relearn procedure is done, then see how its running & perform another ELM operational scan for codes & monitor how the new O2 sensors are doing & monitor any other sensor/s the ELM finds questionable.

There are posts on how to wipe the corrupt fuel trim tables, reset/relearn the cold & warm idle strategy & do the extensive Ford emissions reset drive cycle, if your in a hurry for the emissions monitors to be reset.

 

So, it's been a while. Truck was running great after the ignition repairs.

30 miles after my last fuel top, at +/-2850 rpm, +/-70 mph, it acted like it ran out of gas, restarted, ran out of gas, etc about 1x a mile for ~5 miles (trying to find a place to pull off I-5)

once pulled off, no start condition, no codes. For about 5 minutes, then it ran well enough to get to a safer (wider spot on the off-ramp) spot. Died again.

towed to my FIL's place. ($$$.$$!)

Started right up after the tow-truck left. Idled for about 5 minutes; moved around the lot under its own power, then suddenly died. still no codes.

No significant tools, but a little reading on my phone and some head scratching indicated a potential bad fuel pump.

4 trips to parts houses later (wrong parts/misunderstood you on phone; dont carry it in flex fuel / can only get it from east coast for ($$$$.$$)/ can only buy as whole in-tank assy.): fuel pump replaced. ($$$.$$!) (never everever buying a flex-fuel anything ever again!)

fires right up, get about 2 miles, no power below 2000 rpm, barely idles.. Nurse it back, park it, no codes with my onboard scan tool.

Next day, come out, starts right up, idles well for 5 minutes, stumbles, dies. NO MIL, but I pull a **pending** P0102 (MAF low output.) NOTE: this is the first and only code that it has ever thrown) disconnect, reconnect MAF. Clear code (per FORD factory manual recommendation), clear PCM LTFT tables, etc.

Fires right up, idles 10 minutes, go for drive, fat and happy for about 500 yards, then no power below 3000 rpm. No code.

next morning, starts fine, idles 10min, dies. Pending P0102 again. Disconnect, some minor difference in drivability.

Rent a car, get home. O2 sensors have finally come in at ford dealer. On inspection at home, One is obviously used. go back to dealer, argue with Parts department. Leave in a huff.

Go back to FIL's place with tools, order MAF sensor and more O2 sensors from HIS nearby dealer.

Wait a day.

O2 and MAF sensors replaced. Reset PCM and LTFTs. Ran great for about 100 miles over 2-1/2 days running light, in traffic, on highway, pulling loads, running AC, etc. (WhooHOOO, fixed!)

5 miles from FIL's place, back to fuel starvation symptoms. Lights warning lights when it is making power (check gauge; altenator charge light.) When the warning lights go out, so does the power. Lights on: power. normal dash: no power. lather, rinse, repeat as I nurse it home.

Finally dies at a stop sign. Turns over, catches, tries to run at about 300 rpm for about 10 seconds, dies. Try again with it floored, finally catches, and as long as I keep it above 2500rpm, it'll run- makes enough power to do 45 or so; can't take it faster due to city streets.

2 blocks from FIL's house, have to stop for cross traffic, accidentally let it below 2000 rpm and the fire goes out. Cranks, Kinda catches, but won't run above 300 rpm, no matter what.

STILL No codes. Didn't think to catch a fuel pressure reading (in my defense, it was after midnight on sunday,)

Tow it again. Wife comes and gets me, brings me home.

complain bitterly on internet to people who don't really care that much (beats annoying the wife about it, though)

I've got almost enough money and patience to try once more.

Any ideas?

EDIT: the truck is 175 miles from me at the moment. . . it costs me most of a weekend to go work on it, so keep the ideas coming.