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heavy misfire/stumble, low power, no cel


choatecostoms

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hey everybody,
first time poster long time reader.
honestly i've got a bit of a thick head and like to figure things out for my self but i am literally at my wits end with my truck.

little back story "long made short" bought my 1993 ranger 3.0 last year with engine issues. turns out the guy had replaced the short block not even 2000mi before and whoever did it did a real crummy job, i mean missing bolts, things were loose all around hack job.
anyway, i pulled the motor and went through the whole thing "not my first rodeo" bottom end, indeed checked out to be a replacement short block as there was still cross hatch in the cylinders and no lip. made sure the block and heads were true and re-lapped the valves, verified cam timing, verified everything was at spec torque in the lower end and re-assembled the motor.
after that the truck ran like a top! i put over 500 mi on the truck with absolutely no issues, until i parked it for about 3 weeks.
upon starting it after its short slumber i noticed a slight rattle coming from the motor but continued with my drive, about half way to work the rattle got extremely loud then silent and continued to be intermittent and not RPM dependent the rest of the way to work.
after work i headed to pick up a four wheeler, got there hooked up the trailer and loaded the wheeler up. not 2 miles down the road i literally lost all power the truck would not get out of its own way "no CEL" i limped it home.

since then there has not been a cel so i have been blindly testing, well everything.

since owning the truck i have replace;
coolant temp sensor
IAC valve (due to high idle)
distributor
distributor cap and rotor
spark plugs (motorcraft platinum's)
spark plug wires
fuel filter
both pre cat o2 sensors
waterpump
alternator
all 6 injectors

also to date i have tested;
ignition coil
ICM
TPS
MAP
engine vacuum (holds steady 21hg at idle)
fuel pressure (holds steady 34psi at idle)
cylinder compression (1,2,3,4 and 6 all read about 150-155 but 5 was at 170, 5 also had and odd un-matched injector)

i have had my scan tool hooked up to it multiple times, bank 2 o2 sensor always reads high (rich .7-.9) bank 1 reads lean most of the time .12-.2 but both do fluctuate. although KOER test come back with bank 1 and bank 2 rich errors. and the plugs are black with soot on both sides.

i have been grabbing at strings and banging my head against the hood trying to chase this problem, and i am finally asking for help "ugh the feeling of defeat" any help or insight would be much appreciated.
also i have checked grounds and verified continuity from sensors to ecu, and that "rattle" is still there.
 
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RonD

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Welcome to TRS :)


Rattling could be timing chain tensioner failing, which would cause erratic loss of power.

With engine COLD
Loosen and remove fan belt from crank pulley, so no Fan noise in engine bay
Start engine and listen at the front cover for the rattle
You can only run the engine without a water pump for 2 minutes, so BE QUICK locating the noise.

Blackish spark plug tips should mean actual Rich running
Lean or Rich codes do not mean lean or rich running, they are based on computer calculations for fuel injector open time, just FYI

Rich code is set when fuel trims are negative, i.e. -15%, +15% would set Lean code
This is because the computer is opening fuel injectors for 15% LESS time than it calculated for the air flow, because O2 sensor showed Rich at 0 Fuel trim, 0 is computers calculated open time, so +15% would mean computer is leaving injectors open 15% longer because O2 showed Lean at 0 fuel trim

Fuel Pressure Regulator(FPR) on the engine has the Fuel Return line attached AND a Vacuum hose
FPR can leak internally, fuel is then sucked into the engine via the vacuum hose, so actual Rich running
Check vacuum hose for fuel.

Does Fuel Pressure hold with key off?
It should, if not then fuel is leaking out of the system, could be FPR, or fuel pump check valve, maybe even a faulty new injector.
 

choatecostoms

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I don't believe there is a timing chain tensioner on the 3.0, or at least mine does not have one. i pulled the front cover off when i went through the motor to verify cam timing and didn't see one.

there is no fuel in the FPR vacuum line that i saw, ill put the gauge on in the morning and re check fuel pressures as i have not had it on since i installed new injectors.

i have not tried running without belt yet, i will do this as well in the morning.

the noise seems to be louder under the motor and sounds like its coming from the crankshaft pulley area, but i have probed around just about everywhere with a stethoscope without the fan installed and could not pinpoint the noise.
 

RonD

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OOPS, yes I knew that, lol
3.0l Vulcan didn't use a tensioner
 

choatecostoms

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So koeo fuel pressure is 35 running its 32 remove fpr vacuum its 40. And when you shut the engine off it slowly drops pressure. Is there a good way to pinpoint either fpr, injector or check valve?
 

choatecostoms

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Ok so it appears the fitting on my gauge at the fuel rail is leaking causing the drop
 

choatecostoms

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So on a whim I just replaced the ignition coil (motorcraft) it helped drivability slightly but still is not running good. Also re verified grounds all are good. Anybody have any idea where to look/check next? I am out of ideas at this point.
 

98rachael

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Id say pull your valve covers just to get a look at your push rods make sure none are bent, im going through fixing my dads truck now for a bent pushrod on cylinder 2 similar symptoms to yours
 

kimcrwbr1

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Have you done a compression test? How good is the oil pressure? Maybe a compression and leakdown will reveal something?
 

choatecostoms

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So I got fed up with chasing things down and pulled the motor again. After removing the intake manifold , low and behold I find 3 wiped lobes on my camshaft. After much digging around I found that the short block the previous owner had installed was from an 80's Taurus and was never ment for the ranger. Long story short he had roller lifters installed on a flat tappit cam and no spider to keep the lifters aligned with the cam. Why I missed this when I did head gaskets I dont know ugh (no threaded holes in valley for spider). But it's all back together now with new cam, lifters and pushrods well as timing chain and gears due to noise/slop, and its running pretty good, with the exception of extremely poor gas mileage I'm talking about 8 mpg. After previously going through just about everything and replacing a lot of things I'm at a loss for reason once more. Also the truck starts fine cold but starts hard when warm. Any ideas? List of things replaced is in first post.
 
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RonD

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Check Fuel Pressure regulators vacuum hose for gasoline

Cold engines like extra fuel, warm engines do not


Fuel injector harness could have a short to ground or close to it, causing an injector to stay open longer than it should
When wiring gets older it can crack a bit when you move it around
 

choatecostoms

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No fuel in the fpr vacuum line, is it possible for this fpr to fail in the full open position? After I replaced the injectors but Before I pulled the motor the second time I checked each of the injectors by back probing the connector to verify signal and ground, they checked ok. Also checked impedance of each injector. I will check signal and ground again while wiggling the harness this weekend, see if I cant find a bad/broke wire.
 

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You said you replaced the coolant temp sensor, not questioning your mechanical abilities but are you sure you did the sensor and not the sender? They are commonly confused, especially by parts stores but do totally different things. A bad temp sensor can cause poor starts when warm because it's still telling the ecu the engine is cold and adding extra fuel. As Ron said, cold engines like fuel warm ones don't.
 
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choatecostoms

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Yes I replaced the 2 wire sensor, this motor has a single wire sender for the gauge.
 

RonD

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Fuel injectors should have 12volts on red wires with key on, other wire is the ground which computer uses to open them for a few milliseconds to add fuel

So the other wire should not be a ground when key is on
If you take connector off and test voltage using the two wires is should be 0 volts because there is 12v but no ground.

1993 computer may just have 2 ground wires out to the 6 injectors, called Batch Fire injection
So computer opens 3 injectors at the same time and alternates
All the injectors will have the Red wire
If the "other wires" only have 2 colors then its batch fire, if each injector has a different color "other wire" then its sequential injection, so 6 Ground wires back to computer
 

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