yea for christian!

 

nevermind that...

must be the spark plugs, also, that need changing...

it's doing it again, and the #6 cylinder is throwing the mis-firing code..

 

Mine did the same thing except is that cylinder #3. Changed all the plugs and it runs fine. The old plug didnt even look bad so i dont know what caused it...

 

ok, spark plugs and wires changed already....

it was still doing it...

so i replaced the oil filter, threw some cleaner/booster in there, put $40 worth of super unleaded in it... and it's still acting up...

i can get all the way to 70mph, but it sputters so much.... it's like the exhaust stays consistent, but the motor is spitting...

 

Vacume LeaK? I have no clue

 

bump?

when the motor is cool it doesn't do it...

run the motor for more than a minute, though, and it starts acting up...

 

i own a ford ranger site, and no one has advice...

so sad

is this my punishment for not being prompt w/ stickers?

 

Did you try disconnecting the hose to the EGR as suggested above? Excessive EGR will cause surging or bucking.

Try watching the engine in the dark again. It's easy to crack the porcelain on the spark plugs when replacing them.

If it only does it during high vacuum conditions (idle, part throttle), then you could have a manifold vacuum leak.

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Here's an off the wall idea. The oxygen sensors don't work immediately after you start the engine. There is a short time delay to allow the sensor heaters to bring the sensors up to operating temperature. I guess it's possible that your problem only occurs in closed loop A/F feedback mode when the sensors are in use.

Does it do it at WOT? If so, then it can't be anything to do with closed loop. WOT is open loop using a table for the A/F ratio. If it does it at WOT, then that theory is out the window.

If it does it during part throttle operation but doesn't do it at WOT, then disconnect both O2 sensors and drive it to see if that helps.

 

I don't have to floor it. Just a little more than the least amount possible, or anything over about 2500 rpms...

 

Does it ever do it when you floor it?

 

yes.

 

Ok, then it cannot be the closed loop fuel control.

What about these other items?

 

The spark plugs and wires all seem to be kosher.

What's the EGR?

 

its where some the exhaust goes back into the engine from the manifold (check the drivers side), you'll see the crusty tube coming off of it..

 

Nevermind. The EGR is an emission device that seems to come and go depending on the year and engine combination. Apparently, 3.0's didn't have it in 2002 but 2.3's and 4.0's did.

 

my motor is a 2003 3.0, if that makes any difference.

it's not the original motor.

 

In 2003, 3.0 and 4.0 did not have EGR but 2.3 did. So, it shouldn't matter which engine you have.

 

it feels like how the motor does, when the governor cuts it off from revving high in neutral.

that's exactly what it's like...

 

Sounds to me like you may still have an ignition problem. Cracked plug insulator, wiring to the coil pack, coilpack itself, who knows...

 

went to the mechanic...

i'll see her in a few days.

 

Let us know what the 'poop' is, I am courious to find out.

On a side note, why did you replace your engine?

 

my motor drank too much, one trip out...

burped something aweful...

 

Found out the PCM was toast.

 

Very strange. I wasn't on this topic when it was active, but I was going to suggest unplugging the MAF and driving around. Candice's truck did something similar and I unplugged the MAF and it ran fine. I replace the MAF and problem solved.

Yes, folks, the trucks do run fine if not optimally with the MAF unplugged. But if it's plugged in, then it HAS to work because the PCM is depending on it.

I replaced Candice's 1998, 2.5 liter engine MAF with a 2002, 4.0 liter MAF and it was perfectly calibrated believe it or not. They are exactly the same size. Don't know if that works in every truck, but she's got a nice black plastic 4.0 MAF where she used to have a dull metal 2.5 MAF.

 

The PCM does pretty well without the MAF, using a combination of inferred barometric pressure and Throttle Position Sensor to take up the slack. Take away the TPS and the MAF and things get pretty ugly, though.