ford ranger rough idle p0301 and p0171

It got very cold (below freezing) a few days ago (texas). The next day, quit suddenly, the idle became very rough - but no stalling. The next day the check engine light comes on (it was about time, LOL). Also, the rough idle doesn't seem to improve with temperature / warm up. Engine smooths out at higher rpms but is rough under load / high torque (low rpm) conditions.

Autozone says two codes: P0301 cyl 1 misfire detected, and P0171 system too lean bank 1.

I'm thinking a clogged fuel injector as the common denominator from those codes. Does that sound right? Is it possible that some water / ice entered the fuel system somehow and clogged the injector?

Vehicle is '98 ford ranger, 3.0 L, 97K miles.

Thanks...

Reply to
pedal tothe metal
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Could be wet ignition wires or a bad distributor cap?

Reply to
Ron and Diane

I would start with new cables and plugs and check for vacuum leak

Reply to
johanb

I replaced number one spark plug (looked good) no idle change - still rough as cobb. The resistance of that wire is 8500 ohms and the spec is 7000 ohms per foot. Right about at the spec threshold. Seems like it would have to be much higher resistance to have such a rough idle.

I listened for vacuum leaks but nothing obvious. Is there an easy vacuum test for these symptoms ?

I've heard of using a stethoscope to listen to the fuel injectors (going back to my original thought). Some have recommended listening with a long screwdriver but the engine is rocking so much I don't see how I can do that.

Thanks...

Reply to
pedal tothe metal

Your kidding right ???????/

What about the other 5 cylinders !!!!!!!!!!!!!!!!

Only 1 has to be bad to cause a rough idle.

Good luck

Reply to
johanb

Did you run it with the plug out to see if #1 is sparking? If it's not, I would suspect the coil pack.

If you had ice in an injector, it wouldn't last long after warmup. Instead of a screwdriver you can use a length of garden hose to listen to the injector.

Reply to
gw

No, not kidding. You may have overlooked in my first post. The problem came on suddenly. It was and had been running fine and then all of the sudden it's as rough as a cobb.

This is bizarre. I can't believe this. Some one flipped the "switch" back. Today while driving home, it's back to purring like a kitten. Not the slightest roughness to it. The only thing I've done is replaced plug one - and the old plug was good. Didn't raise the hood today even.

I'm thinking it's one of the following:

1) Whatever was clogging the injector(s) has now passed

2) Number one plug wire is coming and going (that seems odd)

3) Some spark related electronics / computer control is coming and going

4) Yikes, the truck is jinxed

Reply to
pedal tothe metal

No, didn't try that. Wasn't sure if it was safe with electronically controlled ignition to pull the plug and leave it hanging. I guess I can take the old plug and connect it to the number one plug wire (while plug is laying on chassis metal) to test for spark.

Does the coil pack have electronics in it besides just the coils? Perhaps what is driving the coil pack (computer?) is the problem. I have an oscilloscope, may need to test the signal driving the coil pack.

As for the ice / water. I was just wondering if running water through the injector will clog it?

The thing is, LOL, it has to stop running smoothly :-| See my other post. Can a coil pack come and go?

Thanks...

Reply to
pedal tothe metal

I had this issue on my 2000 Ranger with the 3.0 flex. On top of your engine should be a sensor mounted with 2 rubber hoses running down to your EGR tube. The sensor is called the Exhaust Gas Pressure Differential Sensor. They are known to clog. The pain is that there is no code for this problem, it just tells you something else, and you have to cross the ford part # to get a new one. O'reillys got mine for me at the price of $55. Check it out.. Let me know.

Reply to
pkurtz2

Strange that you should mention that.

This past spring that device and the egr were both replaced. In that case the check engine light did come on. That repair was so expensive, $500, (@ firestone) that I'll not do that ever again. As you might be aware, the cost for both egr parts is like $160 at autozone. Firestone was charging double that for the parts and then exorbitant labor. You know there is profit at $160, and you can guess the profit at $320. I used to go to firestone regularly for repairs but have moved and the local store act like crooks. After the repair I asked about what I should do if the light comes on again. I expected to hear: we warranty what we sell. Instead I got: well, it would probably be something else we didn't work on.

I had another run-in with firestrone a couple of weeks ago about rotating my tires (a free service) and once again they acted like crooks.

Anyhow...

I'm fairly sure that my problem is a fuel filter that is disintegrating and the pieces are clogging the injectors. The filter is original equipment. Unfortunately it looks like I've munged the special tool required to release the filter and will have to do some fuel line cutting and replacing. I think I'm going to wait for warmer weather before undertaking.

Thanks for the feedback...

Reply to
pedal tothe metal

Just an FYI, the EGR does not need to be replaced when the diff sensor goes bad. Its just carbon build up in the sensor that causes it to go bad. As for the fuel filter, there is no special tool. There are just 2-3 sets of clips that you have to pull out to replace the filter. A new filter should come with new clips, but if not your parts retailer should carry them in stock and they should be available in a multipack so you can fit all your lines. On my Ranger I have 3 ports on the filter (flex fuel, 2 lines on regular engines) and the pack fixed me right up. I always break a couple clips when I change my filter. If you are having a hard time getting the clips out, push the fuel lines down onto the filter then pull the clips, its much easier. Also rotate the lines a quarter turn each direction to help them slide up and down on the ports.

Reply to
pkurtz2

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