2003 Ranger 4.0 - from great to rough over night?

pearldrumbum · May 20, 2015

My 2003 Ranger 4.0 is sputtering, missing badly, and blowing black smoke. It was running perfect only 3 days ago when I left it at a friend's house while I went on a quick business trip.
When I came back it didn't want to run unless I held the throttle open, and then it was barely running and blowing blue smoke. After a few starts it's now blowing black smoke and running on its own, but still very rough.
I had a check engine light a few weeks ago for the DFPE sensor, replaced it, engine light went away and its run great ever since. What could go wrong while it was sitting for 3 days???
The only thing different over the last three days is it was sitting facing downhill on a steep driveway...
Also no engine light or codes thrown

pearldrumbum · May 20, 2015

Update: it just suddenly decided to start running fine again.
Do you think maybe I have a bad seal or rings in the front cylinder(s) that caused one or more of them to fill up with oil after sitting for 3 days on a steep decline?
All I did was let it idle roughly for about 10 minutes, during that time I unplugged and re-seated the harness going to DPFE sensor and MAF sensor. Turned it off, then started back up and it ran like a top, no smoke, no sputtering or anything.

Lone-Ranger · May 20, 2015

Odd, for sure. If there was oil in a cylinder(s) it should've spat it out pretty quick, but I doubt that was the problem anyway. How many miles have you driven it since picking up from where it sat?

JimRummy · May 20, 2015

Sounds like a bad MAF to me. I had all those symptoms and replac ing the MAF did it. After market intake?
the oil can screw up the MAF if there is too much.

Lone-Ranger · May 20, 2015

There should really be no oil at the MAF though, unless the pcv valve is bad. Forgive me, but I'm not very familiar with the SOHC. Is the MAF not located right at the airbox?

JimRummy · May 20, 2015

I meant the filters oil.

Lone-Ranger · May 20, 2015

I assume you must be talking about an oiled air filter? But how do you know he's got one? OE style air filters don't take oil, and I don't see any mention of him having an aftermarket air filter anywhere...

JimRummy · May 20, 2015

I'm aware.... If you read my first post, I was inquiring. A lot of people foul their MAF up by over oiling aftermarket air filters. That's why I asked if he did. If he had cleaned and oiled (supposing he did have an aftermarket filter) his filter right before that happened, and after letting it dry for a few days the problem went away, it would be an easy deduction to figure out why it happened. It's a big if, but something worth asking. I'm well aware the paper filters are not oiled, that's why I mentioned aftermarket....

Lone-Ranger · May 20, 2015

Ahh, yes. Didn't see that part.

pearldrumbum · May 20, 2015

Sorry for the delayed reply, and thanks for all the input!
I do not have an after market intake. The truck is stock and sitting at a well-maintained 113k. I've driven it about 20 miles since this morning.
it took about 10 minutes of hard sputtering and blowing blue, then black, smoke before it started running right again. I can't duplicate it now, but the Moreno I think about it, I think unplugging the MAF sensor and plugging it back in is what fixed it.
And yes, on this truck the MAF is right at the air box.

Lone-Ranger · May 21, 2015

Very well could be the MAF, if when you messed with it, it started acting ok. I'd take it off and see if there is anything on it to cause it to malfunction. Dirt, lint, anything like that could mess it up. Hopefully that's all it is.

enjr44 · May 21, 2015

Disconnect the battery and let it sit for 15/20 minutes. Clean the MAF and its connector. Clean the IAC valve and its connector.

And for now call it a day. Anything else is just shooting in the dark with sunglasses on.

adsm08 · May 21, 2015

Yeah, I think the MAF was likely the issue as well. Probably a poor connection that was cleared up just by the contact moving over each other when you reseated the connector. I can see that happening in just 3 days, especially this time of year in a place as wet as Washington State.

I would get some electric grease (NOT dielectric grease) and put a bit in all your connectors. It keeps the water out.

JimRummy · May 22, 2015

Hey, speaking of dielectric grease, when I first replaced my plug wires I noticed that in the coil pack there was a decent amount of grease inside each coil (I assume that the previous owners mechanic put it in).. I haven't had any issues, but I now that I think about it, all that junk is still in there.. worth cleaning out or don't worry about it?

2003 Ranger 4.0 - from great to rough over night?

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