Weird. A couple days ago I dumped a bunch of Lucas fuel system treatment in the tank and Sea Foamed the upper end through the vacuum line. Then I parked the truck at my mother's for a couple days while I worked on her car.
So tonight I picked it up (and apparently had a cat mark the interior as his grrrr) and started driving home. CEL is out, good. Truck seems to be running fine, good. Then about 4-5 miles in it starts bucking and spitting, loses power and I coast to the shoulder. Restart, die. Restart die. Let it sit for a couple of minutes...... Restart, runs fine. CEL comes on, Gently accelerate, all good. Nervously drive the rest of the way home 15 miles, all perfectly fine.
So I made it home but that was weird. Any thoughts.
*1994 Ford Ranger 4.0 btw
Can you pull the diagnostic code to find out why the ECU turned on the CEL? Then we'll have something more to go on.
Being a ford I'm surprised it got you home.
OBD 1. My scanner is for 2 so doesn't even plug in. Previously it's said something about MAF sensor bad (it's been replaced). Also has new O2 sensors.
Oh, and Nick: 
All the vac lines are connected good and tight? Yeah check the cel then go from there.
I have heard that seafoam cam possibility open up gaskets and make them leak for a moment but they usually seal back up.
In reply to KyAllroad:
Can you use a method like the one described in this link to pull the codes? (I don't know if your Ranger has the same engine/ECU as the Explorer).
Also, was the CEL on before the initial Lucas/Seafoam treatment?
-- Pete
It does sound like the MAF took a dump. It stopped running until the computer failed the MAF out of the equation, at which point it started running again.
When you replaced the MAF did you get a good new one or a cheap new one/reman one? (Half of those are junk out of the box) Did you replace the connector as well? Seems like most of the time, MAF connectors have broken/loose pins. Mostly GMs but have seen it on Fords too. If you're not awesome at wiring, a few drops of Stabilant on each female pin works wonders for loose pins and won't introduce new problems from an imperfect repair, but it's probably more expensive than a new connector.
In reply to PeteD: it was on before the initial treatments. Weirdly it went off when I started it afterward for a fairly long time before coming on again.
In reply to Knurled:
It was a good one. Actually the mechanic down in Florida was the one who had done it. He tried 4 (!) different new MAF sensors and all three the same code. He had decided it was something else in the sensor gallery sending that fault.
When cold the engine will buck and lurch terribly and then smooth out a bit once it warms up. It's challenging to drive in first gear without looking like a total amature. I had been thinking TPS but my diagnostic skills are weak.
Smooths out when it warms up often means that there's an airflow calculation problem that gets covered up when it goes into closed loop.
Or a plastic intake manifold has a gasket leak, they typically will only have a vacuum leak when cold.
So this is an ongoing issue? I was thinking it was just a one time occurrence.
The lurchy when cold effect is ongoing. The dying on the side of the road just happened once.
Always remember to start with the cheapest item. Try cleaning the MAF, then try replacing the intake manifold gasket, then try plugging all but one hole in the manifold, then running a leaf blower or air gun through the non-blocked-off hole, then run over it with a hose. If it's cracked, there will be air bubbles.
Temperature sensors and 02 sensors have a lot to do with hot and cold running.
iceracer wrote:
Temperature sensors and 02 sensors have a lot to do with hot and cold running.
That's another possibility. Maybe the o2 sensor failed, or the seafoam bunked it up.
Zomby Woof wrote:
KyAllroad wrote:
Any thoughts.
Don't use snake oil
And if you decide to use snake oil, don't get it on your hootus.
I was gonna say clean the MAF sensor. If not it is probably on it's way out.
MAF and O2 sensors are new.
KyAllroad wrote:
OBD 1. My scanner is for 2 so doesn't even plug in.
Can you get it to an auto parts place that'll read the ODB 1 code(s)? That info from the ECU would really help solve this.
-- Pete
I would inspect/replace every inch of vacuum line, check the TPS voltage, if you have a voltmeter and go ahead and buy an OBD 1 scanner. I snagged one from the Zone for around $30.
If you still can't sort it out, take it to a car wash and scrub the hell out of it for 10-15 minutes. Worked for my Lincoln. :
https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1992-lincoln-mark-vii/76290/page6/
You don't need a reader to get codes from obd1, just a paperclip.
In reply to Kenny_McCormic:
Who cares about codes? We want to see DATA. Codes are just the computer's opinion of what is going on. Data is much better. If you plug in the scantool and the Baro reading is like 120hz, when anywhere near sea level has it near 150-155, then you know the MAF is FUBAR. If Baro is okay, then you can look to other things.
I highly doubt it's a bad O2. That would show up as running worse when warm, not better. O2s are probably fine, but i'd want to see what the fuel trims are when it's running fine. Fords have a BROAD latitude for fuel trims, I think something like 50% combined short and long term correction before it sets a lean or rich code.
Likewise, you gotta have a scan tool plugged in if you want to check for vacuum leaks with ye olde propane wand (as opposed to the smoke machine, which is my favorite diagnostic tool now). The computer will correct for the extra fuel so you need to see the fuel trim swing on a scan tool.
And one of the first places I'd look on a Ford would be the PCV and breather hoses. Ford liked to make the rubber elbows out of an oil-intolerant rubber and the hoses love th suck shut and split, usually in a bend. I don't remember if/where the 4.0 has its PCV hoses but every other Ford engine I can think of has had a lot of hose issues in this regard.
I believe there is a 10mm line running to the bottom of the throttle valve that is notorious for rotting out and causing all kinds of shenanigans.
