'94 4.0 Ranger - Misses Under Load and at WOT

[pxbacher]

O2 Sensors are off. Here's the recipe:

1 MAPP gas torch
1 Crow foot O2 sensor socket
1 1/2" drive socket wrench
1 Big channel lock pliers (in case you round off the sensor)
LOTS of Patience

1. Start on the EASIER one - you'll learn how to do it on this one, and there's more room for error (i.e. channel locks) if you mess up
2. Heat the exhaust where the sensor screws in to bright orange
3. Quickly slide on the socket, pop on the wrench, and lean on it
4. Take only what it will give you - it will turn 1/8 to 1/4 turn before cooling too much and freezing up again. If you try to get more, you'll round off the O2 sensor and then you're in trouble. BE PATIENT!
5. Repeat starting at 2 until you're done.

It took me 15 heat/torque cycles to get the passenger side sensor (the hard one back behind the Y pipe) out. Once you do get them out, you're only half done. Almost guaranteed you'll need to re-thread. That's where I am now - need to find the right size tap. Seems like they're the same as a spark plug. Don't waste money on a "thread chaser" from Pep Boys - complete waste of money. The thread chaser from Sears is a little better and maybe worth the $6 if you only have light thread chasing to do. Neither Pep Boys nor Sears sells the actual tap - they do sell spark plug thread repair kits with inserts, but that's not really what I want, as I would need to drill, but don't have room...

Without the right tool (tap), I'm thinking I'll probably just run it up the street to my local mechanic and have him pop them in for me...

-Pete

 

[Z3CHYD]

well i bought 2 new o2 sensors and installed them today....runs about 15% better. I'm not happy and broke. Time to do some junkyard parts pulling and see if I can get lucky...I just want my Explorer to run like it did when I first got it...

 

[pxbacher]

O2 sensors are back on - thank you Bob Blitz (and the Snap-On guy who had the 18mm tap he needed after he broke his old one).

The Good News: It's peppier than it's been in a LONG time!
The Bad News: It still misses pretty good.

The Damage:
2 O2 Sensors: $105
2 Worthless Thread Chasers: $13
Bob's Help: $72
Total: $190

Glad I changed them out, but wish they'd fixed the problem.

Next up - the ICM.

-Pete

 

[pxbacher]

Just dumped in another 12oz of "Dry Gas" (isopropyl). Can't hurt.

 

[pxbacher]

Replaced ICM - same symptoms

BTW, I have copies of the wiring schematics and descriptions from the OEM manual, if you need them. There's a pretty extensive troubleshooting procedure in there too, mostly tailored for a specialized Ford tester...

Not sure what my next step will be. Crankshaft Position Sensor maybe... I'd love to slap a scope on it (I have one) but it doesn't miss except under load, so no way for me to test it while parked in the driveway

-Pete

 

[dennis461]

Did you check the plug wires like I said?

 

[pxbacher]

Did you check the plug wires like I said?

Nope. Not until a half hour ago, after picking up a new set of wires at Pep Boys just so I could eliminate one more thing.

Got home after dark, parked, shut off the garage light and popped the hood and what I saw was shocking. Literally. Arcing in two spots. The long number 4 wire was arcing at the top of the throttle body, and the number 3 and/or the condenser were arcing all over.

Pulled the old wires and the #2 clip even came clean off the wire and was left sitting on top of the spark plug - had to pull it off with pliers. Put in the new wires, and it runs like a champ.

Moral of the story - Just cause you bought the expensive wires a couple of years ago doesn't mean they're still good.

Moral #2: Boy am I a dumb *ss. If not for your stubbornness I'd still be driving around cursing at it. Thanks for that - I owe you a couple of beers at least, and I hope this helps others thinking things are more complicated than they really are.

-Pete

 

[pxbacher]

BTW (permit me a little justification here...) It runs a lot peppier now. I'm sure the wires helped, but the filter was ancient, and the O2 sensors made a big difference, even with the missing. So all told not a complete waste of money on those parts, and boy did I learn some stuff on this little lesson!

-Pete

 

[Z3CHYD]

BTW (permit me a little justification here...) It runs a lot peppier now. I'm sure the wires helped, but the filter was ancient, and the O2 sensors made a big difference, even with the missing. So all told not a complete waste of money on those parts, and boy did I learn some stuff on this little lesson!

-Pete

hmm. time for me to pop the hood at night an see whats going on under there...there supposedly new plugs an wires, but when i pulled on from the left side and one from the right, the driver side has stock style electrode ones, and the passenger side ones are diamoundfire spark plugs...hmmm

 

[slow96gt]

so did the wires help? im having the same problems but i put plugs wires and a new 02 on tonight and the plugs still arc eveywhere?

 

[Big Jim M]

Oh no!

so did the wires help? im having the same problems but i put plugs wires and a new 02 on tonight and the plugs still arc eveywhere?

Please dude...start a new thread instead of bringing aan VERY old one back to life.
In the new thread put what you have done to the engine... Wires, which plugs, coils. etc!.
Big Jim