sparkpulgs and oil gauge

[speedracer954]

I have a 2000 4.0 ford ranger and just recently it started missing. So I replaced the sparkplugs and wires and it is still missing or spudering. I also checked my airflow senser to make sure it was clean so it wasn't getting the wrong reading. On the other hand when I start my truck my oil gauge will come up and 2 seconds later it will go down like there is nmo oil pressure but I check my oil stick and there is oil there. any suggestions.

 

[RonD]

I can't see the two being related unless there is a bad engine ground.
The coil and most of the engine sensors use the engine ground as part of the circuit and the oil pressure sending unit does as well, intermittent grounds cause oddball issues.
There should be a ground strap from one of the heads to the firewall, make sure it is clean and tight.

With no oil pressure you would start to hear "ticking" noises from the rockers and lifters pretty quickly, you don't mention that so I would suspect an oil pressure sending unit issue.
If you remove the wire from the sending unit and turn on the key the oil gauge should go all the way up or stay all the way down.
If you ground that wire the gauge will do the opposite of what it did above.
That tests the wire and gauge.
If they work then either the sending unit is bad or the oil pump, we will hope it's the sending unit, oil filter could be clogged but that's a long shot.
Never use teflon tape when installing engine sensors, it can prevent a good ground, high temp sealant is fine.

Since you replaced the plugs and wires then I would next look at the fuel supply, missing at idle could mean sticky injectors, you could try a can of Seafoam in the tank.
If it misses even at speed then could be a bad injector.
You can test the solenoid in each injector with an OHM meter.

To check fuel pressure you need a gauge.

Fuel pressure regulators are operated by a vacuum line, if the regulators diaphragm leaks that vacuum line can suck extra fuel into the intake, causing rough idle and missing.
Remove the vacuum line and check it for fuel or fuel smell.

 

[adsm08]

Since you replaced the plugs and wires then I would next look at the fuel supply, missing at idle could mean sticky injectors, you could try a can of Seafoam in the tank.
If it misses even at speed then could be a bad injector.

A failed/failing coil is far more likely than a sticking injector on a 4.0. I can count on one hand the number if injectors I have seen be responsible for a misfire, and none of them were on a 4.0.

The number of V-6 coil packs I have replaced on the other hand is quite large.

I agree that the oil pressure sender is likely at fault. If there was genuinely no oil pressure you would start the engine, hear the awful clattering noise, and shut it off right away and be posting about the awful noise, not the fact that the gauge drops back to zero after prove-out.

 

[killj0y]

A failed/failing coil is far more likely than a sticking injector on a 4.0. I can count on one hand the number if injectors I have seen be responsible for a misfire, and none of them were on a 4.0.

The number of V-6 coil packs I have replaced on the other hand is quite large.

I agree that the oil pressure sender is likely at fault. If there was genuinely no oil pressure you would start the engine, hear the awful clattering noise, and shut it off right away and be posting about the awful noise, not the fact that the gauge drops back to zero after prove-out.

I was thinking the same thing on both things. I just replaced my coil on my 2.3. Took a bit to find the issue because I want thinking coil, till I just.unplugged it at the coil to see spark and when there was none booyah easy fix did it in the school parking lot lol. Took all of five minutes. If your unsure swap one out and don't bolt it down, in case you want to return it. Do secure it with a ziptie or something. Are any rangers coil on plug?