Ok.truck was running bad off idle.but would idle fine.replaced plugs wires and coils.has new fuel pump.it would run before any of the work now wont start.i triple checked the wires

 

Welcome to the forum

50/50 test
Spray gasoline or Quick Start(ether) into the intake
Try to start engine
If it starts and then dies fuel is the problem
If it doesn't start/fire then spark is the problem
50/50

It would be helpful to know what engine you have, and that would depend on the year of the Ranger

2001 and older had Lima 2.3l or 2.5l
2002 and up had 2.3l Duratec

They are completely different engines so after 50/50 test results what to look at next would depend on the engine

 

Has 2.5l 4cyl.sprayed ether wont start.has new pump.can hear it run.i check wires over an over they are correct

 

Update truck started but idled ruff still shaking.i give it gas an it seemed ok.but wouldnt idle

 

Its odd..before i did any work truck would idle.but sputter under load.now it wont idle an seems ok under load

 

2.5l, and the 2.3l, Limas have dual coil packs and dual spark plugs

But one oddball thing to keep in mind, ONLY the exhaust side(passenger side) spark plugs and coil work when starting the engine.
Drivers side spark is disabled until RPMs are above 400

Both spark plugs spark at each top-dead-center, there is no alternating, once RPMs are 400+ all the spark plugs are active all the time.

Did you pull out spark plugs?
If so what did the tips tell you about each cylinder
Google: spark plug reading chart

Your Ranger will be a 1998 to 2001, that means it has the OBD2 computer(PCM)
There will be a CEL(check engine light) in the instrument cluster
It should come on when key is turned on, then go off after engine is running
It the CEL working?

If not bulb may be burned out, so if no CEL at key on or if CEL is on after engine starts then you will need to get the CODES using an OBD2 reader/scanner
That will narrow down possible cause of the rough idle

Double check spark plug wires on Coil Packs, easy to reverse a couple

You may have pulled off a vacuum line so now too much air at idle and enough air under load, so original problem could have been a dirty MAF sensor

 

No check engine light when running.i didnt go near any vacuum lines.it is very hard to start.only when pedal to floor an atruggles to idle.i did have light on before was cyl r4 misfire.all plugs were black.cyl 4 on pass side was the worst.i triple checked wires an they are correct.wondering what todo next.cleaned maf an egr.disconnected battery for 15 mins.put 2gal gas in it.

 

Pull off the IAC(idle air control) Valve, two bolts
Connect it's two wire connect back to it if you unplugged it
Turn on the key and the valve inside should slide open all the way
Unplug the wires and it should close all the way
test it a few times by unplugging and plugging in it's wires

IAC Valve is just like a solenoid, apply the 12volts it moves one-way, cut the 12volts and it moves the other way.
If it is not moving test the two wires for 12volts and Ground, key on
If it has 12volts and good ground then replace IAC Valve

Not enough air at startup would make it hard to start and very poor idle

To start a fuel injected engine you should never have to touch the gas pedal, Computer does all that for you by opening up the IAC Valve all the way for starting, this lets in plenty of air.
Then, after engine starts, it will close it a bit to set the IDLE, high idle with cold engine, lower idle as engine/coolant warms up.


TPS(throttle position sensor), has 3 wires, unplug them
Start engine, you should get CEL in a minute or two, but see if start up and idle is better


MAF sensor, do the same, unplug its 6 wire connector and start engine, see if it starts better

 

Removed iac valve an turn key on/off the inner parts do not move.also with unplugged it runs the same as when plugged in.i cannot remove the tps the screw is stripped i removed throttle body for better access still cant remove.i did notice small corrosion on 1 of the pins from the tps plug.cleaned best i could.

 

Get a new IAC Valve for sure.
That could solve all the problems so do that first and then go from there

 

Changed iac valve no change.truck starts idles ok not like it was.still shutters an shakes under load.screw on tps is stripped maybe get a used throttle body?idk what todo

 

If computer and sensors are working as it should then this should happen

Engine cold
Startup should have a high idle 1,100+ RPMs
As coolant in the engine warms up the computer will start to close IAC Valve, and RPMs should slowly start dropping down
After about 5 minutes idle should be down to 750-800 or so

All of this should happen without you having to touch the gas pedal, just turn the key and engine should start and idle should be up high, then slowly drop over the next 5 minutes or so

If your old spark plugs were "black" then engine was running Rich, and O2 sensor near the engine may also be "black", have a look when it is cold

 

It barely idles tho.sputters an shakes alot.when it warmwd up abit it idled okish.but not good.really struggled when give it some gas

 

Can you test the Voltage at the IAC Valve's wires when key is on?

 

Did compression test on #4 hole that spit code after 6 spins of motor i got 40psi.motor is junk?

 

I also learned today tht right before the light came on an started giving her probs.she said she added lil over 3qts of oil cuz oil light came on.idk how many days or weeks she ran it tht low on oil.could tht have caused all these issues

 

Yes 40psi would mean that cylinder can't fire, need 100psi minimum
2.5l should have 170psi in each cylinder

Yes running it low on oil is bad, but doesn't cause low compression.


2.5l has a timing belt, rubber, if it slips then engine will barely run and compression would be low.

2.5l may have holes in the timing belt cover to you can check the timing marks to see if it has slipped

Look here: Replacing your timing belt (with pics) - The Ranger Station Forums

Crank pulley on TC, you may have to rotate engine one turn until lined up with TC again to see triangle
Cam pulley Triangles lined up