1996 ford ranger 4x4 4.0 hesitates

[ranger94]

The engine was hesitating really bad would barley accelerate but I found a unplugged o2 sensor and plugged it in and fixed most of the problem. Now it only hesitates a little but after it accelerates. Any ideas of what else it could be?

 

[RonD]

Welcome to TRS

Common issue for your symptom is a dirty MAF(mass air flow) sensor.

Easy to clean these, read here: http://www.therangerstation.com/tech_library/CleanMAF.shtml

Your 1996 will have 6 wire MAF sensor but the cleaning is the same


If warmed up engine is idling higher than it used to then you may have a vacuum leak, which can cause similar symptoms

 

[ranger94]

I cleaned the mass airflow sensor it was dirty it back it and it ran good for about a min when I took off it sputtered out really bad after about 40 secs and then now it's running like it was before but a little more response. When I hold my peddle down its like the RPMs run but go down like every 1 sec. Maybe pcv vavle?

 

[RonD]

PCV Valve issue is a vacuum leak.

Whats the warm engine idle RPM?

Do you have auto or manual trans?


And after engine is warmed up, unplug the 2 wires on the IAC(idle air control) Valve.
Looks like a can on its side, on the upper intake.
When you unplug it the valve inside will close and engine RPMs should drop to 500, or engine may even stall, either is good it means no vacuum leak(no PCV problem)

If idle stays high then there is a vacuum leak

 

[ranger94]

The RPM's is warm idle around around 1100 or 1000. When I unplugged the IAC it basically shut off. It has a auto transmission.

 

[RonD]

1996 Ranger 4.0l with automatic should have a warm idle of about 750-800, in Park, 850 in gear or with AC on

Manual trans idle is 650 in neutral

When starting cold the idle should be 1,100-1,200rpm, this is based on outside temp so could be higher if it is cold, 40degF

Idle should start dropping as engine and coolant warms up, takes about 5 minutes if outside temp is warmer, 8 minutes if colder.

When starting cold don't touch the gas pedal, just start engine.
RPMs should go up to 1,500 or higher for a second and then drop down to 1,100-1,200.
That's the IAC Valve opening all the way for starting then closing to set cold idle.
Then over the next 5 minutes the idle should start dropping down

Does that happen?

 

[ranger94]

It stays idling at 1000 even when warm and when driving I can hear a small whistling noise almost sounds like a turbo. But I was driving this morning and it wouldn't accelerate then it would run good then would go back to sputtering and no power.

 

[ranger94]

It's was bank 1 o2 sensor changed it now it runs fine.

 

[RonD]

Thanks for the update and good work

Never would have guess O2 sensor with those symptoms