I have a 93 ranger 4.0 and I am having problems with hesitation during acceleration. The truck idles fine, but when i start to accelerate, it will hesitate until I goose the throttle all the way and then it takes off and starts running great. I have recently changed the plugs, wires, fuel filter, pcv valve and air filter. Someone has suggested to me it could be a loose wire at the battery, coil packs, egr valve, or a dirty MAF sensor... Does anyone have any advice for me?
Thanks

 

May be the MAF, have you been running an oiled filter? May also be an O2 sensor, the ECT (engine coolant temp sensor) or a bad TPS (throttle position sensor).

Not the news your wanting to hear but my friends truck did the same thing (94 4.0 ranger 5speed) and we replaced and thought of everything we thought it could be. We ended up running out of ideas and had to replace the engine. The new one runs fine but it bothers me we didn't figure out what the problem was.

 

its is the maf clean it really good and see if it helps. if not replace it. i replaced a whole ton of **** on my truck too and i had a check engine light. unplug your maf and drive it and see if it is any different my truck wasnt any differnt so i know it was the maf. do you have a check engine light or does it come on and go off?

 

My guess would be either the MAS or TPS.
You can test the TPS with a voltmeter if you have one.
You're basically looking for a smooth
voltage climb on the signal wire when the throttle's advanced.

If the reading spikes or is erratic, then the TPS is bad.

 

OK thanks for the advice. I have a check engine light that keeps going on a off every once in a while. If i unplug the maf and the problem goes away then I know it is the MAF? Also, on the TPS which wire do I probe with the multimeter to check for the smooth voltage climb?

 

Blake, the easiest way to fix it would be to read the codes.
Even though the CEL isn't on all the time, there'll still be
codes present. The code will tell which direction to look.
(Most auto parts stores will read the codes for free, in hopes
you'll buy the needed parts from them.)

As to the TPS, it has 3 wires, and the middle wire is the ground.
One of the outside wires is the reference voltage which is 5v.
The other wire is the signal wire, which will vary from about 1v to
about 5v as the throttle is advanced.

I can't tell you which outside wire is which, but you can backprobe
each one with a voltmeter and find the one with 5 v (with key on).
That's the reference voltage wire, and the other outside wire will be
the signal wire, and should have about 1 v on it with the throttle closed.
(A common straight pin is good to stick into the wire for a backprobe)

You are looking for a smooth transition from 1 to 5 v on the signal
wire when the throttle is advanced. If the voltage is erratic, then the
TPS is bad. It's easier to see this with an analog voltmeter if you
have one.
Good luck,
ROE

 

sounds like a problem during closed loop, making me think it is a sensor (o2 or maf)

 

i couldnt get a code to read in my truck because the light wouldnt stay on. get a new maf or clean it im 110% sure this is your problem