Jim Grant's Tech Tips
94
Ford Ranger, No Power and Surging
Q: I have a ‘94 ranger 3.0 and when it's cold it has no power
and it surges. When it's warmed up it still surges in the lower gears
but when in overdrive it’s not noticeable. Also when it’s going
through gears you can hold the gas pedal in one spot and it just goes
like it has plenty of power then it will start surging again. I've put
a code reader on it because the check engine light came on for a second
then went back off only twice. The only code it has given me is amperage
above normal on throttle position sensor and I replaced it with no results.
I don't want to start replacing a lot of parts because I really don't
know where to begin. I'm also going to do a compression check, but other
than that if you can help I would be very thankful because this thing
is about to drive me crazy. .....Angelo.
A: Before
changing any more computer parts check the fuel pressure. Your vehicle
will not run correctly if the fuel pressure is low. Don’t forget about
the fuel filter either. A restricted fuel filter will cause a variety
of problems with a fuel injected engine. There are a couple of computer
sensors on your vehicle that can get pretty dumb and the computer will
not know there is a problem. Your vehicle has a device called a Mass Air
Flow (MAF) sensor. The MAF sensor measures the amount of air entering
your engine in grams per-second. The computer uses this information to
calculate the fuel needed. The problem we’ve been seeing with these sensors
is due to air filter fibers or other debris contaminating the wire used
to sense air flow. The biggest offender is the discount air filters. The
paper fibers used in these filters breaks free from the filter and just
loves to wrap themselves around the MAF sensing wire. The result is clouded
information that the computer just doesn’t know about. Nothing is broken
so there are no computer codes, you just have a vehicle that doesn’t run
right when everything else checks good. A keen eye and some electrical
contact cleaner is what’s needed to remove the offending fibers or debris
from the MAF‘s sensing wire.
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