91 Ranger help

[shaddo]

I have a 91 Ranger with 2.3l and it has been giving me fits!! Ran codes on it and got most cleared but can't get 2 of them cleared no matter what I try. The codes are 21 (cooling temperature sensor out of specified range or ECT out of range) and 52 (power steering pressure switch open) I have changed thermostat, and both thermo sensors. As far as power steering. I have changed out the unit since it was leaking out the front. And it has a new pressure switch.

A few weeks ago when it was on the road it just started to stall out at random times but being a standard it would just jump and jerk and start going again. I thought maybe water in the tank. Treated with heat and it stalled again but was backfiring. So I changed crank sensor. Figured it was something to do with timing. (timing belt was dry rotted when I first got the truck lol) It has right now a new crank sensor, timing belt, EGR valve, ignition control module, spark plugs and wires, coil packs, fuel filter, fuel pump, o2 sensor (threw a code for it and changed it code went away) vac lines are good traced them all and looked for splits and holes or dry rot. Even got a computer out of one from junk yard and put in it.

Now what its doing is it sounds great when its cold, but when it warms up it will start to miss. Especially when you stop the truck and restart. It's not a bad miss more like a lope at times but it's exactly what it was doing when it would stall out going down the road. They RPM gauge will jump when it gets warm especially when accelerating. Also a few weeks ago my heater went out it wouldn't blow at all. Truck ran great when that happened. Heater decided to start working again and the miss came back. Somehow I think they are related...Thanks for any help!!

 

[RonD]

Welcome to TRS

Reads like an electrical issue

You need a Volt meter
Set it to DC Volts

Test battery first, after engine has been off more than 2 hours, after sitting overnight is even better
12.8v is a new battery
12.5v is a 3 year old battery
12.3v is 5 years old, and time to keep an eye out for battery sale

12.2v or lower is a failed battery, won't start engine on a cold morning

Now start the engine and test battery again
Should be above 14volts but below 15volts, at idle
Turn in all the lights and heater fan to HIGH
Should still be above 14volts

If lower alternator could be failing

After engine has been running for 5 minutes or so test better again, should be under 14volts, 13.5-13.8v
If alternator puts out above 14volts after 5min then it will "cook" the battery over time

Test alternator for AC Volts
Switch meter to AC Volts
Ground the black probe to battery Negative
Put red probe on the B+ terminal on the back of alternator, the Stud terminal
Should read no more than .5vAC, if more then alternator is failing, and probaly causing Tach to jump like it did.

On the back of the engine there should be a Ground strap to the firewall, this is the MAIN ground for all the Cab electrics, including computer and heater fan
Heater fan RUNS on the ground not the 12volt side, the Speed selection is a GROUND selection, fan motor always has 12volts.

If you can't find the ground strap then make one, battery negative cable runs to the engine, because starter and alternator use the most amps
So ground strap/wire from engine to firewall will be a good ground, make it so

If you find the strap loosen it and clean it, good clean bare metal connections

 

[Curious Hound]

Yup. What he ^^^ said. My money's on "loose ground connection".

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