97 ranger. 2.3 2wd

When i start my truck the upper rad hose starts getting warm instant and lots of pressure. I plugged in scanner and it shows its in closed loop. After the computer temp sender warms up to 200 degrees it goes into open loop.

Im getting about 10 miles a gallon. And rough idle. Sometimes will stall. Sometimes it will cruise 80mph on freeway sometimes it will barely do 50mph.

Any knowledge and help is greatly appreciated.

 

Welcome to the forum

Reads like thermostat is stuck open, change it
But you could have a head gasket leak as well, read on

Remove rad cap
Remove overflow hose, Plug overflow hose port with gum, putty, vacuum cap, hose with bolt in it........etc
Unplug BOTH coil packs, so a no start

Put a Latex Glove over rad cap opening and seal it with rubber band or zap strap
Or use a sandwich bag or balloon or condom in place of the glove

Crank engine.......watch the glove

If you have a cylinder leak glove will start to bounce, if its a bad leak it will start to inflate, lol

If glove just lays there then no leak, 100% accurate

If glove does bounce, then you can remove 1 spark plug at a time and crank engine
When glove stops bouncing then last spark plug removed was from leaking cylinder, reinstall spark plug to confirm

If glove bounces less but still bounces then you have more than one cylinder leaking, continue on

This test has been used since there were water cooled engines, so long long time



Low power and MPG
On the driver side of engine bay TWO fuel lines come up from the frame and run over to the engine
One goes to the fuel rail, for injectors, that's the IN from fuel filter

The other line goes to the Fuel Pressure Regulator(FPR), looks like a small "can", this is the one you want, the "can" will also have a vacuum hose attached
Remove the vacuum hose and check it for gasoline, shouldn't be any
Replace FPR is gasoline is in the vacuum hose

 

Thank you very much for your quick response. The oil seems fine. No milky or water in oil. But ill still do the test tomarrow and see what i come up with.

 

There should be no pressure in the upper radiator hose on cold start
Coolant needs to get hot and expand, thats what causes the pressure in cooling system, so takes about 5 minutes for pressure to build up

"When i start my truck the upper rad hose starts getting warm instant and lots of pressure"

 

Ok thank you. Ill check that.

 

Ok well i did a compression test. The results are decent. Got around 140 psi on all four cylinders. With engine running and radiator cap off. No air bubbles were present. I let the truck run with my scanner plugged in. When its running smooth the ignition timming is between 20 to 25 degrees. And in open loop. When the truck starts to have a rough idle it goes into closed loop and ignition timming goes between 8 to 10 degrees.

Would these issues be caused becouse the engine cant regulate the temperature becouse of the thermostat not working?

I cheked the fuel lines and see no leaks. I checked the fuel pressure regulater and vacuum lines. Seems dry with no leaks.

I unplugged the idle air control valve the engine almost stalls. Plug back in and runs normal.

Anything eles i should check?

 

140psi is low

1997 2.3l SOHC Lima runs 9.4:1 compression ratio, rule of thumb is to use 18 as the multiplier

18 x 9.4 = 169psi is expected when new, 155-160psi would be high miles, this is COLD test, with good battery for good cranking speed

Lower compression = lower power

140psi could just be the gauge reads low