Hi all.
Im new to these trucks.
1994 Mazda B4000 4x4 4.0 liter.
I run in 3rd gear at 55 mph, I shift into 4th and she shakes and is sluggish unless rpm is above 2500.
if rpm drops below 2100 I have to shift back to 3rd gear.

Is this normal?

She drives best if I'm aggressive.

Also, a bit of shake and vibration felt through gear shifter if I shift into 4th to soon.

Thanks!

 

Drive it like you stole it.....The truck is telling you what it likes..

 

You have a 4.0l OHV engine, best power/torque is at 2,400rpm, so 2,100 to 2,900 would be best power band, highest Horse power at 4,200rpm

But something is wrong if its misfiring(vibration) at 2,000 or less
Should cruise along nicely in 5th(or any gear) at 2,100rpm with instant power if you press gas pedal

4.0l OHV eats spark plugs, lol, well can wear them out fast, it likes Motorcraft or Autolite or NGK brands
Needs big gap at 0.054", spark plugs should come pre-gapped at that
Use regular copper or DOUBLE coating only, single coating is a waste of money

Spark plug wires should be changed every 10 years or so
O2 sensors every 12 years, only sensors that wear out, they run out of the chemical to detect Oxygen

 

I've only had her on back on the road a few weeks.

Yesterday the CEL came on, codes are 117, 172, 185, 186.
Had a busy day so about to research them.

she has 191,000. Ive owned her for 8 years used to drag logs always in 4 wheel low.
She sat un used for 3 years.
Compression is 152 psi all 6 cylinders
replaced fuel pump and fuel pressure regulator
fuel pressure test checked out and held for over 30 minutes so I think injectors are good.
I've run fuel injector cleaner, several brands at various concentrations, and she improved performance little by little with each tank of gas
I cleaned maf, throttle body, iac, and egr.

looks like an o2 sensor test is next

 

Ford 3-digit code list here: https://www.therangerstation.com/tec...3-digit-codes/

For sure just replace O2s if they are over 12years old, MPG will go up, for sure, and you can then trust any O2 or lean or rich codes that come up

Clean MAF sensor, easy to do

Unplug the 5volt ECT sensor, 2 wire Temp sensor above thermostat housing, there is a 1 wire 12volt temp sender near it, thats for dash temp gauge
ECT sensor is only for computer, its used to set Choke Mode when engine is cold
Not hard to replace
Unplug it and plug it back in, that cleans the contacts, at only 5volts any corrosion will cause an issue
Its good to unplug and plug back in ALL sensors every few years to make sure connections are good, and its FREE
DIYers replace sensors all the time, and it works..................but 90% of the time the old sensor was working fine just needed better connection, installing new sensor did just that, lol, but not FREE