Ford ranger

I have a 94 ranger with 4.0 I have replaced every sensor on it I have done fuel test compression test new plugs, wires, coil, mass flow, everything but I still cant get the miss out of it don’t know what else to do please heip

Bad/clogged injector?

The miss may be caused by a stretched timing chain.

To check for this, remove the distributor cap. Have someone get on the crank bolt with a breaker bar and socket. Have them turn the engine over by hand while watching the rotor in the distributor. Then have them turn the engine over in the opposite direction. If the engine can be rotated more than a couple of degrees before the rotor in the distributor begins to rotate the timing chain is stretched.



This may seem insulting, but it isn’t meant to be so . . . why are you so sure your problem is a misfire

There are other problems which can cause an engine to run terribly . . . such as an egr valve stuck open

Are you able to perform an injector balance test?

If your pressures are good, but one of the injectors is plugged, or has a bad coil, the pintle isn’t going to lift, and that cylinder won’t be contributing. In other words, a misfire

By the way, please let us know the compression test numbers

Have you performed a cylinder leakdown test?

Here’s another scenario I can think of . . . and I’ve seen it happen. It is possible to have a broken valve spring, which nevertheless allows you to have good compression.

Can you please explain “replaced every sensor”

As dB above posts, there’s lots of things that can cause engine misses. The first step is to query the engine computer for anything it notices out of whack, in the form of diagnostic test codes. I presume you’ve already done that, and the engine computer is saying everything is fine. So what would be the next logical step ? hmmmm …

I guess if this happened to my Corolla and I didn’t want to take it to the shop and have them put it on their specialized machine which tests the ignition system, and wanted to keep on trying to fix it by replacing stuff, I’d next replace , in this order …

  • Distributor cap and rotor
  • Edit: Cam and crank sensors (may be inferred, and in the distributor)
  • Edit: Distributor
  • Electronic ignition module
  • All bolt-on vacuum operated engine components, including the EGR
  • Intake manifold and throttle body gaskets
  • Fuel pressure regulator and fuel injectors
  • ECM

That could quickly add up to big bucks . . . !

That’s the reason the replace-this, replace-that technique on electronic fuel injected cars often ends in the owner running out of money before the actual cause is discovered.

Have you identified which cylinder is miss firing?

This vehicle is an OBDI vehicle.

It doesn’t identify which cylinder is misfiring.


What did we do before OBD II?

You looked for mechanical failure.

Such as a stretched timing chain.


I would be tempted to pull the plug wires out of the distributor cap one by one and isolate the miss fire myself.

The OP did not state if the miss is random or cylinder specific, and assuming the distributor cap is not cracked or carbon tracked, I agree with Rod Knox about pulling some plug wires.

I’d probably connect a vacuum gauge prior to or after the plug wire pullin’.

I’m with Rod and OK4450 on this.
I too thought of a vacuum gage to detect any sticky valvetrain parts if there are any. At 21 years old, the valve springs can lose some of their spring, and stickiness to the valves can cause erratic running.

I also noticed you hadn’t mentioned the distributor. Have you changed the cap & rotor? Did you check the distributor shaft for lateral play? Worn shaft bushings can allow the rotor to wander around and create random misfires.

I believe that the Ranger 4.0 has a roller chain with a guide and tensioner. If that type chain jumps it would be very noisy. And moving the crankshaft back and forth would result in considerable free play showing up on the rotor even if the chain were like new.

Here’s Ford’s procedure for checking timing chain deflection.

  1. Remove L.H. valve cover.

  2. Loosen No.1 exhaust valve rocker arm and turn to one side.

  3. Install Rotunda dial indicator with bracketry tool 4201-C with cupped shaped adapter tool 6565-AB to the endo of the push rod.

4.Turn the crankshaft clockwise until No. 1 piston is at TDC. The damper timing mark should point at TDC on the timing degree indicator. This will also take up any slack on the right side of the timing chain.

  1. Zero the indicator.

  2. Slowly turn the crankshaft counterclockwise until the slightest movement is seen on the dial indicator.

  3. Stop and observe the damper timing marks for the number of degrees of rotation.

  4. If more than six degrees of rotation is observed replace the timing chain.

Now, instead of going thru all that, the same thing can be achieved by observing rotor in the distributor while turning the crankshaft counterclockwise.


It could be an intermittent problem with the ignition control module or a injector.