Hello fellow Ranger owners,

The Patient:
2003 Ranger FX4 Flareside
4.0
Automatic
145,000 Miles


Here's my issue: My Ranger has been running like a dream until yesterday.

I took off on a parts run for my sons Ranger. I got to a stop sign and as I stopped, it started missing and barely running. I nursed it back home and checked the flashing CEL. It was giving me a misfire on #3.

Since I had been planning on changing the plugs and wires, I dove in and got it done hoping that was the cause of the misfire.

Started it up, same thing. I went to the next obvious item: coil. Replace it, still running like crap. Gave up for the night.

Today, I thought I would dig in using the tips here on the forum. Did the spray down...no errant spark anywhere. Tested fuel pressure: 65psi no drop in pressure on acceleration.

Started pulling wires off the coil one by one. Four of the wires resulted in running worse. 2 had no effect. #3 and #6. The coil was producing plenty of spark on all 6 ports.

At this point I was sure it had to be 2 bad injectors. Since I couldn't get injectors tonight, I moved them around after cleaning them a bit and tried my wire test again. The problem stayed on the back 2 cylinders!?!

I tested for voltage on the back injector plugs and I am getting voltage.

I also used a stethoscope to listen to all of the injectors. The back 2 seem to remain silent.

I have also unhooked the battery for 20 minutes to reset the PCM. Still missing and running rough....

Here's a list of what I have done:

Autolite Double Platinum APP5144 plugs. .062 gap
Autolite Pro Series wires #97051
BDW E97P Coil
New air filter

What should I do next? I really don't know where to go next.......

Thanks guys.

Tim

 

If you are confident it is not an injector, I would look at the PCM. It might be time to have a repair shop run a diagnostic check. It could prove to be cheaper than throwing parts at it. I just had the PCM replaced on my 04 after trying numerous avenues.

 

Good trouble shooting & post info.

With the injectors having B+ to them, but the back two injectors being silent, I agree, wiring from the injectors to the firewall ECM electrical connector, injector & ECM electrical connector/s, or the ECM drivers for those two injectors, belong on your suspect list. Let us know what you find.

 

Perform a wiggle/thump test on the injectors electrical connectors, the computer firewall electrical connector & the computer.

If you get a positive on the wiggle/thump test, look for wiring harness damage, pushed back, or bent pins, spread sockets, or corrosion, in the suspect electrical connector.

The Ranger is known to have a passenger side windshield water leak that'll drip on the computer, so if its been damp in the passenger side foot well, remove the glove box & computer & look for water stains.

More thouhts for consideration. keep us posted on your trouble shoot.

 

Ok, while there is more you could do, since you have tested fuel and spark, I think it would be a good idea to check your compression.

 

Well, sent it to very good diagnostic mechanic. He found a bad intake gasket. That's been replaced, it's better but still not 100%. I'll keep you informed of what he finds.

 

Not to offend but being upfront, if it's still doing it then the diagnostics wasn't very good. The question I would have for him is, what diagnostics did he do that made him think that intake gasket was the problem? This in light of you diagnosing two injectors not firing. BTW and since it's still missing, what DTC's are showing?

*Unlike earlier model year Ranger 4.0's with the OHV engines which were vulnerable to intake bolts coming lose and if not detected and tightened, the intake gasket was vulnerable to failure. You have the SOHC engine, intake gasket problems are not a very common issue.

 

***UPDATE***
The problem turned out to be 2 fold.

There was a small amount of water in the gas that caused the initial miss. From that point it seemed that the engine was extremely tired and apparently had been mis-treated for years before I got the truck.

I took the jump and bought a different engine from LKQ on e-bay. 2011 4.0 with only 41,000 miles. Had it shipped in and I swapped it in.

While doing the engine swap, I needed to change the valve covers and intake. When I pulled the covers off the old engine, It became very clear what was happening. The back timing chain had NO guides left and was barely staying on the upper gear. Apparently the tensioner had given up too.

New engine is in, all fluids have been changed, purrs like a kitten!

All is well in the world.

 

OK, good feedback & to hear all now seems well & your on the road again & this time with a Smile!!!!