This one has me stumped. I have been chasing it for about a month now. Any suggestions on what I should check/test next?

2004 Ford Ranger 3.0 V6 Vin Code: U
285k miles


Truck starts fine when cold. Runs great while being driven. Does not want to start after
warmed up and being driven. Has a noticeable miss at idle.

Example: Truck sits overnight, first startup is fine, once warmed up a slight miss at idle. Drive to destination and shut truck off, come back 20mins later, and it just wants to turn over, eventually starting after multiple attempts.


CEL codes:

P0175: Rich on bank 2
P0300: Random/multiple misfire detected
P0316: Misfire on startup at first 1000 revs
Most recently: P0304: Misfire cyl #4 (confirmed a dead spark plug. Thought the problem showed its face and replaced the injector, turned out to be plug. Still have same starting problem.)


Fuel pressure is good.
Has good spark at coil, wire, and plug
Compression is good on all cyls
Cannot find any vacuum leaks

Since problem started, have replaced due to the problem or routine maintenance:

Both upstream 02 sensors
PCV valve
MAF
Temperature coolant sensor
coil, plugs, wires
#4 fuel injector
crank sensor
cam sensor
fuel filter
air filter
Fuel pump relay
Intake manifold plenum gaskets

 

You did change the ECT sensor, not the ECT SENDER correct?

Then most likely issue will be the PCM, the computer
You can check with Ford Dealer to see if your VIN has a software update for this or similar problem

The 2004 to 2006 Rangers with 3.0l engines did have a TSB about recessed exhaust valve seats, so would have a loss of compression and set P0300, P0316 and then specific P030x codes
TSB seen here: https://therangerstation.com/ford_ra..._05-26-3.shtml

You have checked compression so would have seen an issue if this was the problem, and at 285k miles if this was going to happen it would have already

 

I found the problem to be more than just that one leaking injector. I could turn the key on to pressure up the fuel system, and then after the key was off, the pressure would slowly drop until it had no pressure.

I've now replaced all 6 injectors and have caused another problem. When changing the injectors, the fuel rail crossover hose developed a pinhole leak which sprays gas out when I pressure up the fuel system. The hose doesn't have any clamps, and appears to just be pressed on into place. Can I get another length of fuel pressure rated hose and possibly some fuel injection clamps and replace it with that? Searching for the part number on the hose gives me the whole fuel rail assembly, which also comes up as discontinued.










The arrow that is pointing at the white spot on the hose is where it is leaking. I can lightly run my finger nail over the hose and scrape away the surface of it.

 

Someone else had similar problem on a 4.0l, not sure what they ended up doing

But yes you need to replace the whole fuel rail, wrecking yard may be

 

I considered a junk yard. Ford changed the design of the fuel rail in 05 or 06 (something like that), adding a fuel pressure sensor to the rail, and also changing the location of the fuel supply. So, if I got a junk yard part, I would still be dealing with a 15yr old hose.


Here's how I fixed the busted hose issue.

The OEM hose was pushed on with no clamps. I went to a hydraulic supply shop and asked them if they had anything that would work. They suggested Parker Push-Lok hose, and that's what I used. Pushing the hose on just passed the first barb, I could not pull it back off by hand. I added the EFI clamps just for overkill/extra measure.

To remove the old hose, I used a soldering iron to melt through it, then peel it off. That way I didn't scar up the fitting trying to cut it off with a knife of something similar.









It's all back together, running and driving correctly now. Problem was injectors.

​​​​​​​Thank you for your help.

 

Good work

That fix will come in handy for others, thanks for the details and pics