I'm sure it's completely possible that low compression in cylinder #3 or multiple cylinders could be the root cause of all of this. But, with the truck throwing fuel related codes pretty much since day one the logical side of my brain is not thinking that there's an internal mechanical issue.

I wish I had a spare ECU to try out @Extinct 's idea of swapping in an ECU to see if anything changes. Can't rule that out as a possibility either.

 

Copy that @Extinct, thanks. Plus are new, wires don’t look old but who the hell knows... I wouldn’t be surprised if it’s wires or coils.

I’ll try what you recommend.

 

I’ve been on a family trip since Wednesday and was pretty frustrated with my progress on the Disco.

While on the trip I realized that after I got the P0303 code, when I looked under the hood the dip stick tube was contacting the #3 plug wire.

Like everything else on this truck, the dipstick tube is not in its proper location. Today I did and oil change and messed with the dip stick tube. I moved it away from the plug wire and reset my SES.

Wallah - no doubt p0303 was caused by the plug wire grounding out on the dipstick tube.

Now I’m only getting the P0172 code as I suspected.

So, no single cylinder misfire, only a fueling issue.

- motor runs smoothly above idle except for the occasional miss
- motor struggles at idle. Truck shakes a little because the idle is uneven.
- idle has been right on the money at 750rom or so, but now it’s fluctuating a little.
- new injectors
- have not touched the fuel pump

I’m thinking about doing a dynamic fuel pressure test next. What do you think?

 

Now I am thinking MAF, has that been replaced already? Now that the miss is fixed, lets look at oxygen sensor graphs again. Also, try a test where you unplug the maf, see what that does.

 

@Extinct MAF is a new Bosch unit.

When I got the truck it had a P38 intake elbow with a different diameter MAF housing. I replaced it with a DII intake elbow and a new Bosch MAF to eliminate that as an issue (hopefully...).

I was unaware that there were different size MAF housings but I have two MAF’s that are a different diameter than the new Bosch unit on the truck.

I have not run without the MAF. I can try that.

My Cats are on their way out. They tick and also smell after running. The tick is very obviously from the cats.

As far as I’m aware bad Cats wouldn’t cause this issue, but I assume that certainly does not help.

 

Just went through all this on mine after a 100 parts and $500 i changes the maf and fixed it all

 

It's completely possible I have a bad MAF. I bought a genuine Bosch from Parts Geek I believe.

Here's a quick video of my O2 sensor readings and fuel trims: https://www.youtube.com/watch?v=hbzm...ature=youtu.be

I'll try swapping on one of my other MAF's in this evening.

This is MAF in my truck now https://www.partsgeek.com/gbproducts...YaAlGUEALw_wcB

 

Well guys, the fear that I had about this motor seems to have come true.

got a block away from work this afternoon and a flashing SES, big puff of white smoke out the tailpipe. I shut the motor off and coasted to a stop.

no apparent leaks or coolant loss. No smell of water in the oil or vise versa.

Turned the motor over after diagnosing and it turned freely and then nothing.

Oil might be a little more transparent than normal. Very possible it’s been leaking coolant down the #3 cylinder slowly.

 

Have not been able to pull the spark plug yet. But I will tomorrow.

Motor was running rough, SES light started flashing, then a puff of white smoke out of the tail pipe. I cut the ignition off as soon as I saw the smoke. The truck probably ran for 8-10 seconds after the SES light started flashing.

A buddy of mine who is a mechanic down the street stopped by when he saw me on the road side. I turned it over for him and the truck turned a couple of revolutions, and then Clank. Truck will no longer turn over.

 

Not necessarily fatal. I had a truck blow a head gasket, so much water it hydrolocked the cylinder. Pulled the heads and replaced the hg, ran fine. Start by pulling the spark plugs and turn it over by hand with wrench/socket on the crank. If it turns over then you can take it apart.

Conversely, you could buy a low mile 4.0 from one of the LR breakers.

Sorry to hear about it.