One of my vehicles had me stumped so hopefully someone has some advice. I have a 2010 E250. The check engine light came on with a P0305 code for a #5 misfire. Without digging into things I just swapped out the coil as I had a few on the shelf from another vehicle that I ended up selling. No change. Though it may be defective coil so I installed the second one I had on hand in. Again no change. Next I pulled the plug which has about 9k miles on it just in case it was fouled. Looked good but I still replaced it. Again no change. Next I threw a noid tester on the #5 injector and coil line. Both showed a pulse. At this point I'm thinking injector. Pulled the injector and tested the resistance. Looked good but I still swapped it with #8 as that was the closest inside the doghouse. Deleted codes and drive till light came on. Again... Still #5. Where do I go from here? Compression test? This new engine was just put in about 11 months ago. Thanks in advance!

 

Yeah compression test would be next I think.

 

By "new" engine is that reman'd or a used scrap yard part?

 

 

Did you check the pigtail plug that connects to the coil? I'd think if you were getting a misfire from a compression issue the plug would look oily or rusty when you checked it.

 

I did not check the pigtail itself, but I did install a noid and it showed a good signal.

 

So I did go through and run a compression test on all eight cylinders today and was a bit surprised on what I found. I only completed a dry test.
#1 - 195 psi
#2 - 190 psi
#3 - 190 psi
#4 - 210 psi
#5 - 95 psi
#6 - 185 psi
#7 - 185 psi
#8 - 190 psi

The first thing that got me was the high compression numbers. The test sheet I have on the engine shows it left the facility with each cylinder averaging 175 psi before being installed. What would cause an increase in pressure such as this? Carbon build up? I did look into the cylinders that I could see and the piston was black as could be. Not something I would expect at 9k miles.

Obviously the low compression on #5 is a concern so I performed a leak down test on it. Sure enough it was at about 60%. After listening I found the air was leaking on the exhaust valve. Do I really have a burnt valve after 9k miles? Also I used a long screwdriver on #5 to find TDC and after pulling the screwdriver out I there was black sludge about 1/16" up the screwdriver tip.

And finally, I pulled all the plugs and they look like they was been run 100k mikes. A good amount of build up on several of them. I have attached a pic. Bottom left is #1 and bottom right is #5

Can anyone help me make sense of all this? Does the head really need to be pulled? What is causing the increase in cylinder pressure? Can carbon build up be causing the exhaust valve to not close all the way = low compression? Why so much build up on the plugs? Why so build up on the piston at only 9k miles?

Any help would be greatly appreciated!

 

Have you paid attention to fuel trims both long and short term? How many miles are on the injectors? Me personally I'm not prone to believe DC resistance on an electronic part is useful determining its performance in use. Is the carbon build up you observe perhaps oil sludge from a leaking ring? To my eye the plugs look to be oil fouled but I'm NOT an expert by any means, Here's something I found useful: Reading Spark PlugsI

I'd complete the wet test just for giggles and grins---most likely if any warranty is to apply they'll want those numbers too.

i'm interested in your findings as I have a Ford reman'd long block that had a miss or hesitation from day one. Not a thing shows up on a cylinder contribution test via Snap On Solis scanner, two separate tests by two different highly skilled and competent mechanics. This engine is undergoing the wet & dry compression test and I do suspect an issue with one cylinder. I can feel a small vibration that mimics a misfire that's constantly present. There is also a "slap" sound when slowly revving up past 2500 RPM while parked---that's just not right. Thankfully its under Ford's warranty and they've NOT been the least bit in denial mode so far.

Sometimes even the best reman'd parts have failures---that's not much comfort but we'd not be the first to deal with such things. Another trusted mechanic installs Jasper engines quite frequently and an almost immediate problem with their engines or transmissions crops up. They do pay for initial diagnosis and supply new parts accordingly. The point is crap happens and yes it sucks big time when it happens to us!

Please let us know your progress on all this.

 

No I did not look at the trim numbers. Once I get everything back together I will take a look just to see what I see. But I did stick a scope down each of the cylinder and you are correct. That is oil sludge and a ton of it. It is in almost every cylinder. So without pulling the heads, which isn't easy in an E-250, I'm concluding the heads were not rebuilt properly and the valve guides or seals have been leaking. Whoever rebuilt the heads was fighting a bad hangover or something.

This was not a Motorcraft rebuild. I just could not see paying their $7500 plus install the dealership was wanting to swap in a new reman. So I picked up an S&J Engine with the extended warranty which was about half that and had it installed and an independent shop. I just didn't have time to do it myself. I talked to S&J yesterday and they are sending new heads to the shop that installed the engine. I'm going to have them pull the engine and swap the heads. I'm going to make sure I'm there when we pull these heads. S&J advised they will be covering all the labor. We shall see. I don't have much faith in many of these rebuilders.

 

I paid just over $3K exchange for my engine, direct from a local dealership. Luckily I know a lot of skilled talented & trustworthy mechanics so one installed it for a flat $700, MORE than a fair price. I can see a dealership charging upwards of $7 for an engine swap but oddly enough I've not paid $7K for any one of my vans so far.

This isn't comforting about reman'd engines but one of my customers frequently swapped engines in their fleet delivery vans, had great luck with crate motors just about forever. One time they had immediate issues with one, were asked to do a wet/dry compression test----discovered NO RINGS at all. I'm curious how the assembler didn't realize the pistons fit so easily, like they just dropped right in?

I'd not be surprised what happened with your motor but it does seem oil is leaking into the cylinders somewhere--its good you have the warranty though. Aggravating to have to deal with this but hopefully it won't cost you any additional money.