Wife’s van getting misfire codes

[Jake M]

While you're in there.... Take a look between the cam gears, there's three bolts that serve as galley plugs. Maybe 4 o'clock on one, eight o'clock on the other? It's been a while. Then one in the middle, slightly lower than the other two. I believe (I can't swear to it, but I'm pretty sure...) that the middle middle one feeds the oil pressure that turns cylinder two on and off. (Cylinders 1 and 2 get their own solenoids, and the remaining 4 are ganged in two groups of 2, which makes 1 and 2 NOT stand out in scan data when this happens- Those galley plugs have a very low torque spec, and have been known to back out. It's not enough that I'd call it a pattern failure, but it's enough that it's notable. Especially on engines that have seen an overheat situation, but they can back out on any engine. If there's any evidence that any have loosened or any history of being overheated, (and some techs will do this preemptively just when those bolts/plugs are visible) it's good medicine to remove them, clean them as well as practicable, and Lloctite them in place with a "more oil tolerant" flavor of of your choosing. It doesnt' need high strength, but it's also not a regular service point, so pick your poison. Or if nothing's wrong, let sleeping dogs lie. But it's at least worth peeking at.

 

[great white]

Well sh!te.

pulled the exhaust cam out and checked the rockers on the scuffed lobe. Spins freely, doesn’t have flat spots and no play in the roller.

Next up is to pull the intake cam, but I’m not holding out a lot of hope the rockers are the problem. I’ll still replace them all with new, but that seems like its going to be 500 bucks gone and still have a #2 misfire.
I’ll drop the borescope into #2 cylinder just to check and see if I’ve got some kind of weird failure like a dropping valve seat.

As odd as it may sound, fingers crossed I find the intake rockers are in bad shape. But I’m not holding my breath….

 

[great white]

While you're in there.... Take a look between the cam gears, there's three bolts that serve as galley plugs. Maybe 4 o'clock on one, eight o'clock on the other? It's been a while. Then one in the middle, slightly lower than the other two. I believe (I can't swear to it, but I'm pretty sure...) that the middle middle one feeds the oil pressure that turns cylinder two on and off. (Cylinders 1 and 2 get their own solenoids, and the remaining 4 are ganged in two groups of 2, which makes 1 and 2 NOT stand out in scan data when this happens- Those galley plugs have a very low torque spec, and have been known to back out. It's not enough that I'd call it a pattern failure, but it's enough that it's notable. Especially on engines that have seen an overheat situation, but they can back out on any engine. If there's any evidence that any have loosened or any history of being overheated, (and some techs will do this preemptively just when those bolts/plugs are visible) it's good medicine to remove them, clean them as well as practicable, and Lloctite them in place with a "more oil tolerant" flavor of of your choosing. It doesnt' need high strength, but it's also not a regular service point, so pick your poison. Or if nothing's wrong, let sleeping dogs lie. But it's at least worth peeking at.

Yep, checked the oil gallery plugs/bolts. All in place and all tight.

 

[great white]

On to the intake rockers this am. Not holding out much hope.

I've been vetching for my own leak-down tester for a while.I usually borrow one since i don't use one often. But I could have used one on the Mini cooper rebuild and now the van. Maybe the 302 in the mustang in the near future as well.

So went to Napa Canada and ordered one of these:



I've already done leak-down and compression tests on the engine, but this is a weird fault and the normal problems aren't being fixed by the usual solutions. time to kick up my diagnosis game. And besides, I've borrowed a leak down tester enough times now that it's becoming evident I need to buy my own.....

 

[C-Bag]

While in aircraft school I learned what they call a compression tester is what us automech’s called a leak down tester. The usual compression tester was called an impact tester and basically never used as it’s easily tricked by bad oil rings etc. They also told us how to make our own leak down tester. Looks just like the pic but out of pipe and both gauges are the same. In the connecting pipe between the two gauges I put a plug drilled with of .040” drill. Plug it in and read the gauges and divide the input side gauge by the cyl side gauge and it give you your percentage of leakage. What I particularly liked about a leak down was you could tell where the leak was because under pressure. Out the intake, intake valve, out the exhaust exhaust valve an out the oil filler rings. Can’t do that with a compression tester.

 

[great white]

Well, shoved the borescope down the spark plug hole. Valves all look good. Valve seats all look to be in place and none dropped. Still a nice cross hatch pattern all around the cylinder wall. Had a look at the head over #2 cylinder and it looks intact, no tell tale signs of a crack (carbon trace, lines, etc).

Going back together now. Swapped the #4 fuel injector into the #2 position again just to be sure I didn't mix them up and swap the #2 back into #2 last time.

Starting to run out of ideas....gotta be something simple and stupid. So much so that it's just not obvious....I've got a feeling it's going to be a biotch to the end and there'll be an AHA! moment come out of nowhere when I see it....

 

[great white]

Van is back together. Hit the starter and......varoom! Fires right up.

Idles a little rough with the fuel system pressurizes and works the air through and then nice an smooth.

Hoot up the scanner and no misfire codes. Not even pending.

Ran it up and down the rpm range a couple times.

Nothing. No check engine, no codes, no misfires on the live data screen.

It honestly makes no sense. I didn't fix any obvious faults, so it should still be chucking the misfire code.

All I can figure is maybe one of the lash adjusters I replaced was going south but not collapsed, perhaps one of the roller bearings had a small flat spot causing the roller to skid on the lobe occasionally or perhaps I disturbed something when I took it all apart and set it back to right when I reassembled it. Like a bit of crud in an injector line, a short somewhere on the wiring harness or something unusual like that.

Dunno. It working as per now, but I'm not ready to trust it. I'll get it down off the casters tomorrow and take it for a rip around the subdivision and see if the misfire code returns.

It's a head-scratcher for sure.

I'm almost afraid to hope it's fixed......

 

[wachuko]

Van is back together. Hit the starter and......varoom! Fires right up.

Idles a little rough with the fuel system pressurizes and works the air through and then nice an smooth.

Hoot up the scanner and no misfire codes. Not even pending.

Ran it up and down the rpm range a couple times.

Nothing. No check engine, no codes, no misfires on the live data screen.

It honestly makes no sense. I didn't fix any obvious faults, so it should still be chucking the misfire code.

All I can figure is maybe one of the lash adjusters I replaced was going south but not collapsed, perhaps one of the roller bearings had a small flat spot causing the roller to skid on the lobe occasionally or perhaps I disturbed something when I took it all apart and set it back to right when I reassembled it. Like a bit of crud in an injector line, a short somewhere on the wiring harness or something unusual like that.

Dunno. It working as per now, but I'm not ready to trust it. I'll get it down off the casters tomorrow and take it for a rip around the subdivision and see if the misfire code returns.

It's a head-scratcher for sure.

I'm almost afraid to hope it's fixed......

Let your wife drive it and report back.


I am joking! I am joking!!

 

[great white]

Let your wife drive it and report back.


I am joking! I am joking!!

That will break it for sure!

 

[great white]

Well, took the van for a good long drive, about an hour and a half. Subdivisions, traffic and highway.

No check engine light, no live data misfire counts, no pending codes.

Looks like it might be fixed. Near as I can figure I must have had a rocker arm or lash adjuster at the beginning of a failure. As mentioned, I couldn't feel anything on the #2 rockers when I rolled them on a plate of glass, but there could be one roller in there that has a flat spot and was causing the skid/scuff on the cam lobe and I just didn't feel it when checking. Or perhaps it was a lash adjuster going down but not yet failed and allowing the rocker arm just enough slop to hammer the lobe. All the troubleshooting I did certainly pointed to a duff rocker arm. Meh, fixed is fixed.

Of course, last time we though it was fixed it chucked the same code about a week or so later.

That will have to wait though. It has to sit in the garage for a month or so for the new paint job to harden up completely. Then undercoating and finally back into the wife’s hands.

Fingers crossed her “anti-machine aura” doesn’t break it again…