'04 XC Engine Misfiring-Further Updated (Moisture ruled out - possible defective coils, bad MAF) Topic is solved

[E Showell]

Not sure what you are referring to as "snorkel."
The Over-the-Engine charge pipe came off in November 2019 to do the coils/plugs, but only on the radiator end. Otherwise, was manipulated out of the way on the firewall end, and with very little movement on that end. I would think if I were to have had a problem there, it would have appeared much sooner.

Had the plastic intake to airbox off recently, but only to replace the throttle body and the problem existed before the throttle body was replaced.

Likewise, I had the intake hose to the throttle body off to replace the throttle body, but that too was after the problem arose.

[jonesg]

The Over-the-Engine charge pipe came off in November 2019 to do the coils/plugs, but only on the radiator end. Otherwise, was manipulated out of the way on the firewall end, and with very little movement on that end. I would think if I were to have had a problem there, it would have appeared much sooner.

.

That could cause failure at the flexible joiner, the short soft coupler to the turbo.
I'd pull it and examine it , we're all home gamers but for the sprinkling of pro's who drop by, this where we depart from their approach.
I tend to rationalize away failure points that are a pain to access, if you already did a smoke test I'd try it again, with very low level of air pressure (mouth) to simulate reverse vacuum , equal to but in the opposite direction.
Robert has a decent video on this, I wouldn't run the pump too long, might start blowing seals out, but it does need to be pushed through the system a bit.

[chrism]

I seem to recall you saying somewhere in the thread that you can clear all the fault codes and the car will run smoothly the first time you start it, but when you shut it off and restart it the second time it runs rough and starts throwing codes. Do I have that right? Also, can you run it as long as you want and enjoy smooth running as long as you want up until you shut it off and restart it?

I also find it very interesting that simply clearing the codes makes it run smoothly, even if for a short time. It seems to me that would point to more of an electronic glitch than some major mechanical component issue. For instance if it's a bad coil, then why would it go from bad to good by simply clearing the fault codes?

Try this:
Clear the codes.
Turn on the ignition for just a couple seconds but DON'T start the engine.
Then check for error codes.
If no codes appear then try the same thing again but leave the ignition on a few more seconds.
Try to identify which code is the first to be generated.
If you can't get any codes to appear with just the ignition turned on then try this exercise again but actually start the engine for just a few seconds.
Again, the object is to identify the FIRST code that is tripped. (Some of the better scanners may tell you in what order the codes appeared - I don't know if the simple scanners can do that or not.)

[E Showell]

Got VIDA. I'll give it a shot. Thanks Chris.

[abscate]

Best way to look for holes is to remove all the components and inspect them. A split in a pleat can seal in one position and then open under vibration

Unmetered air on a P2 invokes limp mode per jimmy above. I think that’s what you are looking for.

[E Showell]

I have a roller coaster/mogul field of a steep gravel driveway. Perhaps ECM jolted loose by bouncing up and down the driveway?

Regardless, it is going to my local indie. I need the car, and fiscal year end demands at work will preclude me from getting to it.

[E Showell]

Steve -. I would tend to agree with you re: unmetered air. The only thing that makes me think Chris is onto something re: electrical flaw is that the car will run fine when codes are cleared. That suggests a communication error to me.

[- Pete -]

I have a roller coaster/mogul field of a steep gravel driveway. Perhaps ECM jolted loose by bouncing up and down the driveway?

Regardless, it is going to my local indie. I need the car, and fiscal year end demands at work will preclude me from getting to it.

Evan, if you need an ECM removal tool they are like $20 on eBay/amazon. At least you could check for corrosion etc if you had one.


I’m having some similar suspicions with our 04XC70 in respect to the ECM being possibly flakey. In my case I can’t get the car to reproduce the symptom(s) when I have ViDA hooked up. Also, the codes that do repeatedly get produced are spurious and/or completely unrelated. However, if I clear these in ViDA the car runs better/stronger. I don’t have any misfires nor sensations of a bad coil, though. What I do have is an intermittent loss of boost the source of which feels very electronic in nature. Seems to present itself more frequently on hot days, but inconsistently so. With ViDA hooked up I can’t get it to reoccur at all. What seems to trigger it is if I’m not watching my boost gauge & let it climb over 15psi it feels like it enters a limp mode. Afterwards it seems limited to 7ish psi, however this can be inconsistent as well seeing as I can coax it up to 9-10ish psi. Almost all of the bits on my pressurized side are new, including both turbo hoses, MAP, TCV, ETA (formerly referred to as ETM 01-02), vacuum lines all check out, MAF cleaned, verified Wastegate set appropriately (4ish psi), and all of those efforts made almost no difference whatsoever. The only code I ever had was an ECM 392 - faulty communication I believe it was. I didn’t check how many days it had been populated for so it could easily have been from long ago, and since that initial clearing of it it has not repopulated. Anyhow, sorry to not be of any help, but I’m working on something that seems equally as evasive as with your 04.

Is your ECU fan operational?

[E Showell]

Don't know whether ECU fan works. Moot point now. At Indy being checked. I'll post back when I get word as to what the issue is.

[E Showell]

Ironically, I donated an ECU removal tool to the MVS tool lending library.