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Here's a comparison of the OPParts spark plug wire (black) and the OEM (Bremi) wires (red). ? Note how the OEM wire has an extra rubber boot. ?I'm guessing this is a moisture or dust seal?

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Update on my P0306 misfire saga:

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Mike, good thinking. ?Although the PCV / breather valve was not disconnected, it may have been loose. ?I tightened it and cleaned up the crud, so I'll be able to see if it's leaking going forward.

Mike, are you saying that all of the measurements of the injector resistances are consistent?? That is a good sign for the injectors as a group.? Might be a good idea to check all spark plugs since you have reported oily gunk (msg 162283).? Take that front end off the throttle body and make sure you don't have a bunch of oil causing issues.? One other diagnostic method is to move spark plug wires -? move the suspected bad wire (#6) to a good cylinder, and move a known good wire to #6.? Problem is always that the wire lengths for this AES motor are very different, hence a good reason to buy a wire kit.? HTH,? Mike

Mike,

To follow, this camper has sat for a period of time, so you are working through stuff.

The best guess I can give you is that the part you speak of that is NLA is not inserted completely into the throttle body intake, and so that is shooting oit out and onto the front of the engine.? I would suspect that you have oil on the hood, too.? There is another valve associated with all this plumbing that is on the passenger side of the motor.? Can't speak to it any better than that at this time.? I have shot carburetor cleaner into these pieces just as a hope, and stuff still worked.? Try cleaning the PCV valve of the NLA piece.? It is a simple one-way flap valve (I think).? Take a close look at it.? HTH,? Mike

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2000 Eurovan Camper. ?I have oily gunk building up in two spots on the engine. ?

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Hi Mike,

Mike,

You don't report a history of failure, because probably when you parked the EV there was no failure.? Please confirm this. The P0300 to me is a random misfire code, so that the ECU reports it and then tries to identify it to the cylinder.? IMO, you have to test drive a lot more.? Clear codes to see if the 3 and 6 cylinder codes reappear with regularity.? You're on the right track.? Your mileage does not indicate a mechanical failure, but that is possible.? You can use the fact that the motor is running to figure this out.

v/r,

Mike

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You're right -- that approach works, too. :-)

My approach is not to buy stuff I don't know I need.

That's why I suggest testing/validating first.

And it's rare a single bread crumb leads someone out of the woods.

So the extra stuff provides?a path for further understanding and troubleshooting -- or handing off to a pro. :-)

I've been going back of archives of this mailing list (back to 2008 when I joined) looking for stories about unusual reasons for misfires. There are quite a few of them! [I have very lightly edited or combined some of these for clarity.]

Please add to this thread if you have a strange one.


Common issues: Coil, Plug Wires, Injectors.

Crack in Coil Pack
2009-11-30
Steve (and others)

Earlier this year our 2000 EVC did the same thing. First the plug wires were replaced because there were several small cracks/cuts. Then we replaced the coil, which was the culprit. A small crack in the coil housing could not be seen until the coil was out of the engine compartment, in your hand in the bright sunlight. Steve 2000 EVC 104k "Whitehorse"


Spark Plug Wires
2011-05-14
Brian (and others)

Had a similiar problem with 95 ecv. After 1000$ in fuel injectors and other repairs dictated by the mechanic. The engine still ran like cr**, I watched the engine running at night and noticed the #3 cylinder (which the mechanic said was the problem) the spark plug boot outer jacket was arcing to the cylinder head. These wires had been on the car for about a year, should have been ok! Replaced the wires and everthing is back to normal... This seemed too simple, having had this experience and talking to a couple of VW techs, they said whenever they get a eurovan thats running wierd and the wires have been on for a while the first simpliest, cheapest step is to replace the wires cap and rotor. Start with a clean ignition system and then start figuring where to go from there... Brian


Bad Fuel Injectors
2012-04-10
Sam

Well, it turned out to be bad #3 and 4 injectors. It's possible that some other event caused these two injectors to fail, but after pulling apart they were the only parts that measured bad, and the car is now back together and throwing no codes. For those with open/shorted injector codes, here are some thoughts, in no particular order: * Check injector resistance before doing anything. There is a plug that goes to the injector harness on the drivers side of the head; unplug and check there. All my good injectors, both the old and replacements measured 14.5 ohms. Bad ones measured in the thousands of ohms...


Less Common Issues:

Injector or Injector Harness Not Seated
2011-09-11
Matt

My CEL light came on and I was getting what felt like a misfire every cycle. Although the only code I had and you have in common is 16684 [P0300], I thought I'd mention the fix just in case. The local VW mechanic (I was out of town) checked the harness and found either the injector for the trouble cylinder wasn't seated properly or the harness wasn't seated well with that injector -- something like that. He improved the connections and I've been sailing smooth since. My other codes were 16689 and 17625, in case anyone is ever searching the forum for these codes. Good luck, Matt


Cam position sensor
2017-05-22
Peter

Chased the CEL misfire code for several years through several dealers and several high-end specialty mechanics. Replaced coils, wires, plugs several times, then injectors....Finally replaced a cam or crank position sensor (can't remember which was first), & when 1 was replaced then the other threw a CELcode as bad. Ended up replacing both. Problem solved! 2 years and lots of miles later, no CEL ! I do not suggest ignoring it. Peter, Yosemite Park Area CA 97 EVC Vanpira

Water in the Engine Compartment
2011-01-25
Myself (and others)

I had misfires after getting the engine wet on my 2000. I had decided to spray wash the engine compartment.
What was weird is that the trouble didn't start immediately -- I was able to drive away and it only happened after 10 miles or so. Is there any moisture in your story? The VR6 engines apparently have rather deep spark plug holes in which water can pool. My mechanic used pressurized air to spray the water away and replaced a couple of plugs + wires.

Oil pressure Too High
2011-08-22
Dan Marinucci (via Sam S)


Since about 1995, he explained, he had seen several cases of faulty oil pumps causing extremely high oil pressure. The excessive oil pressure, in turn, pumped up the lifters and held the valves open.

Frayed Serpentine Belt
2010-09-07
Eric (and others)

The check engine light came on last year and was giving off misfire codes for every cylinder. $1,400 later, no one, dealership or otherwise could remedy the situation. That all changed with the recent tranny failure (2nd one. 77K!). The service manager felt so badly about the whole crappy deal (rightfully so) that he made it his mission to diagnose and fix the problem. After several days of shots in the dark, he called the top service guy in Germany, and was told to try changing out the serpentine belt. Lo and behold, the light went off and after a 800 mile drive to and from Burning Man, it remains off!! Seems that static electricity from the belt (aftermarket) was causing the crank sensor to register the misfires. Eric 2000 EVC


Bad MAF
2021-03-16
Spencer

My 02 threw those same codes found it was a bad MAF.


Coolant Temperature Sensor
2009-11-23
Florian

Ok, this will sound weird but I suggest that you take a look at your coolant temperature sensor (replace). We had similar readings (intermittent misfires and a couple of other things) and we replaced the sensor and all was good. My mechanic was reluctant about it (thought there was no point) but he did it anyway and was surprised by the result. There is a thread about the strange effects the coolant sensor has either here or on vwvortex about 2 years back. My 2 cents. Florian 03 MVWK



Misrouted Vacuum Hoses
2010-03-13
Kris (and others)

My 1997 EVC (185k miles) failed Texas emission inspection. It had long had a variety of EGR-related issues, so I dove in and replaced the EGR valve (ouch $$). Now I've got a rough idle and multiple cylinder misfires (per VAG COM) with the EGR vacuum line attached. If I detach the line, the idle immediately smooths out. Ideas? Clues? Suggestions? [Updated later to say the vacuum lines were misconnected]


Eval Purge Valve (N-80)
2010-07-21
jpython
I have a 2003 with 95000 miles and after taking a long run at highway speed, I exited the freeway to a stoplight off the ramp only to have the engine go into a total headspin, rough run at idle barely able to hobble home. After tearing my hair out some research showed [the N-80 valve] a possible issue. I removed it and indeed found it was stuck. I then used gunk to clean it out well. I let it dry very well and reinstalled it and all has been fine since. (I had previously cleaned the MAF, changed plugs etc before this ever occured. It is a cheap thing to try, and cleaning vs replacing worked well. Good Luck.

Low Octane Gasoline / Knock Sensor
2014-06-01
Carl

2003 MV Weekender. Recently purchased Eurovan w/ 150k miles, previous owner said run on Premium, gets lot's better mileage. Now I know the real reason: Running on 87 Octane, I get severe misfire on hard acceleration from stop or rolling start. I can see 40, 50 & 60 or more misfires at Measuring block 14. VCDS seeing the following codes: 16684 - Random/Multiple Cyl Misfire 16688 - Cyl 4 Misfire detected <-- Always this one! 16685 - Cyl 1 misfire & 16689 - Cyl 5 misfire occasionally pop up.

Lose Catalytic Converter
2015-02-09
Nick

I had all 6 injectors replaced which cost a pretty penny. At first it seemed like the problems went away but now the misfire on cyl 3 is back. It misfires under load when the revs are high. It feels like the autotrans is shifting late before it misfires. Some of the old injectors were badly cracked so it really seemed like that was my problem. [...] Turns out my catylitic converter was super loose where it connects to the exhaust manifold and the gasket was toast. Luckily I was able to track down the gasket and tighten that back up. Maybe this exhaust leak is what caused my problems from the beginning? I'm kind of amazed it rattled loose but people have been known to steal catalytic converters in Oakland to scrap so who knows? Either way no misfires from la to Texas so far!

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Re my previous post re spark plug wire thickness. The 7mm vs 8mm thickness may be nothing at all. Just depends on where these wires are routed. If they're near anything hot like manifolds, then I'd consider the thicker wire. But as folks say your mileage may vary. Also, you don't have to replace all wires. Make sure you test those wires you have. You may be able to find a suitable replacement for just one or two if needed.?

Those Euro OEM wires are expensive (great company). Still, I'd ask around in other forums for recommendations.

I like and trust Europarts.?

No matter, always test spark plug wires for resistance. Don't know anything about OPParts.

I'm a bit concerned about the 7mm wires. That may not be the spec for Euro that you need. The 8mm gives extra insulation from heat. Heat causes resistance which causes degradation in voltage in spark plug wire. Something to think about. Maybe someone on this board has the manual who knows specs.

Hello, Michael,

My replies about the issue were speculative -- obd2 code can lead you down funny rabbit holes.?

You're correct about the injector ohm test re clogged or fouled. But that test doesn't account for shorted injectors, leaky injectors, leaky o-rings (which can cause misfire at load which is what you described in your original post) or mechanical issues inside the injectors. So to eliminate injectors entirely you'd need to "flow" them and look for rate/time and then drips after injectors shut off. Then use an oscilloscope to watch for the pintle "hump" in the injector's waveform -- when the injector is energized a magnetic field is created which pulls up the pintle to let the gas discharge.?Absent those tests, the injectors can't officially be ruled out as a catalyst for the misfire codes you received.

That said, I'd examine?all your spark plugs, especially cylinder 2 and 6 plugs! Look at electrode gaps.
Look for carbon tracking on the porcelain which is an indication of arcing in the spark plug boot.
Examine those boots for tears.
Always test new spark plug wires for resistance. Should all be fairly the same. Just keep in mind resistance is measured in ohms per foot. It's possible you have a couple of bad ones.
Look for carbon tracking inside the spark plug connector that connects to the spark plug.?The issue could be just that simple.

You certainly shouldn't have to replace those spark plug wires this soon. Have you checked for mice issues?

If spark plug gaps are nubs you'd have to ask why -- 5,000 miles isn't much to ruin plug electrodes unless something else were going on e.g. a harsh lean (typically) fuel condition. And for that kind of diagnosis you'd need to know and understand your fuel trims.?

Examine the coil pack for any signs of cracks, chips, arcing. If you really want to test the coil, you're going to need a multimeter (or oscope) to diagnose whether the issue is with the coil itself or the inputs to the coil. Simple to do if you have the tools and know where to hook up and what to look for -- safely. Not so easy if you're a diy'er with few tools. YouTube certainly could help you with other tests you can do. Just use caution around the high voltage and fuel.

The vehicle workshop manual would be super helpful for you. You might also consider a monthly subscription to prodemand diy (I think it's called Mitchell1 for consumers). I have no affiliation with software or manuals. They're my suggestions based on my experience.?

Last tip: Use what you can see, touch, smell or hear to validate what's working and what's not in the engine compartment with engine on and off, or even key on, engine off.

Update: I measured the resistance and all 6 injectors were right at 14.8 Ohms, which seems good.

This doesn't prove the injectors aren't clogged or fouled, but does point more towards an ignition problem, especially since the misfires are always on #2 and #6.

The air is drier today, so I'll try clearing the codes and running the van a bit and see if the problem comes back.

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Any opinion on these spark plug wires for a 2000 Eurovan?