TheSamba.com :: View topic - [Solved, hopefully] Oil on #2, lower compression on #1; misfire

Sun Oct 21, 2018 5:14 pm

Compression is lower on cylinder #1
Oil on cylinder #2 spark plug

Significant amount of misfire, giving me a lot of grief. I recently posted a thread on doing timing, and I lied when I said it's fine now after all that advice. It doesn't time right, probably because of the misfire. At 35 degree advance with throttle up it's way off. At 35 degrees at idle it is driveable.

Has high miles but doesn't burn or leak oil generally and runs pretty well otherwise.

Will take it for a leakdown and professional opinion but any insight on whether it sounds more like valves or head gasket or whatever else would help me go in informed. Much obliged.

Sun Oct 21, 2018 6:17 pm

Im defiantly no expert, but I am well versed in timing my engine, and it should be 28 deg above 3000 rpm's with the vacuum hose disconnected, and 7.5 deg at idle with hose connected. Ill leave the rest to the more knowledgeable , good luck.

Sun Oct 21, 2018 6:37 pm

The spark timing procedure and the specification for the air-cooled Vanagon engine is different from that for the 2.1 WBX.

To the OP, what are your compression test results in pound per square inch?

Please remember that to yield a useable result, a compression test must proceed as follows:

1. Engine must first be warmed to operating temperature before attempting the test;
2. All spark plugs must be removed;
3. Battery must be fully charged;
4. Throttle must be held wide open while engine is cranked (otherwise cylinder filling is incomplete);
5. Your helper must crank the engine until the compression gauge reading tops out and ceases to increase.
6. Optional, but recommended for safety: Disconnect the fuel injector electrical connectors.

Get back to us with your results.

Sun Oct 21, 2018 6:56 pm

Howesight wrote: The spark timing procedure and the specification for the air-cooled Vanagon engine is different from that for the 2.1 WBX.

To the OP, what are your compression test results in pound per square inch?

Please remember that to yield a useable result, a compression test must proceed as follows:

1. Engine must first be warmed to operating temperature before attempting the test;
2. All spark plugs must be removed;
3. Battery must be fully charged;
4. Throttle must be held wide open while engine is cranked (otherwise cylinder filling is incomplete);
5. Your helper must crank the engine until the compression gauge reading tops out and ceases to increase.
6. Optional, but recommended for safety: Disconnect the fuel injector electrical connectors.

Get back to us with your results.

Thanks, the compression was roughly 90-120-120-120. It was warm, not 100% operating temp. so this is not scientific.

The #1 cylinder had the lower compression, while the #2 cylinder has a fair amount of oil on the plug (but almost exactly the same compression +/-2 as the other two "good" cyls). I thought maybe this was a piston ring thing, but the oily one is not the low compression one. (?)

I recently changed the valve cover gasket to try to narrow down the cause of this. Something else with the valves? Fuel injectors test identical resistance and I used some fuel additive to clean (no effect).

Trying to narrow down possible causes of the misfire to figure out if I have recourse short of the rebuild. Thanks.

Sun Oct 21, 2018 7:13 pm

Compression is a great gauge of general health. But just as an EKG is a great gauge of general heart health, there are better tests that tell you more.
for your engine, you need a leak down test. This puts compressed air into your cylinder, measures the amount of loss and it there is loss, by utilizing simple listening and visual clues you can tell if your loss is past the rings, past the intake valve, past the exhaust valve or through the cooling system.

Dave

Mon Oct 22, 2018 5:58 am

You have good enough compression that you shouldn't be having a misfire. What year-fuel system is your van? WBXer engines used two different fuel injection and ignition systems.

Does your exhaust sound normal? Are you hearing the misfire through the exhaust or are you determining it some other way?

Mon Oct 22, 2018 10:59 am

Wildthings wrote: You have good enough compression that you shouldn't be having a misfire. What year-fuel system is your van? WBXer engines used two different fuel injection and ignition systems.

Does your exhaust sound normal? Are you hearing the misfire through the exhaust or are you determining it some other way?

Okay, thanks, that's useful.
Yes, you can clearly hear the misfire in the exhaust. Can also see the engine rock, and see it on the flywheel when trying to do timing.
It's a 1990 2.1 - does that establish which fuel system it is?

Does the oil on the pulg cause a misfire, or the other way around, or both?
I'm not clear on all the possible causes of a misfire so I'm trying to eliminate things.

Mon Oct 22, 2018 11:02 am

1986 on is Digifant.

Plugs work good until they foul.
Oil causes fouling.

Try a TriTip NGK plug, three firing tips, less wear.

I've been using them for years.

Dave

Mon Oct 22, 2018 11:04 am

djkeev wrote: 1986 on is Digifant.

Plugs work good until they foul.
Oil causes fouling.

Try a TriTip NGK plug, three firing tips, less wear.

I've been using them for years.

Dave
Thanks - I just changed the plugs, with no effect. They are the NGKs but not the 3-prong guys. I can clean off the oil but it comes back. Trying to get to the cause of that.

Mon Oct 22, 2018 11:09 am

Most often rings are the cause.

Sometimes worn valve guides or excessive blowby or bad venting pressurizing the crankcase.

Dave

Mon Oct 22, 2018 1:26 pm

The reason folks here are suggesting that you do a leakdown test is to isolate whether the low compression cylinder (I presume it is #1 cylinder), is due to piston rings not sealing or due to a valve not sealing properly.

Vanagons, especially Westfalia Vanagons, lead unusual lives. They can spend months at a time, sometimes years, unused.

This leads to situations of "bad gasoline" where time causes the buildup of varnish compounds in the fuel tank which then are pushed through injectors, causing them to clog and acquire poor spray patterns. The varnish compounds are VERY sticky, especially once exposed to ambient air. This is why the varnish-laden gasoline sprayed on the intake valve stems can literally stick an intake valve in its guide. In some instances, the valve is stuck so badly that the pushrod bends.

In less severe cases, the varnish can still prevent the affected intake valve from closing fully, except at higher engine speeds when the inertia from the faster-moving valve can overcome the friction from the varnish compounds. This can cause the frustrating situation of an engine that misfires at idle and low engine speeds, but which does not misfire at higher engine speeds.

The other thing that can happen with engines that are not run for long periods is impacts on the piston rings. Gum can cause the rings to stick in their grooves and not seal properly. Similarly, an engine not run for a long time can, in a cylinder with an open valve, experience serious corrosion of either the cylinder wall or the rings or both, especially if the vehicle is not garaged when stored. That ruins the ring-to-cylinder-wall seal.

If ring problems are due to gum, then a good ring treatment additive can free up the stuck ring(s) and correct the problem. I suggest Yamaha Ring Free. Use as directed. See this link: https://www.westmarine.com/buy/yamalube--ring-free-fuel-additive--2280683

Regardless whether the problem is rings or poor valve sealing, all WBX engines should have their injectors professionally cleaned if this has never been done and especially if a miss is detected. It removes one possible cause of the miss and is normal maintenance anyway. I have had, on various vehicles, clogging that reduced injection quantity in one cylinder by over 20% compared to the other cylinders, so this is a real "thing". Cleaning restores matching injection quantity between the four injectors. New aftermarket injectors are not as robust as the factory units, so cleaning and re-using the factory units is best.

Mon Oct 22, 2018 2:44 pm

Howesight wrote: The reason folks here are suggesting that you do a leakdown test is to isolate whether the low compression cylinder (I presume it is #1 cylinder), is due to piston rings not sealing or due to a valve not sealing properly.

Vanagons, especially Westfalia Vanagons, lead unusual lives. They can spend months at a time, sometimes years, unused.

This leads to situations of "bad gasoline" where time causes the buildup of varnish compounds in the fuel tank which then are pushed through injectors, causing them to clog and acquire poor spray patterns. The varnish compounds are VERY sticky, especially once exposed to ambient air. This is why the varnish-laden gasoline sprayed on the intake valve stems can literally stick an intake valve in its guide. In some instances, the valve is stuck so badly that the pushrod bends.

In less severe cases, the varnish can still prevent the affected intake valve from closing fully, except at higher engine speeds when the inertia from the faster-moving valve can overcome the friction from the varnish compounds. This can cause the frustrating situation of an engine that misfires at idle and low engine speeds, but which does not misfire at higher engine speeds.

The other thing that can happen with engines that are not run for long periods is impacts on the piston rings. Gum can cause the rings to stick in their grooves and not seal properly. Similarly, an engine not run for a long time can, in a cylinder with an open valve, experience serious corrosion of either the cylinder wall or the rings or both, especially if the vehicle is not garaged when stored. That ruins the ring-to-cylinder-wall seal.

If ring problems are due to gum, then a good ring treatment additive can free up the stuck ring(s) and correct the problem. I suggest Yamaha Ring Free. Use as directed. See this link: https://www.westmarine.com/buy/yamalube--ring-free-fuel-additive--2280683

Regardless whether the problem is rings or poor valve sealing, all WBX engines should have their injectors professionally cleaned if this has never been done and especially if a miss is detected. It removes one possible cause of the miss and is normal maintenance anyway. I have had, on various vehicles, clogging that reduced injection quantity in one cylinder by over 20% compared to the other cylinders, so this is a real "thing". Cleaning restores matching injection quantity between the four injectors. New aftermarket injectors are not as robust as the factory units, so cleaning and re-using the factory units is best.

Thanks much for all the useful information.
One thing I can say is that it has been driven daily for the eight years I have owned it, and I don't think it sat long with the PO either. This misfire has been going on for a long time. Unfortunately it's part of a constellation of things that effect each other with the engine timing/mixture. I'm pretty sure the misfire is there at highway RPMs.

I think new fuel injectors are cheaper than getting them serviced (?)

As I said, I will take it for a leakdown, but I am just trying to know as much as possible before paying for service. For context, this is not a $30k westy, but just a ratrod daily driver van. Whether it is a 'top end job' kind of thing or needing a complete rebuild (because of rings) makes a difference.

My cylinder with lower compression is not the one with the oil on the plug, so I'm hoping to narrow down which one is causing the misfire, and that way, the cause. I'm not 100% sure I've checked all ignition/fuel factors.

Mon Oct 22, 2018 2:56 pm

Those numbers arent low enough to have oil on the plugs and a subsequent misfire.
You have a vac leak? That will mess up all sort of things.

Mon Oct 22, 2018 2:58 pm

New fuel injectors aren't as good as original Injectors that have been serviced. A lot of new parts simply aren't worth buying for they are inferior to the originals.

Send them out, you will have top quality injectors working like new.

Dave

Mon Oct 22, 2018 4:12 pm

AZ Landshaper wrote:
You have a vac leak? That will mess up all sort of things.
Entirely possible.

I'm reluctant to mention, much less unfurl the mission accomplished banner, but the ignition rotor was broken, as in a chunk of plastic missing under the contact, which itself looked pretty gnarly. I think it's the second time that has broken.

Replaced that and it does affect the way it runs. With the timing light, I can see it missing less. Have to figure out how to test everything to make sure it's not just missing on ignition -- in which case the compression and oil on plug are just whatever. Will see how it runs when cold.

Mon Oct 22, 2018 9:55 pm

I let it cool down and when fired up again, I can't see it misfiring at all with the timing light, although it is sort of searching for idle a little bit. This is down to replacing the distributor rotor, which had a chunk lopped out of it. Maybe the cap had mounted on wrong which caused it to break, or it's just cheap plastic junk. Lifetime warranty at Auto**** anyway.

At this point I am going to crack an ice cold beer.

Not 100% sure it's resolved, but feel pretty sure it's an ignition miss. I might get a new coil if it still misses a little bit, because it's very old, or try the big distributor cap that might fit better. My initial post caused a classic case of biasing the diagnosis. Sincerely appreciate all the information, although I am saving a s***tonne of money by ignoring most of it. :P

Having access to a lot of wisdom on these things is helpful for persevering with the approach of finding a testable cause, instead of hurling money at it or just taking it to a shop, where an unnecessary leakdown would cost me a couple bills.

Mon Oct 22, 2018 10:02 pm

For what its worth if you don't have the Vanagon Syndrome Capacitor installed in your AFM now would be a good time as one of the things is does is give a smooth signal to the ECU and will thus clean up the idle.

Mon Oct 22, 2018 10:45 pm

Wildthings wrote: For what its worth if you don't have the Vanagon Syndrome Capacitor installed in your AFM now would be a good time as one of the things is does is give a smooth signal to the ECU and will thus clean up the idle.

Cool thanks yeah I do have it, but today noticed that one of the leads is breaking, so could do with a cleanup.