Full Version: Sparkplugs
I have a 2L 914 that if I let sit for a short period of time[week or so] will start just fine, but always has a plug that wont fire. I keep a supply of the right type, but would like to get away from the, 1 plug to change before I can drive it, pain! Jets are clean, other 3 fire up just fine, same plug each time! rebuilt 6 K ago, no smoke! Bob
Have you checked that plug wire for an open circuit. The resistor that screws on the end may be dead.
QUOTE(914Mels @ Jul 8 2011, 01:00 PM) 
Have you checked that plug wire for an open circuit. The resistor that screws on the end may be dead.
From time to time this cyl will fire, I can hear it in the note of the engine above 3/4K
I do have good steady spark at the plug end of the plug wire[OUCH] at all rpms
Post a pic of the bad plug to ID the cause of fouling.
If it's/thay're always clean, then you've got an intermittent open circuit problem due to a short, bad resistor or wire/circuit or dizzy cap/etc. issue - despite your "ouch test"!
If it's/thay're always clean, then you've got an intermittent open circuit problem due to a short, bad resistor or wire/circuit or dizzy cap/etc. issue - despite your "ouch test"!
QUOTE(Razorbobsr @ Jul 8 2011, 11:46 AM)
QUOTE(914Mels @ Jul 8 2011, 01:00 PM)
Have you checked that plug wire for an open circuit. The resistor that screws on the end may be dead.
From time to time this cyl will fire, I can hear it in the note of the engine above 3/4K
I do have good steady spark at the plug end of the plug wire[OUCH] at all rpms
If the resistor is open, you can still get a spark to jump across the gap but with the pressure from your engine compression, it takes alot more voltage to jump that gap. If you dont have a ohmmeter to check it, try swapping the resistor to a different cylinder and see if your problem moves to that cylinder.
QUOTE(Tom_T @ Jul 8 2011, 05:12 PM)
Post a pic of the bad plug to ID the cause of fouling.
If it's/thay're always clean, then you've got an intermittent open circuit problem due to a short, bad resistor or wire/circuit or dizzy cap/etc. issue - despite your "ouch test"!
QUOTE(Razorbobsr @ Jul 8 2011, 07:48 PM)
QUOTE(Tom_T @ Jul 8 2011, 05:12 PM)
Post a pic of the bad plug to ID the cause of fouling.
If it's/thay're always clean, then you've got an intermittent open circuit problem due to a short, bad resistor or wire/circuit or dizzy cap/etc. issue - despite your "ouch test"!
It's the brown connector that screws on the end if the plug wire that connects to the spark plug. they are available separately for a few bucks or it might be worth just replacing the whole wire set. I bought a bosch set online for 21 bucks. If your brave and want to know if its bad right now, take the resistor off and smash it with a hammer, the center part with the resistor will look like charcoal when they burn out. The more delicate way to check it is with an ohmmeter, a bad one will show an open circuit from end to end. The hammer method is better for stress relief.
QUOTE(914Mels @ Jul 9 2011, 01:43 PM)
QUOTE(Razorbobsr @ Jul 8 2011, 07:48 PM)
QUOTE(Tom_T @ Jul 8 2011, 05:12 PM)
Post a pic of the bad plug to ID the cause of fouling.
If it's/thay're always clean, then you've got an intermittent open circuit problem due to a short, bad resistor or wire/circuit or dizzy cap/etc. issue - despite your "ouch test"!
It's the brown connector that screws on the end if the plug wire that connects to the spark plug. they are available separately for a few bucks or it might be worth just replacing the whole wire set. I bought a bosch set online for 21 bucks. If your brave and want to know if its bad right now, take the resistor off and smash it with a hammer, the center part with the resistor will look like charcoal when they burn out. The more delicate way to check it is with an ohmmeter, a bad one will show an open circuit from end to end. The hammer method is better for stress relief.
Just get a new set of wires and cap and rotor. I think you have a bad wire. Everytime you pull it to replace the plug your disturbing the corrosion allowing a weak spark to renew. One other thought is the valve guide is worn allowing oil fouling in that cylinder. I agree you should post a photo of the plug. 
QUOTE(rick 918-S @ Jul 10 2011, 09:37 AM)
Just get a new set of wires and cap and rotor. I think you have a bad wire. Everytime you pull it to replace the plug your disturbing the corrosion allowing a weak spark to renew. One other thought is the valve guide is worn allowing oil fouling in that cylinder. I agree you should post a photo of the plug.
It is possible that the bearings in your distributor are worn out.
Stu
Stu
QUOTE(stugray @ Jul 10 2011, 10:10 AM)
It is possible that the bearings in your distributor are worn out.
Stu
One more free thing to try, if you have a garage you can close the door on to get the engine compartment dark, or wait till the evening, start the engine and watch for sparks jumping off your distributor cap and plug wires. if you see sparks, that's where you have a crack or break in the insulation. You can also mist the wires and cap with a spray bottle of water to enhance the problem. Don't drown the engine just a mist.
QUOTE(914Mels @ Jul 10 2011, 03:34 PM)
QUOTE(stugray @ Jul 10 2011, 10:10 AM)
It is possible that the bearings in your distributor are worn out.
Stu
One more free thing to try, if you have a garage you can close the door on to get the engine compartment dark, or wait till the evening, start the engine and watch for sparks jumping off your distributor cap and plug wires. if you see sparks, that's where you have a crack or break in the insulation. You can also mist the wires and cap with a spray bottle of water to enhance the problem. Don't drown the engine just a mist.
Shortly after I got my '14 I put new plugs in, removing ignition wire & plug, one at a time. Engine started up with no problem but I could never seem to get it to run quite right. After going through the various FI components and replacing hoses, etc., pulled the plugs to see what was happening. One of the plugs looked brand new and another almost new. Checked continuity on the ignition wires and they were fine. Then discovered that two of the wires had been reversed!
Moral of the story is double check the obvious.
Good luck.
keith
Moral of the story is double check the obvious.
Good luck.
keith
QUOTE(luskesq @ Jul 11 2011, 12:50 PM)
Shortly after I got my '14 I put new plugs in, removing ignition wire & plug, one at a time. Engine started up with no problem but I could never seem to get it to run quite right. After going through the various FI components and replacing hoses, etc., pulled the plugs to see what was happening. One of the plugs looked brand new and another almost new. Checked continuity on the ignition wires and they were fine. Then discovered that two of the wires had been reversed!
Moral of the story is double check the obvious.
Good luck. Runs TOO good on 3 cyl to have crossed wires. Bob
keith
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