Which Cylinder is not working?

[shane wescott]

Hi Guys

Reading some stuff on the internet and came across a nifty (sort of accurate) way of telling which cylinder is note working in the event of rough idle/running etc.

Unfortunatly I needed the info sooner than i thought :-(

Cleaned out the car ready for the trip to Alfesta on Wed Night, and when I started it - rough running :-(


So ran it down the road to the local servo, opened the bonnet and used the tip.

Step 1. Place finger in mouth.

Step 2. Wet finger with tongue.

Step 3. Place wet finger on exhast manifold for each cylinder.

Step 4. Listen for sizzle and quickly remove finger

Step 5.  Repeat steps 1 - 4 for each cylinder

After doing this it was clear that cylinder 3 was not running. All the others sizzled (and required quick removal of finger), cylinder three appeared to hold the water for some time and it eventually evaporated.

Tomorrows job is to replace the new (two week old) NGK sparkie in cylinder three and see if it is a dud.

Simple method but seemed to work well for me :-)

Catch ya

Shane

[Al Campbell]

Shane,

I like it!

Can't say I've ever had a new plug go bad, but then these Alfas do funny things.

Tried a similar method after adjusting the brakes. Suspected I had the rear callipers a little tight. Go for a bit of a drive and then check the temperature of the rear disks with respect to the front. I was too lazy to go and get the multimeter & temperature probe, so I used a finger.  Rears were too tight. The burn has healed after a week.

Al.

[alfagtv58]

Great idea in theory, but I like my fingerprints just they way they are!  Surely a drop of water in the same area would give you the same results without the pain and disfigurement that goes with it!!!!!!

You may have already done this, but before you go through the pain of removing one of the spark plugs with multiple socket extensions and uni joints and contorting your body to just the right angle etc, don't forget to rip off the plug lead first and make sure there is spark being delivered through the lead.

nifty (sort of accurate)

I like that, it's actually quite a good description for the internet as a whole!

[shane wescott]

I had thought of using an eye dropper as then the water would all be the same amount (much more accurate), ut my finger was close and almost clean so that was the way to go.

I will find out tonight whether it was the plug or some other spark related issue or not :-)

Catch ya

Shane

[Gary Pearce]

Sounds like a good case for GOLDEN LODGE.

[Luke]

I recently read this same tip in an issue of Grassroots Motorsports (US mag.) Only they suggested using a spray bottle filled with water.

[Jekyll and Hyde]

Alternatively you could pull one lead off the spark plug, listen to hear if the engine runs rougher, refit lead and try next cylinder, and repeat for all cylinders.  When you get to the one that isn't firing, you won't notice any difference in the way the engine runs when you remove it....  Much less burnt fingertips....

[Mat Francis]

good post Shane. my dad showed me that trick a couple of years ago, and has saved me plenty of time since!

To all you other wusses  , it will do you good! a great way to enhance reflexes.

[Sheldon McIntosh]

Never heard of a dud spark plug.  I'm sure they exist...

You haven't had the car idling for a great deal of time lately have you?  It's pretty easy to foul up the plugs if you leave these engines idling for some time (I'm thinking 15 minutes), especially if you might have leaky rings anyway.  Ask me how I know.  How did the old ones look?  And did they all look the same?

I defintitely prefer the "take the lead off" method, but that's a good one, will remember that.

[dehne]

ive only ever heard/used the lead method re the ngk all the brand occasionaly fail straight away have u tried the bosch super4s they are a much cheaper alternitive to golden lodge and work well i put aset in my old alfetta and they went for about two years

[shane wescott]

Pulled the no 3 plug out Wed  arvo before leaving for Alfesta, new plug in, 6 cylinders roaring :-)

May be a dead plug, may be just dirty and clogged. maybe leaky rings on that cylinder :-) will monitor and see what happens in the near future.

1800 klms later still running purfectly. I take Sheldons point about the idle, they did clog with the GL's when in the city. The car wont get much more running for a couple of weeks, apart from the Dandenong Historic Picnic on Sunday.

I will see how it goes but the tip works for me - never too old to learn a new trick.

And Sheldon, I think you are having an influence on me - I saw an ad for a 90 for sale today and my first reaction was - NICE :-)

A doctors checkup is being booked :-)

CAtch ya

Shane

[MD]

Let's take this dud spark plug stuff up a notch. Grounding each plug in turn does offer a clue which cylinders are working the hardest because the engine will show the largest protest when the cylinder that does most of the work is grounded.

The diagnoses does not end there because the problem could be the plug, the lead, burnt valves, bad mixture in the case of ITB's, carbon build up in the chamber etc.

The key thing here is a plug may do an adequate job under no load conditions and so mask a problem. However if the car is chassis dynoed under load, if the plug is suspect, it will really show up in this situation. So if you are having phantom like engine problems, a dyno tune is a sensible place to start. Usually money well spent.