What's wrong with my engine?

I pulled spark plugs 4, 5, 6 and the engine hardly vibrated. What could be the reason? BTW, my sparks are 1 1/2 year old already.

Maybe I´m slow today.

But that sounds as if you have been running your engine on three cylinders?

more info please
did you do it at the same time? one at a time?

and i know from experience that a 200 will barely run with 4 cylinders going, so one running with 3 cylinders sounds a little silly to me

is the motor tuned well? because if it's slightly mis-tuned it'll run rough already and if it is, you might not notice the difference when you remove a plug

Thanks for the replies. I'm no gearhead but I'll try to explain it to the best my ability.

I pulled it one at a time (the tension wires, NOT the spark plugs). The 1-3 plugs made the engine vibrate hard. On no. 4, it barely vibrated. Same thing with 5. While 6 made no vibration at all.

Lately, my car was stalling at 40-50mph. I found out my hose from the vaccum advance (that little circular plate attached at the back of the distributor, I hope I got that right) going to the carb is broken. So I fixed it. So far there's no stall.

As much as possible, I try not to bring the pony to a mechanic since I love fixing it on my own. Not to mention the skyrocketing labor service they charge on you if they found out your a newbie.

This may sound stupid, but I will greatly appreciate if you reply in layman's term.

God bless!

Bunny

OK, what you need to do is check the quality of the spark at those questionable cylinders.

This testing is performed with the engine running. If you have some plastic pliers, or well-insulated pliers, hold the "nose" of the lead about 5-6mm from some bare metal on the engine. Note the spark; how it jumps across to the metal.

Hopefully it goes without saying, but take every precaution to avoid a surprise spark to yourself! Some systems have such a big spark you can hear the click when it zaps someone. Pretty cool to watch if it's not you. :roll:

If the spark is good, pull the plugs one by one, check the gapping and condition. There is a good chance they are not perfect. If they are in good condition, then you will need to perform a compression test.

Adam.

addo":2fept6nt said:

Hopefully it goes without saying, but take every precaution to avoid a surprise spark to yourself! Some systems have such a big spark you can hear the click when it zaps someone. Pretty cool to watch if it's not you. :roll:

Click to expand...

Even if you take precautions, if you are running powerful ignition system, you'll still get wacked from time to time.

I like using a spare spark plug to test the wires. It gives a more controled path for the spark that doesn't include my hands. My current ignition system is very loud when you check for spark, and you can get a spark at least .5cm away from the block. And man...can it wack you if you are holding it wrong...

Slade

I've seen the Bosch coil spark jump over an inch. Now I know why my buddy Dan jumped so high.

I use an extra plug to test. I set the gap wide, and check for spark color. Put the plug into each boot (connector) one at a time, and rest the plug on the engine block. Start the engine. If the engine runs, then: Blue/white=good spark, good coil. Red/orange/yellow=weak spark, need to test coil and the voltage to the coil. Good spark to some, but others have weak/no spark=bad wire, bad distributor cap.

i've had friends who's 200s have ran on 3 cylinders

one time i was cleaning my plugs and my neighbor came and talked to me...i forgot that the plug was in my hand and went to start it up...geez...it ran pretty good for the little while it was running but it was real noisy....hehe...oh man...its one thing to run with a spark plug disconected but another thing to run without the plug at all...oh well....everyone has their moments....also i had moved my coil from the engine block to the wheel well just below the shock tower...which is usually where i rest my hand when i change the timing....BZZZZZBNZZz...well i went and timed the engine and guess where i placed my hand....i learned.... I picked up some sort of lead tester which is supposed to light up if u touch it to the lead....what a piece of crap....dont buy things like this...do it the old fashioned way....

I have to favorite tools for checking spark.

Tool numero uno is a standard 12v test light. Ground the clip and then poke through the tops of the plug wire boots with the probe. Most of the time you will hear the motor start dropping a cylinder. When you hear one that does not change the sound or running condition of the motor you have good indication that something is wrong with the ignition on that cylinder.

Tool 2 is the plastic pliers for pulling off the other end. I am still psychologically scarred from my older brothers getting me to 'help' them with their motorcycles 'here, hold this for me would you?'

Does anybody on here happen to remember the maximum resistance a plug wire is allowed to have before it is supposed to be replaced? I thought it was a ohms per foot sort of reading.

-ron

I had mine run on 3 cylinders for 30 miles. My pertronix lost 3 of the magnetic triggers at night aroudn 10pm. Top speed was 35 MPH and I burned about 6 gallons of gas in those 30 miles, but I made it. Tell me what V-8 can run on 4 cylinders?

Slade

I've seen a few, Slade. Half the time the exhaust note doen't change, either.

the wire to yer carb is that yer choke? try locking it open and see if it stalls

If the spark test doesn't show bad wires, cap, or plugs, I would venture a guess that the compression on those back cylinders might be below average and at that point you may want to do a compression test. If a cylinder is not "pulling it's weight" when it comes to compression and contributing to engine power, you won't notice it nearly as much when disconnecting it's plug wire as you do the cylinders that are making the power. Figuring out why 3 cylinders are low on compression (if that's what you find) is a standard process of elimination (head gasket, valves, rings, etc.) and testing.

CobraSix":1wizd8ay said:

I had mine run on 3 cylinders for 30 miles. My pertronix lost 3 of the magnetic triggers at night aroudn 10pm. Top speed was 35 MPH and I burned about 6 gallons of gas in those 30 miles, but I made it. Tell me what V-8 can run on 4 cylinders?

Slade

Click to expand...

I recall reading in one of the magazines (Popular Science maybe?) back in the 70's where one of the companies was experimenting with a V-8 engine that had a device to de-activate the valves on as many as four cylinders at a time in an attempt to get better fuel economy. It worked, but never made it into production. Four cylinders makes plenty of power for cruise, and the extra cylinders would be cut back in as more power was needed.
Joe

that cut off system was used by gm and specifically in the cadillac.

I'm pretty sure BMW or Mercedes do that even now.

I can second that.

new 5.0l mercedes benz V8´s sport the automatic cutoff system (among 3valves and dual plugs per cylinder) which puts up to 4 cylinders out of service when cruising on part-throttle.
this system is supposed to rise gas mileage from (hold yer breath!) 17,9mpg to 18,3 mpg.

Success through progress!!!



or to put it in other words: plain useless.

Ford did a cut-off fuel system on the 200 cube I6 engine in 1984. The called it a Topaz 2.3HSC.