Are all 8 plugs firing, and how can we tell?

[SAR-4800]

I'm not sure if my '88 Grand Wagoneer has all it's plugs firing after I changed them out (along with new 8mm wires) a week or so ago. They are splitfire plugs (yes, I bought into the gimic) and splitfire wires.

Is there any tell-tale symptom that would be a dead give-away of a cylinder not firing?
Is there any simple way to test for this this?

I just seems I have less power... then again, that could be my imagination.

[JINGA]

Here's the test I've done. Not the safest thing in the world, so do it with caution. If you get hurt, you didn't hear about this from me.

I pull the wire from the plugs one at a time. Depending on the engine tthis might even be doable while the engine is running. That's the dangerous part, but makes a better test.

If the engine's idle doesn't change when you pull off the wire, then the plug wasn't doing anything to begin with. Investigate that cylinder further.

Even an eight cylinder will run noticably badly when missing a cylinder. It would hobble along and sound like total crap I think. Maybe you didn't stuff those wires on there tightly enough when you installed them.

Good luck.

[Chero77]

If one cylinder is missing it should be very noticable. You should be able to hear the miss and if you feel the exhaust you should be able feel a pressure pulse, instead of an even steady flow. I.e. you get a lack of pressure when the engine misses, which makes the exhaust feel like it pulses.

Finding the miss is pretty easy. Just pull and replace each plug wire. One will have no effect on the engine. That's the cylinder that's missing. I would suggest turning off the engine and restarting each time you pull a plug wire.

[SAR-4800]

Ah ha, I didn't even think of this... thanks.
I'll give it a go and see what I come up with.

[<bigjeepguy>]

Check all of your plugs, if any of the plugs look way grimier than the rest, do a compression and leakdown test on your engine and that should do er(unless you have next to no compression then you get to rebuild it)

[Snakeyes_Tx]

Not necessarily true! I ran for 3 months on 7 cylinders before, and couldn't tell a single difference. I never would have if my flywheel didn't break! :D Then I was forced to take that think apart and found it!

[Millerluck]

Here is a safe way.

Put the timming light induction clip around 1 wire at a time like when checking timming. Check all 8 wires. The light should flash for each one when you pull the triger. If a plug isn't firing no juice will go down the wire unless it is leaking to the head or somthing someplace. Witch would keep a plug from working too. This you can check in the dark. If you see any flashes then you have a leak.

I recomend dielectric greas on the boots at the plugs and cap. You can get this at any auto parts place.

Just my .02

Later

Larry Miller

[ September 29, 2001: Message edited by: Millerluck ]

[jeepgods]

another way if you dont have a timing light is to use a test light. with the engine running, ground the test light and poke the point through the top of each plug wire boot at the cap (this will ground the wire) its the same thing as pulling each plug wire off but you dont have to shut the truck off and you cant get shocked

[Dan]

But getting shocked is the fun part. :eek:

[Veepster]

the trick to not getting shocked is to not be touching the vehicle......when you pull the wires off make sure that is ALL you are touching on the vehicle..I guarantee you will never be shocked again.........