Firing on only 3 cylinders

[FB71]

if the rings are worn, you'll get alot of blow-by. Check for blow-by by removing the oil-fill cap with the engine running, and rev to 1500-2000 rpm. Watch for smoke coming out. Light wafting of a few vapors are normal, but if it looks like a chimney, you have blowby. You may have a poorly sealing valve. To check for a leaking exhaust valve (most likely), let the engine idle, and cover the tailpipe with a dollar bill. If the bill gets intermittently sucked up against the tailpipe, you have a leaking exhaust valve. No easy/quick way to check the intake valve without some tools.

[FestYboy]

^the dollar bill trick also works for checking for mis-fires.

[Kitty]

Thanks for the suggestions. I'll be trying this over the next few days (if it stops raining!). I'm also working on getting a compression tester for the weekend. Mechanic at work suggested it might be a burnt valve and I could test it with that. Couple people have said that if its low compression in that cylinder just go ahead and drive it until it dies. Not sure yet how I feel about that idea.

[Unco]

Kitty, it could well be a burnt valve. i had that in a ute that i sold recently.

but please check the obvious first: as others have mentioned, pull one spark plug lead off at a time.

the compression test should show whether you have a burnt valve or not.

if it is a burnt valve (like the one in my ute) you should be able to dive. however, say goodbye to your fuel economy. my 2.0L 4 cylinder ute with a burnt valve used almost as much fuel as my 5.8L V8. this was because you had to floor the accelerator in order to get anywhere.

[Kitty]

I've already pulled wires. I know which cylinder is acting funky. I have no loss of power, no loss of MPG but when you pull that plug wire nothing happens. When you pull the wire off one of the other plugs it sounds like you've just choked the car. Truly, I'm not nuts. This is what is going on with my car. It's really starting to bug the fire out of me because I keep getting told "It will do this, it won't do that" but it isn't and it is!

Why can't my car ever do anything normal?