Misfire Quick Tests (Is it a spark, fuel or compression problem?)

I've had the paid channel for almost 2 years. Even having experience I find the channel exceptional for training. Let's say, top 3 best on You Tube IMHO. It has something for everyone for sure.

I love advanced diagnostics , this guy is a diagnostics master in automotive.

He gets to the root issues quickly, teaches his tricks all without editing, he's the real deal!

Straight to the points. All of them. Acknowledged mistake in assumption and explained it all clearly. Thanks, Dan!

I like watching you do things hands on which puts things in perspective for those of us who lack experience with troubleshooting in certain areas. +1

Happy to see that Pico scope out. Great Job Paul it's always a pleasure to watch you work.

I have the same problem cylinder 4 .sometimes it runs good sometimes it runs bad.but always cyl 4 .the car had a ticking noise after the head gaskets were replaced .so I replaced both rocker arms and lifters .i don’t know that it had a code p0304 before I replaced the rockers because like I said it had a blown head gasket .the machine shop said the heads and valves were ok .when they resurfaced the heads .so now I’m stuck with the cyl 4 misfire .compression test showed bad compression .bit some times it runs great .you nailed it for me .its a bad lifter ona new rocker assembly but more than likely a piece of some thing is blocking the oiling orifice for that lifter. Thanks a million your thorough diagnosis lead me to the only problem it could be .bad lifter or more likely a piece of silicone blocking the lifter orifice intermittently.now I can fix the car for zero dollars .

I had a 94 Chrysler Laser years ago with intermittent low compression on one cylinder similar to this case. It turned out to be a bad valve guide. Using a compression gauge it would read bad one time and OK the next. It also fouled the plug with the bad valve. It was bad from new. The dealer knurled the guides and it worked for 6 months or so, long enough to get out of warranty. I ended up replacing the cylinder head after which it ran far better than when new. Oil in the cylinder made it want to pre-ignite. The knock sensor backed off the timing and it was a stone. After the fix I could lay rubber with it.

Thanks Paul, The real time out in the field diagnostics like this drive the learning from the Premium Channel home. Take care Bill

Excellent video. Although I don’t understand the scope diagnosis completely it certainly opened my eyes to deeper diagnostic techniques.

Can't get much more professional than that, Thank you very much.

it's a dodge caravan, it was beat when it left the dealer lot :))

When you present on video I feel like you are talking directly to me very effectively. Thank you for All your videos S/D!

Gonna sub, not only for the great info, but I see you are still replying to comments today on a 5 year old video. Very rare and commendable. Much respect. Thanks.

Good job sharpening production skills Paul.. your channel is just getting better

The best I’ve ever seen do it so far

I see why it's pointless to further check for anything else than physically checking the valve train, thanks I learned a lot today.

My daughters 2002 mazda626 has a cylinder 3 misfire, changed the spark plug, coil and wires with no change with rough idle I’m at my wits end. Your video has given me other possibilities to explore. Thank you for your video.

Rear valve cover isn't that bad on that van. I did stem seals on one at 485,000 miles. Last I heard it was still running just fine North of 500,000. Commercial van with lots of miles and few cold start heat cycles as well as being in an arid environment and having a dedicated mechanic helped it reach a round trip to the moon and back. Great new tools for the toolbox on my shoulders. Thanks Paul.

I just changed the heads on the 2000 Ranger 3.0 with 188,000 miles. They had known exhaust valve issues over time. Turns out I had cylinders 4 and 6 getting coolant in the chamber which was cracking spark plugs and then once I had the old heads on the bench, 5 out of 6 had brake parts cleaner leak past the exhaust valve seats. Now with new heads with hardened seats, all new head, intake and valve cover gaskets, I am battling high LTFT's. Got new O2 sensors on the way since mine have about 60,000 miles on them with raw fuel from misfires for who knows how long. Good news is that there is no sludge in the motor and the cylinder walls still have the cross hatch on them.