Engine Miss - Simple Way To Diagnose Bad Spark Plug Wires

Does your vehicle seem to have an engine miss, run bad or is the check engine light coming on?

This is a SUPER simple shade tree mechanic to help determine if you have an electrical miss fire like from a bad spark plug wire or a bad ignition coil.

Engine running, one foot FIRMLY on the brake, place into park and give it some gas. Don't OVER stress the engine for too long, the transmission will not like that.

In this example, I brought the RPM up to about 1800 to simulate highway speeds, then let off for a few seconds then brought the RPM back up again.

If the engine starts to buck, stumble or missfire you could have a ignition related problem like a spark plug wire or ignition coil.

if the engine bogs down and looses power you probably have a lack of fuel pressure or fuel volume problem with the fuel pump.

Hope this helps you determine the problem you might be having.

Check out my websites for more information about car repair.

[hellcat]

I've found a few bad wires by leaning over an engine to try and find a vacuum leak or damaged wiring and rested my hand on the coils or plug wires while my other hand is touching metal for a ground. It's one heck of an eye opening experience.

[chrisanderson]

Thats some diagnosis there, guy.
All you did was prove that the brakes work, the engine revs, and you're barefoot.

[reppy]

Well, this was a good way of showing nothing other than you can detect a misfire in person.

[sunking]

The easiest and most basic way to tell if you have bad spark plug wires...go to your car at night in the dark...open the hood...start the engine...go back to your open hood with the engine running...look at your wires...if you see any visible "flashes" on your wires...your spark plug wires are "arcing!" This a basic test from "the old school!"

[enginebuzz]

Just changed my my plugs and coils, it was gutless before. Great video!

[slayer]

the reverse/break test did it for me. After struggling to find what was wrong, tested it and  went to buy wires, and problem solved. Many

[seekintruth]

looks like your dad needed some new engine mounts as well

[trustmymechanic]

Hi there, I would first start by checking ignition components to rule out an engine miss. Spark plugs wires, ignition coil, spark plugs. When the engine misfires (one or more cylinders basically stop working for a split second) it will give the feeling of a transmission problem because the vehicle will buck and jerk. The check engine light can also come on because the computer sees the misfire, and the O2 code could be due to unburned fuel in the exhaust...due to the miss as well. Start there.

[thincrediblewho]

You know, I expected to see you demonstrate how to diagnose bad spark plug wires, but all you did was assume it was the wires. Now, given the fact that the wires were 100, 000 miles old, I would be surprised if they were still good.

But you didn't eliminate other possibilities, like plugs, distributor/cap, coils, or even a disconnected wire. Any one of those could be the cause of his misfire, or a combination of more than one problem. Rather a pointless video.

[pnwadventurer]

haha you crack me up, its guys like you that make this stuff less frusterating

[TheSirjohn]

In about 80% of the cars in shops more than likely its the ignition wires that often get replaced, but that's sometimes not always the case in this video.
A badly fouled spark plug can also cause misfiring(oil fouled) mostly found first.
Other than that its all good.

[kevinnelson]

Where can I purchase these spark plug wires with the cylinder numbers printed on them i have been searching they are hard to find

[OneClickPony]

My 1991 Dodge Stealth R/T non-turbo has a missfire. It idles fine, but rev to 2500 rpm on the curb and it runs uneven. Trying to accelerate strongly from standstill in 1st gear, it staggers then goes fine. Previous owner changed platinum plugs and fuel filter 3000 km ago. But no new sparkplug wires (not sure why, but not on invoice). Engine never dies but does run rough enough to sense it. Could fuel filter get dirty after only 3000km? It has been sitting covered a few winters. Any ideas? THX

[eddieford]

Thanks for the video Austin! I appreciate the time to help us folks that need the help. It only cost me $29 bucks to replace the spark plug wires. Runs like new now!

[OneClickPony]

Okay, thanks Trusty, that is what I did this morning, book it for new plugwires. Not cheap tho, 2.85 hrs to install on this engine, total of $480.

[congero]

I have same symptom as your dad of car chugging as if a cylinder is miss firing but my '07 Mazda 6 has wires leading directly into coils which fit on top of each spark plug. The wires seem rather different than those in your video. Could it still be the wires or could it be the coil itself or the plug?

[STK]

When I am driving my 03' Taurus. sometimes it will start slowing down and I can feel the car chugging along and the speed drops and I can feel the car trying to get going and pick up speed. Sometimes it takes back off others I have to pull over and put it in park shut it off and restart it...itll happen several times in a row happening every couple miles for 20-30 miles and the other times I don't have the issue...could this be spark plug related then? the shop keeps telling me they don't know.

[Thag]

My car is doing that right now and I just brought new spark plugs thinking that was it but it wasn't. It's a 1990 Jaguar xj6 with only 61000 miles everything still original what do you think?

[davidcarmichael]

Sometimes even a blocked fuel injector could cause similar symptoms.    Happy you were able to fix the problem for your faher.

[crakkhausetv]

What exactly you gna see or feel when you accelerate in reverse mode with brakes on ..?? Can you be more specific here..

Thank You