How can you tell if your plugs are misfiring - Cars & Trucks

You can't tell the condition of coils by looking at them.

There should be no holes in hoses. Tape it up, see if it fixes it.

The code should tell you which cylinder as well as the generic 'random misfire' code. The code end 1 to 8 depending on how many cylinders your mystery vehicle has? Knowing which cylind the misfire is, you can swap coils and see if the misfire follow.

'year make model' in all questions, first 3 words please..

Question edited for clarity. Full year make model in title and mis-spelling of 'misfire'.
Question moved to sub category.

The misfire code only tell you that, unfortunately it doesn't tell you why. When swapping parts to test theories, only swap one thing, one cylinder to one cylinder and only one item, the coil, the plug or the wires, not all three. What was the make of the Crankshaft Sensor? Only buy quality OEM replacements as there is a history of bad ones from Mexico and China.

Wouldn't hurt to check the wires again. This has a neat diagram.

https://www.silveradosierra.com/threads/5-3-firing-order-cylinder-diagram.734633/

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My info says you don't have a coil pack. You have coil on plug ignition, one coil for each spark plug. If you have a misfire on a particular cylinder, your trouble code should tell you which cylinder, then you check fuel--spark--compression on that cylinder. A p0300 misfire code is a misfire common to all cylinders, or the computer thinks there is a misfire but can't tell which cylinder.

it could be bad spark plugs, plug caps/wires, coil, fuel injector.. you will have to find out what is causing the misfire and repair. this code tells you that the misfire is not isolated to a single cylinder.

could be an ignition or fuel problem. i can't tell from here.




A live diagnosis is needed to choose your path.

Misfire just means that one or more of the spark plugs is not firing at all, or fires most of the time and sometimes doesn't. You do have an OBD connector on your car, go to AutoZone, they will plug into it and most likely even tell you what cylinder is misfiring. Check the plug and wire. Usually an easy fix. Plug or Wire.

plugs and wires. yes wires are the biggest issue with a misfiring engine. check the gap on the plugs. sometimes they are gapped to far and cause a cold misfire issue. simply pulling plugs and look at color of the insulator will tell the condition of the engine. normal should be a golden tan color darker means its to rich or burns oil white ask means to hot and should use a colder plug

Misfire could be a number of things:
a) spark plugs - change them if used over 15K miles - inspect/regap.
b) spark plug wires - change them if over 15K miles - inspect
c) ECM (electronic control module) - test with HEI (high energy ignition) tester.

The vibrating tells me that the engine is running on less than its normal compliment of cylinders - the shaking is produced by the imbalance caused in the engine by one (or more) cylinder(s)
not firing at all.

The "Check Engine" light probably is coming on due the the misfire condition. Go to Pep Boys or
Advance Auto Pats, where they'll tell you (free) your codes causing the "Check Engine' light to be
lit - the code coming from your truck's computer will probably be one or more of:
P0300 - Random/Multiple Cylinder misfire detected
P0301 - Cylinder 1 misfire detected
P0302 - Cylinder 2 misfire detected
P0303 - Cylinder 3 misfire detected
P0304 - Cylinder 4 misfire detected
P0305 - Cylinder 5 misfire detected
P0306 - Cylinder 6 misfire detected
P0307 - Cylinder 7 misfire detected
P0308 - Cylinder 8 misfire detected
P0313 - Misfire detected with low fuel

Misfire could be a number of things:
a) spark plugs - change them if used over 15K miles - inspect/regap.
b) spark plug wires - change them if over 15K miles - inspect
c) ECM (electronic control module) - test with HEI (high energy ignition) tester.

The shaking tells me that the engine is running on less than its normal compliment of cylinders - the shaking is produced by the imbalance caused in the engine by one (or more) cylinder(s)
not firing at all.

The "Check Engine" light probably is coming on due the the misfire condition. Go to Pep Boys or
Advance Auto Pats, where they'll tell you (free) your codes causing the "Check Engine' light to be
lit - the code coming from your truck's computer will probably be one or more of:
P0300 - Random/Multiple Cylinder misfire detected
P0301 - Cylinder 1 misfire detected
P0302 - Cylinder 2 misfire detected
P0303 - Cylinder 3 misfire detected
P0304 - Cylinder 4 misfire detected
P0305 - Cylinder 5 misfire detected
P0306 - Cylinder 6 misfire detected
P0307 - Cylinder 7 misfire detected
P0308 - Cylinder 8 misfire detected
P0313 - Misfire detected with low fuel

misfire :-------- try checking your 02 sensors /fuel pump and filter.

for 51 cylinder misfire :---
Change the coil. Period. Very easy to remove from the vehicle if it's a 4 cyl. Follow that spark plug wire from the spark plug to the other end. What it's attached to you should replace
for 54 cylinder 5 misfire :---First you have to eliminate the most obvious problems, like spark plug and spark plug wire. If you replace those and you still have a misfire, then it's a good idea to look for a vacuum leak in the intake manifold