Engine misfire?

There are many reasons why a cylinder can misfire. It could be timing, compression, not enough or too much fuel. a fouled or bad plug...

This guide will help us fix it

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

As far as location, I believe #2 is in the rear. If I recall correctly, the front is 1, 3, 5 and the rear is 2, 4, 6.

Is there somewhere I can look to get a exact location web ,car ,manual

To the best of my knowledge, there are no specific sites.

I can't figure out a jerk in my car, from time to time every day the car jerks when accelerating from 15 mph-20 mph during the jerk all dashboard lights come on the engine almost halts as if the crankshaft is stuck. I press clutch and car picks up normally after crossing 20 mph

Hello,

Two things come to mind for this problem, first I would check the battery cables to make sure they are clean and tight. If the electrical flow gets interrupted it can cause an electrical surge which would make the car jerk. Next, I would make sure the engine had new spark plugs because a large engine misfire can cause the same thing.

Please let us know what happens.

Best, Ken

I just yesterday changed the battery, and see some normal driving conditions, I was considering the cables and getting the tune up, but for now I'll have the spark plugs changed and get back to.

Thank you for the reply

Please let us know what happens.

Best, Ken

Today i checked the plugs on my 04 santa fe to investigate a misfire, and the #1 & #3 plug heads were Covered in oil. And it was clean oil which i found strange.

the plugs were Very old and i had a misfire. When i pulled out the number 1 plug the head was completly engulfed in oil, the same if a little lighter on the number 3 plug, i found it strange that the oil on them was clean though, not like the oil on the dipstick. I put new plugs in and pulled the number 1 & 3 again immediatly, they still had oil on them but not nearly as heavy as when i pulled them the first time. I said screw it put em in and see how it runs. Not surprisingly, it still misfires, i assume from a drowning spark plug.


So i guess the real question is this...Where is the oil coming from? I immediatly thought head gasket, but my dipstick doesnt look abnormal at all, rings i thought next, then decided to come here first.
Also i had the timing belt done on it about 9 months ago (by a mechanic) and i was wondering if something could have gone wrong there as well, because the car started misfireing within months of getting this service done

no, the previous repair has nothing to do with this.

The oil comes from the seals on the valve cover that are leaking. the leak is external, not internal. when you remove the plug, the oil goes into the cylinder and all over the plug. the valve cover gasket needs to be replaced with the tube seals.

I believe it is a coil over, if not then wires but anyway, the ends are most likely saturated and need to be replaced. that may be your missfire. if not, then start with a compression test to start.

Roy

My girlfriend's car is throwing a code saying that cylinders number three and five are misfiring. she had the spark plugs and coil packs changed a few months ago and i did the wires yesterday hoping it would make the code go away. wires replaced code clear, drove for thirty seconds and engine light back on same code misfiring on number three and five. Any thoughts on what the problem could be?

Hello,

A couple of things come to mind for your problem, first is a vacuum leak. Here is a guide to help you check around the hoses.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

next is the MAF is starting to get out of range and its causing the misfire codes. Sometimes we have luck cleaning the unit.

Here is a guide to help you:

https://www.2carpros.com/articles/mass-air-flow-service

Diagram (below)

Please let us know what happens, we are interested to see what it is.

Cheers, Ken

My car was running great and had to go out of town for awhile and my son did not start it for three months. now it misfires when I tried to use it. However, after it ran for a few minutes it ran fine. the last time I drove it i could not get over thirty mph and it was misfiring again. I was told the compression in one cylinder is supposed to be 160 but only has 90. is it possible for the gas to have gone bad and maybe the tank needs to be changed or something worse?

Good afternoon.

The compression being low has nothing to do with bad fuel. it may be a valve sticking.

I would get some Seafoam at a parts store for oil. add it to your engine oil and run it or let it idle for about one hour. then change the oil and filter and see if it still has the issue.

Roy

Not sure yet my son is going to get it Sunday and try to work on it. I will tell him to try that but it is not even starting now all it is doing now is spinning like it wants to start.

Okay, when your son gets there have him check and see if the tachometer moves up a little while cranking. that will tell us if the crank sensor is sending a signal to the PCM.

Beyond that, it may be a fuel delivery issue. when you turn the key on, can you hear the fuel pump run?

Roy

Yes, the fuel pump is making a noise when I turn the key on.

Okay, good. You still need to see if the tachometer moves a little when cranking. that can be a reason it has no spark if that is the issue.

Roy

He is on his way now. I went ahead and got the crank position sensor to let him try before we try to push it onto the trailer.

Okay, keep me updated.

Roy

Well that worked it started and it sounded like my old car, lol. but he found some loose wires on the coil pak and a few others so he took it home with him to check it out. thank you so much for all your help. i thought it was a lot worse. thank you again and god bless you.

You are welcome.

Glad you found the issue.

Roy

Changed the crank position sensor running great until I stop at a red light or stop sign now it wants to stall out.

Okay, that could be just a dirty throttle body. make sure the throttle body plate is clear of all carbon around the plate. common problem for low idle.

Roy

Okay thanks, I will check it tomorrow when it is daylight.

Sounds like a plan.

Roy

Just had the mechanic clean the throttle plate. it is doing better, but still acting like it wants to shut off at red lights and stop signs. noticed it still a little hard to start.

Hello,

This can be caused by a vacuum leak. Here is a guide that help help you run a simple test engine cold:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please let us know what you find. We are interested to see what it is.

Cheers, Ken

I just talked to the mechanic that is helping me and told him what you said. will let you know.

Please do

No one can figure it out, lol. going to check the vacuum hoses next. it has a lot of people confused.

Well checked for vacuum leaks and found none he said it could be the ECM do you think that could be the problem.

Okay, no, I do not. that is the last thing it could be and very unlikely.

Did he remove the oil fill cap and check for any vacuum? Intake manifold gaskets are common.

Roy

I did not think to ask him. will let you know.

Not sure will ask Monday and let you know.

Sounds good.

Roy

Last resort changing the fuel pump was told with the car sitting for a few months and the trash and stuff that settled in the bottom of the tank that when I put the seafoam in that when it was doing it's job the fuel pump probably got clogged up so a friend of mine got one and changing it tomorrow

sounds good. keep us updated.

Roy

Will do.

Well got it going not where it needs to be yet changed the mass airflow sensor did it going one day this week and check the calatic converter

Here is a guide to help you check the catalytic converter.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Can you make a video of the problem with your phone and upload it here in your reply?

Please let us know what happens.

Cheers, Ken