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Bad Misfire on 1 Cylinder


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extortion001
New User

Jun 22, 2013, 7:05 AM

Post #1 of 7 (1471 views)
Bad Misfire on 1 Cylinder Sign In

1989 grand marquis 5.0
i just bought the car and changed all the spark plugs/wires and also fuel injector cleaner (it sat for awhile....it ran perfectly fine last week then all of a sudden it started hesitating while driving it around.. no engine light on. so i had my mechanic came over he said it was missing on cylinder 2.. the spark plug, spark plug wire, Distributor were working perfectly fine. so he pulled the spark plug and it had a little oil on it but he switched plugs with a different cylinder to see if that would change the miss and it didn't then we did a pressure test and it was 170 on the that cylinder and also no vacuum leaks.. he said he could hear the fuel injecting "clicking" so that was working.. anyother ideas?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 22, 2013, 7:21 AM

Post #2 of 7 (1461 views)
Re: Bad Misfire on 1 Cylinder Sign In


Quote
he said he could hear the fuel injecting "clicking" so that was working.. anyother ideas?


That test doesn't tell you if the injector is clogged or not. You need to do an injector balance test using a fuel pressure gauge and professional scan tool.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



extortion001
New User

Jun 22, 2013, 7:35 AM

Post #3 of 7 (1451 views)
Re: Bad Misfire on 1 Cylinder Sign In

so more then likely it's a clogged or bad injector on that cylinder? because spark plug and wire are both running good and so is the distributer.. compression test.. what else could it be if not the injectors?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 22, 2013, 7:37 AM

Post #4 of 7 (1446 views)
Re: Bad Misfire on 1 Cylinder Sign In

No, that's not what I said. I said you need to test it more thoroughly.

"more than likely" is not a system we use.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



extortion001
New User

Jun 22, 2013, 7:42 AM

Post #5 of 7 (1440 views)
Re: Bad Misfire on 1 Cylinder Sign In

okk.. well besides a injector balance test what else should i test


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jun 22, 2013, 7:51 AM

Post #6 of 7 (1431 views)
Re: Bad Misfire on 1 Cylinder Sign In

Just do that and we'll see what the results are.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jun 22, 2013, 2:28 PM

Post #7 of 7 (1376 views)
Re: Bad Misfire on 1 Cylinder Sign In

How did you test for spark? Did you use an adjustable spark tester to see if the spark would jump a 3/4 inch gap?

If you don't have a way to check injector flow rate, you could swap injectors, which might be time consuming on that engine. You should confirm the injector is being operated electrically. You might be hearing clicking noises from the other injectors and mistaken the one your listening to be working.

The last thing is you have compression, but is the air moving in and out of that cylinder or breathing? You'll have great compression if an exhaust valve is stuck closed, but the air won't be able to move out of the cylinder. You should perform a dynamic running compression test to see how the cylinder is breathing.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jun 22, 2013, 2:30 PM)






 
 
 






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