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What is 'misfire' and how do you detect it?
- Thread starter AhmedRSi
- Start date
The failure of the fuel charge in one or more engine cylinders to fire or ignite at the proper time. It can be due to poor compression caused by worn or improperly adjusted valves, worn piston rings, a faulty head gasket, or in the case of a two-stroke engine leaking crank seals. It can also be caused by poor ignition due to worn or dirty spark plug electrodes, worn or improperly gapped points or spark plugs, poor fuel delivery, faulty ignition wiring, or faulty distributor components.
you will hear a bang sound and the car will stutter during that bang.
you will hear a bang sound and the car will stutter during that bang.
ur no if there a miss fire you can either hear or feel it. Also modern engines will put the engine manganment light up mostly so that will help to prove and solve the miss fire.
Hear it - easyest place to hear is through the exhaust system, or under the bonnet it will sound like a small pop or stutter in the engine note, also the revs will be fluttering up and down.
Feel if you no what ur looking for you can normaly feel it inside the car because of vibrations or under the bonnet.
Miss fires are all grovrned buy timeing or fouled up plug (plug is two much soaked in air fuel mixture so cant ignite, like you cant light wet paper)
Hear it - easyest place to hear is through the exhaust system, or under the bonnet it will sound like a small pop or stutter in the engine note, also the revs will be fluttering up and down.
Feel if you no what ur looking for you can normaly feel it inside the car because of vibrations or under the bonnet.
Miss fires are all grovrned buy timeing or fouled up plug (plug is two much soaked in air fuel mixture so cant ignite, like you cant light wet paper)
Clio Dynamique 1.4 16V
i had a misfiring engine today. called out the AA and they plugged there comp in and it said there was a misfire in cylinder 3. was caused by a worn spark plug that blew the coil. new coil cost me £49.99
has the new coil fixed it? cuz when mine started mis-firing i got the garage (friends) to change the coil pack and it made no difference. changed the plugs (with the original coil pack) and it was fine.
but if that did fix it then thats not particularly expensive to be honest!
but if that did fix it then thats not particularly expensive to be honest!
Clio Dynamique 1.4 16V
yeh its perfect now the coil had actually blown. damaged or worn spark plugs put a lot of stress on the coil packs thou
bump
problem with my car .. emergency braked on motorway yesterday and after that in 5th gear on motorway at around 60 put foot on accelerator again and heard a bang bang bang noise from accelerator and losing power..
did it in every gear although after a good rev to 4k it cleared it and shot forward and stopped then came back again 2 miles later .. got the loss of power ..
pulled over engine shaking
gearbox shaking
and exhaust poppign .. and runing rough like its cold..
and with my exhaust and decat its really loud .. sounds like a quad bike lol.. anyhow no breakdown cover and 101 miles to go , i set off again...
its lost power and stil missfiring, but it got me to where i wnated at 70mph.. did what i hafta and collected stuff and jumped back in car and did the 130miles back home.. with it missfiring and doing same bang bang bang noice from engine..
takes its time to pick up but can stil get you to 90+ same noise all the way..
what could this be? coilpacks? if so how do i find out which one?
problem with my car .. emergency braked on motorway yesterday and after that in 5th gear on motorway at around 60 put foot on accelerator again and heard a bang bang bang noise from accelerator and losing power..
did it in every gear although after a good rev to 4k it cleared it and shot forward and stopped then came back again 2 miles later .. got the loss of power ..
pulled over engine shaking
gearbox shaking
and exhaust poppign .. and runing rough like its cold..
and with my exhaust and decat its really loud .. sounds like a quad bike lol.. anyhow no breakdown cover and 101 miles to go , i set off again...
its lost power and stil missfiring, but it got me to where i wnated at 70mph.. did what i hafta and collected stuff and jumped back in car and did the 130miles back home.. with it missfiring and doing same bang bang bang noice from engine..
takes its time to pick up but can stil get you to 90+ same noise all the way..
what could this be? coilpacks? if so how do i find out which one?
and never skipped a beat..
Clio Dynamique 1.4 16V
no we dont have HT leads in the 1.4 16V
172 Race Car
Easiest way to diagnose a misfire is to diconnect the injectors one at a time. These can be accessed under the fuel rail guard on the front of the engine (nearest the radiator)
With the engine running (and misfiring obviously) dissconnect one injector plug, if the engine runs worse or misfires more then that cylinder is working fine as you have just taken its fuel away and created a misfire on that cylinder.
If the engine note/running is exactly the same with the injector wire disconnected then the misfire is on THAT cylinder. You have taken the fuel away from that cylinder and it has made no difference, meaning that the fuel wasn't being burnt anyway so that is the offending cylinder.
Simple and no fancy code reader or difficult diagnostic process needed.
As said 1.4' and 1.6's use a coil per plug system and are very prone to failure (they do not have plug leads.) This can give a misfire on one or more cylinder depending on how many coils have failed, altho its usually one but it could be more. Ive also seen water get into the plug holes causing a misfire this can be hard to track down using the above method so if your unsure take out the coils and inspect the plug holes for water.
172/182 uses a wasted spark coil pack system with HT leads. Because they are effectively two coils moulded together and cylinder 1+4 and 2+3 share a coil they can fail in a variety of ways. sometimes they short internally and cause a very random misfire or hesitation. The above method for misfire detection will find a faulty plug or lead and narrow it down to the affected cylinder. You may diagnose the coil with this method also but not in all cases. sometimes with these type of coils you have to just try another known good one to be sure
All the above is for an ignition misfire. Misfires can also be caused by many other things like faulty valves, headgasket, compression, injector/fueling issues etc etc. But plugs, leads and coils are by far the most common faults and relativly simple to sort out on modern cars
With the engine running (and misfiring obviously) dissconnect one injector plug, if the engine runs worse or misfires more then that cylinder is working fine as you have just taken its fuel away and created a misfire on that cylinder.
If the engine note/running is exactly the same with the injector wire disconnected then the misfire is on THAT cylinder. You have taken the fuel away from that cylinder and it has made no difference, meaning that the fuel wasn't being burnt anyway so that is the offending cylinder.
Simple and no fancy code reader or difficult diagnostic process needed.
As said 1.4' and 1.6's use a coil per plug system and are very prone to failure (they do not have plug leads.) This can give a misfire on one or more cylinder depending on how many coils have failed, altho its usually one but it could be more. Ive also seen water get into the plug holes causing a misfire this can be hard to track down using the above method so if your unsure take out the coils and inspect the plug holes for water.
172/182 uses a wasted spark coil pack system with HT leads. Because they are effectively two coils moulded together and cylinder 1+4 and 2+3 share a coil they can fail in a variety of ways. sometimes they short internally and cause a very random misfire or hesitation. The above method for misfire detection will find a faulty plug or lead and narrow it down to the affected cylinder. You may diagnose the coil with this method also but not in all cases. sometimes with these type of coils you have to just try another known good one to be sure
All the above is for an ignition misfire. Misfires can also be caused by many other things like faulty valves, headgasket, compression, injector/fueling issues etc etc. But plugs, leads and coils are by far the most common faults and relativly simple to sort out on modern cars
Clio Dynamique 1.4 16V
or you could plug ur laptop in and in my case it said "misfire in cylinder 3" which is the 3rd from the right stupid french lol
ok it went away and now has come back really light .. misfires for 5 secs everytime you start up and then here band there intermittingly.
so i did as you said and disconnected 1 by 1 and tbh during the 5 sec on start up i cant tell..
i also bort 1 coilpack and fitted it in each cylinder 1 by 1b and still did nothing..
could it be spark plugs or more than 1 coilpack?
ok replaced the spark plugs this morning..
started car and it was misfiring like mad but then again engine was cold.. so took it for a drive.. misfired here and there while drivging
back home and misfiring on idle then about 5 mins later it sorted itself out, so still intermittent..
so cant be the plugs?
o one thing i did notice though after changing plugs, and it never did this before with the old plugs.. was that when i disconnect each cylinder 1 by 1..
1 and 4 make the misfire worse
but 2 and 3 stall the car..
what does that mean?
have i put the spark plugs in wrong? yes it was my first time doing them lol and ive been told i shud have measured the gap on the plugs.. but at the brief look at them, they all seemed the same and are the ngk bkr6e plugs..
in the book it said it was these for the 1.4 16v?
so could it be coilpack 1 and 4 then since 2 and 3 stall the car?
im confused
lol help!
ps. i think it maybe has gotten worse with the spark plug change.. i dunno
started car and it was misfiring like mad but then again engine was cold.. so took it for a drive.. misfired here and there while drivging
back home and misfiring on idle then about 5 mins later it sorted itself out, so still intermittent..
so cant be the plugs?
o one thing i did notice though after changing plugs, and it never did this before with the old plugs.. was that when i disconnect each cylinder 1 by 1..
1 and 4 make the misfire worse
but 2 and 3 stall the car..
what does that mean?
have i put the spark plugs in wrong? yes it was my first time doing them lol and ive been told i shud have measured the gap on the plugs.. but at the brief look at them, they all seemed the same and are the ngk bkr6e plugs..
in the book it said it was these for the 1.4 16v?
so could it be coilpack 1 and 4 then since 2 and 3 stall the car?
im confused
lol help!
ps. i think it maybe has gotten worse with the spark plug change.. i dunno
