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Old 24th November 2005, 17:26   #1
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Default Engine misfire?

I would like to know what all are the causes for the missing in engine??
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Old 24th November 2005, 21:42   #2
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a:The ignition coil would have conked.
b: spark plugs need replacement
c: plug wires need replacement

These are the most common causes of "missing" sparks or misfiring.
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Old 25th November 2005, 00:35   #3
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Missing is done deliberately in some high performance engines, someone once told me...
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Old 25th November 2005, 10:06   #4
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Quote:
Originally Posted by v1p3r
Missing is done deliberately in some high performance engines, someone once told me...
Hey,

This is news to me as well. Anyways what you are probably referring to is the erratic idling which is common in cars with high lift cam shafts which give a kind of rumbling sound to the engine.

Coming back to the point nade by Ravi why hasn't anybody concluded a loose plug wire or bad fuel or water in the fuel.

@nitrous - the car will not start or work with a conked ignition coil.

Misfiring can also be caused with incorrect tuning or wrongly set ignition timing.


Ravi you need to be a bit more specific. Is it a carb car or MPfi. If MPFI then the reasons could be different as evertything is controlled by electronic sensors and the ECM.

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Old 25th November 2005, 10:35   #5
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In diesel missing can happen due to improper air fuel mixture. For example NA indicas do missing at high altitudes but turbo ones do not feel the pinch.
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Old 25th November 2005, 10:45   #6
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Viper: I replaced the ignition coil in my ikon, last week since there was misfiring in the 1st and 3rd cylinders. By conking i didnt mean it didnt totally work.
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Old 25th November 2005, 13:24   #7
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Quote:
Originally Posted by v1p3r
Missing is done deliberately in some high performance engines, someone once told me...

Well "missing" as a term is a misnomer the correct word would be "Anti-Lag" systems for turbos it actually is an unctrolled explosion caused on purpose in between the engine and the turbo. This can be achieved by injecting fuel into the exhaust housing and allowing it to ignite by the hot exhaust gasses or in some cases where some tuners deliberatly miss the ignition cycle on one cylinder at very low RPM's to allow the airfuel mixture to ignite in the exhaust. Other basic methods follwo keeping your idle rpm at close to 3000 - 4000.

This is critically to keep the turbo's spooled up during off throttle and low throttle conditions.
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Old 15th November 2010, 15:29   #8
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I am suffering missing in my three vehicles Esteem (carb version), Kinetic Honda & Splendor. Started searching Team-Bhp for missing and got this thread and surprised that there is no posting since last five years.

I am putting up my views (need experts review).

I will talk only about petrol engines (carburetor).
1. Isn’t the missing is another name of bad/ wrong ignition timing? Spark occurs later than its required.

2. Missing is an electrical problem (the wiring, current source to be checked instead of carburetors & injectors)
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Old 15th November 2010, 15:42   #9
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Missing can occur even due to rich AF mixture; missing can occur due to faulty coils & also due to clogged or dirty air filters.
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Old 15th November 2010, 15:50   #10
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Missing is basically the absence of firing or improper firing of the cylinders. It can happen for a variety of reasons.
Since your car is a carburetted one it can be either due to
- Delco issues, point or condenser.
- Can be also due to the spark plug wires or as simple as disconnected spark plug wire.
- It can also be due to a wet spark plug, which means it can be covered with engine oil.
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Old 15th November 2010, 15:50   #11
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Quote:
Originally Posted by (Alok) View Post
I am suffering missing in my three vehicles Esteem (carb version), Kinetic Honda & Splendor. Started searching Team-Bhp for missing and got this thread and surprised that there is no posting since last five years.

I am putting up my views (need experts review).

I will talk only about petrol engines (carburetor).
1. Isn’t the missing is another name of bad/ wrong ignition timing? Spark occurs later than its required.

2. Missing is an electrical problem (the wiring, current source to be checked instead of carburetors & injectors)
Misfire can be due to either electrical, which includes, plugs, wires, coil etc as well as fueling (carb or FI set up). Even an old/worn out engine or bad fuel, can cause missing.

Explain the scenario's in each vehicle separately, for others to help you better. At what RPM, is it random or has a regular patern. Age, condition and time of last tune up etc.

Last edited by Jaggu : 15th November 2010 at 15:52.
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Old 15th November 2010, 17:26   #12
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Quote:
Originally Posted by aargee View Post
Missing can occur even due to rich AF mixture; missing can occur due to faulty coils & also due to clogged or dirty air filters.
It would have to be an extreme rich mixture, which is in the region of 8:1 or lower. It is more likely to happen at very lean mixtures.

Plug fouling can be the cause for msifiring. The otherwise very good NGK plugs do not like fouling at all and usually need changing.

Sometimes the spark gets blown out, which depends on various circumstances.

In some ECUs you will find corrupted processors and in other ECUs internal wiring corrosion was the cause (the worst I know of was the Marelli 59F).

A faulty coil can work when cold and misfire when getting warm or when it is shorting out, which is not consistently.

The list of causes would fill the sheets of an extra long toilet paper roll.

Quote:
Originally Posted by v1p3r View Post
Missing is done deliberately in some high performance engines, someone once told me...
In very high performance engines this would lead to harmonic balance situations leading to the disintegration of the engine block.
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Old 15th November 2010, 18:44   #13
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Quote:
Originally Posted by CPH View Post
It would have to be an extreme rich mixture, which is in the region of 8:1 or lower. It is more likely to happen at very lean mixtures.
Couldn't understand this; are you saying the ratio of 8 to be the quantity of air or fuel? If you say 8 is air, then 8:1 is lean mixture, but if you say 8 is fuel, then the vehicle WILL never start. Pls help understand.

Quote:
Originally Posted by CPH View Post
Plug fouling can be the cause for msifiring. The otherwise very good NGK plugs do not like fouling at all and usually need changing.
Well, its the other way, plug fouls when there's too much of rich mixture. Well, I'm talking about motorcycles as I've learned the hard way through experimenting.

Last edited by aargee : 15th November 2010 at 18:45.
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Old 15th November 2010, 18:52   #14
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Quote:
Originally Posted by aargee View Post
Couldn't understand this; are you saying the ratio of 8 to be the quantity of air or fuel? If you say 8 is air, then 8:1 is lean mixture, but if you say 8 is fuel, then the vehicle WILL never start. Pls help understand.
I think this should help you understand Air to Fuel ratio.

Air-fuel ratio - Wikipedia, the free encyclopedia
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Old 15th November 2010, 19:06   #15
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Quote:
Originally Posted by aargee View Post
Well, its the other way, plug fouls when there's too much of rich mixture. Well, I'm talking about motorcycles as I've learned the hard way through experimenting.
Quote:
Originally Posted by Jaggu View Post
I think this should help you understand Air to Fuel ratio.

Air-fuel ratio - Wikipedia, the free encyclopedia
Sry, I'm wrong here; misfire happens when the mixture is lean & the vehicle bogs and/or flutters when the mixture is rich.
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