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2017 Forester XT Touring CVT
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236 Posts
Discussion Starter · #1 ·
problem with cylinder 4 in my 01 automatic in cold or wet weather new plugs new wires Bosch and ngk
And pleanty of dielectric grease

Compression test found no substantial leaks
The engine doesent nock it only happens at start up or a little after startup while car is idling then once I clear the code it won't come back for about 4 days
200000 miles plus and going to do a timing kit change soon

I'm thinking coil but just don't know

I be been looking at the freeze Fram data on my code reader it says Cl fault fuel sys 2

Which I know is a closed loop fuel fault
maybe replacing upstream o2 sensor (the one before the cat)
Any advice would be appreciated
 

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1998 Forester S 4EAT
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574 Posts
I've been told that a dirty EGR valve will cause a cylinder 4 misfire.
 

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2004 XT 5 MT
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1,113 Posts
A good mechanic can check the o2 sensor voltage wave form and compare that to fuel trims etc to tell you if you need a new o2 sensor. They could also check the waveform for the coil secondary waveform. I would find someone thats good at diagnostics before you start throwing parts at the car. Ask them is they do diagnostics of voltage and amperage waveforms of these parts and if they look at you funny go elsewhere.

Coil wave form diag:
http://youtu.be/Nq-54h7z9uU

EGR diag:
http://youtu.be/HT4OnP4U0to

Lastly you could throw a vacuum gauge on the intake vacuum and see what going on they cost about 20 bucks. But if your compression numbers looked good this might not give you any information as it appears it's not a mechanical and more of an spark or fuel problem.
http://www.gregsengine.com/using-a-vacuum-gauge.html
 

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2017 Forester XT Touring CVT
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236 Posts
Discussion Starter · #4 ·
good info

A good mechanic can check the o2 sensor voltage wave form and compare that to fuel trims etc to tell you if you need a new o2 sensor. They could also check the waveform for the coil secondary waveform. I would find someone thats good at diagnostics before you start throwing parts at the car. Ask them is they do diagnostics of voltage and amperage waveforms of these parts and if they look at you funny go elsewhere.

Coil wave form diag:
How to Test a 4-wire C.O.P Ignition Coil - YouTube

EGR diag:
GM EGR Valve Testing (P1404 Case Study) - YouTube

Lastly you could throw a vacuum gauge on the intake vacuum and see what going on they cost about 20 bucks. But if your compression numbers looked good this might not give you any information as it appears it's not a mechanical and more of an spark or fuel problem.
Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine

thank u my man i stepped up and got a better code reader that does graphing
and better communicates whats going on with the i/m monitoring

still looking in to it but i think i want to wait till the winter is over and see what happenes i might just replace the one injector and see what happens

because to tell u the truth out where i live most mechnics wont know anything about the wave forms '

i fell better waiting because if the problem goes away in warmer weather ill know that its the injector seal then
because the entire system says its good on the code reader once warmed up and i cycle through drive cycles
 

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2004 XT 5 MT
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1,113 Posts
thank u my man i stepped up and got a better code reader that does graphing
and better communicates whats going on with the i/m monitoring

still looking in to it but i think i want to wait till the winter is over and see what happenes i might just replace the one injector and see what happens

because to tell u the truth out where i live most mechnics wont know anything about the wave forms '

i fell better waiting because if the problem goes away in warmer weather ill know that its the injector seal then
because the entire system says its good on the code reader once warmed up and i cycle through drive cycles

Sounds like a plan. I should have worded my post a good diagnostician can do this, there are plenty of good mechanics that don't use computer diag. However it is the best way to know if there is a problem with a part or not. They can look at the fuel injector waveforms as well.
Careful watching these videos they can become addictive :)
Fuel Injector Driver Designs - YouTube
 

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2002 Legacy GT 5MT
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26 Posts
A bad fuel injector can cause a misfire. Left long enough, it can result in burned valves.

Best wishes,
Myles
 

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2017 Forester XT Touring CVT
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236 Posts
Discussion Starter · #7 ·
A bad fuel injector can cause a misfire. Left long enough, it can result in burned valves.

Best wishes,
Myles
i know what u mean but im not really worried about it cause everything runs fine once sf is up to operating temp and a mile or two was put on it

id be much more worried if she was knocking but since not then this has become more of an effort of my pickyness and perfectionism

i hate seeing the idiot light come on and as a responsible car owner and mechanic i keep track of my car and do testing through out the year so when i miss something or cant fix it with in the week its get very annouying


so far it has not come back for the last few days mostly cause iot has not been that cold

ehhh im sure there are alot of u out there that fell the same way
 
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