2002 Civic ex Misfiring

Tracecross30

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Hey guys,I’m new to this forum. I just came across it while searching for answers to me problems that I’m having with car at the moment.
i have a 2002 civic ex ,manual transmission, for about a month ago I got this check engine light and it stays on. It only go off for a few minutes and come on again.. i did a scan and it gives me codes for misfiring
p0301
p0302
p0303
p0304
i changed fuel filter,coil packs and spark plugs from the dealership but,the problem stays.i did a compression test and it was successful because From cyl 1-3 is showing 185 and cyl 4 is showing 180 so that should be fine there but I will check back on the that cyl to see if it’s the valve need to be replac or my compression ring is off. I’m having A rough idle that I don’t think is normal and yesterday I was noticing that the idle dropped below 800 RPM and the car shut off 3 times on me. I also got a code that said I have a Pcv valve leakage and that Pcv valve shouldn’t need to be replaced because i put i on there about 8 mounts ago but I changed it for the dealership type. I sprayed carb cleaner over the Pcv valve area while the engine running and other places but the engine didn’t make any changes. I have a code for Catalyst Converter to but a mechanic said he don’t think anything wrong with my cat but the code still there. any good info will help Please..
 

grcauto

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"I also got a code that said I have a Pcv valve leakage".....what is the code? What are the fuel trims doing? No restrictions to intake or exhaust?
 

Tracecross30

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"I also got a code that said I have a Pcv valve leakage".....what is the code? What are the fuel trims doing? No restrictions to intake or exhaust?
Sorry,i dont remember the code.i can look it up and tell you Saturday because i will be working on my car started tonight until Saturday about midday. Yes,I'm having bad gas mileage..
 

nickb2

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"I also got a code that said I have a Pcv valve leakage".....what is the code?
@grc, I think maybe that code does not exist. I will try looking for that, but somehow I think this will be useless endeavor. Normally, what we get on these old hondas is a air intake boot problem, which gives these symptoms. Probably, op saw a code, but not a pcv code, as I don't think asian cars like P052e for example. Can't wait for op to post back, this sounds like a major vac leak, or a maf not reading due to a split.

@op, basics as usual, this one should be easy to find, cuz it is not intermittence. Basics, air, fuel, spark.
 

Tracecross30

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Ok. I unplugged the 02 sensor from the cat and I don’t feel and more rough idling so it might be my cat that’s bad and need remplacement.
 

nickb2

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I have a code for Catalyst Converter to but a mechanic said he don’t think anything wrong with my cat but the code still there. any good info will help Please..
I am on vacation today, so will try to give a few pointers, it may help. I am stronlgy advising you get live data and maybe post those PID's here so we can gander at the fuel trims. I am guessing those will be lean. Have you put a vac and fuel pressure guage to this?

Your compression is fine, and maybe you should see if the exhaust manifold is not cracked. These hondas all crack at the same place. The unmetered air from that crack will also cause your code symptoms. In the following video, you will clearly see where they ALL crack. It is a classic on these nippons.
 

nickb2

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Sometimes, if the manifold is not to ugly, I weld them. Your best way to attack that is by using a disc wheel and grind a v groove all along the crack. I prefer using this type of rod. Here is a link. I don't know where you live, but if you don't have a welder, you can bring that to a weld shop, they will know what to do. https://www.homedepot.ca/product/forney-industries-estci-18-inch-x-1-lb-contaminated-cast-iron-electrode/1001204687?eid=PS_GOOGLE_D25 - E-Comm_GGL_Shopping_PLA_EN_Tools_Tools_PLA_EN__PRODUCT_GROUP_pla-558432696403&gclid=EAIaIQobChMIgdv-0p-65gIVxZ6zCh3UdA0-EAkYAiABEgI_-PD_BwE&gclsrc=aw.ds
 

nickb2

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If your manifold is ok, then we really need live data, cuz a 4 cyl coding a mis on all 4 is something inherent to a vac leak, low fuel pressure, or as wrote above, a o2 not getting proper reading and enriching or leaning out.

It makes me laugh so often with these cars when I see a brand new o2 sensor, but somehow, the tech did not see that glaring at you crack. Waste of time and money.

A trick I use is whilst monitoring the short term fuel trims, I spray brake cleaner here and there while observing the STFT. If they change drastically where I am spraying, you just found a leak. You can also do a propane enrichment test if you don't have any cleaner on hand. Again, live data here is needed, also, beware, this is propane, so caution is always good here.

You can google on how to use propane for misfires. Also, using live data, you will know if your in open or closed loop. For this, you want to be in open loop, not in full fuel control mode.
 

nickb2

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So, to summarize, you have done several steps already in deducing stuff. One, we know all cylinders are @ 180ish, well in the 20% acceptable range. Your not to high, not to low, no reason to suspect something there. Timing can be adjusted on these. The marks are real hard to read, using a small wire brush and a paint marker helps. 2002 civic for bat.jpg
 

nickb2

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I don't know if I mentioned this here, but it is an optispark system, sometimes, just blowing some shop air in the dizzy cleans the optispark wheel and improve idle.

By disconnecting the TPS sensor, you should be able to force the ecu into open loop for extensive testing of the fuel control system. ;) You don't want the ecu correcting strategy when testing for vac/air leaks with propane. This is why I prefer using brake cleaner and using a scanner to watch the trims instead. Also, propane is more volatile. :eek:
 

nickb2

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I know I am putting alot of info out there, but I always find more is better, but some times, colleagues here say I may give to much and confuse, if I am doing so, plz stop me at anytime, I will auto correct.

Often, a good diagnostic tech needs to use Sherlock Holmes theory. Again, propane is a last ditch, I strongly don't recommend it unless you have nothing else.
 

grcauto

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Ok. I unplugged the 02 sensor from the cat and I don’t feel and more rough idling so it might be my cat that’s bad and need remplacement.
You mean you 'removed' the O2 sensor and it smoothed out? If so, the exhaust is restricted.
 
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