'96 Civic CEL codes: what to do?

mrpepsalgado

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Is it possible to be a fuel injector ? I once had this happen to my wife's Honda Pilot. We kept getting misfire on different coils, egr valve and it turned out to be an injector.


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98civex

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The car has Plugs, cables and cap and rotor that were replaced less than a year ago - it's always had a light on since I bought it , the guy I bought it from said it was an 02 sensor yet the scanner at autozone didn't detect it .


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So it's always had an 02 sensor issue that was neglected. So as I stated its possible this neglect has caused your cat to foul up.

If the code has been there why not put in a new 02 sensor and take it from there?
 


mrpepsalgado

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So it's always had an 02 sensor issue that was neglected. So as I stated its possible this neglect has caused your cat to foul up.

If the code has been there why not put in a new 02 sensor and take it from there?
The main reason is because the codes don't show sensor , so there's that doubt and also , the car just started to misfire .


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98civex

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You didn't mention it was misfiring, or maybe I didn't see it in your posts. All I gathered was you had it scanned and it showed those codes.

If it's misfiring check all ignition components. Distributor cap, rotor, plug wires, plugs and inspect your fuel injectors. Simple basic stuff first before going more advanced like head gasket, compression etc

Do you get a misfire for a specific cylinder? That'd be the place to investigate first
 


Restotech

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P0420 is a cat code. This is either the cat or secondary o2 sensor. (Downstream). P0301 is a misfire cylinder 1. Closest to the timing belt. If you are not familiar with what can cause a misfire then it might be best to have a shop diagnose it for you. There can be a number of things that cause a misfire.
 
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mrpepsalgado

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You didn't mention it was misfiring, or maybe I didn't see it in your posts. All I gathered was you had it scanned and it showed those codes.

If it's misfiring check all ignition components. Distributor cap, rotor, plug wires, plugs and inspect your fuel injectors. Simple basic stuff first before going more advanced like head gasket, compression etc

Do you get a misfire for a specific cylinder? That'd be the place to investigate first
Yes it just started misfiring but the engine lights been on for a long time - the cap, cables and plugs are all new and this is why I am
Leaning towards injector , the scan reads coil 1. It will bean expensive experiment if I change it and it is not the problem. Which is downstream and which is up? Can someone specify the locations ?


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Mr.Baker

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Which is downstream and which is up? Can someone specify the locations ?
It was already specified....

Upstream would be pre-cat
Downstream would be post-cat
How many miles is on this car?
Have you considered having the valves adjusted?
Has it ever been done?
Valve adjustments, to get them back into spec, can cure a misfire.
 
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mrpepsalgado

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It was already specified....



How many miles is on this car?
Have you considered having the valves adjusted?
Has it ever been done?
Valve adjustments, to get them back into spec, can cure a misfire.
182k and I'm not sure if they've ever been changed


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98civex

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Yes it just started misfiring but the engine lights been on for a long time - the cap, cables and plugs are all new and this is why I am
Leaning towards injector , the scan reads coil 1. It will bean expensive experiment if I change it and it is not the problem. Which is downstream and which is up? Can someone specify the locations ?


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Doesn't matter how new parts are. Check them. Quick test to rule out plug wires is to simply swap the #1 wire with another and see if the misfire moves to that other cylinder. Then investigate the injector.

Quick test for that is to unplug then reseat. Friend's 99 civic had a misfire that doing so cured his issue.
 

mrpepsalgado

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Doesn't matter how new parts are. Check them. Quick test to rule out plug wires is to simply swap the #1 wire with another and see if the misfire moves to that other cylinder. Then investigate the injector.

Quick test for that is to unplug then reseat. Friend's 99 civic had a misfire that doing so cured his issue.
Excellent tips, I've also heard to move injector and tiger scanned to see if misfire moves as well. I'm going to attempt this , thanks .


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Mr.Baker

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182k and I'm not sure if they've ever been changed
With that many miles and it being unknown, you may want to look into having that done.
It's a good chance it can cure the misfire, especially if everything else checks out as good, such as the plugs, wires, injectors, etc.
 

rbealer

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Anyway idk about the 6th gen but I know on the 4th gens if the valve cover gasket is bad then oil leaks into the spark plug well. Fouling out the plug and causing a misfire.

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Diana Nam

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Anyway idk about the 6th gen but I know on the 4th gens if the valve cover gasket is bad then oil leaks into the spark plug well. Fouling out the plug and causing a misfire.

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its usually like that regardless of the generation the oil makes it harder for the plugs to receive the spark. electricity don't work so well in oil
 


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