new_climber

My 98 civic EX started throwing a P302 code, cylinder 2 misfire, when idling, also smells like it is running rich at idle even after she has warmed up. And it is idling pretty rough but not all the time. I have good compression, replaced plugs, wires, cap/rotor, and both O2 sensors. After doing much reading here, it seems like my next step is a Leak down test. I plan on stopping by Harbor Freight this weekend and getting the kit to do this test.

What my question is, if I have a valve problem, would it not happen all the time? It seems like I have more of a vacuum leak in the intake then something wrong with the cylinder, but why then am I getting the P302 code? I say a vacuum leak, because if I take my foot off the brake (set the Ebrake) she will idle fine all the time, only when I am on the brake, here and there she will idle down very low and kick out the code.

Any thoughts? I am due for a timing belt, and if I need to pull the head and work on the valves, I would rather do it all at the same time....

thx for the help.

Former User

Compression test the cylinders.

new_climber

I did a compression test...they were all the same. i can't remember what exactly they were, but all cylinders were the same. Engine was cold...

that is why i say my next test is a leak down...am I on the right path?

Former User

A leakdown test won't yield any useful information if compression is good.

new_climber

That make sense, so where else do I go?

I don't think it is a cylinder/valve issue, just because it comes and goes. Could a vac leak in my intake somewhere..a cracked hose say, cause my symptoms?

What about an electrical issue. I tested my injectors, they are all the same ohms, not sure if this is a good test or not. Maybe I will try swapping injectors??

any other suggestions??

Former User

I'd start by re-inspecting the ignition system.

joey1320

Try swapping the injectors around, since you already ohm'd them. After that, if it still comes back on number 2, I would look into doing a hot compression test. Please post results.

new_climber

Thx much for the replies...I will swap the injectors around this weekend and reply back.

Hot compression test, I always thought it was not a good idea to unscrew the plugs with the head hot...but it is ok??

joey1320

If you used a quality plug, a small small dab of anti seize and torqued the plugs to spec, there should be no reason to not remove them hot.

Now don't go all crazy and start using a half inch impact gun, but a hand ratchet and just use your arms. Remove them, do a proper compression test and see how healthy the engine is.

new_climber

Well, i swapped the injectors, #2 and #4. I also adjusted my idle from about 400rpms up to about 750rpm with no load. But I am still getting the P302, cylinder #2 miss.

I will proceed and do the hot compression check, hopefully this weekend.

She runs much better now, just still kicks out this code when I am idling...also still have the slight hesitation at around 2500rpms...

Former User

new_climber

Well, finally got around to doing the Hot compression test...

Now I am finding cylinder #2 might have issues..

#1: 135 PSI
#2: 95PSI
#3: 145psi
#4: 135psi

Does this mean I have issues in cylinder #2??

What would be my next step, a leak down??

If i am replacing some valve, would it be recommanded to just replace all the valve, and complete upper end rebuild? There is 240K on the motor...

Any suggestions are very much welcome...

Thx

eghatch9295

iTrader: (1)

you without a doubt have a problem there. its leakdown time, but before then, redo the comp test and drop some oil down cyl 2. any changes?