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94 Honda Civic DX
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Discussion Starter #1 (Edited)
I have a 94 Civic DX with the d15b7 motor. I've been battling a misfire for a few days now and can't seem to get it to go away. I have done TONS of research across many forums and have tried everything I have seen. So far nothing has fixed it. I'm in need of help now. I have changed/checked all of the following parts and all are currently within spec to the best of my knowledge.

Spark plugs (tried 2 sets. One iridium & one stock from the dealership)
Plug wires (tried 2 sets and both were in spec)
Distributor cap & rotor button
Ignition coil
Distributor as a whole
Fuel filter
Fuel pump
ECU (tried 3 different ECU's)
O2 sensor

Checked:
Compression (low but even)
Vacuum
Fuel pressure
Fuel injectors (all work, have not taken out to check for spray pattern)
Ignition coil kv
Ignition timing (16 BTDC)
Valve adjustment (all are within spec)

The misfire typically happens under load but once it starts it will also happen when free revving the motor. That being said, when driving it yesterday the misfire seems to go away after 4,000 rpm unless giving it full throttle. Then you can hear the misfire thru the entire rpm range. It seems to come about quicker if I hold a steady throttle while cruising (say 50-60 mph). But if I oscillate the throttle somewhat while driving at highway speeds it either won't happen or if it does its takes longer to come on than if I just hold the throttle steady.sorry for the long post but I'm trying to be as descriptive as possible.

Forgot: when it starts misfiring I can turn off the engine and turn it back on and the misfire seems to disappear temporarily.
 

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how did you check the injectors? if you just used a noide light thats only going to tell you if a signal is bieng sent to them.. it doesnt really sound like a fuel problem though, if it was it be alot more consitant miss.. take a look at all your sensors, iat, coolant temp, etc because the send info to the ecu as well. test there resistance and compare them to spec.
forgot to ask but is your check engine light on?
 

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94 Honda Civic DX
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Discussion Starter #3
Checked injectors by unplugging each of them individually. Also checked the ohms in each injector. Also used stethoscope to listen for clicking in each injector. Each is clicking and all ohms are pretty even. And unplugging each one individually causes misfire in each corresponding cylinder.

Edit: check engine light is not on
 

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94 Honda Civic DX
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Discussion Starter #4 (Edited)
Would low compression cause the misfire? Last time when I checked it it was at like 115. Wasn't sure how much of that was from the a6 cam I have in the car.

Edit: after another compression check they are actually closer to 110. But all are even.
 

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ej8
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Would low compression cause the misfire? Last time when I checked it it was at like 115. Wasn't sure how much of that was from the a6 cam I have in the car.
yes and no.
If your piston rings are bad. Burning oil can foul out the spark plugs and cause a miss.

If the headgasket is leaking. Coolant can do the same thing.

But first is there a check engine light?
Does it idle fine or misses at idle?
HOw do the plugs look when you removed them? Pix would be great.
And what did you gap them to?


*edit
also i dont remember fully but i thought if you used a a6 cam in a b7 that you needed and adjustable cam gear to set the valve timing right.
 

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Discussion Starter #7
Compression is all even. Within 3-5 psi. No check engine light. Occasionally misses at idle. It's intermittent. Sometimes it will randomly misfire at idle. Sometimes it runs perfect at idle. I'm new to posting, as you can tell, but I will try to post pics of the plugs. Plugs I used were NGK Iridiums (pre-gapped to spec) & NGK's straight from the dealership (also pre-gapped to spec)
 

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94 Honda Civic DX
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Discussion Starter #11
Iridium plugs. 1-4 left to right. One of the plug wires I bought wasn't connecting to plug 1, causing a different misfire and as you can see it started to foul that plug. Needless to say I replaced them. Put my old wires back on because as it turns out there was nothing wrong with the old wires.
 

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Did you find a fix for this? I am having the same issue as of 3 days ago. I'm going to be doing some troubleshooting this weekend. I'll update you if I get anything solid.
 

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As with you I checked plugs, wires, cap, rotor. Finally got a better look at things yesterday and noticed a slight gap between the cap and distributor itself. This ended up being the culprit. As with your case I also was having a misfire under load almost the same conditions as yours. I hope with a little more checking you figure this out!
 
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