I have a '95 Civic DX with a D15B7 motor. I recently replaced the head gasket and now I have a miss. When I replaced the gasket there was no apparent wear or carbon deposits in the cylinders or head. I've narrowed it down to the #4 cylinder and I've determined that it's definitely getting spark. I'm not losing any oil or coolant so I don't think there is a problem with the new head gasket. I'm thinking that the injector got dirt in it(or was damaged) but I don't know the best way to test an injector. I've run a couple of bottles of injector cleaner through and there has been no improvement. That's about as far as I've gotten as it's damn cold out and I have limited access to a garage.
Thanks.

 

How do you know cyl 4 is the problem?

Have you compression tested the cylinders?

If you think injector 4 is bad, swap it with one of the other injectors to determine if the problem moves with the suspected bad injector.

 

I pulled the plug wires from each cylinder and they all caused the engine to idle rougher except the one closest to the distributor(no change).

I haven't done a compression test yet, I'm hoping to do one in the next couple days(waiting on a garage).

I was thinking about swapping the injectors to see what happens but I'm going to wait till I do the compression test (those harness clips seem to be a pain to get disconnected).

I was wondering if anyone else had encountered a problem like this. Could I have left I sensor unplugged(it doesn't seem likely) or would a bad connection somewhere cause this? I know a compression leak seems to be the most likely culprit I just am not looking forward to tearing the engine down again to track down the problem

Could a valve be sticking? I can't see the valve(s) being bad as they looked like they were in excellent shape.

 

Is the ECU throwing code 16?

Does injector 4 fail to make the normal clicking noise?

Is there 10-13 Ohms of resistance between the two terminals of injector 4?

Does the YEL/BLK wire of the injector connector have battery power?

Is plug 4 wet with fuel?

 

To unplug the injectors, use a small flat screwdriver to push up the spring wire on each side and hook it on the plastic. Then the plug just pulls off.

It is better to check for bad cylinders by disconnecting the injectors, as a few people have had their ignition coil ($60) blow out from disconnecting the spark wires with the engine running. I and others have done it without problems, but maybe if the coil is weak it can't handle it.

You might have a bad spark plug or wire, or a crack in the cap that shorts out the spark to #4.

Adjusting the valves too tight will cause a dead cylinder, you would notice that on the compression test.

 

By the way, you can compression test the cylinders yourself. You need to purchase or rent a pressure gauge. For details, see link in my signature.

 

mk378,
Thanks for the info on unplugging the injectors. It looked like that was what you would do but doing it was a different matter. The plugs are new and the cap and rotor only have a few hundred kms on them. The wires seem OK too(prepare to cringe) as we put a plug in, grounded it to the block and checked for the spark. Also I never did any adjustments to the valves.

RonJ,
Big time thanks for all of your tips. I will be checking each one out as soon as possible. Also I do plan on doing the compression test myself(I checked out the link already). The garage in question is to keep the cold, snowy Canadian winter off of me while I try to fix this thing . It's hard to wrench on a car with mittens on .

Thanks again. I'll keep you posted as I go down the checklist.

 

Well the plot thickens. We tested the compression it was 190-175-175-190(from cylinder 4 - 1). Plug 4 was dry but seemed to have a little soot around the outside edge(all the plugs did). The injector has 12 ohms of resistance and there is voltage at the connector (12v I think). I swapped the injector with cyl 1 and... cyl 4 was still dead???

If the timing was off a tooth could it affect just the one cyl? I would think all of them would be acting up.

 

1) Check for spark at plug 4 and compare to plugs 1-3:

Do one plug at a time. Remove plug wire from a spark plug and insert a spare plug into the end of the free plug wire. Ground the threads of the spark plug against a metallic area of the valve cover while a buddy cranks the engine. Failure to properly ground the spark plug against the valve cover could possibly blow the ignition coil. You should see bright blue spark at each plug. Plug 4 may have no spark or weak orange spark.

2) Check the ignition timing as follows:

 

If spark at cylinder 4 turns out to be fine, then you may have a problem with the ECU or the wire running between the ECU and injector 4. Here's how to test: