1995 Civic #4 cylinder is dead!!!
 

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 :rolleyes: 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:D) 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:mad:

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 :D.

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:

Attachment 23286

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:

Attachment 23284


Attachment 23285

We put a spark plug on the wire for cyl 4 and it had a nice blue spark, it seems very strong and consistent. I'll try the other tests that you've given me and I'll have the timing checked.
Thanks.

You know I just saw something in another post that got me thinking. Just so I'm 100% sure which point on the distributor cap is cyl 1. It's a D15B7 motor or are they in the same spot for every motor made that year(95). I saw this picture and if my distributor is the same I think I started at the wrong terminal :rolleyes:
P.S. You might as well give me the firing order as well in case I screwed that up too.

Attachment 23266

The diagram of the distributor cap is correct for your Civic. Cylinder 4 is closest to the distributor, and the cylinder order is 4-3-2-1, with cylinder 1 farthest from the distributor.

The firing order is 1-3-4-2, as the distributor rotates clockwise looking at it from the cap end.

If you think about it, switching the wires around is going to have to create at least two dead cylinders. Generally the engine won't run. It can run on two cylinders but it will be very hard to start.

mk I would think that too but at this point... I just don't know anymore. Bear with me, if I'm looking at this right, when the distributor is in the car the #4 terminal is on the bottom? I think mine might be in #3's spot, I'm definitely going to have to take a look at it.

I'll let you know in a bit.

The wire to cylinder 1 should be at about 10 o'clock with the distributor on the car. Then go 1-3-4-2 around clockwise.

:rolleyes: Nevermind I'm a s#$%head, wishful thinking.

OK so I've run into a bit of a snafu. It's a little warmer today so I thought I would try to pull any engine codes, well I can't find the jumper plug. I pulled the carpet back and looked all around the ECU for the jumper plug and there doesn't appear to be one. Could it be located somewhere else? I see a harness and the wires going to my blower motor and that's it. I felt all around as far as my fingers would reach and nothing. WTF :confused: Has anyone found theirs in a different spot?

Click the CEL link in my signature and scroll down the page. You'll see that you need to remove the passenger-side kick panel. The service connector branches from the main wire harness just above the ECU. Use a paperclip or a small piece of wire to jump the connector.

The ECU is completely visible (someone already pulled back the carpet to access it) and I can see the harness that is plugged into it. I followed the harness up as far as my fingers could reach and didn't find any connectors branching off of it. I tried to snap a couple of pics with my cell but they were no good. I've looked a far as I could see without an adequate light (cells don't make good flashlights either) but I couldn't see the connector. Is it plugged into anything(I didn't think it was supposed to be)? I may have to remove my glove box to get a better look.

P.S. Your links rule, I figure that main relay repair will probably come in handy at some point.

You'll need to look for a square green rubber thing somewhere above the ecu. It holds the connector. It'll have a blue plug, if I remember my 5th gens correctly. It'll be the only thing around there with two wires going to it.

I think I already know the answer to this but I'm going to ask anyway. Will the computer out of a '93 standard work in a '95 auto? I have access to one and thought it might be a fairly quick way to see if I have a computer issue.

It needs to be the same type of ecu. A manual one won't work right on an auto car. But, if you're only trying to make the engine run, not drive... it might work? Anyone else know?

You can't switch ECUs manual to auto. The car will run, but the transmission won't shift right and the CEL will come on.

In other words, he could toss it in there to test the engine and see if it runs, but not to drive anywhere. And since the CEL is stored in the ECU, he could swap back to the other ECU and have no CEL.

So I broke down and took the car into a shop to see what they thought. After some tests it was determind that the signal going to the #4 cyl was weak and intermitent. They concluded that the ECU or the sensor in the distributor was bad. I believe I already have a 'how to' for testing the ECU now I just have to track one down for the distributor. I'll keep you posted.

What signal? Did the mechanic say that spark for cylinder 4 is weak and intermittent?

Sorry mobile post lol. It was the signal to the injector that was weak and sometimes it wasn't there for a pulse or 2. They figure its the ECU but he said if I had access to a distributor to try it first.

This is a curious suggestion as the distributor has nothing to do with the fuel injectors.

He said the distributor was a long shot but if I knew someone that had one laying around it might be worth a try. He said there was a pickup or sensor in the distributor that might be going. That being said he didn't know how it would effect the one injector and he stressed that it was most likely a faulty ECU. Me's thinks ECU might translate in $$$ unless I can find a used replacement (or a parts car). We'll see tomorrow. :D

It's the ECU or the wire running between injector 4 and the ECU (see diagram in my earlier post).