Hey everyone. First off I would like to say thank you to all of you who post and answer questions on these forums. I have gained so much knowledge and insight for working on my cars by browsing the threads here. I finally registered an account here and have a problem of my own.


I have a '93 Civic DX Hatchback (manual transmission, 190k miles) that was getting oil in the spark plug wells. When I say oil in the spark plug wells, I mean A LOT. I had oil seeping into the spark plug wires and coming out through the distributor cap. I eventually got around to taking the rocker arm assembly off and replacing the lower tube seals that sit underneath the assembly. The O-rings were so old and brittle, they just snapped apart. After bolting the rocker arm assembly back on I did a valve adjustment to get everything back in order.


After doing the valve adjustment, I am now having an idle problem ONLY when the car warms up to operating temperature. There is no fluctuation in idle speed, only a rough idle that sounds like the engine is hiccupping (not misfiring, or so I think?). I need some help and any insight as to what might be causing the problem. I have adjusted the valves three times now and I am still having the issue. Accelerating in the car has no issues, everything is smooth and I do not hear any valves hitting or knocking around while accelerating or while the car warms up. When I'm sitting at a light, I can feel the engine hiccup while the engine runs. Could I be having another problem other than the valves being adjusted wrong? I set my lash to 0.008 inch on intake and 0.010 inch on exhaust. My Haynes manual states that 0.007 to 0.008 inch for intake and 0.009 to 0.011 inch for exhaust is the range I need to be within.


Now I'm not saying that my valve adjustment is perfect, because its my first time dealing with this stuff. I also changed spark plugs, distributor cap, rotor, and spark plug wires after doing the job on the lower tube seals. Could replacing the lower tube seals have brought another problem that wasn't noticed until now? Do I need to reset the ECU, or even adjust the idle screw or distributor? Or could it be that my valve adjustment is just not what it should be? Any help and suggestions would be greatly appreciated. Thank you.

 

First thing I think I might touch base on. When you did your valve lash, did you do it with the engine stone cold? By that I mean the next day after it sat overnight? If you did not, then your lash may be a touch too tight.

Second thing I'm going to hit is the lower spark tube seals under the rocker arm assembly of the D15B7 will not put oil in your distributor. Oil coming out of your cap is totally different than oil in your spark plug tubes. You've fixed that but not the oil in your distributor. That is another seal that is much less fun to fix but is fixable if you don't mind taking your distributor apart.

Thirdly, the oil in your distributor can easily wreck your idle. The oil conflicts with the spark in the cap. And even when you clean it up with a new cap or brake cleaner or whatnot, the oil returns due to the distributor shaft seal being bad.

 

TomCat, thanks for your quick reply. Yes, I did the adjustments with the engine completely cold. Let it sit overnight and never started it until I was finished with the adjustment.

So I think what happened with me finding the oil on the distributor cap was due to the oil in the spark plug wells. My theory is that when the oil pooled up, the heat and pressure from the engine caused the oil to somehow get 'sucked' into the spark plug wire and leak out through where it connects to the cap. I never found any oil in the area where the rotor and coil sit. However, I am not saying this isn't a possibility. I'll definitely go check the distributor for any signs of oil leaking through. Just wondering if that sounds like a possibility to you?

At least I have somewhere to start diagnosing the issue. I will try to get around looking at it when I can. Thank you for your suggestion!

If anyone else sees this and has suggestions, please let me know! I am really baffled by what's going on.

 

I see, so you found the oil on the plug wire boots on the distributor but no oil inside the cap at all. Any red dust inside the cap?

One item that affects idle for cold to warm is the FITV. It's mechanically controlled via coolant temperature. A common "fix" is to open the end cap and screw the white screw plug in more. The common consensus on the old FITV's is to screw it in maximum. This is supposed to let in more air when cold and less (almost none) once warm. However, I would think if it wasn't working once warm, your idle would be high or possibly surging due to the IACV not being able to counteract the extra air from the FITV.

This is why I still think it is likely something to do with the distributor. There is tests for the ignitor (ICM) and the coil you can do.

I don't know if you pulled your distributor off, it is also possible to put it back on 180 degrees out. The tangs are offset but people still have managed it without too much difficulty.

 

Now that you mention it, there was a bit of red dust on the old distributor cap when I had removed it for a replacement. I have also noticed what might be some fresh oil underneath the distributor, not sure if it's from the seals you mentioned before or messing with the valve cover. I should be able to get to diagnosing the distributor this weekend to check it out. Would it be helpful to take the distributor out and apart to see if I notice more of that red dust? I haven't seen any since I replaced the new cap and rotor. So maybe it's possible there's more hidden away inside.

 

The red dust is known as the red dust of death. Usually means the bearing is giving up. You run it a bit and take the cap off and see if you notice any floating around.

Oil under the distributor is more in line with the o-ring on the distributor and is easily replaceable. Also that o-ring is not the distributor shaft seal I mentioned earlier that lets oil inside the distributor.

If your ignition timing is good, that would also mean your mechanical timing is good, so rough idle would either be air or ignition related. When is the last time you checked your air filter?

 

Last time I checked air filter was when I noticed I was having the idle problems. I wanted to check to make sure that nothing was clogging the air intake system. It's been a long time since the air filter was replaced. But when I looked at it, it seemed pretty clean. Maybe I should just replace it anyways. Couldn't hurt, right?

Still haven't been able to get out and take a look at the distributor, my courses for school right now are kicking my butt. Once I do get around to it I will definitely update this thread. Really appreciate the information you're providing me, if there's anything else that might help (i.e. taking pictures) let me know what I can do to help pinpoint this issue further.

 

Okay, got an update with some pictures. Went out to look at the distributor cap and found the red dust. There wasn't any on the cap (most likely because it's new), but I did find it all over the distributor. Took the cover off to get a picture as well, I'll let the images speak for themselves.

Also, when I went to put the rotor and cap back on, the car won't start now! I'm guessing this has to do with a faulty distributor? Should probably add that I'm not getting a CEL. I don't think this old of a year will throw a CEL for a distributor, will it?


I resized these images to make them fit a little better, if it's too hard to see, I'll blow them up again

 

I believe it's time for a new distributor. It's also the most likely culprit for the rough idle and the now no start.

Try and locate an OEM distributor. Everyone says the after market ones are garbage 99% of the time so a waste of money as well as your time.

 

Alright, replaced the distributor, had to go to AutoZone to get an aftermarket. Really hard to locate an OEM, and being that this is my daily driver I needed something to at least get me going. I'll be on the lookout for an OEM part if possible.

However, the car now starts and runs great! I can't thank you enough for your help in diagnosing my issue, I could kiss you! Haha, but seriously thank you. You helped me learn a lot here and I hope this helps others who might be facing similar issues (even though there's tons of posts about distributors). But once again, thank you so much.

 

Hey guys, I'm back. Unfortunately my car is still having a rough idle issue. After replacing the distributor it seemed to run well. I'm still having a rough idle when the car warms up though. It's not as bad as it was before but I can tell the problem is still present.

I went and checked my pcv valve. The pcv valve seemed to be broken so I went and replaced that as well. Now the car revs a lot smoother/ quieter, so I'm assuming there was an issue with that. However the idle problem is still there.

I know TomCat suggested the FITV, I have yet to try that solution. Could it also be my IACV? I've heard of people having problems with those, but my car isn't getting that "surging" idle symptom. Also when I turn headlights on or just the cabin cooling fans, the idle rises. This is why I have reason to believe that it's not the problem. I read somewhere that it could be a bad MAP sensor. I tried to test the voltage by back-probing the sensor, but there are some rubber gaskets around the wires that don't allow me to get anything behind there. Any other way to test them besides a vacuum pump? I'm at a complete loss here as I thought the problem was fixed, but it doesn't seem to be.

Maybe I should take it to a shop, but I really don't like mechanics touching my stuff haha.

 

What’s a rough idle to you? Try taking off and cleaning the iacv then reset the ecu. Could be that aftermarket dizzy taking a **** already, it happens that fast.

 

Loading the electrical will cause idle to rise as the alternator needs a touch more to supply. That is normal.

Cleaning your IACV won't hurt.

Have you done a compression test? Make sure you do it with throttle wide open. I usually disconnect the distributor and I am paranoid and unhook all 4 injector wires too even though without dizzy signal the ecu won't fire the injectors.

You might just have a tired engine to where the idle is not as good as it once was.

 

Sounds as though the engine might be misfiring. I hear it hiccup through combustion cycles every now and then. Was wondering if it could be related to fuel delivery, maybe changing the fuel filter? Couldn't hurt I'm sure. When the car is running and I put my hand on the outflow line leading to the fuel rail, I can feel a rapid ticking through the tube. I'm guessing this is the fuel injectors working? Maybe it's getting clogged up?

When you say reset the ecu, does that mean do an idle relearn by disconnecting battery or fuse for about 10 minutes, then start it? I have yet to do that because I'm unsure whether 93's require this. Maybe that's my issue?

Haven't done a compression test yet. Thanks for that info, I'll see what I can do for that. Gotta find my compression tester first lol. It is a '93 with 190k, so yeah it could be that it's just a tired old engine.

 

Yes the reset ECU is pull the backup 7.5A fuse for a minute (FSM says like 10 seconds but we suggest longer) and replace. Do this when the car is warm. After the fuse is put back, start the car with no load, electrical or mechanical and let it idle for a few minutes. I think FSM says 1 minute but once again, letting it idle for a few minutes won't hurt anything and gives you a better window for the ECU to dial it in. Actually maybe it says 5 minutes idle.... I don't have the FSM on this new PC yet and my old sources seems to have finally gone the way of the dodo bird. I'll have to find my DVD backup. Let it idle for a full 5 minutes after pulling and replacing the fuse with the car fully warmed up. Going over is better than going under time.

If you don't reset the ECU it can take months they say for the ECU to correct from what it has built over the duration.

 

Tried resetting the ECU by pulling the fuse. Didn't seem to fix anything for me unfortunately. I talked to my friends dad who is a mechanic, he said from what I've described that it seems a valve is too tight. Might just go back and try adjusting the valves again.

If I did a compression test, would it help me pinpoint which valves are the ones out of proper adjustment? Was just curious to see if that could save me some time and hassle adjusting each valve. But I might just do that anyways. Still at a loss here as to what might be going on, even though it could be the valves lol.