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So, a couple of months ago, one of my distributor caps cracked and engine ran on four cylinders only. I didn't have the time to do it myself, so the mechanic replaced only that one dist and rotor. The other one stayed in.
Then, few days ago, I start the car, I hear a little "clang" and the car runs like a pig. It feels exactly the same as when the other distributor broke - no power, rough etc. I didn't even drive it, just shut it off immediately. I figured - the other distributor cap cracked for sure.
Today, I open the engine and guess what - the distributor AND the rotor are not cracked! They are both looking solid, except, the rotor has MAJOR amount of burnt stuff on the contact edge, and I am wondering - could that be the reason for misfire/no fire on one side? I mean, I never noticed any problems before, but now all at once this...
I always thought that rotor or cap crack and that's why the engine doesn't run; if it was corrosion, it would slowly create problems maybe at start up or whatever.
Any ideas?
I also recently changed the driver side coil (NGK), and both igniters with used ones from E-bay - comes out old ones were fine (I changed them because I thought that that's what failed, not the distr).
What would be your guess? I haven't put it together yet, to see if it is the rotor that had a burned contact, but I honestly could not see much of metal there, it was all covered with dark crud. Almost like molten plastic or something - that bad.
Here is the picture of the rotor that is burnt - could that be the cause? (I guess I was misled by the clunk I heard, but then, my outer tie rod needs to be replaced. so maybe that made the noise just at the right time)
Here is the picture of the rotor that is burnt - could that be the cause? (I guess I was misled by the clunk I heard, but then, my outer tie rod needs to be replaced. so maybe that made the noise just at the right time)
That much of corrosion doesn't cause any problem, in my experience. On the other hand, even a minor crack causes a serious leakage problem. I'd check the sparking capability using a home made variable gap tester. It can change the spark gap between 5mm to 20mm. At under 1 ATM, the spark can travel more than 10mm. All you have to do is to use it instead of a spark plug. In this case, one cylinder doesn't work but this is a quickest way to judge. You also had better to check the spark connecting it to the output of the ignition coil. A weak ignition coil or igniter can't generate enough arching power to travel more than 10mm. Usually nearly 15mm should be OK.
That much of corrosion doesn't cause any problem, in my experience. On the other hand, even a minor crack causes a serious leakage problem. I'd check the sparking capability using a home made variable gap tester. It can change the spark gap between 5mm to 20mm. At under 1 ATM, the spark can travel more than 10mm. All you have to do is to use it instead of a spark plug. In this case, one cylinder doesn't work but this is a quickest way to judge. You also had better to check the spark connecting it to the output of the ignition coil. A weak ignition coil or igniter can't generate enough arching power to travel more than 10mm. Usually nearly 15mm should be OK.
Thank you yamae! When the other rotor broke, I actually thought it was an igniter and replaced them both with used ones. But it was not igniters, it was the rotor, so I am going to put my old, good, igniters back and see if that was the problem.
Its just that weird clunk that confuses me... (but my outer tie rod was shot, so maybe that was where that came from).
It should be pretty easy to check for spark at each of the wires going into each distributor. Start there and work forward / backward based on what you find.
From quick reading of the above, it does sound like a spark issue, but of course don't rule out other causes until specifically tested.
So, a couple of months ago, one of my distributor caps cracked and engine ran on four cylinders only. I didn't have the time to do it myself, so the mechanic replaced only that one dist and rotor. The other one stayed in.
Then, few days ago, I start the car, I hear a little "clang" and the car runs like a pig. It feels exactly the same as when the other distributor broke - no power, rough etc. I didn't even drive it, just shut it off immediately. I figured - the other distributor cap cracked for sure.
The biggest question I have is why did your mechanic only change one and not both caps and rotors. Half the engine is apart and it's only $20 more in parts. But, that's the past.
I would suspect that rotor just by the picture, that thing is burnt up. If it started running the same way it did when the first rotor and cap were bad then you'd think it is the same problem. If I was you I would put on a new rotor and cap. Did you test it for spark before you took it apart this time?
You mention a "clang" at start-up. Is it like the engine jumping as if the tranny or engine mounts are bad? Mine jumps and makes a loud clang about once every 40-50 starts and I know it's cuz of the tranny mount.
The biggest question I have is why did your mechanic only change one and not both caps and rotors. Half the engine is apart and it's only $20 more in parts. But, that's the past.
Oh, don't get me started. I was furious. He says 'But I only ordered one!" (and he did that BEFORE asking me if I want him to go ahead and replace it himself). So he ordered only one, fixed the problem and then called me to say "There, car is running fine now". I used to trust him blindly because he had the same car and is really smart, but that was a shady move. He knew the other one was bound to fail any time soon. Besides he charged me $500 for labor, which was an overkill. IT doesn't take anywhere near five hours to do this job.
Originally Posted by deanshark
I would suspect that rotor just by the picture, that thing is burnt up. If it started running the same way it did when the first rotor and cap were bad then you'd think it is the same problem. If I was you I would put on a new rotor and cap. Did you test it for spark before you took it apart this time?
You mention a "clang" at start-up. Is it like the engine jumping as if the tranny or engine mounts are bad? Mine jumps and makes a loud clang about once every 40-50 starts and I know it's cuz of the tranny mount.
Yeah, that clang noise worried me, and it was not loud, so I was sure it was the rotor/cap... No I didn't check for the spark, but get this: after I finished everything, I found out my battery died. Stupid og me - I didn't disconnect it, and it was probably dying already, so the interior lights kept running all day long, I ran windows up and down few times, and then I put in the key and - it barely span once or twice and that was it. I tried turning on my car stereo - it wouldn't even turn on... So now I need a jump start and a new battery and hopefully the car will run.
I also put in my original igniters replacing the ones that I put in unnecessarily which were used anyway. Maybe one of the igniters failed? I already replaced driver side coil, with NGK one, so that should be OK, and if nothing, then it is the other coil, which is an easy job.
The plot thickens:
First, I replaced the rotor and distributor cap with new one yesterday.
Then the car ran badly again, so I replaced igniters - because I took out my original ones a few months ago, and replaced them with used OEM ones from e-bay. Today I put back the original ones which were working fine, and the car ran fine! Success!
I drive around the block few times, add coolant, test my brakes, everything's fine. Hear a little something from LBJ, so those will have to go too. Then, an hour later I go to a store, car runs like a rocket on the highway, and I get out of the store, and start the car and it runs on four cylinders again! What gives???
The only thing that was not replaced was one coil - the one in the middle (drivers side I replaced few months ago). So I limp home couple of miles and replace the coil with another one that was working fine before. Start the car - nothing. Still runs on 4 cylinders.
At this point there are only few possibilites:
1. ECU? I have another good one to try.
2. Bad connection somewhere? But why would it show up all at once like that?
3. Premature failure of one of the rotors/dizzies?
General troubleshooting advice, that seems like it applies here:
You've got an intermittent problem. Comes and goes. So you need to be very cautious about coming to any conclusions, since they could be invalid due to the problem being intermittent.
For example, if the fault is present, then you change a part and it's fixed ...
If the problem were not intermittent, you could reasonably conclude that you isolated the fault and fixed it. Done.
But since the problem is intermittent, you should be more cautious. Maybe even swap the bad part back in to see if the fault comes back, then swap the new one, etc. until you get reliable enough results to form a conclusion. Yes, this is extra work, and no you would not necessarily do this at first. But at this point ...
Swapping parts is a great way to tackle problems like this, but of course can get expensive, so raiding a junk yard car for multiple related parts may be cost effective.
When swapping is not an option, consider that electrical parts are still governed by the laws of physics (just ones we can't always see so directly). Tapping or bending them can affect their electrical performance. Wiggling loose/flaky wires is the clearest example of this. That sort of testing can provide very conclusive and immediate feedback in some situations, or nothing at all in others.
Also, if you find that swapping parts seems too difficult, it may be helpful and non-obvious to know that the engine should idle perfecly smoothly with a TON of stuff removed. Everything in the air intake up to the throttle body can be removed. Timing belt covers, ignition wire covers of course, drive belt, fan, etc. can all be off and it will run. With all that stuff removed and easier access, it may be easier to do the testing. When idling in that mode, no air goes through the throttle body; it all goes through the IACV, so putting your hand over the throttle body will have no effect, but blocking the IACV hose will kill the engine.
General troubleshooting advice, that seems like it applies here:
You've got an intermittent problem. Comes and goes. So you need to be very cautious about coming to any conclusions, since they could be invalid due to the problem being intermittent.
For example, if the fault is present, then you change a part and it's fixed ...
If the problem were not intermittent, you could reasonably conclude that you isolated the fault and fixed it. Done.
But since the problem is intermittent, you should be more cautious. Maybe even swap the bad part back in to see if the fault comes back, then swap the new one, etc. until you get reliable enough results to form a conclusion. Yes, this is extra work, and no you would not necessarily do this at first. But at this point ...
Swapping parts is a great way to tackle problems like this, but of course can get expensive, so raiding a junk yard car for multiple related parts may be cost effective.
When swapping is not an option, consider that electrical parts are still governed by the laws of physics (just ones we can't always see so directly). Tapping or bending them can affect their electrical performance. Wiggling loose/flaky wires is the clearest example of this. That sort of testing can provide very conclusive and immediate feedback in some situations, or nothing at all in others.
Also, if you find that swapping parts seems too difficult, it may be helpful and non-obvious to know that the engine should idle perfecly smoothly with a TON of stuff removed. Everything in the air intake up to the throttle body can be removed. Timing belt covers, ignition wire covers of course, drive belt, fan, etc. can all be off and it will run. With all that stuff removed and easier access, it may be easier to do the testing. When idling in that mode, no air goes through the throttle body; it all goes through the IACV, so putting your hand over the throttle body will have no effect, but blocking the IACV hose will kill the engine.
Tough problem. Good luck.
Thank you oldskewel, that's what I'll have to do. I was thinking that the problem could be affected by higher temperature. I will try the car again now, its a cool morning, and if it fires up on all 8, then it is temperature related. IF not, it may be contact related - got shaken out of whack last night and lost contact. I do have few plugs which were snapped and don't have the little thingy that prevents them from falling out...
I was also thinking that there is a possibility that I didn't plug in the new coil properly. Gotta check that now that I am more rested.
Update:
Checked the coil (the one that's easy to see) and found that the connector on the back of it was loose - dosconnected, It was the square, smaller one below the round one. The tab is broken and I guess it found its way out of the slot.
I plug it back in, and guess what - the engine still runs like a pig.
At this point, this is a puzzle worthy of a Sherlock Holmes. The only things that comes to mind is that somehow that weak contact ruined the coil, perhaps it arced. So I put in its place another coil, used, but good.
Nothing again.
This leaves only the ignitor/s. But I can't find where are the old ones, they were good, at least one was.
Update #2:
Just replaced one igniter and tried it again - ran the same way. Then replaced the other igniter - again, ran the same way.
At this point I have:
- Both rotors and distributor caps replaced, with new ones made in Japan
- Both Igniters replaced (made no difference, so old ones were fine)
- Driver side coil was replaced by me about six months ago, with NKG one. It's practically new. Old one was not bad though, and I kept it.
- The other coil I replaced with another used one that was working. That did nothing.
The only thing that is left is probably NKG coil? Or ECU?
I also checked the exhaust after I shut it down and for a long while, a foggy trail was slowly coming out of the pipe - I smelled it from up close and it was the smell of fuel. I am hoping that means that the problem is not fuel delivery
Any other thoughts and opinions?
Also, could it be that the engine is flooded? I had to crank it to see if it ran well, but as soon as I saw that it didn't I shut it off. So it ran few times today for about three seconds each time. Lots of time between cranks - at least one hour each time.
Replaced the ECU and put in the other, good one, and engine still runs the same.
Pulled out the new NGK coil that was put in few months ago, replaced it with an old Denso one.
Still the same.
So, it is not the two coils, it is not the two igniters, and it is not the ecu. The two rotors distributors are also new.
I don't know what to do any more.
Well, to answer my own question:
- Distributor cap/rotor, coil, igniter, in that order, would be the most likely culprits.
- Barring that, wires and plugs are the next suspects.
All of the above in case you know it's not fuel supply or something else that is not electrical.
06-12-19, 06:38 PM
Most likely cause of four cylinders not running?
The biggest question I have is why did your mechanic only change one and not both caps and rotors. 
Half the engine is apart and it's only $20 more in parts. But, that's the past.
