2000 Honda Civic - stumbles on it's face after about 15 minutes of driving

I just bought a used Honda Civic. It's a 2000 with a 1.6L SOHC.

I have driven the car 3 times so far. The first time was a test drive. On the test drive it was fine for about 15 minutes of city traffic. I had a little bit of open road and I did some relatively quick accelerating (up to about 3000 or so rpm). While the tach was around 3000 I saw it drop sharply around to 2500 and sputter back and forth. Then when I came to a red light it stalled. I cranked it and it started on the second crank. It seemed to run fine for the remaining 15 or so minutes of my drive back to the dealer.

After buying the car I drove it another 10 miles the next day and under acceleration up a hill the engine did the same thing (symptom with the tach dropping and it bogged and almost stalled.) Lucky I was close to my destination.

On the next day- I put my PICO amp clamp on the feed wire to the coil (black guy with a yellow stripe). It looks like the distributor, wires and cap are new (they are much cleaner) I was measuring the current draw. I started the car and the oscillations for the secondary look good to me. The current draw peak is about 6 amps. It moved a little bit during driving (it went down to 5.8 or so). I brought the laptop on the passenger seat and went for a drive with the current clamp stuck around the wire and the pico on the drivers seat..



The car did not stall, but I only went to pick up a pizza, and a new fuel filter for the car. I drove about 8 to 10 miles maybe. I tried to do the same acceleration style to mimic the conditions that made it stall earlier.

Oh- and I did take the PGMFI relay out, and the solder joints look great. This car only has 74000 miles on it.

I have not figured out what is causing this yet but if any of you have suggestions I would be glad to entertain...

hi something doesn't look right about that coil ramp there is no turn off oscillation but looking at your symptoms I would say a crank signal might be dropping out if the tach is dropping back in rpms maybe do a crank waveform and check crank sensor circuit integrity under load I have never actually had a n oscilloscope in my hands but I hope too someday it would be awesome ........

chief eaglebear wrote: hi something doesn't look right about that coil ramp there is no turn off oscillation but looking at your symptoms I would say a crank signal might be dropping out if the tach is dropping back in rpms maybe do a crank waveform and check crank sensor circuit integrity under load....

Hmm... once I had a 2003 Ford Ranger that had an intermittently shorted crank sensor. It had similar symptoms but it would completely die like I shut off the key at speed. It threw a P0320 or P0340 (I can't remember which one). This Honda isn't throwing codes. Before I bought it, I scanned it and it had P0300, 301, 302, 303, 304 and1399 which is a Honda OEM random misfire code. I cleared these and they haven't returned.

The car is now showing all monitors ready (so I could actually pass emissions!)

I'm wondering is 6 amps is a low draw to begin with or it should be higher (like 10?)

Replace the relay only way to be 100% sure it is okay

6A does seem a bit low for these coils, but I could be remembering wrong. :silly: It'd be awesome to see the ramp when you catch it stumbling.

This Honda coil-in-cap design distributor is a classic failure point, not only with the coil but the ignitor. You can replace them independently, but it's way easier/faster to just do the whole distributor IMO. The camshaft keyway is offset so you can't get it wrong. Then just reset the timing.

You might give the cap and wires a spray with a water bottle, too. You could be fighting

Andy.MacFadyen wrote: Replace the relay only way to be 100% sure it is okay

I know but it looks perfect. I looked at it under a magnifying glass. Literally there are no cracks and nothing looks melted. I would just re-solder it before buying a new one. I fabricate my own circuitry and I have a hot air rework tool to work on PCBs.

Tyler wrote: 6A does seem a bit low for these coils, but I could be remembering wrong. :silly: It'd be awesome to see the ramp when you catch it stumbling.

This Honda coil-in-cap design distributor is a classic failure point, not only with the coil but the ignitor. You can replace them independently, but it's way easier/faster to just do the whole distributor IMO. The camshaft keyway is offset so you can't get it wrong. Then just reset the timing.

You might give the cap and wires a spray with a water bottle, too. You could be fighting

My plan is to do just that. I have the PICO 4425 so I have 4 channel capability. I think I will have to do some more driving with the current clamp on there. I have not taken the cap off yet but it looks super clean and new. So are the wires, so is the aluminum part of the distributor. I bought the car used with 74k on it so it probably gave the last person trouble. They probably tried to fix it and when it still acted up they said "screw it" and traded it in.

Maybe I should put the crank sensor on one of the other channels and then turn down the sampling rate a little bit so I can get a really long buffer.

I think I may have discovered what is going on here. I tore the front of the engine down to do a timing belt job and when i removed the valve cover I found the seals that go around the spark plug tubes (at the top) were completely shot and falling apart. Really bad actually. Numbers 1 and 4 had about an inch or 2 of oil at the bottom. I think the spark was leaking through the oil into the head. I haven't started it back up yet after replacing the timing belt because I am doing a bunch of other work too (steering rack and new pump) but I will let you all know.

samsepi0l wrote: I think I may have discovered what is going on here. I tore the front of the engine down to do a timing belt job and when i removed the valve cover I found the seals that go around the spark plug tubes (at the top) were completely shot and falling apart. Really bad actually. Numbers 1 and 4 had about an inch or 2 of oil at the bottom. I think the spark was leaking through the oil into the head.

I hate to say this but I don't think that is the problem. I had this discussion with our mechanic the other day when we were tracking a misfire - he said he has seen plenty of cars with the tubes full of oil without a misfire, as have I. Somehow it doesn't seem to track in oil.
I hope I'm wrong though and it fixes the problem.

Revs dropping under acceleration usually suggests weak spark due to a crack in the coil or open circuit in an HT lead or rotor. The spark is strong enough to jump the spark plug gap under normal driving but with quick acceleration, especially a load up a hill, it finds somewhere else to jump due to the higher compression.
I've seen this with a cracked coil (Ford engines with coil mounted to block, Toyota distributers with internal coil) where the gap is big enough for it to be easier for the spark to jump the plug gap in normal conditions but under load it's easier for the spark to jump through the crack in the coil. Also with one external coil and a long Ht lead, sometimes the lead breaks down internally and creates a powdery gap to add to the spark load, and with some Bosch distributors with a rotor with a built in suppression resistor, the resistor goes open circuit and adds an extra gap to the circuit. With your system it could be the rotor or a cracked coil. Also measure the resistance of the leads. Another trick is to remove the distributor and give it a spin and check how far the spark can jump (earth the body of it so you don't find out the hard way that the spark isn't making it to the engine block ) Sometimes you will see a nice strong spark with a smaller gap but as you increase the gap instead of the spark getting long and thin it just suddenly disappears - because it is jumping elsewhere - which is why I mentioned giving the distributor body an earth that conducts better than your fingers.
Also, if there is another gap somewhere it is possible that under load the spark goes back through the igniter module and overheats it causing the cutting out and hard starting.

I think I did fix it. I have been driving it now for about maybe 100 miles and I haven't seen a miss or the same style stumble. I did change the timing belt but the marks were on before I changed it and they still are spot on now after I put the new one on. I did also change the power steering rack and pump but that has nothing to do with it.