Honda J30A1 with missing spark plug

A friend driving her high mileage Accord had a misfire 130 miles from home, and drove to a mechanic who diagnosed it as a spark plug leaving the cylinder. I have pictures, but no real way to confirm the diagnosis.

I know I can drive something with a missing cylinder. Can I disable that fuel injector by just unplugging the harness?

I'm going to get it here and figure out if the remote mechanic was right or a jerk, and probably heli-coil it.

Happens pretty regularly. 120 miles may have beaten the spark plugs hole beyond repair, not to mention all the spark plugs bits that have run through the cylinder. Helicoil works as long as there is a seat left for the plug to seal to.

Edit:. I read properly and see she was 130 miles from home, didn't drive 120 miles. It should be fixable, but I'd be happier towing rather than driving with the injector unplugged.

Thanks for the reply.

The spark plug appears from pictures to have come out whole, though I can't say much for the bits of aluminum from the head.

If I vacuumed the chips out and maybe used a borescope, why would driving it make it worse? There would be no heat. Am I missing something?

Additionally, how successful have people been with heli-coil in place, without removing the head?

If the head has to come off, how annoying is the timing belt situation on these V6 Accords?

Driving it with a dead cylinder will beat things to pieces from vibration under anything more than light throttle.

rslifkin wrote: Driving it with a dead cylinder will beat things to pieces from vibration under anything more than light throttle.

That was my thought. V6s rely on a specific firing order for smooth operation. Drop a cylinder and the thing is going to try and shake itself to pieces since the combustion events aren't balanced anymore.

pointofdeparture wrote:

rslifkin wrote: Driving it with a dead cylinder will beat things to pieces from vibration under anything more than light throttle.

That was my thought. V6s rely on a specific firing order for smooth operation. Drop a cylinder and the thing is going to try and shake itself to pieces since the combustion events aren't balanced anymore.

Hey now, I have driven lots of stuff with misfires. I drove a four cylinder with two cylinders once. I am pretty sure that won't be the issue.

I could see harmonic issues causing failures if you did that for 50 or 100k miles. 120 miles though? I don't see how it would be an issue.

tuna55 wrote: Hey now, I have driven lots of stuff with misfires. I drove a four cylinder with two cylinders once. I am pretty sure that won't be the issue.

A 4 cylinder isn't nearly as bad as a V block. I've driven a 4 that dropped a cylinder. It was down on power and a little shaky at idle, but not particularly rough even at WOT.

On the other hand, I blew an injector driver in the Jeep ECU once... Had to keep the revs up a bit to minimize throttle use, as anything over 1/4 - 1/3 throttle (depending on rpm) was like sitting in an out of balance washing machine... And that's a V8, so a dead cylinder is a smaller proportion of the firing events.

rslifkin wrote:

tuna55 wrote: Hey now, I have driven lots of stuff with misfires. I drove a four cylinder with two cylinders once. I am pretty sure that won't be the issue.

A 4 cylinder isn't nearly as bad as a V block. I've driven a 4 that dropped a cylinder. It was down on power and a little shaky at idle, but not particularly rough even at WOT. On the other hand, I blew an injector driver in the Jeep ECU once... Had to keep the revs up a bit to minimize throttle use, as anything over 1/4 - 1/3 throttle (depending on rpm) was like sitting in an out of balance washing machine... And that's a V8, so a dead cylinder is a smaller proportion of the firing events.

I have definitely driven a V8 with a missing cylinder. A lot. You're over-reacting.

I am not worried about that.

In reply to tuna55:

How bad a miss are we talking here? Even a cylinder with valve damage and 60 psi of compression fires a little bit and doesn't cause nearly the shaking that a 100% dead miss due to no fuel or spark does. I've seen plenty of misfires that didn't feel all that bad (which is why I was surprised just how violent the shaking was from that one).

rslifkin wrote: In reply to tuna55: How bad a miss are we talking here? Even a cylinder with valve damage and 60 psi of compression fires a little bit and doesn't cause nearly the shaking that a 100% dead miss due to no fuel or spark does. I've seen plenty of misfires that didn't feel all that bad (which is why I was surprised just how violent the shaking was from that one).

I've driven V8s with a missing spark plug wire, and the four cylinder I mentioned earlier had one missing spark plug and a separate missing wire.

Beware - I've seen these engines blow the plug out because the head corroded away around the spark plug. Usually the cylinder up front on the passenger side.

In reply to Knurled:

How can I tell the difference from the outside?

In reply to tuna55:

When you try to thread in a new spark plug and it just sort of rattles around.

5 minut jbWeld for metal???

Ok bad idea.

I have no particularly good reason to say, "Don't drive it.". Just seems like there is potential for trouble.

I'm in the camp of not worried about driving it.

With no plug in the hole it will have zero compression and you'll probably hardly notice missing the cylinder except at idle.

I wanted to mention the shaving cream trick if you are helicoiling with head on. Put piston all the way down, fill hole with old school shaving cream, drill, then turn cylinder by hand to kick out the cream and all the shavings. Vacuum the rest out. Never had to do it personally but it sounds like a great idea.

I've never done it with a Honda, but I have put a helicoil in a Subaru without pulling the head.

I didn't use shaving cream, just vacuumed out as much as I could.

If the head is aluminum, then any chips are going to be softer than the cylinder walls, so there is a high probability that any left after vacuuming will go out the exhaust valve before causing any notable harm.

If you can get at it, and have access to the necessary tools, I would put the helicoil in before driving it back.

Otherwise, unplug the injector and drive it home, with the expectation that with an open plug hole you will probably have exhaust circulating into that cylinder and causing some funny smells and noises in addition to the vibration.

I rode a V-2 on one cylinder 60 miles.

If the plug blew out, "There's probably something wrong with that motor." What do you have to lose? The rest of the motor?

Robbie wrote: I'm in the camp of not worried about driving it. With no plug in the hole it will have zero compression and you'll probably hardly notice missing the cylinder except at idle.

And then when you melt down the catalyst, that's just the car telling you that you shouldn't'a done that.

Knurled wrote:

Robbie wrote: I'm in the camp of not worried about driving it. With no plug in the hole it will have zero compression and you'll probably hardly notice missing the cylinder except at idle.

And then when you melt down the catalyst, that's just the car telling you that you shouldn't'a done that.

What? How? No fuel in that cylinder.

Yeah, as long as there is no fuel going in there. That's how I lost the Esprit.

I drove a 2.0 Lima from Boston for about 45 minutes with a plug blown out. It was loud in the tunnel but no damage.

(Also drove it around with the oil so low it wouldn't read on the dipstick and it didn't seem to suffer any major damage so there's that.)

Dr. Hess wrote: Yeah, as long as there is no fuel going in there. That's how I lost the Esprit.

How about when the engine starts dumping fuel into the remaining cylinders on that bank because the O2 is reading all that free oxygen and thinks it's lean? Two rich cylinders plus one pumping air equals slagged cat.

Yes, misfire should disable closed loop, but "should" isn't always "does".

In reply to Knurled:

No spark plug = no compression = no air pumping into exhaust. It will probably be fine.

My concern is any photos I've seen of the Honda V6s with blown out plugs typically are junk due to the corrosion damage that caused the failed plug in the first place.