mrau92me

173k miles on the engine and 40 miles from home Easter Sunday on I-65 passing a semi and our engine starts missing really badly and it shuts down...had to pull into middle of the interstate. Looked under hood & smoke was coming from the front driver's side coil.

We bought a coil and when loosened the bolt the top of the coil came out easily but the bottom couple of inches were not attached. Turned the ignition over but it would not start (thought it should run on 5 cyl).

Had it towed to the nearest mechanic on Monday (they aren't specialists in Honda/Acura). He came back and said the plug was melted into the cyl head, which is kind of what we expected, but he said that he thinks there's more damage than just to the head because he believes the engine should run even without that cylinder firing. So, he assumes there's cyl &/or piston damage and it's beyond his capability.

Is he correct, did fuel wash out the cylinder? Or, is there a protection in the computer that would shut the engine down if a plug completely stops firing? This is my sis-in-law's family's car and I'm trying to save them some money. Any help would be appreciated. Note: I'm not sure if they've even replaced the timing belt, but I don't think a broken belt would've caused this.

mrau92me

I'd like to add that a different coil and all 6 plugs were changed about 12,000 miles ago (a year ago), so this coil that melted was most likely one that came on the car when it was new. It got so hot that the wrapping on the wires leading to the top of the coil melted away.

Skirmich

1 the spark plug tube is completely removable so its not melted into the head by any means, remove the valve cover and the tube can be replaced.
2 no, the coil cannot do damage to the head physically if the engine doesn't want to start on 5 cyl perhaps there is more damage to the electrical side.

mrau92me

Thanks for the great info, Skirmich.

I just found out that the mechanic did not remove the remaining part of the coil & the spark plug. So, are the spark plug tubes attached to the valve cover or the head? Basically, if we remove the valve cover, do you think it will be obvious and probably easy to get the plug tube and burned up coil debris and spark plug out?

As far as more damage to the electrical, I was kind of wondering that too. The sheathing around the wires coming from the coil wire harness to the burned coil's connector was burned up. It doesn't appear that those wires are broken though. Would you recommend a fuse to check? Seems the mechanic would've already done that. Could a short have killed the computer without blowing a fuse first?

Skirmich

The spark tubes are pressed into the head, This video isn't specific to your engine but you get the idea:

As for the electrical I sincerely don't know where to start, I am not electrical saavy of any sort.

mrau92me

So, after talking to the original mechanic that looked at it, he says that he did remove a stub of a spark plug and it's on his desk. He told me that the threads in the head were essentially gone. So, Skirmich, are you saying the threads are in the spark plug tube, not the head?

The current situation is that it's at another independent shop now, who works on Acura's. They're saying they replaced the bad coil and looked at the top of the engine and that it is fine. But, they're saying the motor's locked up and so it must be something wrong in the bottom of the engine, so they say the engine must be replaced. And, they quoted over $4400 for an engine with over 100k miles. I think it's time to take it somewhere else, because the starter motor worked and turned over just fine when we left it on the interstate and the previous mechanic confirmed it to me as well.

Skirmich

No I never said that.. The spark plug tube is a cylinder to separate the Valvetrain from the outside, so you can replace the spark plug and nothing will fall into the valvetrain or oil will fall into the spark plug. The threads are in the head as it should..

At this point I sincerely don't know what went wrong with your engine.

csmeance

This has happened to a few 3G TL folks when the A/C drain backs up and fries/short circuits the ECM under the center-stack/radio area. IT always causes the melted on coil pack and then then car doesn't run properly because the ECM is damaged.

You can remove the damaged plug and coil and use a heli-coil or time-sert as needed for repair to the head if the threads are damaged. No need to remove or replace whole head.