Damage by running on 7 cylinders?

[MntDriver]

Hi, I ran about 160 miles on 7 cylinders due to a spark plug wire burning out. What damage, if any, happened to my 8.1 liter engine?

[DriVer]

Quote:

Originally Posted by MntDriver Hi, I ran about 160 miles on 7 cylinders due to a spark plug wire burning out. What damage, if any, happened to my 8.1 liter engine?

I do not expect that you damaged the engine. On the other hand that spark plug and wire will need to be replaced.

[JMonroe]

Might want to change the oil. I'd suspect it may have been diluted by some of the gas being introduced into that cylinder, but not being burned. I bet your catalytic converter was plenty warm on the ride home too. I've seen vehicles burn (inside carpet will catch fire) from raw gas being introduced into the cat. Far less likely at highway speeds than in town. I'm surprised you didn't get some kind of check engine code?

Long term, I'd agree there's probably little, if any permanent damage.

[two2go]

Does the engine control unit really send a message to the odometer display if a spark plug does not fire? I think I read someplace that there are codes you can get via a OBD reader, but I can't find that info now. I do worry some because I did a self-install of my wires, but the coach seems to run fine and I clocked over 8 mpg on our last trip.

[DriVer]

A misfiring spark plug wire will not send a DTC to the IP's Command Center. I also have not seen where a DTC will post on a Scan Gauge II as well. A Tech II will scan and find a misfiring cylinder.

[two2go]

Quote:

Originally Posted by DriVer A Tech II will scan and find a misfiring cylinder.

I checked to see what a Tech II is, and they are $3500-$5k , so I'm thinking that's not a must have for my tool box. Have to find a local shop with the goods I guess.

[Max Hubrich]

MntDriver,

If a cylinder is not firing, no combustion, or damage to worry about. It should have sounded like it had an exhaust manifold leak.

Put a new wire on it and go. Look at a whole set of Taylor Extremes with boots. I think Oemy has them.

I ran a Chevy 454 for a thousand miles or so, with one wire off- It just loved it when I put all new wires on it- .

[MntDriver]

Quote:

Originally Posted by Max Hubrich MntDriver, If a cylinder is not firing, no combustion, or damage to worry about. It should have sounded like it had an exhaust manifold leak. Put a new wire on it and go. Look at a whole set of Taylor Extremes with boots. I think Oemy has them. I ran a Chevy 454 for a thousand miles or so, with one wire off- It just loved it when I put all new wires on it- .

Thanks for all the helpful responses!

Max, I went ahead and changed the oil today (approx 160 miles on 7 cylinders, approx 170 with 8 cylinders)....and YES it did sound like it had an exhaust leak while running on 7 cylinders.

I had Taylor Extremes on there, and the one that was not sparking was broken I think by me when I pulled it off to change the plugs...the end broke and I didn't know it, and it never fired for the whole 160 miles.

I replaced the Taylor Extremes with a NAPA LIFETIME wire set. They don't look as nice and thick as the Taylor Supremes, but then again, they are one third the price with a better garantee. I will keep the 7 Taylor Supremes as spares.

[max49]

Don't worry about it Mtn Driver. I drove all the way back from Moab on 7 cylinders, I didn't feel like messing with it with my newly broken femur. Coincidence or not, the cat and muffler must have gotten hot enough to melt my wires going to the jacks. Of course, my engine blew up 2 months later, which I still wonder if the # 5 cylinder had any thing to do with. None of the mechanics think there is a connection there, but I still wonder.
The cheap, stock, OEM style plugs have lasted longer for me than the big 10.4 MM wires. I won't buy the expensive ones again.
I made a heat shield to protect the wires, out of roof flashing. The muffler on the driver side is not that far a way from the hundred wires or so , in the frame channel.
.

[TXiceman]

For that distance, probably not a problem. I after replacing the wire and plug you might get a compression check on it is you are worried about the engine. The unburned fuel could wash down the cylinder wall and provide a bit less rig lubrication on that cylinder wall. To run a compression check they will need to pull all 8 plugs and check the compression pressure on all 8 cylinders. This will tell yo if that cylinder may be damaged. Also change the oil as it may have been diluted a bit.

Ken

[millsrv]

There is a big potential problem concerning the catilytic convertor. If raw fuel passes through the missing cylinder and into the exhaust system it can overheat and melt the catalyst causing the catalytic convertor to become blocked.
Usually, if there is a misfire there should be a check engine light and a PO300 code.
Some engine management computers can actually identify the missing cylinder and shut off that cylinder's fuel injector in order to protect the cat.
In any case, checking for a damaged catalytic convertor would be a good idea.