PO307 code after induction/TB cleaning, no prior issues
 

I did the induction/TB cleaning the other day and got the SES light cleared at Advance Auto today. Five minutes later the light came back on, so I went back to check the codes and find out what was going on. PO307 shows up, a cylinder 7 misfire according to the scanner. I had the code cleared again, and the SES light didn't turn back on until I had driven fifteen miles or so. I've never had the SES light come on before the induction cleaning during the 8 months I've owned the Disco. Any ideas on what I've broken and how to fix it? Thanks

Cylinder 7 is a "scary" one as that could indicate a head gasket leak. I would try to pull that plug to see what it looks likes. Swap wire 7 with 8 if you are manually dexterous.

I sure hope you're wrong about the head gasket leak! I pulled the plug and initially thought it looked OK color wise, but upon close inspection the electrode is gone, black in color, certainly beneath the insulator. I pulled the plug next to it and the electrode definitely protrudes from the insulator as it should. The previous owner installed these Bosch Platinum Plus plugs with new wires about a year and half ago, less than 10K miles. Did the Seafoam and TB cleaner maybe grenade the spark plug? Should I replace all of the plugs or just the bad one?

What is the gap? If the electrode is gone in 10K that is suspect, could definitely just be a faulty plug (rare). What kind of wires are on there?

Plugs are cheap, do buy some new ones.
Buy anything you want, cheap copper plugs to Iridium's, whatever you feel like but make sure you replace them all.

What plugs are you running and who's plug wires?
As Spike mentioned, replace the plug/plugs as necessary.

I am willing to bet money that your misfire code was cause by the induction and throttle body cleaning.

Change/clean the plugs and give it a shot.

That's what I thought it had to be, so does the induction and TB cleaning potentially cause damage?

In any event, I opened the service history and found I was wrong, the plugs had been replaced over 20K miles ago, so they were a bit older than I thought. I bought all new plugs, Advance had Denso double platinum plugs on sale for $1.99, so I installed those. I had the SES light cleared again, drove for 20 miles with no return of the light. I suppose the one plug could have been bad as all the rest looked quite normal and uniform, althought they did have more wear than I would expect for 20K on platinum plugs.

The wires are light gray and say "Leoni" on them, maybe cheapo wires? I don't know if they are any good or not so I'll probably order a set of Magnacores. From the looks of it, the wires won't be nearly as easy to change as the plugs were.

If you have alot of carbon build up then doing a induction/throttle body cleaning will dislodge alot of it and it can foul the plugs and set off mis fire codes.
But plugs are cheap so not a big deal if you ask me.

That makes sense and if the only thing it could affect is the plugs, then it is an easy fix.