I agree with PAhonda's comments; most likely valve damage when the original belt broke.

 

Thanks. I am not mechanically savvy to do it. Both options seem like a lot of additional money. Not to mention $600 that are gone due to timing belt. What kind of money do you expect on both options

Second - do you think low compression in one cylinder can cause misfiring in other cylinders? Or could it be headgasket (read somewhere something on it) on the low compression cylinder that is causing misfiring elsewhere as well

 

I don't know exactly what the engine computer uses to set misfire codes. Older cars also had a tougher time setting the proper misfire code for a specific cylinder.

On my 05 TSX, I had a coil pack go out while I was driving on the interstate. When I checked my codes, I initially had a misfire on #1 and #2 and multiple misfire codes. After clearing the codes, I only got misfire on #2. I'm guessing the computer couldn't quickly set the air/fuel ratio to keep the O2 sensors from reporting properly and set multiple codes.

The low compression is not due to a bad head gasket. Usually you have a head gasket failure when the engine overheats and warps the cylinder head or engine block. Low compression is causing your misfire codes likely due to damaged valves.

Cost is hard to estimate.

Take a look at your bill for the timing belt and see what the labor time cost and the per hour rate. The cylinder head replacement would be at least that much in labor probably plus 1-2 hours.

Call you local machine shop and ask them what they would charge to rebuild your cylinder head and mill it, so it is perfectly flat.

The shop that did the work probably should have done a leak-down test when they got the engine in time and the belt installed to verify you didn't do any damage. Especially since you had a broken timing belt on an interference engine. It would have cost you more money to get the head repaired, but you wouldn't have the low compression problem now. You may want to talk to the original shop to see if there is some kind of deal you can work out.

 

A few comments:

• I'll echo PAhonda (again), just because the computer is indicating multiple misfires on different cylinders, doesn't in any way mean that's what's really happening; my 2001 lost a single coil over a plug, and depending upon when the codes were read, three, four, and even five cylinders were reported as misfires.
• Repairing your car, either by having the head repaired/swapped, or swapping the engine, will most likely be a very cost effective investment, assuming the rest of the car is in good shape.
• Think about the repair this way; how much would it cost you to sell the Accord for next to nothing (given it's current condition), and then buy something as nice of a similar vintage? Most likely MUCH more than repairing your car.