I have a '98 Honda Civic with 140K miles on it. It has been running great but recently had a little trouble with it. The check engine light came on and car was driving with a lot of jerks. Scanner said all 4 cylinders are misfiring and that random misfire detected. I took the car to a shop and they said there is nothing wrong with spark plugs, wires, distributor, rotor etc and after compression test on the cylinder found they are not getting enough compession as there is lot of carbon build up and that's what is causing cylinder misfire. The fist step is to DECARB the engine.

Question: Can someone explain what exactly is involved in decarbing the engine and how much it should cost?

Later they said decarbing have not fixed the problem and quite possibly the valves are not sitting correctly and will need to take the cylinder head off, send to machine shop and replace the bad valve(s).

Question: Is this possible? and how much should this type of service cost?

 

if it was running fine and then "all of a sudden" started missing on all four cylinders the first thing I would think would be water in your tank..... could try some heat it could save you a lot of unnecessary repairs......have you ever had your timing belt changed? seems to me like if your timing was off and your exhaust valves were opening too early your compression would read low.....but I could be wrong.... sounds like they are trying to take you for a ride

 

Thanks for the reply. Yes the timing belt serive was done at around 120K miles. DECARBING --> Is this same as flushing the fuel line?

If there is carbon build up in the cylinder, it should increase compression and not decrease it, correct? Becuase, having build up will reduce cylinder volume.

 

according to my old man who is a big block builder a lot of carbon should increase compression but you could also be fouling plugs, I would definitely like to see the compression test myself or you could go by a tester and test it yourself