My car is back together and running, however........ an issue is causing some concern so hopefully someone can help answer my questions.

The car starts, idles and drives well apart from what feels like a misfire. 1st and 2nd gear seems fine but under load in any gear there is a mis-fire that makes the car shudder. Also, it certainly doesn't feel as quick as it did prior to the engine damage which I'm putting down to the mis-fire.

As the car has been remapped and now fully rebuilt due to the damage, any idea if the mis-fire could be down to the map?

Would it need to be mapped again?

Thanks

im presuming it bent some valves when cambelt let go. when head was taken off did you/who ever did it handle the injector tips? may well be blocked if so.

timing out aswell?????? although would imagine it would misfire all the time with timing out

Dervs can't misfire in the same way can they as they work on compression, not a spark? :S

Sounds like it might be the timing being out?

Dervs can't misfire in the same way can they as they work on compression, not a spark? :S

Sounds like it might be the timing being out?

If an injector isnt working properly, poor spray pattern, not set correctly it will cause a missfire exactly like a petrol.

Ah, thanks. Live and learn!

Yeah valves bent!!

Everything was replaced, 8 valves, hydraulic litters, pulleys, tensioner etc etc.

When the head was returned from the machine shop my mechanic sent it back as he wasn't happy with one of the injectors. They sent it back saying it was fine.

So if the injector is blocked I would imagine it's a head off job again then??

im presuming it bent some valves when cambelt let go. when head was taken off did you/who ever did it handle the injector tips? may well be blocked if so.

timing out aswell?????? although would imagine it would misfire all the time with timing out

Would it misfire when revving the engine whilst sat stationary? It didn't when I did that, only under load from third gear upwards. It definitely wasn't pulling as it should either.

im not certin but i think the amount of diesel injected when stationary and revved is different to when it is underload. head doesnt have to come off to check injector. if its only done it since it has been rebuilt take it back to the mechanic who rebuilt it. he should of found it on test drive when job was complete.

also if its only under load check MAF sensor is plugged in/flowing the right way- should have an arrow showing which way air flows through it.

hope it gets sorted

Take it to a garage, either the one you went to or another and get them to at least carry out a leak off test for the injectors.

Either and injector fault or the compression has been altered with the head skim

Skoda state that diesel heads should not be skimmed. There are three head gasket thicknesses available, and if the thickest gasket doesn't raise the head to the original level it will never run right, as the combustion timing will be out. Ask the garage if they used a micrometer to check original gasket thickness, and if the head skim (in thou) equaled the extra thickness of the new head gasket. Although expensive, it is always better to fit a new head after a timing belt failure.

Remember diesels rely on the compression to trigger the combustion phase. If the head is sitting too low, the combustion will occur too early relative to the piston position. In effect the combustion timing will be too advanced, occurring well before TDC. This has the effect of greatly reduced power that feels like a misfire.

Skoda state that diesel heads should not be skimmed. There are three head gasket thicknesses available, and if the thickest gasket doesn't raise the head to the original level it will never run right, as the combustion timing will be out. Ask the garage if they used a micrometer to check original gasket thickness, and if the head skim (in thou) equaled the extra thickness of the new head gasket. Although expensive, it is always better to fit a new head after a timing belt failure.

Remember diesels rely on the compression to trigger the combustion phase. If the head is sitting too low, the combustion will occur too early relative to the piston position. In effect the combustion timing will be too advanced, occurring well before TDC. This has the effect of greatly reduced power that feels like a misfire.

Thanks moggy, some good info there that I didn't know about but my mechanic did. The head was not skimmed so the injectors are being whipped out for a check.