My skoda is running rough under heavy load.

I had it on the diagnostics yesterday.

3 codes.

1 temp sender which I knew about as guage wasn't working. New one fitted and working now.

2 was something to do with a little black canister. The car is a rally car and this has Never been connected.

3 was an ecu fault.

Any thoughts on what my next move should be? Might also be worth mentioning that the rev counter only works intermittently.

It's less of misfire. Rather a flat spot under load. But not always at the same point.

Thanks.

I think you've got an iffy connection to the rev counter; fix that and the flat spot will probably go away too.

Look for air leaks?

Is it running cool? Check if a new thermostat would help.

hi, quick update,

spark plugs replaced,

fuel filter replaced,

re plugged in and still the same ecu fault code,

replacedd ecu with a second hand unit, had it programmed to the key,

exactly the same,

just had the clocks out, sorted a loose connection on the rev counter, this now appears to be working fine,

still the same flat spot under load,

I cant find any air leaks,anywhere, everything looks in tip top condition, being a rally car from near new it has spent most of its life garaged,

The diagnostics are now showing no fault codes after a 10 minute run,

Any more ideas? im scratching the hair off my head trying to sort this one!

Any more ideas? im scratching the hair off my head trying to sort this one!

Well... as I said in a previous topic, you got to go back to basics.

What needs an engine to run well? It needs 6 things

1. enough fuel
   
2. enough air
   
3. strong spark
   
4. perfect timing
   
5. strong compression
   
6. unrestricted intake and exhaust
   

Take it one by one, see if you're confident enough on all points, and decide if in the end you need a chip tuning.