morning all

got a octavia vrs on 54 plate with 16000 on the clock at work at the mo, with a misfire at speed anywhere between 70- 110. (won't go over 110)

downloaded it on our bosch machine which came up with combustion failure on number 2 cylinder, i replaced the coils and spark plugs but it did not cure the fault, ive swopped over the injectors to see if the mifire changed cylinders but no difference!!

when your loading up the engine through the rev range in 2nd and 3rd gears there is nothing dosn't miss a beat! only there when your flat out in 4th and 5th, ( and i mean flat out :eek: )

iv'e made sure nothing is bloking the air intake, the fuel tank is not sucking in, basically iv' been through most of it.

also changed the boost valve, dump valve and maf sensor as a last resort, i was sure it was going to be the coils, but no!!!!!!!!!!

just wondered if you old boys have got any good ideas!

cheers

Jas

Take it to a dealer under warrenty?

thats the last resort, but i'd still like to cure the problem myself with some top tips from this forum!

jas

You seem to have replaced just about everything you can - and at considerable cost! Does the Bosch computer you used replicate all the functions of a VAG dealer's 1551/2 or 5051/2 or is it essentially an OBD computer? Try swopping the No 2 coil pack and spark plug with another cylinder to see if either replacement could be faulty. (I have had a few expensive experiences in the past chasing elusive ignition problems only to find that a new spark plug put in to replace a faulty one is also faulty!)

problem is if you have replaced parts yourself will that not invalidate the warrenty anyway?? I cannot see the point in doing the work yourself at your cost if the car could be repaired for free?

Skoda genuine parts come with a 1 year guarantee - or 2 years if bought from an Audi dealer.

cheers for the replies!

iv'e already swopped the new parts, there not at fault.

basically i work for the local constabularies workshop, and we do alot of our own warranty work!

we run an endless fleet of vrs's and iv'e never had this problem before, normally its coils or possibly a boost pressure sensor.

this one's really got our brains going!

cheers

Jas