After Valve Job ??????

[Keith Sturtz]

Ok so on my 1990 Audi TQ 200 I got the valve job done now i have a 
couple of issues .
1  The check engine light flickers or comes on for a second when excel 
orating  .
2  The speedometer does not for the most part work at first it was 
jumping every second or so, now every 5 minits or so it will jump back 
up this did not happen before the valve job ( R&R HEAD) so it has to be 
something loose so my ? is ...  Were Does Spedo  get signal ( sensor ? 
)  from .