Help! Need Some Advice
 

Hello,

I have Hyundai sonata 2007 when I drive around 40 - 45 mph constantly car is giving jerks and when I increase speed or decrease speed then it works fine. Exactly When I drive in between 40 - 45 MPH I have this issue. Could you please help which parts I need to fix. Is this something a big problem? Thanks!

Impossible to tell unless someone else has had this issue.
Is it engine or transmission?
Is it engine knock or misfire?
Is it a vacuum leak?
(sorry don't know much about automatic transmission)

DELPHI Injectors caliberation
 

hellow
I have my Grandi10CRDI driving with acceleration mulfunction , not every day, saldom it happens. Last week same problem arise and take help some local adviser to ressolve by removing and cleaning of injectors. After cleaning we unable to start the vehicle and by next day take my vehicle to nearest authorised dealer. Now according to dealer technician they explain that injectors needs caliberation and it can only been done at Delhi.
My question is here ,
1. Is it really caliberation of injectors required ?
2. Is there any process of recodification or any reinstallation required in every removal of injectors from engine ?
please suggest how to start my vehicle.