Slight niggly issue either regarding idle speed

[den9112]

Hi , i have a 1.6tdi owned for a month now one owner from new with 76k full history ..The first thing i did when i purchased the car was have the software fix rollbacked from a recomended company via the VAG emission facebook page..having had that done i then did a full service with OEM filters oils etc (minus the fuel filter which waa documented as being done recently but will still change when i can afford a hex can cable) dont want to gamble on not doing the refill correctly..I also changed the thermostat and housing...I have since done just over 1900 miles and only noticed 2 regens and one was 2 days ago..The car is giving decent true mpg around 50-55 i am using branded premium diesel at the moment and i also use redex fuel cleaner and have for all my diesels in the past in fact i have a 120d series one with 136k and still returns 45mpg and i have used redex in that for 5 years and is a very refined diesel engine ...Now to my issue , i have done a scan with a obd2 scanner and came up with just one fault being the instrument cluster and that is down to me resetting the service interval just after the dealer did the same ...(i just serviced it myself for piece of mind) so no other faults showing ...The issue i am getting is two fold firstly when i initialy fire up from cold i get the usual high idle until i set off then it drops to around 7800rpm however after a good long run i switch off then back on again it only goes to around 750 until i hit the throttle were it will stay at 780 now i am not sure if this is related but i also notice that on first throttle and this is warm cold after a run or not i get a bit of a rough throttle just the first touch then after that its smooth it feels like you have the wrong gear gear and that feeling when its about to stall thats the best i can describe it.Car runs great cruising with no flat spotts and pulls decent for a 1.6tdi ..Sorry about the long post just thought i would get as much info in as possible ...ps i am hoping to aquire a hex can cable soon so i presume that would help with me changing the fuel filter ,cleaning throttle body and also letting me check the injector values ..I was wondering also if it could be a software issue after my rollback ...Any help or advice would be apreciated .Thanks

[Crasher]

The CAYC engine is very prone to idle quality issues, the dealer diagnostic system has an online function that I have used to calm the problem but often a new set of injectors is the only solution. Proper VDO A2C9626040080 units at £435 are not that much cheaper than the genuine 03L 130 277 S at £529.81 each but then again £400 cheaper a set could be worth it. Personally I would recommend you stay well clear of reconditioned units. They are easy to install (you must use new bolts) but they must be coded into the ECU.

[den9112]

Thanks for the reply but i dont think i can be paying nearly £2000 for a new set of injectors ...I will check the values once i get the vcds and hopefuly i may only have the odd one suspect injector that i can live with but i just dont have a bottomless pit of money to fork out £2000

[Crasher]

And it is a common problem caused by these insanely overly complicated modern cars and it is only going to get worse. When in 10 years time I am telling the owner of an A3 hybrid that they need a new battery and the part alone is £6.5k plus installation in today’s money, well it does not take a genius to work out what is going to happen.

[den9112]

Usualy when i purchase a car i do factor in costs for serviceable items etc but to actualy think of having to change 4 injectors on a car with just 75k on the clock and one owner is not something i factored in,i did factor in a DPF change or off the car clean and also a possible EGR however i am still going to purchase the Hex can cable ..The car does idle evenly it's just annoying me that it it needs a slight tap on throttle to get it to its regular idle speed which is 780 ..I am very old school was always used to buying a haynes manual when i got a new car that let me see what the factory idle speed should be ,i can't even find that for the car anywere ,i know that vcds lets you raise or lower the idle speed but without knowing the value how do you know you are adding or subtacting the correct value..I have had a look around for the VDO injectors and i can get 4 for around £1000 i suppose worst case it shows all 4 out of value which i believe is plus minus 2.8 then thats what it is but it does idle smoothly enough it's not like there is a obvious missfire etc ...At first i thought 800rpm would be a logical tickover speed ..I suppose if i get the hex can i can up to 800rpm and see if i notice any difference ...I dont mind getting my hands dirty but nowadays i have to brush up on the computer side and it's not my strong point but always willing to learn

[Crasher]

Could you do me a favour and knock a zero off your RPM figures, except the last one.... In some cases VCDS lets you alter the idle RPM, but by no means not all.