As per the title, when hot or cold, the Q7 will sometimes not start straight away. The engine will crank strongly but will not fire. After the 3rd or 4th attempts of 7 seconds of cranking, it will start.

General starting seems to take around 4 or 5 seconds of cranking before it will fire.

Vag Com / VCDS doesn't show any error codes.

I have had the fuel filter changed and this hasn't affected the starting issue.

Any ideas?

Thanks.

I generally wait for the preheat light to go off but even if I forget and crank it only takes about 3 seconds to fire up. Once warm it is almost instant.
I have not read a solution but two or three owners have made this same complaint. I think all in the UK.

If you generally do not lock your car just hit unlock button before you get in anyway. The Q7 has a priming pump that is actuated by unlock.

morning long cranking and sometime no start and theres a white smoke , when its start ill leave it idle for 10 minutes turn off then try to restart it will start cleanly but sometime it will take a long cranking 7 sec. to fire up or no start at all , but when it starts then try to drive the vehicle it run no problem it run fine also theres no error code , i have replace the battery , fuel filter , fuel pressure sensor , fuel pressure valve , high pressure pump , fuel retention valve , 6 injectors , egr , coolant temp sens. crankshaft sens. cam shaft sens. maf sens. i also tested the cylinder compression and it was fine , all above replace still the same symptoms scan it with vag no fault code , almost everything is replace , ive been doing this for 2 weeks , the ECM was also updated thru svm still desame , grrrrrrrr now i will try a new ECM for this will see what happen

I think the plugs need a second or two to warm, and there's a little indicator on the dash that goes out when they are warmed. Also, diesel engines don't always warm well if left to idle as they are rather efficient, so one needs to drive a bit to warm the engine. Do you live somewhere cold or leave the vehicle out at night? It is December. I recall some other comments/posts in this forum about slow TDI starts even in warm weather.

morning long cranking and sometime no start and theres a white smoke , when its start ill leave it idle for 10 minutes turn off then try to restart it will start cleanly but sometime it will take a long cranking 7 sec. to fire up or no start at all , but when it starts then try to drive the vehicle it run no problem it run fine also theres no error code , i have replace the battery , fuel filter , fuel pressure sensor , fuel pressure valve , high pressure pump , fuel retention valve , 6 injectors , egr , coolant temp sens. crankshaft sens. cam shaft sens. maf sens. i also tested the cylinder compression and it was fine , all above replace still the same symptoms scan it with vag no fault code , almost everything is replace , ive been doing this for 2 weeks , the ECM was also updated thru svm still desame , grrrrrrrr now i will try a new ECM for this will see what happen

Have you tried connecting a battery pack/jump starter to the charging posts under the bonnet and seeing of this improves the starting?

i havent try yet replacing the ECU , its hard to remove the connector socket from the ECU ,cos theres a 4 bolt security enclosing the socket connectors , ive already tried putting a jumpstart at the engine bay jumpstart post with already a new battery replaced still no good , but starter is good it cranks speed is 320 rpm ive measured it with vas in measuring block , no air fuel in fuel lines no leaks , glow plugs are good also , when i try to start ignition on wait for glow plug to turn off and then start just cranking too long , im from phillipines its tropical climate the car has only 19198 km

Haven't run into this problem on my 2010 Q7 TDI - but will keep my ears open if I hear anything.