V6 not starting on first try!

Last week my car has been developing a problem, it used to start flawlessly every morning (sleeps indoors), but now, it won´t start on first try when cold, i have to give a first try, just a sec, and the seccond time i turn the key, it comes to life perfectly.

I was thinking it can be the fuel pump not building up enough pressure, but now i think it´s something else. Compression is ok though, that´s one thing not to worry about.

The car just got a full service, valve adjustment, cam belt and tensioner changed, oil change, filters, spark plugs, cleaned the injectors, fuel tank and more things.....

Is there any sensor i can check?? Idle valve is ok, has 100 miles on it.

the relays might be moving causing a bad connection for the ignition system, check the connectors on the 3 relays at the back of the engine bay

I had the same problem as this on my v6..Always started on the button.Then 2nd or 3rd time... It turned out to be the coil pack ...disconnect the wire and undo the 4 bolts ( easy job ) with the engine cold and if it is knackered you will see cracking on the " mating " side.. Changed mine for a spare I had ... all o k.They can be bought for £75 I think..

well, coil pack was ok, relays are ok too.

Will buy a fuel pump on monday and see how it goes from there. dind´t have one in stock.

Bought the coil pack though, no difference, will keep it just in case.

Have a good weekend everybody, thanks for the tips!

Have you tried switching on and leaving for 30 seconds? If it fires after this, check the fuel filter before changing the pump!

Do you have access to an in line fuel pressure gauge?

I wouldn't go for the pump either, if anything check the plug gaps first, they may have squished one or two whilst fiting them. Check the plug caps are screwed on tight and that the leads are OK, failing that it leaves the crank sensor as you say the coil is OK.

Well guys, my car suddently decided to fix itself, haven´t had any trouble starting cold since sunday, today started perfectly (freezing 2°c).... fuel pressure seems to be ok. Filters, spark plugs and ignition system is ok too (changed filters, plugs, oil, grease and belts 200 miles ago)

Will start checking the sensor cables one by one, that must be the problem...

Thanks everyone for your help! Will post what happened as soon as I get an idea, maybe it helps someone else!