Eric (Plug Guy)

About 3 months ago we noticed the ignition was a bit hesitant. Not too delayed, but a split second or two enough to notice. Blew it off. Still going on. Took it in for check at dealer. Dealer indicated battery was good (our first suspicion) and was relatively new. Diagnostics pointed to low pressure fuel pump and possibly high pressure pump near engine. They replaced the low unit(s) and readings then matched, but the problem was still there. Replaced the high pressure unit(s) and did not resolve. Took out new high pressure unit(s) and reverted to original.

No answers for the past day or two. Tech Line involved. Trying to sort out what might cause this as nothing else was going on, no weird electrical outages, no hesitation while driving, no problems.

Suggestions?

Jack88

I had that happen on a Suburban I had, it turned out to be a check valve in the fuel system had failed and was allowing fuel to slowly run back into the tank when sitting. Longer than normal start times was the only symptom. Not sure this applies here, but this is an issue I haven't seen on an A8. I assume the fuel filter was changed, right? Any other issues or seemingly unrelated symptoms?

Eric (Plug Guy)

Resolved:

Replaced fuel regulator (along with low pressure units from the other day). Appears to be resolved for now.

stickman1970

I'm having the same problem. At least I think it's the same problem.
With no notice after shutting down, when I go to start the car, it just drags and drags in trying to start.
It's almost like there's a starter problem.
At first I thought it might be a crank shaft position sensor, dealer change both. Still happened.
The stealership kept it for two days trying to repeat the problem, and of course it wouldn't.
So what I have to do when it happens is to shut down so it doesn't keep dragging.
Bump the push button start again, feather the gas, then it will finally kick in with a shudder.

What's frustrating, is there's nothing I can nail down as to when it's going to happen.
No instrument panel light, no shudder at shut down, nothing.

MP4.2+6.0

No magic pill in here, but one low cost thing I always do for these early on is dump a bottle of Techron in, in case it is just simple fuel system gum, leaky injector maybe, etc.