Wayno

I tried to start my 06 Stang one am several weeks ago and it was like the ignition would just not catch and turn over. Plenty of battery juice, and I could hear the fuel pump come on. It just would keep conking out. I tried several times and decided to have it towed to a local Ford dealer. The dealer said their were no codes present and the only problem showing was the mass air was off and it was running rich. They recommended a mass air and O2 sensors but could not guarantee anything. I said never mind I will tow to a nearby mustang performance shop since it has a Kenne Bell blower. They said it runs but it is running "rough" but driveable. When I picked up the car it fired up and ran like nothing was wrong. I then drove it home and it drove fine for the last several weeks until the other day. This time I was able to get it running but it ran very rough like when you try to start up a carbed motorcycle that has been sitting for a while. After a couple seconds it ran fine.

Anyone have any ideas? I am afraid to drive it anywhere. I plan on taking it to the performane shop this weekend.

Nuke

Almost sounds like it's a fuel issue. From your post, I'm thinking the fuel could be stale. Also, when was the last time you replaced the fuel filter? Do you drive it enough that you could run a tank or 2 with SeaFoam in a short time frame before you begin replacing parts?

Wayno

I replaced the fuel filter this past summer along with the plugs and there were no problems. I had been driving it daily so I am doubting stale fuel. I do lean more to it being a fuel issue. Computer? Timing? Electrical? I am in uncharted familiarity with blown 4.6L's I am more familiar with the fox 5.0 motor. I have run and do run periodically sea foam although not recently so I kinda doubt the fuel quality.

moosestang

Stock coils? I would pull all the plugs, see if any are wet. Although it should really set a lean code if one isn't firing.

So it starts now? How's the idle? vacuum? I assume you have a vacuum/boost gauge at the very least.

Stock throttle body? have you cleaned it? Clean the MAF sensor? It will start and idle with the MAF unplugged, so a bad one shouldn't cause a no start.

Make sure your bypass valve is working. It should be open at idle and closed with the engine off.

You really need to datalog it.

moosestang

check all your grounds! Unbolt them, sand them, retorque them. I'd check the fpdm ground in the trunk as well as all the chassi/engine grounds.