Hey guys just picked up an 09 DB9 and its started stalling randomly when clutch in coasting and going from high rev to idle. Otherwise it seems perfectly fine and silky smooth. I've heard of a fuel tank issue in the V8V causing this but never once seen it mentioned about the DB9. Anyone have insight into this?
No CEL or anything like that but gauge does say Engine Stalled every time it happens
Thanks in advance

 

Congrats on the rare Aston. The 2009+ manual DB9s are super rare. In the last 5 years, I think I've only seen 3 for sale. And one of them is now mine

Where are you located. Show us some photos of the car.

 

My guess is vacuum leak. The car can't catch the idle down fast enough and it drops below 500 rpm causing a stall. Or dirty throttle bodies, or MAF sensor. TBs are easy to clean, the MAFs are common (at least on the 06).

Awesome cars!

 

I believe this link may provide some answers.

https://www.6speedonline.com/forums/...ne-stalls.html

 

I'm sorry I misspoke it's actually a 2008.



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I've read about this issue before but I've never once seen it reference DB9s, only V8Vs. So before I rip apart to get to the fuel take access port I wanted to make sure that was even a thing on the DB9s

 

V12 should not stall from the extra fuel introduced like the V8. Usually you get a feeling balance issues. Oxygen sensors reading lean on LH bank and Rich in RH bank.
How does the clutch pedal feel and do you have history if its been replaced?
The pilot bearings don't have a whole lot of grease when assembled, dry bearing will keep the input spinning with the clutch pedal depressed and it usually makes noise cold on first couple of take offs. Faint squawk or chirp.

 

I don't have a lot of experience with stick shift astons so it's hard to say but nothing feels particularly wonky with the clutch pedal to me. I'm pretty sure it's on its original clutch since it's only at 20k miles and I don't recall it being mentioned in the service history (will double check). But I also haven't noticed any odd noises either. Honestly it drives flawlessly and runs pretty well no codes or anything. It's just this one weird stalling issue but it seems pretty persistent lately.

I can pull some data on the fuel trims and o2 and see if there's any imbalances

 

Mine did this. I cleaned the Throttle bodies, and replaced the MAFs with after market (they are a standard item) and reinstalled. Fixed this problem. I am not sure if that fixed it, or if the reassembly removed a vacuum leak as either would cause this issue. I believe it occurs because the computer can't adjust fast enough to the the blip of the throttle. If you ease off gently it will stop at 800 rpm, but if you let go, it drops below 500-600 rpm and dies.

YMMV & GL!
Larry

 

Why would you put the clutch in while coasting? Let the engine wind down until revs are low enough to disengage clutch/stop.

 

Mine would die if I blipped the throttle in neutral. The TB clean and MAF replacement fixed it.

 

Well that explains alot. Surprised none of this triggered a CEL

 

This happened to me once as I was approaching a border checkpoint in California, scared the **** out of me. Solution was just to never clutch coast until the engine was wound down and down shift a few times to keep the revs from dropping like a rock and I haven't had it happen again since then, not like I want to try to repeat the issue.

 

I Went ahead and replaced the MAFs and cleaned both throttle bodies and put new gaskets in. They were pretty clean anyways but its part of the generalservice I need to do anyways.

Still no change in behavior. Stalling may have even gotten worse actually. I drove it down to about 1/2 of gas so far and it still stalls regularly almost always going from 2500rpms+ down to idle.

 

I'm pretty sure the codes that I am throwing are just fr when the vehicle stalls out. Because after replacing both MAFs I'm now getting the same "MAF signal intermittent"
"o2 sensor stuck rich"

I'm also have a lean code on both banks now that I didn't before. But I get the feeling most of these are just triggering right before the engine stalls out.

At this point I'm thinking it's the vapor purge hose inside the fuel tank. Which is going to be difficult as hell to access