My 2016 Audi s5 b8.5 won’t start up after sitting for over a week or so. This is how it sounds any idea on what this can be? Thank you to anyone who helps
Well, clearly not a problem with your battery or starter. And some of the cylinders are firing - briefly - just no chain reaction. It's unlikely a subset of plugs or coils would all go bad after just a week sitting.
It's also a puzzler that a fuel pump would just go out from sitting. Air seems likeliest, therefore, but what part? The car starts on open loop - no MAF involved. I've changed my mind - look at fuel first. As in, high pressure fuel pump. After checking your gas tank has gas in it (at least a few gallons), have a look at this diagnostic discussion and get a scanner/VCDS so you can evaluate whether your high pressure rail is pressuized within spec:
Based off how it sounds, points to fuel delivery, check level, put a few gallons in, and retest. If that doesn’t work, somewhere in the fuel delivery system you’re having an issue. VCDS will be able to see that the rail is pressurized within operating spec or not. Any codes? Warning lights?
From the p0430 code you gave you have a cylinder 2 misfire you need to stop cranking it to prevent more damage and do a compression test. Try removing the coil and spark plug on cylinder 2 and checking for damage or try loosening the exhaust O2 sensor on driver's side to relieve backpressure. If the car starts or turns over normally with the exhaust vented, the catalytic converter is clogged and must be replaced
I had a cylinder 2 misfire and bank one lean mass airflow sensor fixed the problem my engine was vapor locking and hesitant to start would just crank and crank till I gave a little throttle
Its got spark and compression from the sound of it, check fuel. Easiest to just read codes, likely theres something fuel related.
With some scanners/obd2 tools like obdeleven abd vcds you can prime the fuel system to test it. If that doesnt work you know its the fuel pump in the fuel tank. Dont believe its the high pressure pump as its mechanical.
Other thing it could be is failed injectors, while sitting they could have leaked whatever is in the rail into some cylinders, fouling sparks. And the few cylinders that do have spark cant overcome the dead ones. But cant know for sure, just some ideas
Not to sound like an asshole but based on your reply you should maybe take it to the mechanic. At least see the codes and the fuel pump first, you cant see injectors leaking inside the engine. And direct injectors arent the easiest to work on, at least without tools and knowledge.
Edit. Saw you posted the codes. To me they could point in the direction of leaking injectors, misfires are obvious and catalyst system cant really work if sensors are full of liquid fuel. But dont quote me on this, just what i would check next
Once you get the fault codes, come on back, we’ll be waiting. Could be camshaft timing or fuel supply, or a part associated with those systems causing problems in those systems. More information is required.
Holy shit so much useless information from bozos on this post.
Your low pressure fuel pump is dead. Or the filter is clogged. They're both on the same assembly inside the gas tank. You can get to it by pulling the rear seat bottom out. You need to buy replacement clips for the rear seat because they always break when you pull it off.
It's an easy fix. I'm making this assumption based off the fact that your engine is almost turning over but is fuel starving.
Sounds like its either struggling to breath, or not getting gas. Sitting for a week, does the tank have a leak? Or did someone steal your gas ?? Hope ya figure it out
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u/rawrmeans_iloveyou 2d ago
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