Hey guys, new to the forum!

Ive bought an insurance write off audi s3 2014. All work has been done and ive finally got it out on a drive yesterday!

All runs and drives perfectly. Only issues I'm having at the moment is; 

Loud start up revs sits at 1k for a minute then drops and quietens down during idle (am I right that this is normal?)

Engine oil level ok

Rough idle, it stutters like its about to stall maybe every 30 secs?

Bit smokey during idle (fault code shown for this)

Also loud rattle when engines warmed up, seems to be coming from camshaft cover top end.

Disconnected both camshaft magnets but didn't make a difference, (rattling wasn't loud at that point) 

 

I have plugged diag in and the fault codes shows; 

Ive changed spark plugs due to misfiring when I first bought it, I don't want to throw money into the car for replacing the wrong parts. Can anyone point me in the right direction on which part I need to be looking at? 

 

 

Could it be a cam sensor or lambda sensor 

Could be leaky injectors. Not suggesting you replace the injectors. You could pull them, clean and replace the copper seating washers. Not sure if there’s an ‘o’ ring on the main mode of the injector too? If you do pull them, replace the bolts, they are stretch bolts and torque to yield, once only.

Use a little ceramic grease on refitting.

If an injector was damaged, I’d expect a further error code. Any new injector needs to be coded to the car.

P0420 error likely to be inefficient catalytic convertor. Not sure any of the off the shelf products work. If it were me, you could try Forté products, including injection cleaners. Another option is to access primary oxygen sensor to inspect the cat itself. A lot of work, yes, but only way to confirm visual inspection with endoscope camera (with light) that works with your phone, just to be sure it’s not broken up. Bear in mind this was a crash damaged car.

Thanks for the reply guys, and a friend of mine who's a mechanic has found time to come look into the car with me and the injectors seem spot on, he reckons the camshaft magnets need replacing so they are on order, the catalyst error has cleared itself? So will keep an eye on it anyway

Keep us posted on how you get on 

Will do!

 

So...

Camshaft magnets done, car insured again, idles smooth and knocking noise gone quiet

Gone to take car into a friend's bodyshop (5 mile drive) 

Knocking nose starts again just down the road from bodyshop and starts running rough, sounds almost like metal on metal, plugged diagnostic in and cylinder 4 misfire.

Compression test shows (from 1 to 4) 175 - 175 - 175 - 150.

Looks like im going to need a new engine at this rate 🤔 🙃