Help with a running problem on boost please

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S£

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I come across a problem with my S3 yesterday, when driving gently it's seems fine but when I put my foot down a bit and the boost comes in strong (around 2500-3000) I get what feels like a misfire, just like when a coil pack goes. Happens in any gear, basically when the boost peaks.

I've dowe a scan and it's not showing any faults, also a missfire log and no cylinders are missing, also done the maf test thing recommended for checking for boost leaks, at 3000rpm I'm getting 8g/s am I right I thinking it's got a small boost leak? as I should be getting 9-10g/s

Would this cause my miss/juddering problem? Anyone else had a similar problem?

Hope someone can help, cheers
 
This happened to me on my old AGU. Does is still misfire when cold? Interestingly, mine would run fine for a few minutes when cold, then start missing once warm when boost went above 10psi.

I changed the plugs for brand new denso IK22's, and this didn't help at all. I spent months trying to solve the problem and replaced almost every other ignition part, only to find in the end it was the plug gap too wide!

New platinum NGK plugs in there gapped correctly, and it's been perfect ever since.
 
Cheers prawn, it does it from cold to hot.. But surely if it was a miss it would show up when I take it for a run plugged in?? The plugs are old though, I've had it nearly 3years/25,000 miles and not changed them yet, got a service in 1000 so was going to do them then..
 
s3dave said:
Lol 25k....I think it would welcome some plugs....
Click to expand...

Lol... that's what I was thinking 10k ago but the garage was like, nah they're fine they'll last till next service!

I might start there tomorrow then, best plugs and gap for a mapped S3 anyone??(AMK)
 
Last edited:
Managed to get two fault codes this morning



1.3 Special Notes
16684/P0300/000768 - Random/Multiple Cylinder Misfire Detected

Possible Causes
Air Intake System leaking
Fuel Supply faulty
Injector(s) faulty
Ignition Cable(s) and/or Spark Plug(s) faulty
Ignition Coil(s) faulty
Exhaust Gas Recirculation (EGR) Valve (N18) stuck/open
Camshaft Position Sensor (G40) faulty
Possible Solutions
Check Misfire Recognition
Check Air Intake System
Check Fuel Supply
Check Injector(s) and Injector Sealing
Check Ignition Cable(s) and Spark Plug(s)
Check Ignition Coil(s)
Check Exhaust Gas Recirculation (EGR) Valve (N18)
Check Camshaft Position Sensor (G40)
Special Notes
This DTC indicates that one or multiple cylinders are misfiring, but the ECU fails to identify the cylinder.

And


16686/P0302/000770 - Cylinder 2 Misfire Detected

Possible Causes
Ignition system
Fuel injectors
Fuel pressure
Running out of fuel
EVAP canister purge valve
Evaporative emission system
Low compression
Base engine problems
Controle Module damaged
Special Notes
This feature search for engine misfire in a specific cylinder. Most of the time the cause for a misfire is a lack of combustion in a cylinder due to absence of spark, poor fuel metering, or poor compression.


Is the anything I can rule out or look close at because the car does run fine until heavy boost?
 
Yeah cheers guys, just changed the plugs and swapped the packs over for the drive home, now missing on cylinder 1.

I'll get a coil pack Monday, it did look shot as soon as I took it out, surpisingly the plugs weren't that bad.
 
audi upgrades
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