Hello, I recently bought an Audi S1 2.0 2014 8X, however I'm getting cylinder 3 misfire when the accelerator is pushed right down. I've replaced the spark plugs but the issue continues.
Misfire Repo Steps
- Around ~4000 RPM, the car begins to judder
- If I continue to press the accelerator, then the ECU flags up, puts the car into limp mode.
- I get the TPMS system flagging (although I believe this to be a red-herring)
- Then it flags the cylinder 3 misfire.
- If it starts to judder and I take my foot off the accelerator, I can bring it back and stop it from misfiring.
I've had this issue since I've got the car, it's only done 45000 miles. I've done some research some found it could be 4 things, which I've listed below, I was going to logically go down this list and replace these components one-by-one until it's fixed but any advise is much appreciated!
Thank you!
Misfire Repo Steps
- Around ~4000 RPM, the car begins to judder
- If I continue to press the accelerator, then the ECU flags up, puts the car into limp mode.
- I get the TPMS system flagging (although I believe this to be a red-herring)
- Then it flags the cylinder 3 misfire.
- If it starts to judder and I take my foot off the accelerator, I can bring it back and stop it from misfiring.
I've had this issue since I've got the car, it's only done 45000 miles. I've done some research some found it could be 4 things, which I've listed below, I was going to logically go down this list and replace these components one-by-one until it's fixed but any advise is much appreciated!
1. Misfire Under Load (Most Likely) - £110-160
- Cause: Faulty coil pack (especially cylinder 3)
- Symptoms: Juddering at high RPM, limp mode, code P0303
- Solution: Replace coil pack
2. Boost Leak / Pressure Spike - £140-320
- Cause: Cracked hose, split coupler, or loose clamp causing inconsistent boost
- Symptoms: Only happens under full throttle, potential overboost leading to limp mode
- Investigation: Inspect all charge pipes, intercooler hoses, diverter valve
- Solution: Replace damaged pipes; consider silicone upgrades for durability
3. Fuel Delivery Issue - £100 - £700
- Cause: Clogged fuel filter or weak low-pressure fuel pump (LPFP)
- Symptoms: Juddering at high RPM, especially under load
- Solution: Replace fuel filter; test and potentially replace LPFP or HPFP
4. Sensor Malfunction £35-180
- Cause: Faulty MAF, MAP, or TPS giving incorrect readings under load
- Symptoms: May trigger limp mode or cause improper fueling/boost levels
- Investigation: Scan with OBDeleven or VCDS; monitor live data
- Solution: Clean or replace affected sensor
Thank you!
