Fuel System - MIL ON, DTC P0300/P0301-P0306 Stored
01 MIL on (P0300 and/or P0301 - P0306 stored in ECM)Transaction No: 2019948/4
Release date: Dec. 8, 2010
Condition
^ MIL on.
^ One or more of the following DTCs are stored within first 60 seconds, when coolant temperature is between 10-39°C according to freeze frame data shown above.
- DTC P0300 (Random/Multiple Cylinder Misfire Detected).
- DTC P0301 - P0306 (Cyl.1 Misfire Detected - Cyl. 6 Misfire Detected).
^ For A4, A4 Cabriolet MY07, 08 and 09, A6 MY07, 08 and 09: This TSB only applies if TSB 2024632 already has been performed.
Technical Background
Low fuel quality in combination with a short distance driving cycle allows hydrocarbons to form carbon deposits.
Deposits interrupt tumble for efficient fuel / air mixture, causing cold start misfire.
Production Solution
Not applicable.
Service
A4, A4 Cabriolet MY 2007 - 2009, A6 MY 2008: Ensure TSB 2024632 has been performed. Follow the procedure below only if the condition persists after performing TSB 2024632.
To address carbon on the injectors (Case 1):
1. Add fuel additive G 001770 A2 directly into the fuel tank, following the mix ratio. For example, 120 ml per 30 liters gasoline, 300 ml per 20 gallons of gasoline.
2. Drive the car 60 miles. Note in and out mileage on RO.
3. Allow car to sit overnight.
4. You will have one chance per day to do this correctly: Ensure ambient temperatures are between 40-80°F. Check for cold start misfire.
Tip: There is only one cold start per day, and the ambient temperatures must be between 40-80°F.
Tip: This method was proven to be very effective when carbon deposits on the injectors are the root cause.
If misfire discontinues, carbon on the injectors were causing misfire. The repair is successful and complete.
5. Please advise the customer to use Top Tier fuel. (See TSB 2014753.)
To address carbon in the intake ports (Case 2):
1. Save new DTC log.
2. If misfire continues on 1 or 2 cylinders, staying at the same cylinders, swap the injectors and continue with step 3 (no testing at this point). If there are multiple misfires or traveling misfires, do not swap the injectors.
3. Remove intake manifold and air distribution housings (tumble flap housings) from each cylinder bank.
4. Rotate the engine so the intake valves of at least 3 cylinders are closed.
5. Obtain a tie-wrap tool (Figure 2) or other acceptable tool (Figure 3 and 4) to loosen the carbon.
The tie-wrap tool allows you to get into the corners of the intake port, which otherwise are hard to access. It also allows you to clean the port damage-free.
A nylon or carbon steel tube brush, 1/2 inch, may also be used.
Tip: If using this tool, bend the brush to access all areas of the valve and port.
When using a sharp tool, ensure the tool will not damage the components.
6. Add BG211 as solvent to the intake port. Add solvent only to the level shown in Figure 5.
Note:
The solvent (Figure 5, 2) cannot touch the valve guide (Figure 5, 1). This is to prevent solvent from creeping up the valve guide. Solvent in the valve guide may damage the valve shaft seal.
7. Apply the solvent in all 3 ports at the same time.
8. Let it soak for 10 minutes. If you need to soak the carbon longer then 15 minutes, make sure no solvent is leaking into the combustion chamber. Use borescope to verify (plugs removed).
Note:
Never soak longer than 3 hours.
9. Use the tie-wrap tool (Figure 2) to continuously agitate the carbon surface as shown in Figure 6. The carbon will slowly loosen.
10. If necessary, rotate the engine (solvent needs to be removed in advance) so the valves are open and the carbon around the seat can be directly accessed and removed with a brush.
Tip: All carbon around the valve plate edge and in the intake port / valve seat needs to be removed.
11. Rotate the engine until the intake valves of the other 3 cylinders have closed. Repeat steps 7-10.
12. Crank the engine (plugs still removed) to remove any possible residuals in the combustion chamber. Reinstall the air distribution housings and the intake manifold with new gaskets.
13. Perform an oil service.
14. Erase DTCs.
15. Confirm repair under cold start condition. (Again, the ambient temperature must be between 40 and 80°F, and the car must have been allowed to sit overnight.) If no misfire is detected, the repair was successful. If misfire followed injector, replace the injector.
16. Give one bottle of G17 to the customer. Instruct the customer to add the G17 after 3,000 miles.
16.a Please advise the customer to use only Top Tier fuel. (See TSB 2014753.)
Warranty
Required Parts and Tools
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service manuals for the latest information.