About a week ago my 2009 T2 3.6L V6 threw a CEL and immediately started rough idling combined with occasional fast at idle at start for ~5 seconds.
Pulled the codes - P2187 (Lean Idle Condition Bank 1) P2189 (Lean Idle Condition Bank 2).
I've seen these lean idle conditions (albeit different DTC codes) before on various Audis (i.e. A8 4.2L). These lean idle conditions are typically caused by failed upstream O2 Sensors on one bank or another - but I HIGHLY doubt that BOTH upstream O2 Sensors failed SIMULTANEOUSLY sufficient to cause the lean idle on BOTH banks on my 3.6L V6 T2.
The Ross-Tech VAG-COM Wiki suggests that with code P2187 the EVAP Purge/Shut-Off Solenoid Valve (N80) could be faulty.
With engine running at idle there IS a constant vacuum leak from the small, open, atmospheric port at the top passenger-side of the EVAP Vapor Canister located at the back of the engine up against the firewall. This vacuum leak really 'screams' at you when you open the hood and is immediately apparent. When this open atmospheric vacuum port is momentarily plugged, the rough idle cleans up. This vacuum leak is the exclusive vacuum leak I can find anywhere in the engine compartment.
Ross-Tech Wiki for P2187 also suggests that an intake air leak after the MAF as a possible cause of the lean idle condition. The EVAP Vapor Canister vacuum port is, in fact, located AFTER the MAF and is most likely the source of the intake air leak. This would also make sense given that BOTH banks are seeing lean idle.
As such, I suspect that the EVAP Purge/Shut-Off Solenoid Valve (N80) is not CLOSING to shut off the vacuum source (from the vacuum pump) to the EVAP Vapor Canister after start and is pulling a constant vacuum through the open atmospheric port and into EVAP Vapor Canister during idle - thus leaning out the idle mixture and throwing the P2187/P2189 CEL codes.
Coincidentally, recently and occasionally during cold start, the intake will 'backfire', or 'fart', through the EVAP Vapor Canister, further suggesting that the EVAP Purge/Shut-off Solenoid Valve (N80) may also not be OPENING properly at cold start sufficient to apply vacuum to properly evacuate the EVAP Vapor Canister. This condition may be dumping a dose of fuel-rich intake air from the EVAP Vapor Canister into the intake manifold at start. Thus, the intake backfire at cold start.
As an aside, in my research on this condition, I did come across multiple sources of information discussing intake manifold EXPLOSION on the 3.6L V6 T2 caused by a saturated EVAP Vapor Canister dumping fuel-rich intake air into the PLASTIC intake manifold at HOT start. This problem is attributed to 'topping off' the fuel tank during filling and over-saturating the EVAP Vapor Canister with 'wet' vapors from the fuel tank. The wet vapors from the canister combust in the intake manifold and EXPLODE the plastic intake manifold. So, on the 3.6L V6. topping off the fuel tank at filling is a practice to avoid for sure!
Thorough searching of all the Club Touareg threads discussing the EVAP Purge/Shut-Off Solenoid Valve (N80) and the EVAP Vapor Canister produces no definitive information on diagnosing or replacing either component on the 3.6L V6.
So, I come to the 'wise masses' on Club Touareg asking...
Has anyone experienced a similar lean idle problem necessitating replacement of the EVAP Purge/Shut-Off Solenoid Valve (N80) and/or the EVAP Vapor Canister on the 3.6L V6? If so, can you offer any thoughts, pointers or guidance?
Many thanks in advance!
Moto
Pulled the codes - P2187 (Lean Idle Condition Bank 1) P2189 (Lean Idle Condition Bank 2).
I've seen these lean idle conditions (albeit different DTC codes) before on various Audis (i.e. A8 4.2L). These lean idle conditions are typically caused by failed upstream O2 Sensors on one bank or another - but I HIGHLY doubt that BOTH upstream O2 Sensors failed SIMULTANEOUSLY sufficient to cause the lean idle on BOTH banks on my 3.6L V6 T2.
The Ross-Tech VAG-COM Wiki suggests that with code P2187 the EVAP Purge/Shut-Off Solenoid Valve (N80) could be faulty.
With engine running at idle there IS a constant vacuum leak from the small, open, atmospheric port at the top passenger-side of the EVAP Vapor Canister located at the back of the engine up against the firewall. This vacuum leak really 'screams' at you when you open the hood and is immediately apparent. When this open atmospheric vacuum port is momentarily plugged, the rough idle cleans up. This vacuum leak is the exclusive vacuum leak I can find anywhere in the engine compartment.
Ross-Tech Wiki for P2187 also suggests that an intake air leak after the MAF as a possible cause of the lean idle condition. The EVAP Vapor Canister vacuum port is, in fact, located AFTER the MAF and is most likely the source of the intake air leak. This would also make sense given that BOTH banks are seeing lean idle.
As such, I suspect that the EVAP Purge/Shut-Off Solenoid Valve (N80) is not CLOSING to shut off the vacuum source (from the vacuum pump) to the EVAP Vapor Canister after start and is pulling a constant vacuum through the open atmospheric port and into EVAP Vapor Canister during idle - thus leaning out the idle mixture and throwing the P2187/P2189 CEL codes.
Coincidentally, recently and occasionally during cold start, the intake will 'backfire', or 'fart', through the EVAP Vapor Canister, further suggesting that the EVAP Purge/Shut-off Solenoid Valve (N80) may also not be OPENING properly at cold start sufficient to apply vacuum to properly evacuate the EVAP Vapor Canister. This condition may be dumping a dose of fuel-rich intake air from the EVAP Vapor Canister into the intake manifold at start. Thus, the intake backfire at cold start.
As an aside, in my research on this condition, I did come across multiple sources of information discussing intake manifold EXPLOSION on the 3.6L V6 T2 caused by a saturated EVAP Vapor Canister dumping fuel-rich intake air into the PLASTIC intake manifold at HOT start. This problem is attributed to 'topping off' the fuel tank during filling and over-saturating the EVAP Vapor Canister with 'wet' vapors from the fuel tank. The wet vapors from the canister combust in the intake manifold and EXPLODE the plastic intake manifold. So, on the 3.6L V6. topping off the fuel tank at filling is a practice to avoid for sure!
Thorough searching of all the Club Touareg threads discussing the EVAP Purge/Shut-Off Solenoid Valve (N80) and the EVAP Vapor Canister produces no definitive information on diagnosing or replacing either component on the 3.6L V6.
So, I come to the 'wise masses' on Club Touareg asking...
Has anyone experienced a similar lean idle problem necessitating replacement of the EVAP Purge/Shut-Off Solenoid Valve (N80) and/or the EVAP Vapor Canister on the 3.6L V6? If so, can you offer any thoughts, pointers or guidance?
Many thanks in advance!
Moto
