Check engine light but no other indicators - VW say OK to drive "but not too far"

[MIG]

Several drive cycles are required to mark a pending fault code to confirm the status and turn on the light.

If they had taken the intake off to do the seal, they may have introduced a small air leak creating a miss at idle.


If you use the VCDS to monitor the live data while the car is running, you should be able to see the counter increase.

[The J Man]

Thanks MIG

I assume the date/time of the misfire in the report is the FIRST one, not the latest?
That would put 3 of them on the evening after I picked the car up - the 4th cylinder was just past midnight (same night)

So it was 3 weeks ago - that's quite a few drive cycles!

It DOES look like they reset the faults on the day I picked the car up so I'm not sure if there were misfires or not before I left it with them.
I'm getting the other car serviced tomorrow so I'll have a chat to the service managers - they seem competent and friendly enough.


... I'm still looking for a bicycle though

[DV52]

So it was 3 weeks ago - that's quite a few drive cycles!

Forgive me if you are already aware and just to add to @ MIG sage advice, a "drive cycle" is a defined term in OBD II speak!

I thieved this from HERE

The VW OBD-II drive cycle is an eight-step process. Total drive cycle time is 12 minutes.

NOTE: Do not leave the key on prior to the cold start or the oxygen sensor (O2S) heater monitor may not run.

Step 1: Cold Start — The ECM determines the presence of a cold start by comparing the engine coolant temperature to the ambient air temperature during startup. The engine is considered cold when:

• Engine coolant temperature is below 122°F.

• Engine coolant and intake air temperatures are within 11°F of each other at startup.

During this period, the O2S heater, misfire, AIR, fuel system, and EVAP monitors run.

Step 2: Idle 2 1/2 Minutes — Turn the air conditioning (A/C) and headlights on to help the misfire monitor—the additional electrical loads help even out combustion pulses. During this period, the O2S heater, AIR, EVAP, misfire, and possibly fuel system (if operating in closed loop) monitors run.

Step 3: Accelerate — Prior to accelerating, turn off the A/C and headlights (if you had them on during step 2). Open the throttle halfway until you reach 55 mph. During acceleration, the misfire, fuel system, and EVAP monitors run.

Step 4: Steady State Cruise 3 Minutes — During this portion of the cycle, the O2S, AIR, EGR, EVAP, misfire, and fuel system monitors run.

Step 5: Decelerate — Gradually coast down to 20 mph without applying the brakes. Also, on manual transmission vehicles, remain in high gear and do not press the clutch. During this period, the EGR, EVAP, and fuel system monitors run.

Step 6: Accelerate—Apply ¾ throttle until reaching 60 MPH. During acceleration, the misfire, fuel system, and EVAP monitors run.

Step 7: Steady State Cruise 5 Minutes — During this period, the CAT, O2S, AIR, EGR, EVAP, misfire, and fuel system monitors run.

Step 8: Decelerate — Gradually coast down to 0 mph without applying the brakes. Also, on manual transmission vehicles, remain in high gear and do not press the clutch. During this portion of the Drive Cycle, the EGR, EVAP, and fuel system monitors run.

Don

[The J Man]

that's
...
complicated

[The J Man]

Update: misfires are likely due to carbon deposits (195000km engine)

[7ur7le]

give it the italian tune up

[The J Man]

give it the italian tune up

That's on my list of things to try before the service in January

[Call me Al]

Any evidence the Italian tune up works?

I keep telling my wife to 100% accelerate our R when going up on ramps to 100 kph.

[7ur7le]

Any evidence the Italian tune up works?

I keep telling my wife to 100% accelerate our R when going up on ramps to 100 kph.

when in doubt.. give it the italian tune up

[7ur7le]

Update: misfires are likely due to carbon deposits (195000km engine)

take the manifold off the engine and clean the cyclinders out urself by filling it with carb cleaner and a soft brush then paper tissue the gunk out (with the cylinder turned to close).. some guys make a home made tool with a dremel / rotary tool with with zip ties attached to it and use it to scrape the gunk off. apparantly doesnt damage the cylinder and works really well by their experience.

Theres some writeups online for them have a google.