Skip the auto shop - Our mechanics make house calls

Q: Bank 1 running to rich and injector 1 contribution fault Intermittent.

asked by on

've been getting misfires at idle when the car is hot, on cylinder 1 only (i'll see cylinder 3 sometimes but it's very minimum)

When first starting the car from cold in the morning, it will stumble a bit and then will run fine. I suspect that's because the car is already running rich so there is leftover gas.

I have a VCDS that I have been using a lot to troubleshoot this issue and this is my constant reading at idle.

Code: Address 01: Engine (8E1 910 559 F)

10:48:35 Group 032: Lambda Control (Mixture Adaptation) -16.5 % Adaptation (Idle) Bank 1 Sensor 1 -3.0 % Adaptation (Partial) Bank 1 Sensor 1 -10.0 % Adaptation (Idle) Bank 2 Sensor 1 -3.3 % Adaptation (Partial) Bank 2 Sensor 1

10:48:35 Group 033: Lambda Control -3.2 % Lambda Control Bank 1 Sensor 1 1.938 V Sensor Voltage Bank 1 Sensor 1 -3.7 % Lambda Control Bank 2 Sensor 1 1.938 V Sensor Voltage Bank 2 Sensor 1

10:48:35 Group 054: Idle Speed Stabilization 782 /min Engine Speed (G28) Idle Load

My car has 201000 miles.
My car has an automatic transmission.

Hi and thanks for contacting YourMechanic. What you are experiencing is a misfire detected in cylinder 1 and a random misfire in cylinder 3. This could be caused by either the fuel injectors not firing, the spark plugs fouling out, or a possible blow by ring issue. What I recommend to do is check the injectors to see if they are working. With the engine running, you could remove the injector harness to the injector and see if the engine drops in RPM. If the engine drops in RPM, then the injector is working. If the engine stays the same, then the injector is not working.

With the engine off, you could remove the spark plugs from cylinder 1 and cylinder 3 and switch them with another cylinder. This will make the symptom change to other cylinders if the spark plugs are causing the problem.

If the injectors are working fine and the spark plugs are switched and your engine still is having trouble, then you would need to do a compression test. Check the compression on the first puff and then max out the puff. The pressure indicated on the first puff needs to be half or more of the final puff. If it is less than half, then the rings are probably worn. If all the problems are tested and checks out okay, then I would suggest having a professional, like one from YourMechanic, diagnose the misfiring issue properly so that this issue can be resolved.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  • Home
  • Questions
  • Bank 1 running to rich and injector 1 contribution fault Intermittent.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: My car idles sometimes and there's a problem with the spark plug and coil all the time

Hello. Idle issues can be caused by a few different things. A few common causes are faulty coils, or an issue with the idle air control valve. The ignition coils are the components that generate the engine's spark. It may...

Q: The ignition is not functioning properly for both keys. 1998 Mercedes Benz CLK320

The problem sounds like the EIS - Electronic Ignition Switch. It can be a costly and time consuming replacement. Be sure both keys are with the vehicle if you take it in for replacement. You may be able to start...

Q: Can bad U joints cause engine vibration

Hello, thank you for writing in. The misfire is likely the cause of the vibrations you are feeling. When just one cylinder is having a misfire, you may have a bad spark plug, a weak spark due to a failing...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.