My car is displaying the engine management light on the dash. To date my mechanic has replaced a pencil coil and cleaned the airflow meter. First he said it was the lambda sensor that was not connected correctly.

My car shakes and shudders on start up. Sometimes it revs itself to 2000 without me pressing the accelerator. When I take off the car has no power and struggles to go faster that 20mph. After approx 3-5miles it seems to jerk then normal power resumes.

Does anyone have any idea what could be causing this?

Thanks so much for any input.

  • It sounds like it is having problems in Open Loop mode, before the O2 (lambda sensor) and MAF (airflow meter) are even being used, but I'm not really sure. In this scenario, once it gets to Closed Loop mode and starts using these two sensors, it runs like it should. – Pᴀᴜʟsᴛᴇʀ2 Jun 9 '14 at 21:10
  • @Paulster2 : I believe the issue here is with the engine management in cold-start enrichment mode. Open loop is more at Wide Open Throttle. – Zaid Jun 10 '14 at 19:58
  • @Zaid ... Open Loop mode happens at start-up. Usually happens for a set period of time during warm up, then will switch to Closed Loop, where it is running off of all of the sensors. This could be considered "cold-start enrichment mode" (different manufacturers, different names). The PCU will also throw the engine into Open Loop when near WOT (settings vary by manufacturer as to where exactly this happens). – Pᴀᴜʟsᴛᴇʀ2 Jun 11 '14 at 11:28
  • Hi and thanks for the response. The problem remains the same. Once the car 'jerks' after a few mins of driving its normal. I drove 50miles and then stopped, turned the ignition off and back on and even tho the engine was still hot the car still had the same sluggish issues for the first few km again. – Lorraine Jun 25 '14 at 7:39

There are two distinct symptoms here:

  • The engine sputters only when in "cold-start" mode and struggles to run smoothly. When the engine is deemed "warm" the issue goes away.

  • The engine sometimes revs up to 2000 RPM at idle.

Assuming your Golf runs a Bosch fuel management system, there are a few likely causes for this behaviour:

  1. Unmetered air is entering the engine through some air leaks. This could be due to a leaking gasket, seal or hole in the intake tract that may not necessarily be visible to the naked eye.

  2. A faulty/failing idle speed stabilizer. This would prevent the idle speed from staying constant.

Based on the information provided in the question, I believe the latter possibility is more likely to be the cause for your troubles.


Thanks for the replies, turned out I needed a new lambda sensor!

  • 2
    Lorraine, it's great that your issue is fixed. In the interest of future visitors, it would be great if you could share a few more words about why / how you found out that the lambda sensor was bad and how you know if fixed the problem. At that point, you could accept your own answer and the next person to come in with the same problem would see this as a likely option. – Bob Cross Jul 11 '14 at 20:55
  • This answer definitely needs elucidation. In the question you mentioned that the lambda sensor was initially thought to be the reason for the issue (and subsequently the issue persisted), yet now you say a new lambda sensor fixed the issue. – Zaid Jul 14 '14 at 6:15

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