The BMW N20 Engine is a popular turbo charged 4 cylinder engine equipped in many BMW models produced from 2011-2017, which have a problem of developing misfires when they age. Here at Tolima’s Auto Center, we have seen many BMWs come into our shop with misfire issues or stalling. Customers will come to our shop with misfires on all cylinders or random stalling when they are waiting at a red light on their N20 equipped BMW.
Once we hear the symptoms from the customer we will start diagnosing. We will start by checking the computer for current or stored codes. Then we will go through the usual checks for spark, fuel, and air. As we eliminate the possibilities for simple fixes we will start to check the engine timing. Then we have found that more and more often as these engines age we find that indeed the timing chain has stretched.
The timing chain synchronizes the top and bottom halves of your engine. If the chain stretches then the engine will no longer be synchronized and this will cause misfires and stalling. It is not normal for a timing chain to stretch prematurely, but we have found that one of the many possible reasons this happens is due to infrequent oil changes.
BMW started recommending 10,000 mile oil change intervals which we have seen cause issues as these engines age. As 10,000 miles is the recommended oil change people generally push the oil changes even further over that mileage before changing the oil. The spent oil loses its ability to lubricate the timing chain and tensioners causing the chain to stretch and the engine to go out of time.
Replacing the stretched timing chain on a BMW N20 engine is a laborious process. which requires special tools and knowledge to do the job right. If the job is done incorrectly and the engine isn’t timed properly with the chain then the misfires will continue or the engine will experience metal to metal internal impact which will destroy it. That is why it is always a safe bet to count on shops experienced working on BMW engines like Tolima’s Auto Center to do these complicated jobs with a warranty.