I recommend a cylinder contribution test, with the engine running disconnect ONE ignition coil connector at a time to see if the engine slows down when disconnected. If the engine looses some speed then this coil is working under light load, this does not mean that it works under heavy load while accelerating from a stop. Even if all cylinders show contribution, you will need to monitor the RPM to see how much it drops as less of a drop is a weaker cylinder. If it seems that they are all working, move #1 and #5 to #2 and #4 position to see if the computer will turn on the check engine light with new codes for 2 and 4, if the problem follows the coils, then buy new coils and plugs. If the problem stays on 1 and 5 then spark plugs are suspected, be sure to buy original parts, not cheap replacements, the spark plugs do all the work to produce good gas milage so they will pay for themselves over time. These cars are known for bad coils, VW has updated the part number several times. Make sure the computer is not holding 1 and 5 as a problem right now before doing this test and driving around for a few days if it takes that much time for the check engine light to come back on. If you can rent a compression gauge you can do a compression test also just to be sure you don’t have a mechanical problem but if all cylinders are working I would guess the engine is running smooth. When you change spark plugs, read each plug and see if 1 and 5 look different from the others, this will help tell the story.
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I recommend a cylinder contribution test, with the engine running disconnect ONE ignition coil connector at a time to see if the engine slows down when disconnected. If the engine looses some speed then this coil is working under light load, this does not mean that it works under heavy load while accelerating from a stop. Even if all cylinders show contribution, you will need to monitor the RPM to see how much it drops as less of a drop is a weaker cylinder. If it seems that they are all working, move #1 and #5 to #2 and #4 position to see if the computer will turn on the check engine light with new codes for 2 and 4, if the problem follows the coils, then buy new coils and plugs. If the problem stays on 1 and 5 then spark plugs are suspected. These cars are known for bad coils, VW has updated the part number several times. Make sure the computer is not holding 1 and 5 as a problem right now before doing this test and driving around for a few days if it takes that much time for the check engine light to come back on. If you can rent a compression gauge you can do a compression test also just to be sure you don’t have a mechanical problem but if all cylinders are working I would guess the engine is running smooth. When you change spark plugs, read each plug and see if 1 and 5 look different from the others, this will help tell the story. If oil down in the spark plug well or dirty coils then that is part of the story also.
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Cylinder contribution test and move ignition coils (edit).
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https://www.youtube.com/watch?v=OImYDPSvoQM
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Do not buy aftermarket parts as mentioned in the video.
I recommend a cylinder contribution test, with the engine running disconnect ONE ignition coil connector at a time to see if the engine slows down when disconnected. If the engine looses some speed then this coil is working under light load, this does not mean that it works under heavy load while accelerating from a stop. Even if all cylinders show contribution, you will need to monitor the RPM to see how much it drops as less of a drop is a weaker cylinder. If it seems that they are all working, move #1 and #5 to #2 and #4 position to see if the computer will turn on the check engine light with new codes for 2 and 4, if the problem follows the coils, then buy new coils and plugs. If the problem stays on 1 and 5 then spark plugs are suspected, be sure to buy original parts, not cheap replacements, the spark plugs do all the work to produce good gas milage so they will pay for themselves over time. These cars are known for bad coils, VW has updated the part number several times. Make sure the computer is not holding 1 and 5 as a problem right now before doing this test and driving around for a few days if it takes that much time for the check engine light to come back on. If you can rent a compression gauge you can do a compression test also just to be sure you don’t have a mechanical problem but if all cylinders are working I would guess the engine is running smooth. When you change spark plugs, read each plug and see if 1 and 5 look different from the others, this will help tell the story.