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Coding Plug for S54 in a 318is

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    Coding Plug for S54 in a 318is

    I recently got my S54 swapped 91 318is on the road for the first time (yay!) and now I'm trying to make sense of which coding plug I should be using for my tach. As of now the cluster is completely stock with the tach that goes up to 7k. I know there are a number of older threads on this, but I haven't been able to find a definitive answer on this topic for the S54. The engine is idling high and I need to wire up the OBD port so I can actually confirm what rpm it's at, but my initial impression is that the tach is reading higher than it should. Do I need to be using the 6 cylinder coding plug to get a correct reading on my stock tach since mine car was originally a 4 cylinder? Based on my research I think the answer to this is yes, but I just wanted to verify.

    Eventually I'll need to switch to a tach that goes up to at least 8000rpm for the S54. From what I can tell there are a couple options.
    1. Use an overlay that only goes to 8K in combination with a standard 6cyl coding plug
    2. Use an overlay that goes to 9K in combination with an 8K coding plug from an S38 M5

    Are there any other alternatives that I'm missing here? Is Bavarian Restoration the best option for ordering these parts?

    Also, my cluster has the fuel economy gauge in the bottom part of the tach, and I noticed that the 9k rpm tachs don't seem to have that. Can I remove that from the cluster and run a 9k rpm tach?

    Well after some more research and conversing with BavRest I think I have the answers to most of my questions. There are essentially 3 options

    1. Stick with the 7K tach and use a standard 6cyl 325i coding plug. The tach will read correctly but the needle will just swing past the 7k marker on it's way to the 8k S54 redline
    2. Use a Bavarian Restoration 9K tach with the standard 6cyl 325i coding plug. This shifts the base position of the needle slightly and requires a delete of the fuel economy gauge because the 9K tach covers more area.
    3. Use an M5 or M3 style 8K tach with an S38 coding plug

    For now I'm sticking with options 1 or 2. I can't seem to find good information on how to remove the tach needle and I don't want to break anything, so it's tempting to stick with option 1. If anyone has more details on how to do this please let me know.