M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Engine + Driveline => Topic started by: blysccr on April 30, 2008, 10:20:59 PM

Title: hit rev limiter at 4500
Post by: blysccr on April 30, 2008, 10:20:59 PM

like title states, my e30 m42 hit a revlimiter at 4500 rpm. what would cause somethingl ike this to happen? where can i start? thanks

Title: hit rev limiter at 4500
Post by: Shift_Now on April 30, 2008, 10:49:04 PM

I had the same problem.  does it feel like the car is reving to 6500rpm though?  my problem was the coding plug in the guage cluster.  check part numbers

Title: hit rev limiter at 4500
Post by: blysccr on May 01, 2008, 06:11:45 AM

yeah, just like the rev limiter was moved down. same sound same feeling. how can i diagnose the coding plug?

Title: hit rev limiter at 4500
Post by: Shift_Now on May 01, 2008, 06:13:39 PM

I don't know how you would diagnose it.  I ended up finding a website that listed all of teh coding plugs and what car they came with.  and for some reason, my car had one out of a 325i.  try http://www.realoem.com for a part number adn see if it matches the one you have?

Title: hit rev limiter at 4500
Post by: blysccr on May 01, 2008, 08:28:01 PM

yeah...didn't find it...

Title: hit rev limiter at 4500
Post by: blysccr on May 01, 2008, 08:43:55 PM

i got 1 2 1 5 on the stomp test- something to do with afm /maf...no vacuum leaks and i know my throttle cable isn't the greatest, but it shouldn't make it cout out....hope this helps

Title: hit rev limiter at 4500
Post by: Jimmy Lewis on May 02, 2008, 09:11:23 PM

I had the same issue, it was the coding plug. My cluster had been replaced with a 6 cylinder cluster and the previous owner didn't swap over the coding plug, I just swapped out the coding plug from the original cluster to the newer one, problem solved. I would find someone parting an old M42 car or someone who has a bad cluster, I'm sure you can track down a M42 coding plug pretty easily. If the car seems to run strong minus the cluster reading out the proper RPMS, it is the coding plug. An easy way to know is to see where the car shows idle, the car should idle at just around 800rpm, if it shows around 500, its the coding plug.

Title: hit rev limiter at 4500
Post by: blysccr on May 02, 2008, 09:30:47 PM

i'll have to check that thanks

Title: hit rev limiter at 4500
Post by: blysccr on May 02, 2008, 09:54:33 PM

yeah. you're right. it idles at like, 490 rpm. so now my question, where can i get some kind of materil on how to replace it? thanks a lot

Title: hit rev limiter at 4500
Post by: Jimmy Lewis on May 02, 2008, 10:35:07 PM

I would check more general E30 forums such as R3vlimited for things of that sort, they have a much wider member base and they have been around a while. The actual removal isn't too hard, the key is to take it relatively slow, not to break any of the plastic pieces surrounding the steering wheel and cluster. I personally, didn't take this route and I used too much force in some places and ended up cracking a few pieces, but if you are careful it can be done fairly easily with nothing to show for it. Good luck!