Inaccurate Tach

[Calan]

I've noticed in the last day or two that my car seems to cut out around 6700rpms, even though my rev limiter is set to 7200.

So today I paid closer attention to it and then checked the Link log. Sure enough, on the factory tach the cutout happened at 6700 rpms, but in the log RPMs climb steadily to exactly 7200 rpms. The tach seems to match up with Link at 3000 rpms, but drifts off a bit as the RPMs go up. It is still nice and steady and shows no other issue, except not matching Link at redline.

I can't think of a connection, but this seems to have started when I went to the larger injectors a couple days ago and got the E85 tune happening.

The CAS is a '90 that I cleaned up and rewired a while back during the rebuild, and should be in good shape.

Any ideas?

 

[dirtbike_79]

The only thing I can suggest is to clean your power transistor plug and terminal. My tach started bouncing all around in the summer and it turned out that the power transistor plug was all green and corroded. I realize those aren't your symptoms, but its just something easy to try.

 

[Calan]

Well I have changed coils also in the past few days, now that you mention the PT. Maybe it has something to do with that?