I installed an autometer cobalt tach in my 05 sunfire a few months ago using the tach adapter pn #9117. I tapped into the pink wire at the module. The problem I am having is an in-accurate rpm reading. It's about 200 rpm higher than it should be?? I'm reading 1000 at idle and I know I'm not idling that high. I am no rookie at installlations of this sort. I just thought I'd ask on here to see if anyone else has had this problem? Any help would be appreciated...

proper cyl. setting?



car audio noob since 1984.

Yes sir, like I said. I'm no rookie to this type of thing.

Maybee the adapter box or tach is out of calibration a little. A bad or weak signal should make it read low, not high, so it almost has to be an equipment issue. Unless your factory tach is actually low, and the aftermarket one is correct. I know that some variation is common, the question is if 200rpm is too much of one.

I am positive that my factory tach is reading properly at idle. I figured that there would be a difference under heavy acceleration, the stock one is slow. I'm betting on the tach being the problem. I had a feeling it was, just wanted to get some other input... Thanks guys.

yup i ahd the same issue with the 9117 and the cyberdyne tach, after a week it went to 0 though so not sure on yours i would call ahad at autometer and ask him to dig with the techs.