Hi guys, been awhile since ive been on the forums. Last night i noticed for the first time that my Autometer Tach (driven by Ford Racing driver) is now way off the factory marks. When I hit around 5000 on the stock tach, im now getting around 6000 on the Autometer!!! Crazy and getting on my last nerve. I checked all connections their fine, and pulled positive cable for bout 30 minutes to see if that would reset it, it did not. After i did a few test runs, if you rev slowly the autometer will match the stock tach, if you go WOT the autometer revs way faster and outruns the stock tach. Which is really going to screw me over on the track, Ill have to guess where to set the shift point!!!

Any suggestions, should I try changing the Ford Racing Driver, or you guys think it might be the Autometer or the CPS (crank position sensor) going bad??? Thanks any help will be appreciated.

 

i'd trust the autometer tach over the stock tach. i've seen a couple times where the stock tach can be off as much as 1200 rpms because it samples slower (dont know the correct terminology for it).

 

The Autometer tach is to be believed over the stock tach.After all,Ford buys everything from the lowest bidder.Everything is fine.

 

I would assume that too, except for one thing, I hit the rev limitier dead on with the stock tach around 5900-6000, and when this is happening, the autometer will read between 6500-6700. Now i know my stock internals aren't revving that high. Ive dont have a chip removing the limiter so it still avtivates like it did when i first bought the very stock mustang. I don't know guess ill just have to replace some things till it gets right.

 

A dyno will give you the correct readout but what about a handheld tuner?Someone wrote in about how to get a digital readout from the odometer,this might be more accurate than a needle sweeping across a dial?

 

I found this on www.Mustangworld.com

http://www.mustangworld.com/ourpics/fcar/dtcodes.htm

and it shows exactly how to get a bunch of digital read outs... even the Tac

 

Cool tip, im pretty sure the factory is close to accurate, the rev limiter comes on at the exact rpm that its supposed to, however, the bulb blew in the tach, not sure but maybe it had something to do with it, not sure, but 2 things going wrong with the tach in 2 days!!!