My factory tach is reading about 7k at my 2-3 shift. When I hook up a diagnostic scanner, it's reading 6350.. which is what it should be. Everything seemed to be fine with my old set-up.

• Has anyone else had problems with the factory tach being highly inaccurate?
• Any suggestions for another tach? I was looking at a digital 2-1/16 pod mount unit from Nordskog. Any better ideas?

Thanks

 

What scanner are you using?

The old version of Datamaster was limited to 6375rpm I believe, something to do with the number of bits used to transfer the data. There is a newer version out which will read all the way up.

 

Stock tachs are way off, especially with higher RPM. However, if what he said is true, you may want to try another scanner just in case.

 

The scanner is the AutoXray EZ-Scan 5000. It was about $530, so it better be damn good and accurate .

Here's the scanner:
http://www.autoxray.com/product_detail.php?pid=96

Thanks guys

 

yeah, my tach is way off across the whole band, thats pretty accurate for the stock tach though.....

 

I have a stock tach and a Autometer tach hooked up to my MSD box. The Autometer tach has always read lower than the stock tach. My shift points are set at 6300 and the stock tach wil read about 400 rpms higher than the Autometer. The stock tach shows me shifting at 6500-6600 rpms. Stock tachs are not very acuarate.
HVY SS

 

I was kinda wondering why my T/A would still pull around "5800-6000 rpm"

 

Mine was off by 2 or 3 hundred also.

 

factory tachs are natually off. The factory will set them to read higher and slower so the average goon doesn't over rev the engine. OEM tachs are there to look pretty and not much more... since the law doesn't say anything that means the speedometer will be more accurate then the tach.

 

lol ya mine is off too

1.As soon as i hit the nitrous tach goes to 7k and spedo goes to 150mph, make it a little hard to race, have to go off feel.

2. the other day the car was showing low voltage when driving around town, in 1st gear spedo said 5k and 90mph. Not sure what the problem is , maybe the altinator is not charging and maybe the nitrous kit has a grounded wire somewhere.

Let me know what you find, my 94 is starting to show alot of promblems, maybe its time for a little upgrage , Ls1??