I asked this question once before... no answer, so I did a search... nothing

My idle reads 1000 when i'm at 850. My dyno pull was to 5450 when my tach read 5800. I NEED to fix this PLEASE

 

they are all like that, the pcm reads a different value than the tach on the dash, thats just the way it is.

 

So then it can't be fixed? You can't have the PCM adjust something?

 

My tach is the exact same. I think its just the poor quality of the OEM tachs. An aftermarket tach would do much better

 

I haven't seen a stock LT1 tach that was accurate. They're all about 300 RPM more at 5000+ RPM and 100-150 at low rpms.
Solution - aftermarket tach.

 

Nothing can be done in the PCM. That is not where the fault is. It is the conversion from digital to analog at the gauge and the inaccuracies of the movement of the gauge, itself. If it was off the same amount over the whole rpm range, you could just reposition the needle.

 

So an aftermarket Tach should fix this problem? Really?!

Where do I get them!! hahahaha Hell yea... A tach that is correct, man that would own!!

 

When my car was an M6 with the factory 800rpm idle speed, I got the same readings you are seeing. My solution....

http://cjcfo.fbody.com/members/injun.../DCP03456a.jpg

 

as i said in the last post they are all that way. I used my scanmaster as my tach.

 

But Injuneer... how much did all that cost? Man that looks expensive!! haha

I just want my RPM tach fixed... thats all. I guess the speedometer is alright... haven't noticed anything foolish on it.

 

I would just shift at around 6200... that should put you at 5800ish. Aftermarket tachs are not cheap! An alternative to a tach is a simple shift light. Instead of reading the tach, you just look for the light.