Thom

Hi everybody,

Just curious if some of the folks on here have noticed a relative lack of accuracy of the tachometer.
It seems like mine reads 7600 RPM when actual engine speed is 7000 RPM.

Thanks.

ekoz

I have the rogue tuning data logger. It was showing my idle at 840, any my tach was reading around 1100....i haven't check at any other rpms.

TurboTommy

In the mid RPMs my tach reads about 200 RPM higher.
At redline it reads about 3 - 400 RPM higher.

Richgreenster

I have an old smt-6 which tracks RPM. Mine is very close to what the tach reads with in 25 RPM's. I hope this is acurate because I am setting my max redline using the SMT-6 and occasionally hit it on the track.

Rogue_Ant

Most of the factory tachs tend to be optimistic...

Verified many times with my logger, and other ignition pickup meters.

t3rra

Mine seems to be about right up 2 3k then around 3.2 on logs is 3.4/ 6 on dash then sorts off corrects it self just over 4k haven't been able to check over 4k due to been well in to boost and speed

Tom M'Guinn

Here's a picture of the speed sensor pulse. At about 550us per tick, that translates into about 826 RPMs, yet my tach was showing just under 1000 at the time. So I'd say mine is pretty inaccurate really. Having said that, other than getting the idle speed right for smog, it's probably academic...

Thom

Thanks everyone.

It was easy for me to recalibrate it through my aftermarket ECU but I heard there was some kind of circular spring inside the tachometer that could be "more or less" retightened to make it read accurate back again.

refresh951

I am also quite interested in this. My tach reads high across the board. This was particularly frustrating at the drag strip when I hit the rev limiter and ruined an otherwise great pass. Difficult for my brain to do the translation accurately in this situation.

shortyboy

i have the older smt-6 as well and according to log its 950rpm but dash says 1100rpm

99dart

That's why it's nice to install an aftermarket tach of choice. Find one with a shift light and set it to come on where you want to shift. It helps knowing you don't have to concentrate on the little tach needle when banging the gears.