Tack reads low by 500 RPM, Temp gauge low

dt racer

New member
Joined
Apr 5, 2014
Location
Ontario Canada
TDI
1999.5 Jetta TDI
First ever TDI, love it. Bought it used. Fixed a bunch of stuff on it (some neglect and stupidity) but cant figure out what is wrong with the Tach and temp gauge.

Since I bought my Jetta the tach reads around 450 at idle and the engine falls flat at 4,000 on the tach (really 4,500), so it is just consistently off by 500rpm. The temp gauge works but it reads low as well (90 is overheat, first 3 bar lines on the gauge is OP temp, cold reads 1/2" below the 3 bar lines). The Fuel gauge, ODO and clock work fine.

The previous owner had replaced the regular dash with a chrome bezel. I am guessing it could be something he did when changing over. I took the chance of moving the RPM needle to 950 while it was running at idle (has no plastic cover, you can touch the needles). It worked fine for a 20 min drive...until I turned off the car and restarted. Then it recalibrated itself and it is back to reading 500rpm low.

I tried several searches but didn't come across this in the forums anywhere. Any ideas? Thanks.
 
Top