Author Topic: tach questions for 1.6td (Read 2466 times)

boostaholic · « **on:** November 29, 2005, 08:28:46 am »

ok so i have a 1991 td jetta.. it had a/c i swapped out the a/c and had a parts car td jetta without a/c so swapped all the pulleys and alt.. now my question.. the rpm is now.. 600 advanced when driving.. i know the tach runs off the alt.. is there anyway to recalibrate this? or can i use my old altenator? from the a/c? thanks is advance

QuickTD · « **Reply #1 on:** November 29, 2005, 08:36:35 am »

If you disassemble the cluster there is a calibration trimmer potentiometer located on the right hand side, on the tach circuit board. I would recommend drilling a hole in the cover to allow access to the calibration pot with the cluster assembled. You can then plug the cluster in and adjust the calibration with the engine running. You can use a photo tach on the crank pulley for a reference, or just set to where you think it should be, perfect accuracy isn't really critical...

boostaholic · « **Reply #2 on:** November 29, 2005, 08:40:21 am »

well.. can you run an aftermarket tach in these cars off anything else? so its more accurate?

QuickTD · « **Reply #3 on:** November 29, 2005, 09:03:37 am »

Quote

well.. can you run an aftermarket tach in these cars off anything else? so its more accurate?

Why? Seems like a lot of work and expense when all you really need to do is adjust the stock cluster... Like I said, it can be perfectly accurate if you have a good reference to calibrate it to. I usually use a hand held photo tach.