Ok now I've got the proper resistance and it still doesn't work. I've added a 330k resistor parallel to the 100k on there. That gives me 75k wich erics site says should work for a v6. Well heres what it does. The tach never reads below 1500rpm even with the car warmed up and you can tell its idling around 700. And when I take it out for a drive it doesn't climb as fast as the engine does and then all of a sudden it shoots up to 4000. But wont go about 5000. And I know I was running that thing out to 6000 at least!:D So has anyone actually modded a turbo tach for a v6?
You were running a 3.8 at 6 grand and didn't have to go back and pick up your crankshaft? :D
About the best idea I can come up with is to put a variable resistor (0-100k trimpot) and temporarily install a diagnostic tach (either a cheap aftermarket one or a timing light with tach display, etc). You could adjust the trimpot until you get it to read the same as the diagnostic tach
And I just paid 13 bucks for a bag of 500 resistors to get 1. I've got a second tach, I'm going to mod it and see if it will be any better.
Well the second tach reads about 500 rpm higher all the time than the first one. !!! WTF
That's because you suck :D
I think you're gonna have to go with the trimpot on this. AFAIK the 75k resistor theory is only a theory (I don't know of anybody that's actually modded a tach for a V6). While logic would dictate that a 6-cyl value would be halfway between an 8 and a 4, this is only if the resistance variation value is linear. If the variation is on a curve it could be anywhere between 50 and 100k
Is there not a "calibration" resistor in there as it is?
I'm not that familiar with the later tachs, but I know on some of the earlier Fox tachs there was an adjustable pot. resistor that they set and "lock" with a dab of paint.