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jimmcc jimmcc is offline
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Join Date: Jun 2005
Location: Birmingham, Alabama
Posts: 274
Originally Posted by jimmcc View Post

What about the connections Jim? it's not like there is much current draw to overcome a dirty connector(s)... LOL don't worry, I know better than to argue w/ you over electronics!!
A dirty connector would probably create more of an intermediate problem (gauge bouncing) than an inaccurate reading unless the connection was really dirty. Having the connection tight and clean will help.

I ran a curve on the stock sensor from my 1980 (original sender I would assume) and if I recall it read about 7 ohms at atmosphere and around 130 at the upper limit. I looked for that data earlier and can't find it at the moment but was surprised at how quickly the gauge hit the upper limit. I'll look for it later tonight. What I did notice was excessive wear at the low end as I slowly ramped up the pressure. That is probably why the tach gauge shows little at the bottom and then jumps to about .2 bar.

I should pull both the sender and tach out of the car and set them up on the test bench and determine which component contributes the most to the error. Know where I can borrow a newer one for reference?

Depending on what boost level is desired the GM based sensors are a relatively inexpensive way to go. Output is 0-5v. As rsrmike pointed out the 2 bar sensor is good for 1 bar of boost and the 3 bar is good for 2 bar. The only loss is a bit of granularity in the measurement but that is not a problem.

rsrmike is welcome to argue anytime. He's usually right!
Old 11-18-2008, 02:44 PM
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