Funky Tach

[Kain]

The otherday my tach started acting kinda funny. When I'm driving it's completely fine, but when I turn the car off, the needle only drops to about 500-600 rpm instead of going all the way back to zero. It dosen't happen all the time, and when I start the car again it resumes normal operation. It's just a little thing, but it annoys me. Also, I fear it may be a warning sign of a failing tach sensor or the tach itself. Any ideas on what causes this, how I can remedy it, or if I should just try to ignore it. Thanks.

P.S. I've not done anything to the car since before it started hapening either. I've not even opened the hood, so I'm positive it's not something that I did to cause it. After it started doing it, I did check the sensor and it seems to be fine.

[manybrews]

its the tach itself.

i wouldnt really worry about it. theres nothing you can do to fix it anyway.

have you added all those damn aftermarket gauges or something?

[Kain]

Nope, haven't touched a thing. The only thing I did that even remotely came close to a part of the guages is I turned the tach sensor about 90 degrees so it would clear my breather filter. But that was over a year ago, and the tach just started doing it's thing last weekend. Funny thing is, if I pause the key in the "acc" position before turning it all the way to off and removing the key, the needle goes all the way back down to 0. I figure I'll just live with it until it gets worse in which case I'll probably replace the whole tach or something. But I don't envision anything like that happening.

[manybrews]

the "tach" sensor? what are you talking about when you say "tach" sensor?

[Kain]

It's a little...well, for lack of a more accurate term, "sensor" on the distributor. It's about 3/4 of an inch long and just a bit smaller around than the tip of my pinky. It has a single wire running out of it which shortly dissapears into the wiring harness. I've been told that that's the sensor which reads the spark as it comes around and makes the tachometer work. Sounded pluasable to be, since the exact same sensor is in the exact same place on my Colt. Am I decieved as to what this little device is? It sits right under the nipple on the valve cover where the air intake connects to it via a small, ugly black bit of tubing. I wanted to put a breather filter on, mostly because I didn't like the look of that little ugly black tube, but the sensor on the distributor was in the way. So I turned it 90 degrees so it faced front-to-back instead of side-to-side. That gave me the clearance I needed for the breather filter.

[manybrews]

ahhh.. i think i know what your talking about.

is it a silver colored cylinder with a single wire coming out of it? if so, its a noise filter. it has nothing to do with the tach except cleaning up a signal.