I'm just wondering, what kind of problems can be caused by the tach filter. Can it actually cause the engine to cut out if it is no good? My car died on me yesterday. Before it died I noticed that the tach needle was bouncing around. I changed out the ignition moudule to a spare one I carried and made it to my destination. I was able to get to a local Autozone store and had the ignition modules tested. They were all good. I took the tach filter off because I was installing a Crane Fireball HI 6 ignition. The car runs very good now and I was wondering if all the problems I had were caused by the tach filter going bad. Anybody know what kind of problems can be caused by a bad tach filter?

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I don't know a direct answer to your question, BUT, I had my tach bounce around pretty bad before (and eventually it died). It turned out to be nothing more than the connection on top of the ingnition coil (the plug was cracked and on hard acceleration, it would slide off slowly).

Maybe it's worth looking at?

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I do not think it will actually cause engine problems on the car... I know the car will run with it unplugged.

A couple of summers I was having a heck of a time with my GT. It would run fine, and then start to lurch, almost like I was mashing on and off the gas pedal, and eventually die. I took it to GM and they replaced the computer, the whole ignition system, plugwires, TPS sensor, and it did not fix anything. Ogre told me to check the tach filter so next time it started to act up I pulled the filter connection, and lo and behold it ran fine. From what I understand, when the tach filter is acting up it can electrically interfere with some of the other components in the car. Give it a check, just pull it and see if it fixes the problem.

I did pull it. I had to when I put in the Crane HI-6 ignition (sorta like the MSD but digital). I was just wondering if this is what was causing my car to die every once in a while.

Hello everyone. Yes, a bad tach filter can cause problems. From strange "hiccups" to having the engine cut out and die at the most inopportune times.

The Ignition module would cause the symptoms you are describing. That is usually how they act as they start go out. I always have a spair and tools with me as it is a common fiero thing do to all the engine heat back there.

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could somebody tell me what the tach filter looks like and where it is? Has anybody just bypassed the filter with straight wire? Can it be done and will there be any adverse affects??

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It is a little can type thing about half the length and the same around as a AA battery. It is mounted next to the coil and has 2 white wires coming out of it. I don't have one now as I run my tach off the tach signal wire in my Crane HI-6 ignition box.

I thought my tach filter was bad but it turned out to be the plug connector. I replaced it with a 2 prong trailer connector, works fine.

I can't for the life of me find this little bugger.. Is it located between the distributer and the coil? should I easily be seeing this unit when looking down on the engine compartment.. It is possible that it may have been removed already as I don't know what kinda work the previous owner had done to the car. If it has been removed what else could be giving me the symptons that a bad tach filter would give.Alot of the wires are old and brittle and I don't wanna be monkeeing around with them if I don't have to be. Any and all help would be greatly appreciated
( car is a V6 )
P.S. If it isn't too much to ask could somebody also describe what the oil seending unit looks like and it's location aswell?
Thanks ahead O-Time
James

I was just having this problem on my Indy. Both the tach & amp meter were jumping around. It turned out to be that I had a short in the positive battery cable. I was able to jiggle it and the car would die. It wasn't shorting out to ground, just losing connection. Replaced the wire and haven't had a problem since.

If you decide to upgrade your ignition with an MSD 6A capacitive discharge multispark ignition box, you can get rid of the tach filter forever. You just hook up the MSD box, take out the tach filter and place a jumper wire in it's place.
The purpose of the tach filter is to remove noise spikes from the sensor line which are generated by the stock ignition system. If the filter goes bad either the tach goes dead or it works rather poorly. If you add the MSD box you get two improvements with one change. The MSD box hookup provides a much higher energy spark and a stable tach signal which needs no filtering.

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