I've been having a problem off and on for a little while now. The tachometer at some point while driving starts going crazy. It'll randomly go up and down from 0 - 4000rpm real fast, like it's twitchy. In the past I've fixed this problem by messing with the wires connected to the ICM inside the dizzy, one of which is the tach signal wire. The problem goes away after messing with the connectors so I'm lead to believe there is something wrong down there. However, last night my car broke down and no amount of playing with the connectors got it running again. I barely made it to where I was going. I'm now an hour away from home and need some serious help finding out what might be wrong. Sometimes when the tach needle is going crazy the car will start jerking. It also sounds like tin cans rattling around in the engine bay when it's doing this. It usually doesn't happen right away, but it has always come back at some point while driving. I don't know if heat is messing up the connection or what. If driven like this, the car will run for a little while (very poorly) but eventually dies. I couldn't even get it started this morning. Please help. I need to get home tonight!

The car is a '98 Civic EX.

Thanks in advance to anyone that can offer some advice.

 

I had a similar problem like that once in my Mazda MX-3, except it was my spedo going crazy instead of my tach. But instead of fixing it i crashed the car into a deer and totaled it. . .so .. i really can't help you at all umm sorry lol.

 

check the connection the same thing happend to me in a gutted to shiot crx i had to re soder the wires

 

Did you try replacing the ICM? Could be there but chances are it's in the ignition coil. (Main source of the tach feed)

 

The ICM and coil are both pretty new. I replaced both a couple months ago trying to fix another problem. Turns out only the coil was bad, so I have the old ICM to try that is probably still working. I haven't gotten around to trying this yet. I might also redo the quick connect terminal because I suspect the wire might not have been crimped tight enough, or it's come loose.

I got a ride home so I have a few days to think this over before heading back out and trying some more ideas. This was my wife's car btw, and my car is working fine.

Anything else I might be missing?

 

Anyone think the sending unit could be bad (faulty sensor)? What all does the sensor consist of anyway? Just a magnet and pick-up coil?

I'm going back to the place where it is this Sunday, so I am hoping that I'll have a better idea of how to fix it then.

Thanks.

 

Does the sensor for the tach ever go bad? Is the tach tied to the crankshaft angle/position sensor, or does it have it's own?

 

the icm goes bad and when it does the tach becomes jumpy. even though the coil and icm are new if you do a compression test without taking out the fuse it can cause severe wear and burn them out fast.

 

That's good to know that the ICM can cause a jumpy tach. However I didn't do a compression test on this car. Maybe it was bad to begin with? Anything else that could cause it to go bad?

When I was fixing the problem with the coil a few months ago I replaced the ICM first. Later found out the insulation around the coil broke down and it was shorting against its case. I'm guessing there was still a spark, but could this have somehow ruined the new ICM?

Thanks for the help.

 

Hey there, look who it is. Have you considered trying a different cluster or a different tach to see if the signal is bad or if it's just being misinterpreted?

 

Hey SVO...

Haven't tried a different cluster/tach, might be able to do that if we take my car out to look at it again. Thanks for the suggestion.

 

open your cap and remove the rotore you will see 4 plugs, use a plier and make each one tight(remove one at a time) then put dialectic grease on it. it should fix your problem. i had the same problem

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Flatland2D &raquo;</TD></TR><TR><TD CLASS="quote">It also sounds like tin cans rattling around in the engine bay when it's doing this.</TD></TR></TABLE>

thats not good

make sure ur alternator isnt going too