undefinedundefinedundefinedHello i am inquireing about a problem with my tach at idle when cold the tach will not register at all but as the engine warms it works properly.Then as driving down the road the meter jumps eraticly with very small power loss. Can someone help me????????????

 

First off welcome to the 'club'.

Secondly the year and model of car is helpful, along with any modifications that could helps us solve you problem.




John

 

it is probably a bad trailing ignitor. I don't know what year car you have but on the 81-85 model years the ignitors are little black boxes bolted to the side of the distributor. The trailing ignitor is the one closest to the alternator. You can find ignitors on eBay a lot of the time.

 

appllo00,

So the tac (which is exactly the problem I have on my 84, so I've given it some thought) sounds like A) your tac is bad (not likely, but hey, when it 's cold, you gotta wonder), B) the connection to the rear ignitor needs looked at, or C) you need a new rear ignitor (I got some on eay, 6 for $20, for you appllo00, $4.00 american plus shipping).

Ray

 

when i had a bad alternator it seemed to jump like you're saying. so could this be the problem? tell me, is your voltage meter steady at like 12-13, or does it get really low sometimes?

 

my tach also jumped when my alternator was bad.

 

What it does is control the firing signal that is sent to the coils. If they go, you get no spark.

It's almost 100% sure to be your trailing ignitor and it's overheating likely. There's heat-sink-glue from factory but by now it's no doubt gone. Couple that with it failing and there you go. The tach runs off that ignitor so without it the tach is gone. 2nd the power loss is almost certainly because when the ignitor goes off you're really just running on your lead spark plugs. With the rotaries the trailing plugs don't do ALL that much so that's why it doesn't stall or anything.

 

I was interested in his question because I have had a very similar problem with the tach on my 84 for several years now, sticking on cold mornings until the car warms up, then it works normally. Other than an erratic tach, the car runs fine and has plenty of power, no problems with the alternator, everything electrical works fine. And I am familiar with trailing ignitor failure because I had this problem with my 85, first the tach goes, then the trailing ignitor fails, then the fuel pump shuts off and the car stops running. It might be that my trailing ignitor is taking a few years to fail, but I'm thinking it might be something else, like maybe the tach itself?

Ray

 

My tach always sticks on cold mornings. I've tested both the tach and the ignitor and both are good. The problem is, at least in my case, that the actual needle needs to be lubed. For now, all I do is turn on the hot defrost and it starts to work in short order.