I have a question... I was driving on the Thruway this week and I noticed a couple of times when I had the cruise control on, my tach would read about 3700 Rpm, and then all of a sudden my tach would jump up to +- 4700 PRM without any change of engine speed, and then jump back to 3700. I also noticed this one other time when ideling, the tach read 750 RPM and then would drop to almost nothing and then jump back to 750. Any ideas... I guess it's not too big of a deal.. but it had me puzzled?? Any tips would be much apprecitated.

Eric

 

You know I had a similar problem 2 years ago. I was driving north on I-5 back to WA from CA and I was in Weed, CA my engine floored and my tach started jumping around all over the place. It did this for a few months intermittently, then after that, it was back to normal. I never did figure it out exactly. I suspected it had to with the "hot" aftermarket ignition that I was running (not running it anymore, but it is still installed) that caused it. Due to the weird cap/plug wires on the 92-95 3.0 V6, I decided not to use it until I figure out how to run plug wires that have "normal" connectors at the distributor cap. I don't have any idea whether the 88-91 V6 and 92-95 V6 have interchangable distributors.

 

I had the same problem in my 95 just the other day...I was coming down a hill and came to a stop at the light and noticed that my tach was resting at 0. Naturally I thought my truck wasnt running. I thought about turning the key but then I could hear in my head the sound of a grinding starter so i decided to give it some gas and the tach jumped back up to normal...not sure what would cause this though? bad connection at the distributor...or at the tach? Just a guess

 

I have seen this on other imports (cars), but there is a chance that its the same problem. Check the ground point in your drivers kick panel, and make sure that it is tight. These have been known to work loose, and a loose connection will cause all kinds of fun wierd things to happen, a dying tach one of them. Maybe also check the grounds at the distributor.

 

Okay...I've been following this thread for sometime...Here's my experience. My version of the "jumping tach needle" starts at engine start up...when I start my engine up, the needle doesn't move for sometime.....The time period differs b/w 7-10 secs to as much as 30 secs.....After this time period it literally "jumps" to the correct reading. After this "warm up" time....it shows no problems whatsoever.....

My jumping tach needle woes began after installing my halo reverse indiglo gauges....I love my gauges by all means...I'm pretty sure I didn't damage my needle assembly...after I discovered that I the original center holes were too small, I generously widened the holes......Not my cleanest job...but it worked.....

So I like the suggestion that maybe there's a loose wire somewhere? A groundwire that might be loose......wouldn't this affect the whole cluster's performance and not isolate only the tach? Unless I ripped/loosened a wire that I was unaware of, the only things I disconnected/altered were the plugs connecting the cluster, the ground wire of the cluster (wired it to a ground screw on the steering column...does anyone know what the existing ground wire here is for?), and the power wire (I tapped my piaa power wire that was tapped into my dimmer).....

When I have sometime....I'll try grounding the cluster somewhere else.....I'll also disconnect everything and reconnect them again...and just plain look for a source of the jumping tach needle. This will also give me a chance to find the location of the extra screw I found after putting everything together the first time.....this always happens to me.....does it you?

Any Ideas?

Thanks

 

Anyone ever get a solution for this. I am having the exact same issue orignally mentioned.

 

Same problems here too. When my lights are on and when I come to a stop, the tach drops to zero. Give it a little gas and it jumps up to where it should be.

 

I'm no expert but this sounds like a bad connection. The only experience that I DID have with a similar condition was with the tach on my boat. Turned out that my voltage regulator was about to crap-the-bed.