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Tachometer weirdness

The tach in my 2007 Suzuki Forenze is acting weird. On my home from work the other day at highway speed, I noticed it read 4000 rpm. First thing I did was look down and make sure the car was in drive instead of a lower gear. Then I rolled down the window to listen and make sure the engine wasn’t revving too high. It was normal. Got all the way home shut the car off and the needle was on 2000. I went out later and it had fixed itself, but it did it again today. I am in Indiana and it’s been very hot and humid and I thought maybe the humidity was affecting something. Either that or it’s just one of the many things about this car to hate. Don’t ever buy one. I can’t wait to trade this thing in.

It does sound as if your tachometer and not the transmission is acting up. But it may be that your car’s automatic transmission is not shifting into the highest gear every time it should. I know you listened for high revving, but how did the car feel? If it felt like you were going as fast as you can go at around 65 mph, then the car was stuck in a lower gear than was intended for highway speeds. If this happens again, ignore the tachometer and pay attention to how the car responds at highway speeds to going downhill (it should feel loose and you should almost maintain speed or even accelerate depending on the grade. If you let off the gas and slow down immediately, then you are not in the correct gear).

I bet you are due for a transmission fluid and screen change anyway. Have that done, and see if there is any improvement.

Here’s your problem. You drive a suzuki.

On a more serious note though, maybe your tach cable is loose eithere at the transmission or at the back of your control panel.

It feels perfectly normal. It doesn’t drive any differently than it did. It’s doing it through every gear and continues to stay at 2000 rpm when it’s shut off. I’m hanging on to it until I can be less upside down on what I owe and it’s gone. But it’s little things like this that worry me on trade in.

Then your tachometer has an issue. There is a way to calibrate the instrument, but any attempt on your part will be costly. If you are going to trade this car in, let it be the dealer’s problem. In their hands the solution is nearly free. I was more concerned that your transmission was failing. Use the car according to your own judgement until you are ready to trade it in.

I drove to another town about 25 miles away, drove from one side of that town to the other shopping and then back home. It didn’t do it once. Go figure. One more thing to hate about this car, I guess.

Are you guys reading this correctly, the OP is talking about a tacometer and some are talking about calibration and the cable at the transmission? we are dealing with engine speed not vehicle speed.

In the old days, speedometer and tach needles were curled by a spinning magnet driven by cables from the transmission and the engine. I’d bet that for a 2007 Suzuki, vehicle speed sensor and crankshaft position sensor send those data to the car’s computer and the computer sends its signals to the appropriate gauge. If there no check engine light, then I think that the computer is getting the correct signal from the engine’s crank position sensor and that the problem is the tach itself. Since it is an automatic, a tach is essentially decoration.

It is a decoration that is very popular with car buyers.

Were there even any Cable driven tach’s besides on diesel after the advent of the electronic age. I seem to remember even in the 70’s tach’s were electric off the coil.

The ones I remember were fuel injected Corvettes in the '60’s - they had 2 drive cables from the distributor - 1 went to the pump in the fuel injection and 1 went to the tach.

I agree that it’s pretty much a decoration in an automatic. Today it’s only sitting on 1000 instead of 2000. Did I mention I hate this car? lol

OK, Grandpa!!

Years ago a friend had a 1976 Chevy Monza, you could get a 4 cyl, 6 cyl, or 8 cyl in the car. The tach was the same for all 3 it had a switch on the back of it to select the number of cyls. When his used to act up he just hit the top of the dash until it read correctly.