On my S3, the rpm shown by the counter seem twice too high. Maybe the Lumenition Ignition is the culprit. Does anyone know the remedy?
Thnks a lot
Josh
Josh did you just add the ignition to the car and this happened?
Hi Terry,
No, this was done by a pre-owner. He apparently had no means either to fix the problem.
Josh
If you are saying it always reads 2x what it should, then it suggests a tacho from a six cylinder car is fitted instead of one from a 12 cylinder car. The correct tacho for a v12 car as the words “12 CYL” written in the middle of the dial.
If you are suggesting it sometimes reads incorrectly, it suggests a problem with wiring to the tacho, the grunding of the tacho or an internal fault in the tacho, because you are not reporting any misfires or dropping cylinders.
kind regards
Marek
On the back of your tachometer there’s either a round label or a rubber plug that covers a hole. Inside, there’s an adjustment potentiometer that you can tune with a screwdriver. Match the tach to any good shop tach.
If you find you can’t get enough adjustment, there are more invasive techniques for calibration. Read about them here, or send it out to a shop:
Josh I need to get a better feel for the problem. When you accelerate normally from a stop does the tachometer go to 4000 to 5000 rpm when you or the transmission shifts? (Is is a 4 speed or an automatic)
Hi Terry,
It’s an automatic. The rev counter starts at around 1200 in idle and then goes up without hesitation, very smoothly, to 7000 rpm indicated and more. It goes up and down with the gears shifting.
I counter-ckecked it with a timing gun: the gun shows half as much as the instrument. The former owner has had all instruments overhauled, the bill says they dealt with a 12 cylinder. They may be wrong, however.
Thanks for your interest in my problem. Josh
Hi again, Terry
Sorry, I just got the message. The gear change takes place, depending on how far you push the gas pedal, at between 2500 and 5000 rpm indicated. Acoustically speaking, all seems quite normal. But the rpm can also go up to 7000 rpm, with the pedal on the metal. The whole thing “bewildered” me, as the transmission had been overhauled: was the shifting faulty or the rev counter? Right now, I’m sure it’s the counter. Josh
I don’t know what to say, I’m familiar with the 6 cyl tachs that are like yours but not the V12. The 6 cyl ones read pulses from points, and won’t work on electronic points with out an adaptor. Yours reads electronic pulses from an electronic system. I suspect that it’s not compatible with the Lumenition ignition system . You may need one of these: