Rev counter issues

[gmac50]

Hi everyone

I have a Corsa B 1.2 16v Automatic

Fitted new clocks yesterday with a rev counter

Electric clocks fitted straight into my exsiting electric plug

Everything works ok,speedo,temp,fuel etc

The only thing that is concerning me is the rev counter! It doesnt seem to be showing the correct revs at speed
i.e when im doing 70 mph it will sit at 2000rpm which seems very low!
my friend has the indentical car 1.216v auto fitted with a factory rev counter clocks and his car sits at 70mph at the first bar after 3000rpm

The KW code on the speedo also matches my old clocks as well

Contaced the Ebay seller today who confirmes they came from a 1.0 16v

Is there any way i can calibrate the rev counter? Would resetting the ECU help?

Tested engine limiter and it only went up as far as 4000rpm before stopping!

Can anyone help?!
Thanks you!

[johnny]

Not familiar with the workings of automatics I'm afraid

But a quick way to narrow down what's at fault is to swap your clocks with rev counter with your mates known working clocks,

At least then we'll know if it's the clocks or the signal

[gmac50]

Ok thanks will try that!

[coupe77]

Sounds like you got the wrong clocks for your car unless it's not getting the correct engine speed signal from the cam sensor


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[diggerhole]

The 1.0 is a 3 cylinder car. 1.2 I suspect is 4

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[johnny]

I'm assuming he ment 1.2 16v since the 1.0 is 12v and the speedo codes match so it should be the right clocks

[coupe77]

The 1.2 is a 4 pot and is a lower revving


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[Deedee91]

I fitted some auto clocks to my car once and the Rev counter was showing miles out doing 4000 rpm in 5th doing 35 haha.

Don't know if the clocks were nakered or that they were auto clocks (I drive a manual).

Do you know what box is in it?

[Deedee91]

I mean the code btw (f13 etc)

[diggerhole]

Sunday morning after night before. Let's try to resolve this.
There are three different issues here. On the speedometer will be a k code. This is indicates the pulses per kilometer needed for the speedometer to read correctly. I previously did a how to on this and showed how to calculate the deviation if you use a different set of clocks. The pulses come from the gear box sender and can be effected by tyre changes , gear ratio adjustments etc. For most of you, you are quite safe as the fashion is stretch tyres. The smaller rolling diameter means you are always under the speed limit. Tyre ratio calculators are in abundance online.
W codes for cable speedometers are rotation per kilometre of the cable.

All rev counters also have a code. This code however is hidden while it is in the binicle. Petrol rev counters receive a pulse from the ecu each time a cylinder fires. The 1.0 12v is a 3 cylinder so produces 3 pulses per revolution. The 1.2 16v is a 4 cylinder so you get 4 pulses per revolution. So a 3 cylinder rev counter will read incorrectly in 4 cylinder car and visa versa. Desiel rev counters are driven from the w terminal of the alternator. This gives approx 12 pulses per revolution. So petrol rev counter in desiel car will read crazy high.
The binicle can be dismantled and the board on the back of the rev counter swapped. If you have the old binicle this should sort the the issue. Other people have used pulse generators and re soldered the board to get the result they need. More info on google Only for the brave really. Also to keep on the right side of the law you should adjust any odometer to match the correct milage for the vehicle. A how to on clocking is in the forum. It is only illegal if you are tryjng to mislead someone. Remeber a corsa b binicle is many dials and each has a code. The w/k code a is just for milage and speed.

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[diggerhole]

Big love to all

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