Richard Anderson Posted April 11, 2003 Share Posted April 11, 2003 I've just had a new model Caterham tacho (0-8K) installed becuase the old one was waving about badly and although the new one is a definate improvement it :- 1) Still waves around a bit 2) doesn't seem to be calibrated properly....either that or my SLR now revs to 9K+! :-o 3) as soon as the revs approach anything near 6K+, just jumps to max Will twisting the tacho so that max revs are at 12o'clock help to check it's over-exuberance (ie has to work harder against gravity)? I have a MBE ecu....what do I check to make sure it is generating the pulses correctly? Link to comment Share on other sites More sharing options...
Chris W Posted April 12, 2003 Share Posted April 12, 2003 Richard The only real way of ascertaining whether the tacho, or the signal to the tacho, is at fault is to connect an oscilloscope to the black/white wire on the back of the tacho. There should be good square wave pulses of 6v amplitude running at twice the engine revs (due to the wasted spark system). If the pulses look good throughout the rev range then the tacho has a problem and vice versa if they don't. As you have changed the tacho and that didn't cure the problem, I suspect the pulses are dicky. Worth checking too that you have good solid connections to the back of the tacho. The relevant wires are: green = +12v (with ign ON), black = ground, black/white = input pulses from ECU pin 55 (small ECU connector) I appreciate that finding an oscilloscope is not easy - I have one but have no idea of your location. I am located near Dunstable in Bedfordshire. Chris 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Richard Anderson Posted April 12, 2003 Author Share Posted April 12, 2003 Thanks for the tips Chris....I will try tracing though the connection and making sure all the connections are good, and if that doesn't work I may well come and pay you a visit as I don't live too far away (Heathrow). Link to comment Share on other sites More sharing options...
Chris W Posted April 13, 2003 Share Posted April 13, 2003 Richard If you want me to help, email me via Blatchat and I'll give you directions to my home. Heathrow is about 35 miles from me. (about 30 mins or so with no commuter traffic on the M25). Chris 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now