Tacho wiring

[sheel]

Hi guys,anyone know the procedure for wiring the tacho following an ecu change,I assume the wiring originally cam from ecu and direct into interface block???
Rich

[Bassfiend229hp]

sheel said:

Hi guys,anyone know the procedure for wiring the tacho following an ecu change,I assume the wiring originally cam from ecu and direct into interface block???
Rich

Hi Richard,

There should be a direct tacho output from the replacement ECU itself ... I assume you're now on coil packs rather than dizzy?

Phil

[sheel]

Hi Phil,,yes I have a tacho feed from the canems but I'm unsure as to where it wants to go ref the tacho itself,probably didn't explain myself too well in the original post as having a quick look the existing tacho wiring feeds into the speed interface box (I assume that's what it is) but then where does it go or do I just hook into it here ?
Thanks
Rich

[Bassfiend229hp]

sheel said:

Hi Phil,,yes I have a tacho feed from the canems but I'm unsure as to where it wants to go ref the tacho itself,probably didn't explain myself too well in the original post as having a quick look the existing tacho wiring feeds into the speed interface box (I assume that's what it is) but then where does it go or do I just hook into it here ?
Thanks
Rich

My tacho is fed straight from my CANEMS tacho output...

Phil

[sheel]

Thanks Phil makes sense to connect directly I think in its original format the tachometer and speed sensor had something to do with idle speed ie the ecru knew when the car was stationary etc with our new format that all goes out the window
Thanks
Rich

[carsy]

Rich, you will probably need a tacho driver to make it work.

This is Emeralds.

http://www.emeraldm3d.com/sensors-and-relays/tacho...


I`m sure Canems will do something similar.

[Bassfiend229hp]

sheel said:

Thanks Phil makes sense to connect directly I think in its original format the tachometer and speed sensor had something to do with idle speed ie the ecru knew when the car was stationary etc with our new format that all goes out the window
Thanks
Rich

Who knows with the TVR wiring ... I sometimes think even TVR themselves didn't know some of what went into that thing.

I would love to rip the loom out of mine and rewire it completely - I have a friend who has re-loomed a number of cars (and fabricated new looms for several race / drag cars) but he's proving very reluctant to pick up on my suggestions that perhaps he could do mine.

Phil

[Hoofa]

Just as a thought, I tried the emerald driver box and it sort of worked but every now and then the needle would bounce around, the real fix is to send the tacho to speedy cables and get it converted to run direct from the ecu without the need of the interface box, no more wobbly needle

Whilst on the subject of rewiring, mines being converted to run of a motec pdm module, no more fuses and relays

Edited by Hoofa on Sunday 3rd January 19:21

[sheel]

Phil,know what you mean with the wiring,it's a disaster def a fire waiting to happen,not sure if it's me but seems over complicated for the application plus it's got a miriad of alarm interconnections in it which I would like to pull out as I'm fitting a new alarm but that maybe courting disaster
Carey,thanks ref your note,the canems has come from Cog favourite lloyds, they did ask about my tacho and have added an additional black box for this,I will double check with them in the am tho for connection point
Rich

[Bassfiend229hp]

carsy said:

Rich, you will probably need a tacho driver to make it work.

This is Emeralds.

http://www.emeraldm3d.com/sensors-and-relays/tacho...


I`m sure Canems will do something similar.

I haven't seen a tacho driver box under my dash ... certainly looks like mine's driven direct off the ECU however mine are the old black rimmed gauges where the speedo has the digital / LCD odometer that loses its backup battery after 15 years if that makes a difference.

Phil

[ChimpOnGas]

sheel said:

Hi guys,anyone know the procedure for wiring the tacho following an ecu change,I assume the wiring originally cam from ecu and direct into interface block???
Rich

Rich, on the original 14CUX & distributor system I think you'll find the tacho is driven from the distributor, the 14CUX does need to see an RPM signal but ultimately that signal originates from the distributor.

I'm not aware of there being a 14CUX tacho driver, but there is a TVR road speed signal box that outputs from the speedo to tell the 14CUX ECU if the car is moving or not which it needs to know to ensure the stepper motor is controlled to correctly manage engine idle characteristics.

Are you sure you're not looking at this TVR speed signal box? If so all you need to know is you no longer need it with your Canems system.

Back to your original tacho question, as you no longer have a distributor you need to drive your tacho directly from the Canems ECU RPM output, however... there are issues with this.

I have a Canems ECU & Caerbont gauges, initially I had tacho bounce when the ECU was directly wired to the tacho. To solve the problem David Hampshire of Canems Engine Mangement systems (working in conjunction with Lloyd Specialist Developments) created a tacho interface module.

This little box of electronics is designed specifically to interface the Canems ECU with the TVR Caerbont tacho, taking the RPM from the ECU and providing a smooth and matched signal to suit the TVR tacho it completely resolves the bouncing needle syndrome.

Talk to Lloyd Specialist Developments, they may even hold the module in stock as it now comes as standard with all their Canems TVR engine management conversions.

Problem solved

[Sardonicus]

ChimpOnGas said:

Rich, on the original 14CUX & distributor system I think you'll find the tacho is driven from the distributor, the 14CUX does need to see an RPM signal but ultimately that signal originates from the distributor.

I'm not aware of there being a 14CUX tacho driver, but there is a TVR road speed signal box that outputs from the speedo to tell the 14CUX ECU if the car is moving or not which it needs to know to ensure the stepper motor is controlled to correctly manage engine idle characteristics.

Are you sure you're not looking at this TVR speed signal box? If so all you need to know is you no longer need it with your Canems system.

Back to your original tacho question, as you no longer have a distributor you need to drive your tacho directly from the Canems ECU RPM output, however... there are issues with this.

I have a Canems ECU & Caerbont gauges, initially I had tacho bounce when the ECU was directly wired to the tacho. To solve the problem David Hampshire of Canems Engine Mangement systems (working in conjunction with Lloyd Specialist Developments) created a tacho interface module.

This little box of electronics is designed specifically to interface the Canems ECU with the TVR Caerbont tacho, taking the RPM from the ECU and providing a smooth and matched signal to suit the TVR tacho it completely resolves the bouncing needle syndrome.

Talk to Lloyd Specialist Developments, they may even hold the module in stock as it now comes as standard with all their Canems TVR engine management conversions.

Problem solved

Yep far as I know the Emerald and definitely Megasquirt ECU's need these too whether internal or external

[sheel]

Hi cog thanks for the info,yes it's as you say with the old Lucas system,lloyds have supplied the tacho interface and mine are the later gauges so it's just where I connect to,I will call lloyds and have a chat, when I originally bought the system they did say there was a known problem and this interface box from them was the cure
Regs
Rich