Ideas to use a 3rd party rev counter with any modern FIAT

[lewey]

This is really for the serious modifiers. I like putting 1368cc FIREs into older cars to give them a new lease of life. How can I wire an original or other 3rd party tacho to the engines when I don't want to use the modern CANBUS dash?

Some models retain coil packs, so there are options but the 1368cc models all have coil per plug ignition and no tacho outputs. So what tricks do people know to extract the RPM? Can I utilise the RPM/TDC sensor some how whilst retaining it's use for the ECU?

I'm currently wiring in a Bravo 150 Sport T-Jet engine into an Uno (see Uno section), but the discussion will cover many other engines of course.

 

[lewey]

I spent this evening trying my first fairly wild idea.

Using an old 1994 Panda ECU I wired it up to the crank sensor of the Bravo engine, gave it power, ignition and earths and used the tacho output on it connected to the Uno rev counter. Unfortunately there seemed no response when turning the engine on the starter. Not sure if the starter would turn it more than 400 RPM to begin registering though.

 

[EI4GGB]

what happened the bravo the T-jet came out of ? you could use the signal off a cam sensor (F = rpm / 4) or off the crank sensor, but you would have to make up something to convert this to the correct frequency for the older rev-counter (F = 2 x rpm). I've done this for engine conversions.

 

[lewey]

what happened the bravo the T-jet came out of ? you could use the signal off a cam sensor (F = rpm / 4) or off the crank sensor, but you would have to make up something to convert this to the correct frequency for the older rev-counter (F = 2 x rpm). I've done this for engine conversions.

Thanks for replying. I don't understand how to use the crank or cam sensor signals with my rev counter when it wants a switched earth? The crank pulley on any FIAT I've had has been a 60-2 tooth affair. I'm going to need some bespoke electronics to deal with this, is that what you have made in the past?

I was thinking about a 4 diode setup on the coils until I realised that they are three pin designs. Power and earth on two pins and a trigger voltage on the other. This won't work either.

I just don't know enough about electronics to understand what I need to make.

 

[lewey]

The Bravo was hit in the side and had both doors bashed in and B-pillar bent. Cat B write off I think. I got the engine from a breaker.

 

[petrolhead69]

http://www.canm8.com/products/canm8-rpm-can-bus-rpm-signal-interface/59/

 

[lewey]

http://www.canm8.com/products/canm8-rpm-can-bus-rpm-signal-interface/59/

Nice one! I had assumed that the CAN bus was all very much proprietary and so products like this would not be forthcoming. A quick search using the right terms cam up with that canm8 box in on the Halfords site.

I suppose if it works it is a neat solution.

 

[dave]

*Please note, some vehicle CAN systems do not support this output. be sods law it dont work on fiats

 

[lewey]

Only want RPM, the asterisk refers to other functions. I won't be taking it for granted that anything works until I've seen with my own eyes. This is where a real shop return policy could come in use..

 

[dave]

ah yeah my bad

 

[petrolhead69]

I used the similar one on my clk320 to get a speedo mph signal when I was retrofitting comand sat nav. Worked a treat. I picked it up off ebay for £23 and the seller offered returns if it wasn't compatible.

 

[lewey]

My brief research shows that RPM output is actually pretty unusual. I've only found the one I linked above to claim RPM output. Most are for speed for audio units.

 

[petrolhead69]

How have you gotten round the immobiliser, flashed the ecu? or is it easier on fiats? I would imagine the immobiliser would want to talk to the body control module or cluster on a canbus car? you might get the odd fault code as well as it's probably expecting a speed pickup off the abs to adjust idle and a signal from the aircon for load compensation.
just a few of the issues I've had doing engine swaps on bmws mercs and audis. I'm glad Ive given up arseing around with cars thats why I've no hair left...
I should have stuck to 20xe novas.

ps if your going for big power later I can thouroghly recommend megasquirt, It's so versatile and neatly sidesteps your canbus issue. I used to run it with the dual table mod for an lpg conversion, you can run plenty boost and advance on 110 octane autogas

 

[lewey]

I haven't got round the immobiliser, I'm just using it all as it was in the Bravo. Once you have the wiring diagrams, you can get the wiring down to a bare minimum, retaining the body ECU and CAN link to the engine ECU.

There are pics and some detail in my thread.

I did something similar a couple of years ago with the Panda in my signature. I really went to town with that, using most of the features of the original Punto body computer. There are a few permanent error codes. Things like "There's no steering column", "You never go anywhere" and "All air bags are broken". Just means I plug in code reader every now and then to check for any new ones.

The main difference between this Uno project and the Panda is I am using as little wiring and electronics as possible from the donor and retaining Uno wiring for everything other than engine. Therefore using Uno dials.

 

[EI4GGB]

does the T-jet use coil per plug or wasted spark ?. if coil per plug they usually have an amplifier built in which is fired by a pulse from the ECU, so you could use diodes to OR the triggers together with a pull up/down resistor followed by a simple buffer amplifier to feed the rev counter. very simple electronically.

 

[lewey]

does the T-jet use coil per plug or wasted spark ?. if coil per plug they usually have an amplifier built in which is fired by a pulse from the ECU, so you could use diodes to OR the triggers together with a pull up/down resistor followed by a simple buffer amplifier to feed the rev counter. very simple electronically.

It is coil per plug. There is a trigger wire for each plug. I'm afraid that my electronics knowledge is not good enough, so without wiring diagrams and specific component specs, it's not going to happen.

I actually have bought the aforementioned CANM8 device to experiment with. This outputs a +12v pulse per revolution. I have this working, but I'm still going to need to do something to this signal to make it work with the rev counter. Can you help with this stylers?

 

[lewey]

Update: the CANM8 device appears to just output battery voltage all the time on the correct yellow lead. I put it on my handheld scope and it is not "pulsing" at all. The device's LED is on when the CAN BUS is connected correctly and the ECUs are specifically in the list of compatibility for all features. What a mess.

 

[Adrian Bravo]

Have you checked the other outputs for any pulses?

Do you know the software version of your CANBUS? The April 2009 pdf for that canman says it goes upto Bravo> 2007 Software Version:18

Maybe you have old stock? You might need to find the latest version or update your CANMAN box somehow?

This one from 2007 does not list the Bravo
http://www.ncs-systems.com/uploaded_images/pdf_637.pdf

but the later April 2009 one does http://www.canm8.com/product_pdf.php?id=3

Wonder if these pins are configuration pins?

 

[lewey]

That 2009 PDF says 2007 onwards, not up to? The old Bravos didn't use CAN BUS systems, so I think it is just referring to the new Bravos basically. The software version is written on the box as 25.1, so certainly one of the newest.

It is a good point about other outputs. I wouldn't expect anything other than the purple "ignition on" wire to output anything. What actually happens is the purple wire is at 0v, the green, pink and yellow wires output battery voltage before the can lines are even connected and don't change when they are or when the engine is started or whatever. The LED does comes on solid when the CAN lines are connected. There are no installation instructions whatsoever.

For reference, the wiring is:

RED Permanent 12v+
BLACK Ground (0v)

WHITE CAN HI
BLUE CAN LO

PURPLE 12V+ 'Ignition On' output (1A Max)
ORANGE 12V+ 'Lights On' output (1A Max)
BROWN 12V+ 'Reverse Gear' output (1A Max)
PINK 0V (Gnd) 'Park Brake On' output (1A Max)

GREEN 12v+ Speed output (150mA Max - 1Hz / MPH approx.)
YELLOW 12v+ RPM output (150mA <Max - 1Hz / RPM approx.)

 

[EI4GGB]

if you do get the RPM output on the canman working then just try connecting it directly to the rev counter coil input. On the old type dashes they usually have three screws holding the rev counter in, and connecting it to the flexi-print. ign +12V, GND and coil pulse. Only problem is that the older rev counters worked off the coil/distributer, so would see 2 pulses per rev. so at 1Hz/rev it would read half the actual RPM.

not sure how the outputs are structured on that can interface, but maybe they need pull up/down resistors to work (just a resistor connected to +12V or GND, depending on polarity of outputs). On the pic of that unit I can only see single ended outputs.
If there is no way to configure the can interface, it could be a waste of time as manufacturers do change CAN message addresses.