R400D: ACES SureShift 2 doesn't work

[John Vine]

My 2008 R400D came with a SureShift 2 already fitted.  It's never worked (other than a constant green "low revs" light).  Up till now, this hasn't bothered me, but I thought it was about time I sorted it out.

The existing values (set by CC perhaps?) are:

Shift-up: 7400
First up-light: 5000
Shift-down: 4000
No of cylinders: 4

Those seem reasonable settings, BUT, according to the User Handbook:

Note that the number of cylinders should be set to the number of sparks which will be delivered by the coil from which the signal is being taken during two complete revolutions of the crankshaft. Many engines use a multiple coil or multiple distributor systems, in which case, the number of cylinders should be set to the number which are fed by one coil, eg for a four cylinder engine using two coils, the system should be set up as if on a two cylinder engine because each coil delivers two sparks every two complete crankshaft revolutions. Likewise, for a V12 engine using two coils and two distributors, the unit should be set up as if working on a 6 cylinder engine. A similar principle applies if a coil feeds one two stroke cylinder, or four stroke using a ‘wasted spark’ (spark plug fires on every cylinder revolution). The coil will deliver two sparks for every two revolutions and so should be treated as a twin. 

As the Duratec has a separate coil per cylinder, I'm wondering whether the value "4" is wrong.  Should it be "1"?

JV

 

[martyn]

In a normal Caterham factory installed setup, the shift lights aren't connected directly to the ignition coil.  Instead they run from the tacho signal wire supplied by the ECU.  This makes that confusing paragraph in the SureShift instructions largely redundant and a bit misleading.

It all depends on what the MBE outputs as its tacho signal.  I.e, does it output one pulse per revolution, or four, or whatever..?  Because the MBE is a dedicated 4 cylinder ECU I presume it outputs four pulses per revolution.  This is "sort of" verified, because 4 cylinders is the correct setting for the shift lights on my sigma which I believe is wasted spark.  Your settings look correct and that they haven't changed since it was first configured.

I'll presume your unit is receiving power and lighting up.  Ruling out a 12v or earth problem..

Firstly, check that the display unit shows the RPM on its screen when powered up and engine running.  If it doesn't the unit is either broken or you have a wiring fault on the tacho feed from the ECU.

Next I would set all the values really low.. Shift up: 800 rpm, First up light: 600 rpm.  Or whatever is the lowest values the unit will allow.  This should cause all lights to flash continuously at idle. Then go through all the cylinder options.  If you don't get any flashing then there is some other problem.

With an RPM displayed on the control unit and all the parameters stupidly low, you're only really left with a wiring fault between the control unit and LED unit - probably bad soldering inside the LED unit. Open it up and check inside.  Check for continuity back to the 7 pin connector that goes into the control unit and for shorts between the LED terminals.

[John Vine]

Thanks, Martyn, that's really helpful. 

Yes, the unit is getting power ok.  When I first turn on the ignition, all the LEDs light up for second or two, and the SS2 reads "RPM ?????".  (The dinner gong is ringing now, so I'll fire her up and try your suggestions tomorrow....)

JV

 

[martyn]

I just edited my reply above to remove an incorrect bit.  I incorrectly said the tacho feed wire has an inline fuse.  It doesn't, the fuse is obviously on the 12v line.  So I guess you can rule that out.

All lights coming on when you switch on the ignition - yes that's normal and rules out a wiring problem in the LED unit.

"RPM ?????" is also normal when the engine is stopped.  The question marks should be replaced with the actual RPM when you start the car.

[John Vine]

Thanks for that.  More news tomorrow....

JV

[John Vine]

Well, it seems like the "no of cylinders" setting was the culprit. 

I fired her up. At idle, the tacho read about 1140 while the SS2 read about 290.  I increased the revs to about 2000 and the SS2 followed suit to 500. 

Then, to be sure the shift lights were working ok, I reduced the Shift-up from 7400 to 480 and the First-up from 5000 to 390.  Revving the motor to 2000 turned the LED display into a veritable Xmas tree, with the sequence increasing just as you'd expect.

I still don't know where the SS2 is picking up its ignition signal as I've yet to trace the wiring through. 

To finish, I reset the "up" values and altered "no of cylinders" from "4" to "1". 

I'll give it a road test and report back.

JV

[Jonathan Kay]

Well done.

I think I've seen an explanation somewhere of the "number of cylinders", wasted spark set-up etc...

Jonathan

[martyn]

Nice work.

That is interesting though and perhaps my understanding of how the MBE outputs the tacho signal is wrong. Maybe it does just pass through the pulse from the coil.  Seems I got lucky on my sigma and the first setting I tried (4 cylinders) just happened to work.

[martyn]

If you didn't already know, you can set up multiple profiles.  I have road and track profiles.  The only difference is that the road profile has the shift down point set to 900 rpm.  This stops that annoying light coming on and off as you drive.  It only comes on when you really need it i.e. about to stall!

[John Vine]

multiple profiles

I didn't know, but I've just found it in the Handbook.  I like the idea of a track one and a road one.  I might even add a night-driving one (with reduced LED brightness).  Time to have a play, methinks.

JV

[martyn]

Shouldn't need a profile for brightness. The up and down buttons adjust the brightness on the fly.  My control unit is by my right knee, so I'm constantly adjusting it up and down as I drive into the sun or away from the sun, or as it starts to get dark.

[John Vine]

Tested it today -- worked exactly as it should.

JV