Easimap usb can For R400D

[slap_ed]

I've got an Easimap usb-can comms interface number 985 which I used on my old Sigma 150. (Now sold)

Question. Is this compatible with a 2011 R400D standard set-up?  If it is, does anyone know the TPS voltage and at what tick over? Or indeed any other official settings applicable to the above car. I've just had the car so I'm trying to gather general information about it.

Cheers

 

[aerobod - near CYYC]

The MBE 985 interface is compatible with the R400D 992 ECU.

On my car the TPS voltage varies from 1.27V at closed throttle to 4.68V at full throttle. The standard Caterham map seems to assume throttle site 0.0 at about 1.0V and throttle site 15.0 at about 5.0V (implied from data logging, as ECU map is encrypted) so my R400D was running only from throttle site 1.0 to about site 14.0 according to my Easimap data logging on the 992 ECU (probably due to manufacturing tolerances).

[slap_ed]

Not too familiar with the sites. I'm guessing that this is where a given site tells the ECU to change the fuel ratio/level, timing etc?

My tickover is quite good for most of the time but on the odd occasion will hunt around a bit, but not to the extent of stalling. CC South told me to start the car without touching the throttle because the TPS is set/learnt each time the car is started. This does seem to work but I'm finding it difficult to get out of the habit of not blipping the throttle a little. I take it the 992 number is marked on the ECU itself, I'll have a look to see if it's the same one, should be I hope.

I'll have a play this coming Saturday and compare reading with yours. I take it you too are not sure of what TPS voltage should be at a given tickover?

 

[martyn]

Inside the ECU, the TPS voltage is converted into a 'site'.  It is this site value (ranging from 0 to 15) that is used in the maps.  It is much easier for the person doing the mapping to work with the easily understood 0-15 range for throttle position rather than some arbitrary voltages.

You can see both values in easimap by calling up "Throttle angle 1" and "Throttle site 1" in the real-time view.  Watch these as you press the throttle (with the engine off) and see what you get.  It’s interesting that Aerobod doesn't get the full range..  On the sigma that would indicate a problem with the throttle stops or cable tension not being set correctly.  Perhaps the duratec map is different though so would be interesting to compare what you get.  In the sigma, it’s easy to determine the idle TPS voltage because it is the value that equates to throttle site 0.0 (again this might be different on the duratec if it does run from 1 to 14).

I’m not sure the MBE ECU does learn the idle TPS voltage at startup.  This is easy to test though by watching the throttle site in easimap.  Start up with the throttle pressed a quarter.. If the ECU does re-learn, then the throttle site value won’t start increasing until you get to get to that same quarter throttle position.

[slap_ed]

Just had a spare 20 mins. With Easimap connected my sites run from 1.0 to 15.1 with a voltage of 1.22 volts to 4.69 volts ( plenty of slack in the throttle cable )

ECU is a 38L036A ser 00052346. I see there is a later one on the Caterham website 30L153A

[aerobod - near CYYC]

My 2012 R400D used the 30L153A until I changed it for an MBE 9A4 ECU, so likely some differences in the map loaded in the different ECUs, but I believe the 38L036A is also the MBE 992 based ECU (in Easimap it will tell you which chip file it is using, if it has 992 in the name, it is a 992 ECU).  I believe your ECU may be the part number for use with the roller barrel throttle bodies, whereas mine is for the plenum.

My 30L153A ECU does not learn the throttle range at engine start. I think the occasional engine hunting (especially at idle when the engine is warm) is due to the throttle being at throttle site 1.0 when the throttle is closed, the map is expecting the throttle to be slightly open.

[slap_ed]

So unless CC divulge the actual setting we'll never know the site information I presume?

I've just downloaded the latest Easimap version R50. It doesn't have anywhere near the amount of option to monitor as the old version R33 I think. Which version do you have?

Easimap picks up 992ab94p

Mine is a Plenum on 38L036A

[martyn]

Is it possible to see site 0.9 or lower?  Or is it pegged at 1.0 as the minimum (even when a really low voltage is supplied)?

If 1.0 is the absolute minimum site then it is fairly safe to say that is the correct idle position and you can read off the corresponding voltage.

What you cannot find from easimap is what the throttle idle opening/RPM should be at that throttle position.  If you're happy to assume that your TPS has never been moved since it was originally correctly calibrated then you can gradually increase your idle screw until you transition from site 1.0 to 1.05.  The very last point before leaving site 1.0 will be the correct idle position and revs.

Not sure that is particularly understandable, but cannot think of any better way to put it.

[slap_ed]

It does drop to site zero. It seems to go zero, 0.5, 1.0, 1.2, 1.4, 1.7 etc in odd jumps.

I don't think the TPS is moveable, the two screws hold the TPS on only. If you loosen the two screws it doesn't move.

Is the 1.05 a typo? Do you mean 1.5, it seems to increment as above.

[martyn]

No not necessarily a typo, but I was unsure of what the smallest increment is.  What I should have said is the next increment greater than 1.0 (whatever value that is).

I'm afraid I'm at the limit of my knowledge now.  The sigma 150 map is relatively straight forward: 0.0 is idle and 15.0 is WOT.  Based on this it is easy to adjust the TPS so it confirms to that range.  From what you're saying, it appears that the duratec idles at site 1.0 so that calls into question my understanding of how these MBE ECUs work.

Anyway, if your TPS is indeed not adjustable, this is all irrelevant.  Set your idle speed to whatever you're comfortable and balance the throttle bodies.

[aerobod - near CYYC]

I can't say exactly what config the encrypted Caterham map has for throttle sites in the 992 ECU, but I expect that it is quite similar to the map in my un-encrypted 9A4 ECU. Basically there are voltage values in the map for throttle site 0.0, 1.0, 2.0......14.0,15.0. Any values for sites between the ".0" values are interpolated by the ECU, they are not explicitly stated in the map, but the data logging captures them as values with a throttle site resolved to 0.1, in the range of 0.0 to 15.0 (i.e. 161 distinct values). On the 9A4 ECU it is easy to set the throttle range, as I just set the voltage values at site 0.0 and 15.0 and whether the TPS rotates clockwise or anti-clockwise, together with what the default TPS voltage value should be if an out-of-range voltage is detected.

My belief is that Caterham have not paid the most attention to optimizing the throttle site mapping to TPS voltage on the R400D, just leaving the settings as "good enough". Ideally the TPS minimum voltage with the throttle closed should always map to throttle site 0.0 and max throttle against the mechanical stop should map to 15.0, but the TPS used doesn't seem to be aligned with the map very well, perhaps just due to manufacturing tolerances, or maybe due to inaccurate mapping.

Any throttle site can be used used to indicate any throttle position, as long as there is a continuous transition from open to closed that reflects the volume of air flowing through the throttle, it is then a matter of having the correct fuel flow values in the fuel map to reach the necessary lambda values at a specific throttle load site for a given number of revs. At idle with the closed loop narrow-band lambda sensor, my data logging indicated an oscillation when at throttle site 1.0 under certain circumstances, probably due to a bit too much fuel (compared with throttle site 0.0) causing the revs to rise above the idle value which then causes the lambda value to be rich, the ECU then tries to adjust to a target lambda which is likely 1.0, the mixture goes lean and the revs drop below the target idle value, more fuel then has to be injected to reach the target lambda again. This oscillation happens about once every 3 seconds (1/3 Hz), the oscillation frequency of the lambda sensor at idle. On my car this oscillation occurred when the engine was well warmed up (needing less fuel for idle due to lower intake air density), with the engine speed typically varying from 850 to 1200 RPM.