Thread: TD6 economy

I had been watching my economy slowly degrade over last year. I work 200km west Toowoomba and fuel consumption been 10.6L/100km for months now.
Yes, new air filter , etc, etc. and now 240,000km
Other day had a few hours to spare so FINALLY bolted in EGR bypass/block and a tuning box. Both these been sitting in back of car for 6 months!
Last trip out west, pleasantly surprised and hard to believe, average now 8.3L/100km.
On 100km stretch, flat going, it was sitting on 7.9! at constant 100kph. the average rise due to town and hilly highway driving.
No, I can't remember the name of the tuning box, but it plugs into sensor at end of common rail. It can be adjusted up/more power or back/economy. it cam preset about at 33%. UK supplier.
Next week I will be on trip to Snowies so will be able to give it a real test! About a 3000km round trip

These by dash display, which also underreads speed by abt 3%; checked with an external/ not RR GPS.
Power? at current setting does seem more responsive

Originally Posted by donrover0

...

I believe it is a result of signals direct from the injectors to the computer in the instrument pack where it is calculated.

.....

I agree with dougal. It is a calculated "measurement"

There is no signal back from the injector to any ECU - the injector does not transmit any signal - the injector harness is completely anologue. The engine ECU monitors the injector for closed circuit (or not) - the ECU has no idea how much fuel the injector has put in. This is why injector issues often don't throw a fault, you can have a dead piezo/solonoid allowing zero fuel in and the ECU would not know a thing - it detects something connected on the harness but has no idea it isn't opening. The injector has no mechanism of measuring volume, has no knowledge of pressure, it just opens and closes on command.

There is a "throttle position" variable that the engine ECU uses to fuel. As Dougal mentions that either comes from the sensor under the right pedal or from the ECU when on cruise control.

Most new petrol engines have a "choke", doesn't mean there is a flap in the air intake, it is just a ECU parameter constant that when invoked, gives higher fuel mix when cold.

Originally Posted by donrover0

This plug-in box is supposed to learn the current driving situation , then adjust accordingly and is always communicating with the ECM and "suggesting" a slightly different/variable map. It has 2 selectable programs.
I have yet to screw it fully back to " economy" setting, but will soon.

...

Suggesting? Hey? How does it do this. The TD6 ECU (I bet any car) does not accept map changes from other ECUs – another ECU would have to be accepted into the group, and the functionality would have to be written in the original car. AND The fuel map files cannot be updated, only overwritten – it is deleted and a new one copied in. The engine would stop while this process is happening because for a period there would be no fuel parameters at all - so this is one super magic box.

No matter what functionality is programmed into a box, if the car ECUs do not have the functionality to accept "suggestions" they ain’t going to happen.

The majority of these boxes alter the analogue signals - either between the engine ECU & injectors (hold them open longer) and/or ECU & sensor/s (modify the signal to fool the ecu into thinking boost pressure needs to be increased for example) - most of them aren’t even on a digital BUS to be able to suggest anything. The ECU has no knowledge they are there, if it did, it would fault it's arse off.

Direct from BlueSpark web site - “This enables the tuning box to modify the signals from the ECU in real time” – It is not communicating with anything, it is just intercepting, adjusting and retransmitting the analogue signal on the harness – and it is not truly ”realtime”, it can’t be, there is processing time, so any signal is delayed, only by a millisecond or 3,4,5, but it is delayed – that is the big difference between a box and remap that their site seems not to mention.

Do you really think for 149quid someone can develop a custom ECU that integrates digitally on the proprietary BUS? It would be completely different for every vehicle – just ask Black Box solutions how different the LR range is – let along other manufacturers. There is a reason remaps are more expensive – because even the “off the shelf” files are still custom writen for each model on a dyno. These boxes are just a fancy voltage regulator, with a different plug - they are far from clever.