Bio V's Dino Diesel economy L/C 100

The guy at the Volume Plus said 40% Bio although a Forum member recently said its 70%.
So I don't really know.
KEN

Meh, I started my surf up on 100% BD at camp in Dwellingup one morning at 0 degrees, it had got down to -3 overnight. No noticable starting difficulties. The BD had no additives as it was backyard type stuff.

I always top up at Jindabyne with Alpine Diesel as the car is parked at our lodge in Smiggins Holes, right in the snow.
Never had a problem by doing that.
Interestingly another bloke parked near with a diesel purchased fuel just before Cooma and he had freeze problems with his fuel system. Had to call NRMA.
KEN

Hi Jeffwa,

An adaptive ECU in a diesel? I'd like to learn more. Do you have any refs. to info on this? What measurement do they use to provide feedback to adapt to?
Ian

"The combination of EFI and Toyota's vane-type injection pump provides optimum fuel injection timing and volume.

Features of the fuel pump include a spill control valve, timing control valve, fuel temperature sensor, engine speed sensor and correction PROM (Programmable Read Only Memory). "

Site Link

Air flow sensor, air temperature sensor, electronic throttle position sensor, throttle body position sensor, crankshaft position sensor, engine speed sensor, water temperature sensor, Oxygene sensor, manifold pressure sensor, turbo pressure sensor, injection pump correction resister, first gear position sensor, oil pressure sensor, vehicle speed sensor, starter signal sensor etc etc etc.

Hi Jeffwa,

I didn't question the fact that electronically-controlled diesels use a large array of sensors to choose the appropriate rate of fuel delivery for the current engine and ambient conditions, using either the factory-standard 'maps' or ones modified by aftermarket chips/re-programming.

I questioned, and still question, the term "adaptive" and your assertion that there is some ability for the " ECU to change/adapt to the higher cetaine level in the biodiesel" Based on what measurement?

The list of sensors above includes "Oxygene sensor". Please correct me if I’m wrong, but I didn't think any diesels used exhaust gas oxygen (EGO) sensors. Petrol EFI engines use EGO (or "Lambda") measurements to provide real-time feedback on the accuracy of the air/fuel ratio and "adapt" the standard maps accordingly. Also, they use knock sensors to alter the ignition timing and hence to "adapt" to fuels with different octane ratings (e.g. normal Vs premium unleaded).

EGO is a meaningless measurement on a diesel, as they always run a lot of excess air. And a "knock" sensor would have little value in a compression-ignition engine, I would think. So, my original question remains: what measurements/sensors are used to provide this "adaptive" feedback and what does the ECU do with the information?

PS: Apologies for Ken for going OT.

Well seeing as you obviously know a lot more about this than I do, you can answer my question. In the Toyota Service manual for my engine it states this (as quoted above) "correction PROM (Programmable Read Only Memory). "

What is that?

Can you also please explain to me (I have never understand how or why this happened) why when I changed from 100% dino diesel to 100% Biodiesel my fuel economy dropped (as reported above). After I had been working on my car and had my 3 battries disconnected for over an hour, my fuel economy suddenly and very noticably improved to slightly better than what I was getting from 100% dino diesel previously. I also had a perceived increase in low down torque and this cannot have been a plasebo effect as I was not anticipating any change as I had not disconnected the batteries for any other reason than to access the area I was working on so was not expecting any change, I ended up trying to think back to what I had done that could have improved the power. Seeings as I was only wiring up headlights and spotlight relays at the time, that was the logical conclusion.

If it's not the ECU managing fuel and or timing differently, what is it? It must be somthing. At the time I was doing identical trips each day in the same ambient temperatures and was filling the 4wd up with a hand pump in the garage, so the fuel results would have been pretty accurate.

Hi Jeff,

I don't claim to know more than you, I'm just asking you to back-up your own claim with facts.

"correction PROM (Programmable Read Only Memory)." I don't know what it does exactly in the Toyota system but I think the pertinent words are "Read Only Memory" - it is programmed at the factory and can only ever after be READ, never written to. So, is would not be possible for anything to change or "adapt" the program in it while the vehicle is in service.

I cannot explain your experience with your bio-diesel after disconnecting the batteries, but I don't doubt your account. Just a vague theory: perhaps your ECU had detected a momentary fault with one of the standard sensors at some time in the past and "locked out" that function? (Just for example, say it had reverted to "fixed" timing or some other "fall-back" setting.) Perhaps your disconnection reset the ECU fault memory and when you started-up all was again working correctly, including the previously "locked-out" function? As I said, just a vague idea and I can't prove anything one way or another.

But, unless someone more knowledgeable can tell us for sure, I remain of the opinion that current diesel electronic control systems are not "adaptive" to fuel characteristics.

Acutally a ROM is Read only memory, Programmable Read only memory is short for erasable reporgammable read only memory or EPROM.

All ROM's are programmed to start with, that's how they get that way.

Perhaps the Eprom is only programmable from an external source, but I coulnd't say for sure.

I would have thought that if I had an ECU fault my engine or transmission lights would have lit up to notify me that a fault code had been reported?

We're getting a long way OT here but...

"Acutally a ROM is Read only memory, Programmable Read only memory is short for erasable reporgammable read only memory or EPROM." - Well, I think we're both right to some extent. There were originally 'once-only' PROMs (not used much any more, I believe). Then came EPROMS which were erasable by exposure to ultra-violet light. Next came EEPROMs (Electrically Erasable ROM) which, as it says, can be erased and re-written competely electrically. So I suppose (but my electronics knowlwdge is not good nough to be sure) an EEPROM could theoretically be 'updated' by the engine ECU in service. But an EEPROM is non-volatile memory, so it wouldn't be 'reset' or 'wiped' by having the batteries disconnected. AFAIK, EEPROMS will retain their contents for years, unpowered.

"All ROM's are programmed to start with, that's how they get that way." Agreed. I said the same thing.

"I would have thought that if I had an ECU fault my engine or transmission lights would have lit up to notify me that a fault code had been reported?" Yes, good point. Said it was just a vague idea. So I've now got no explanation for your experiences with bio-diesel. But I'd still welcome any info from those who know for sure whether your vehicle's system has any 'learning' ability and what inputs drive that ability.