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I suppose it'd be too easy if I could just get a clone such as this and just plug it into existing connector, setup and it'd work?

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Should do although I'm not sure if there would be a difference between your B and the later D spec ECU. I tried the 7805 trick (Yes, it's a 3 legged beastie where you put 12V (or anything up to about 40V if you are feeling really mean) on one leg, ground another and 5V comes out of the remaining one) on a car that would cut off after 90 seconds unless a computer was connected to the diagnostic port when it would run fine for as long as you wanted. It didn't work although the 5V was applied to one of the sensors and I suspect it wasn't back feeding the rest of the system. Had we had more time I could have opened up the ECU and fitted it inside but didn't. So it might work but didn't on the one I tried it on.

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I'm going to dig out the Veroboard having just lashed out 78p to RS for a next day delivery L78S05CV, Single Linear Voltage Regulator, 2A 5 V, 3-Pin.
If the ECU is knackered, I've got little to lose!
EDIT- and it comes with a 31 page data sheet. I can have hours of fun reading that :)

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Here's the one I made (hope you've got some caps to decouple it)

enter image description here

and then wrapped it in glue lined shrink wrap but with the tab sticking out so it could be bolted to something solid

enter image description here

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Hah! You even used the same component I've ordered. Would have saved me minutes of research if I'd known that!
Using 0.33mF (input) and 0.1mF (output) electrolytics to decouple for switched loads.
Will testbed it on serial port. If it works (and solves problem) will stick it inside the ECU.

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Not having opened up the ECU box yet (sort of seemed like the last resort) but using the Landi Renzo clone pinouts diagram, it looks to me like there are 2 points (or at least 2 different pins, implying to me there's not a single rail 5v inside ECU) that need 5 volts injecting:

  1. Pin 2 on the serial port (power supply serial comm) to pin 45 ECU in
    enter image description here

  2. Pin 1 on switch (Power supply switch) AND Pin 3 on pressure switch (5v supply pressure sensor) to pin 50 ECU. Shown as spliced together outside of connector
    enter image description here

I'm looking forward to opening up a few jars of Lucas smoke once I'm let loose on this. If the ECU's not knackered already, there's a good chance it will be after I've finished surgery on it :)

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That's probably why my effort failed, I injected the 5V at the pressure sensor so probably wasn't back feeding everything that needed a supply. Seems the cure for the Photobucket disease is to do a full refresh of the page by holding down Shift and hitting the reload button. The pictures should appear when the page refreshes.

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Photobucket has corpsed completely at the moment. Can't even log in to upload to my library. Serves me right for saying it was working fine for me the other day!
I wish I had the correct pinout for my particular AEB though. The Landi one is close, but wiring colours vary and obviously being for the D version, has a lot more connected (the OBD stuff at least) where I just have empty sockets.

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Today I can see your pics again (Richard) yesterday it showed only a tiny square. (Not participating in this thread but learning)

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Photobucket's alive again. Have updated #206 above with the pinout diagrams to support my guesswork!

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Took a day out from LPG yesterday to address urgent windscreen wiper issues, except fitted new pet/ gas selector switch, just in case.
No change.
Have parts in hand now to move on with 5v supply so, after sealing plenum area and putting cover back on, sorting starter motor intermittency on blue car, back onto the LPG.
I suspect I'll bring the ECU home to do it, as I'm going to open up the tin as my office at home is a nicer environment to do electronic stuff...

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ECU in 'such as this' (Orangebean above) should work, provided the initial install was done to spec. Due to the none truly sequential nature of early ECUs (not reading any petrol injectors except front on each bank), on an older ECU you might get away with incorrect wiring on rear 6 cylinders where you wouldn't with later truly sequential ECUs. Then, when it works, there is scope (in certain limited situations) for the old ECU to deliver better results than the new one - SInce old ECUs only read Pinj from front cylinders, enrichment during acceleration for other cylinders could be adjusted/mixture enriched or leaned. On newer ECUs the adjustment only allows mixture leaning during acceleration, so, if you have very long pipe runs the older ECU could compensate for delayed gas delivery to ports by pulsing gas injectors for a bit longer, new ECU cannot.
Taught Tinleytech about this a few times, this was probably the most recent

Agreed with all points on 7805 trick, tbh I don't remember now where I connected 5v from 7805 but since it worked when I tried it I suppose must have been to serial connection. I only have one reservation on this... was it a fluke in my case, due to something unrecognised going on... e.g., an actual (communicative) connection on serial might wake some part of the main chip in the ECU, which might be the real reason for ECU working when serial connection is connected.

SImon

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I'll report back on the success (or otherwise) once I've played around!
Know if any of these are a plug, programme and play clone of my 2856?
http://www.ebay.co.uk/itm/TARTARINI-AUTO-LPG-AUTO-GAS-5-6-8-CYLINDER-ECU-110R-00-6030-67R-01-6018-/142269192031?
http://www.ebay.co.uk/itm/RANGE-ROVER-P38-4-0-TARATINI-AUTO-LPG-AUTOGAS-ECU-E13-10R-02-0676-E13-67R-010091-/152416321869?
http://www.ebay.co.uk/itm/272547031327?
Hard to find a 2856 used. Only ones I've seen have been D type, which is a bit too advanced for my system.

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Wouldn't like to say on the first one, second is an Etagas and the last one is a Prins so definitely not an AEB ECU.

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The first one is an AEB2568 but with a slight deviation due to being made for Tartarini. It is pinout compatible but uses a different cabin fuel changeover switch and the spec of the temperature sensors it uses are a bit unusual. It you got the Tartarini switch it could be made to work, just cut the usual AEB119 type switch connector off and connect the connector for the Tartarini type switch up, colour of wires all match up. The only other slight difference is in the way Tartarini systems are calibrated, they effectively have a built in shape of map for the (limited) types of injectors that can be set, so the default figures in the user defined map are therefore all zeroes and you enter plus or minus figures to deviate from the built in map (actual map is underlying/unseen map plus figures you enter),.. unlike other systems where (if you have access to the full map at all, sometimes this needs V6 software or hardware key to access) you enter numbers between 0-255 and adjust the map directly. In cases where you can't use V6 software and don't have hardware key on other systems you cannot fine tune the full map, you can only adjust 8 numbers each of which effects a block comprising 1/8th of the actual map, so before V6 software better installers (who wanted fine control) had to buy hardware keys, a different key for each brand/sticker on the front of the AEB2568 ECU. You wouldn't really need the fine control for very good results on a P38.

I have 3 different types of switch connectors wired up to the LPG ECU on my own car to allow testing of ECU's and switches.. This is particularly useful for testing how modern ECUs / firmware fair on a 6 cylinder engine (more on this below) .

No need for me to check the other two ECU's since Gilbert has already done so.

Don't forget it's AEB2568 not AEB2856...

It is very unlikely you'd have any problems using a newer ECU, and even if there were problems they would point to shortfalls in other aspects of your LPG install that you might want to put right anyway, in which case it would run better after making the changes than it could have run with the old ECU anyway.

I like to keep at least one good working example of an old type AEB ECU in stock but at the moment I only have an old OMVL one that is broken because it doesn't connect channel 3 on bank B petrol injector wires together when switched to petrol... works great on gas, but doesn't allow running properly on petrol! They prove useful for confirming install issues are due to modern AEB2568s, which seem to have issues particularly when fitted to some 6 cylinder engines possible example here, leading to another disagreement with Tinley.... I am just about to buy a complete old Zavoli (AEB2568 based) front end, trusting the seller on this that all parts are in good working order.

Simon

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Shame I've just bought a shiny new switch for the 2568 really! Wonder if LPGshop would do an exchange?!
When you say the temp sensors spec on the Tartarini are unusual, does that mean I can't use existing Zavoli ones?
Don't suppose you're planning on selling on the Zavoli front end Simon? If so, let me know!
Thanks for the info. I'll hold off buying the Tartarini eBog one until I've tried out the 5V supply theory on the existing one. Who knows, it might actually work!
While I think about it, Richard and Simon, any ideas what the current pull on the 5V rail of the Zavoli system is?

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I've got a feeling, from when I repaired one for someone, that the 5V regulator in there is a 1A version so the 2A one you have will easily be up to the job.

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Blimey- found a used, 28 day warranty, 2568 looks like C on the bay in Exeter!
enter image description here
£60 or offers
Will try a little fishing with an offer and see what happens...

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OB, I was planning on keeping the ECU in line with intention to always have a working old type ECU here but if your struggle continues I might sell to you just to help out; I am likely to get hold of another at some point over the next 6 months or so anyway. But if I were you, unless you can get one really cheap, I'd get a new version. Dunno where you got the switch, but if you go back to the same firm and say you just bought a switch, can they do you an electronics bundle but not include the switch it might work out well? All those crispy wires you'd be replacing, and you'd get a spare pressure sensor too... Or just buy a new ECU.

5v current draw won't be much, it only has to drive the few mA for the sensors.. unless it also powers the electronics in the ECU... But as memory serves there is nothing attached to a heat sink in the case, so would seem whatever combination of bits provide 5v they're not expected to need to sink much heat.. for a 7805 this implies not flowing much current. As a kid I used a 7805 and 7806 to power a BBC computer from a car battery when camping, this setup (overloading 7805 by some margin) needed a massive heat sink which I removed from some electric equipment I found down the quarry (come tip) when out shooting. I was always bringing stuff home to attempt to fix or dismantle for the components hehe.

Simon

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Thanks for the kind offer re the ECU Simon. Fortunately managed to get the 2568 C mentioned above for a great price and with a 28 day return warranty. I'm still going to try my 7805 on the old one, just for the hell of it!
Guess I'll be back to the "what software works" question for the C. I'm going to start with 6 and work backwards.
Also looking forward to the calibration, having read the manual (s) and translated from Italian English to UK English. I'm hoping that chasing that little red dot around the screen isn't quite as complicated as they make it sound!
Going to make sure that petrol side is 100% first though. No point in calibrating anything until the ECU agrees that I've been through all the drive cycles and Nano is reporting nominal results for O2 sensors etc.
BTW I'm enjoying a mental picture of you slogging over the moors with a car battery and a BBC Micro in your rucksack on your childhood camping trips!