LPG Discussion Forum

My Series Land rover Leonardo set-up has been peachy from the day it went in. Only issues has been getting Windows 10 to mount / see the AEB175 with original AEB Leonardo software. I can only get OMVL Millenium and Pegaso variants to work. And yes, some old AEB175 ECU don't seem to hold settings at power down

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I made hard-work of it, the installation work has paid dividends. Particularly now.

In the last few weeks it's played-up. And I'm flummoxed.

Be minded at all times I'm able to see what my Pegaso/Millenium is doing real-time via a WB gauge. Pegaso/Millenium nails stoich very well.

My current fault.
After between 5-20 secs as we back off the throttle to idle. I'm forced to sit at the lights revving at 1000+rpm because left at idle, it'll idle fine for 5-10, maybe 25 secs then cut out. It'll start-up immediatly and provided I gun it, meter to stoich and be dandy. Until... the next throttle off, or 5-6 seconds at idle? Not sure, seems worse when hot?

I've a heap of AEB175 ECUs; steppers; and a spare TPS and even a spare 5V power supply. Can't be too many Series Land-rovers, with 5V supplies; a TPS & Hall-effect fuel-gauge.

1. My first thought was the stepper. It's a wear item, I've got plenty - tried swapping that first. Nope same problem.

2. I swapped my Pegaso for a Millenium. Nope.

3. I thought I had an iffy TPS. Swapped it. Nope same problem.

4. Thought I must have an iffy 5V power supply to the TPS. Swapped it. Nope same problem.

5. Thought I'd try a third ECU. Just because I'd run out of ideas. Nope same problem.

6. Thought brown coil signal wire was dropping the reducer solenoid . Seems good. Soldered it anyway

Having swapped everything, I'm beaten. Why can't I move the problem, and why is it only happening at idle or very low throttle, yet is happy doing all it should at 1/4 throttle; 1000ish rpm and up?
It's stopped making sense to me. Maybe it's still the safety relay function playing-up. It would account for low revs cutting-out. I think? To eliminate that, even though the safety relay function must work, it starts easily? - my next trick is to mock in a spare AEB551-Safety Relay in parrallel to the Leo, as 'belt and braces. Maybe I have a wiring fault or the main Leo plug is iffy. Logic has left the building - I chase my own tail.

Rather than relying on the WB gauge, what is the Leo software telling you? Is it losing the rpm input for some reason? Do you have overrun shut off turned on? Is that kicking in and shutting the stepper down? Why have you got the safety relay in there, the Leo does what that is doing anyway, all you are doing is complicating things so giving more potential failure points.

Gilbert. Thank you for your words. I seem to have got lost. At the moment I can't get into any AEB175, my Win 10 laptop does that every now and then, I assume it's a Win10 issue? I'm a Mac user, and for whatever reason clicking on the App in Win 10 won't always boot. The OMVL or Pegaso application won't fire-up. I'm blind. This is not helping. I'm trying to borrow or source a cheap XP laptop.

The over-run shut-off is turned-on, the WB hits 1.50 Lambda in shut-off. .The WB gauge now indicates over-run is not kicking-in. Hence my first attack on the TPS and its 5V supply.

The fact that I can't move the fault despite switching to spare AEB175s has me still thinking I've a wiring; or AEB 175 plug issue or; a missing rpm input; TPS input. Only I can't get in via Win 10 to tell.

I agree blind-swapping stuff is just as likely to add issues. I suspect the AEB175's safety relay function - thus my plan is to test this by adding a AEB551 in parrallel next - because I can. A functioning bit of software would be a better return on effort. PCs do this sort of caper. Proficient techies fight them, keeps them in work, suspect /I need to master them.

I've got mate with a old PC coming later in the week.

I wouldn't even attempt to run comms software under Win 10 which is why I keep a very old Toughbook running Win 2000, the predecessor to XP. Got a proper serial port too so no faffing around with USB to serial adapters. Would your wide band even show if the shut was kicking in? It shows 1.5 lambda when in shut off but if it shut right down at idle, it would momentarily show 1.5 but is that because it has shut off or because it has stalled out?

@CNG I replied to your PM earlier today, this week is a busy time for me converting an American RV with 500cubic inch 8.1 litre engine to LPG with multiple LPG tanks and I'm maybe a bit behind schedule with it but I'll be up for a chat next week.

Agreed with all Gilbert's said. Also I wouldn't bother wiring in an extra AEB551, in fact (and as Gilbert said) I would remove the existing AEB551 you fitted and for the reasons Gilbert said.

Not much to add...

Did you set the correct number of cylinders and related settings (boils down to number of pulses per crank rotation) in AEB175 / Galileo software?

Are the points OK and condenser OK? If not they can cause an ECU not to read rpm correctly.

Vehicles that have a wb sensor fitted as standard usually show 1.9+ lambda equivalence during fuel cut off / over-run conditions. They wouldn't run under any sort of load, even idle, at 1.5 equivalence because the mixture would be too lean. - If it doesn't cut out due to not reading rpm, make sure it doesn't cut out due to leaning out. The usual applies - If it gets appropriate air/fuel mixture and sparks at the correct time it will run, so one of those 2 things must be missing when it stalls at idle. Obviously if it gets no fuel because an ECU or rpm safety relay decides the engine has stalled so shuts off fuel then mixture will go extreme lean (no fuel) and it will stall.

Hallelujah. Finally, finally Win 10 stops sulking and allows Pegaso to boot (and load the ECU).

It's not seeing the TPS. We're getting somewhere. Now to find out why no TPS?

Thanks gents, too much pain. I'm going to follow your words, get a Win 2000 laptop.

Sorted. A sick TPS sensor. My guess the ever iffy 5V power-supplies sold on eBay. Can't find better. I've had them as phone & sat-nav chargers and they don't last.



My guess, it popped the TPS.

Will try my luck with another type.

Next task is a proper Win 2000 Laptop.

Harder than I thought, I've heaps of USB variants - trying to source a serial interface.

Build one.....

The thought had crossed my mind -only I had it I'd find one easily. Can bread-board something, I was hoping I can find an job half-done RS232 kit.

Lookoing at this, it'd take too much time to make my own RS232. And no guarantee it'd work anyway.

I have umpteen USB versions. Going that route, I was using Macs back when, what's the ideal set-up, and something I can still get a battery for?

Biggest problem with USB versions is they are actually a USB-Serial adapter and a serial cable. So you need a driver for it. The two main types of adapter use either a Prolific chipset or an FTDI chipset. Prolific chipset works fine with something like a mouse but not reliably with comms software, you need one with the FTDI chipset for it to be reliable. At the end of the day going Serial - USB - Serial isn't the best way of doing it.

I've built 3 or 4 using that circuit in Veroboard and all have worked perfectly first time every time.

I've found and ordered a lead. CCY. Don't have an enclosure in the lead like the AEB item?

I'm going to follow in your footsteps, find a Win2000 era RS232 Toughbook or similar. Getting a laptop from that era where it's still possible to source a car-charger and decent battery might be a challenge. Looks like I'm in for nearer £200 than £100 all in.

I nearly suggested making your own 5v supply for the TPS since those you're buying are proving unreliable...

Good point, a 7805 and a couple of decoupling caps.....

I was thinking, 5V for a fuel-gauge and a TPS can only pull in the milliamps. Surely Shirley, not a struggle for something rated at 3A. I'll give it one more go.

Apart from being busy this week, other reasons I didn't mention it were because I partly expected Gilbert to say the same (so I didn't have to lol), there is the potential for the TPS to fail (short) and break the 5V supply and I wasn't sure if those other things you'd tried with the 5V regs (charging phones / satnavs) would pull too much current.. I know some of the USB specs but not all and not much about 'USB charging' specs which I believe some examples of can pull more than a couple of Amps.

But my main reason for posting again now is to say connect the negative of the 5V supply to the same potential as the AEB175 controller, i.e. connect the earth of the 5V setup close to the earth wire for the AEB175.

IIrc there's a 7805 or 5V supply inside the AEB175 itself, if so it would be possible to connect to that feed. But it would risk blowing the AEB175 as a unit if the TPS were to short, which would raise the question how do we know the previous 5V supplies blew the TPS's and not the other way around...

It would be interesting to know what's inside the 5V supplies that failed, and if the design ought to have a heat sink fitted (for 3A charging) do they have a big enough heat sink fitted...

Those encapsulated ones use a Buck converter circuit so don't need a heatsink as they don't generate heat. The top one that CNC shows is identical to the one I have in the ashtray on my car to supply a pair of USB charge sockets. Works perfectly except for one thing, it will power a satnav, dashcam and will charge an Android phone but won't charge an iPhone for some reason. Maybe an iPhone needs a slightly higher voltage and the output is lower than the threshold, I've no idea, but as I only know a couple of Apple users, I've never looked to find out why.

Finally managed to get an RS232 Laptop. I understand Win 2000 is the ideal, this came loaded Win XP Professional. Can't get AEB software to load the AEB175 ECU. Assume, as a Mac user, I've got a port No. or Baud rate wrong? Anyone know this, I googled for ever, seems it's not mentioned.