Advice please!

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Pinger
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Re: Advice please!

#61 Post by Pinger » Mon Mar 09, 2020 1:08 pm

Gilbertd wrote:
Mon Mar 09, 2020 12:17 pm
I've had a couple of backfires in the 10 years I've been running it like this (both caused by me). One blew the gauze filter off the MAF while another blew the top off the airbox. The plenum is full of an LPG/air mixture at precisely the correct ratio to burn so it does give a big bang but when that bang has a choice of going straight out through a 75mm diameter inlet or fighting it's way round lots of corners to get inside the rocker cover, it's going to take the easy route.
Not an A or B choice for a flame! It can go as many places as there are flammable pathways. My observation is that you have been lucky twice over.
Gilbertd wrote:
Mon Mar 09, 2020 12:17 pm
I suspect the only reason you got a crankcase explosion was that it was before the car had been serviced and you had a lot of petrol vapour in there too. The engine isn't going to be drawing LPG/air mix into the crankcases through the PCV system as that will be at a higher pressure to expel the vapour out of the crankcase and not suck anything in.
Modern day motors pretty much run with slight vacuum in the CC. If they didn't, the PCV system wouldn't work. The driver of the flow is the vacuum below the throttle butterfly and the only inlet for the CC is the other pipe at the induction system. If it can access LPG than the CC will see LPG. We're a long way from the old systems that merely stuck a CC breather pipe into the air filter to account for blow-by.

Why though, inlet backfires? Slow burning mixture still burning when it comes time to open the valves I get - but why doesn't it all dissipate during the exhaust valve open period?

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Re: Advice please!

#62 Post by Gilbertd » Mon Mar 09, 2020 2:08 pm

Pinger wrote:
Mon Mar 09, 2020 1:08 pm
Why though, inlet backfires? Slow burning mixture still burning when it comes time to open the valves I get - but why doesn't it all dissipate during the exhaust valve open period?
I have absolutely no idea and have never really thought through the mechanics of it but I do know that a very weak mixture will cause an engine to spit back through the inlet. Having spent quite some hours setting up triple DCOE Webers with no air filters just intake trumpets on a 4.2 Jag engine, I can tell you that the trumpet with the flame shooting out of it at me was the pot that was running lean. An ignition induced misfire will also do the same thing. So a dodgy spark plug or a loose HT lead (what caused both my bangs) will do just the same. I ran my old Saab 900 down to nothing and that spat back and blew the idle control valve pipe off the inlet manifold.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Re: Advice please!

#63 Post by Pinger » Mon Mar 09, 2020 4:39 pm

Re the actual back fires. My Chevrolet has three pop-off valves and still blew the PCV pipe off of its spigot. To my mind, MAFs, injectors, and any other sensors must take a hiding when it happens. Do you use pop-off valves? I read somewhere that they have too much inertia to be of use. If so, reeds would be better. I think I saw reeds for an MB application somewhere (TT IIRC). Tempted to go that route and thinking of renewing elements of the induction system, not least because a resonator has been deleted to enable fitment of one of the pop-off valves. Resonator was there for a reason. Dare I delete a pop-off valve though?

How critical is cross-firing ie, preventing plug leads touching each other?

Back to my motor - got a little bit more done today. The throttle pedal being so low in relation to the brake pedal was annoying me so went to do something about it. Transpired that there was so much slack in the cable (no adjustment possible) the pedal was nearly on the floor (idle position) and full opening of the butterfly non existent. Now remedied, maybe this has been contributing to unpredictable auto box shifting and peculiar throttle response.
There was an inch of play to take up. Which I did by bending the kink out of the pedal so it's now straight. Back to straight I have a nagging feeling. My suspicion is that the bend wasn't there when it left Chevrolet. How else does an inch of slack appear?

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Re: Advice please!

#64 Post by Pinger » Fri Mar 20, 2020 4:27 pm

Gilbertd wrote:
Fri Mar 06, 2020 8:21 pm


Lead can be got from https://www.lpg-kits.com/, click on LPG Autogas Interface Kits at the left side menu, then the same thing on the smaller menu that appears then scroll down to AEB.
Back again...
I now have the leads from the link and have installed the appropriate drivers - but cannot tell which software I should use. Does it matter or are the systems sufficiently different to require the exact version? All I know about mine is OMVL Millennium REG matic is written on the ECU and the system was installed in 2002. There appears to be two 'versions' for OMVL Millennium hardware.

I've been driving, covered about 60 miles so far and noticed yesterday the LPG switch/gauge momentarily go from 3 green lights on the 'gauge' to 4 and the amber light on the left was flashing. Only briefly and then returned to solid amber and 3 greens. What, if anything, does that signify?

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Re: Advice please!

#65 Post by LPGC » Fri Mar 20, 2020 4:59 pm

Cross firing can cause backfires on any fuel, don't want a plug to fire on it's cylinder induction stroke.

You'll need the correct Millenium software, there isn't much difference between appearance and functionality of any AEB175 software... but incorrect software won't work (so you couldn't for example use Leonardo or Pegasso software with a Millenium ECU).

OMVL has 5 main flavours of software, the only flavour that will work with OMVL's AEB175 'Millenium' is Millenium software.

Probably too much info (none of the following OMVL software will work) - Other flavours include OMVL C (none slave none sequential but electronic pulse injection), early OMVL N (up to around software version 4 sequential slave electronic pulse injection), later OMVL N (same but after around software V4, this is the latest 'normal' type that works on AEB2568 and MP48 ECU's, now up to V6.X) and OMVL Piro (another type of sequential electronic slave ECU that was supposed to take over after N but had it's own problems and had a short production run).
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Re: Advice please!

#66 Post by Pinger » Fri Mar 20, 2020 5:25 pm

I think I've narrowed it to Lambda systems! I'll have another look later at what's on offer software wise.

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Re: Advice please!

#67 Post by Gilbertd » Fri Mar 20, 2020 5:35 pm

Pinger wrote:
Fri Mar 20, 2020 4:27 pm
I've been driving, covered about 60 miles so far and noticed yesterday the LPG switch/gauge momentarily go from 3 green lights on the 'gauge' to 4 and the amber light on the left was flashing. Only briefly and then returned to solid amber and 3 greens. What, if anything, does that signify?
As there are no baffles in an LPG tank, the fuel can slosh around all over the place causing the level at the float to change. I know mine will show less fuel if I am turning to the left or going downhill and more if I am turning to the right and going uphill, so if the level is close to the point where it will switch from 3 to 4, then it will alternate. The yellow LED flashes quickly with the red petrol on steady when it is waiting to change over from petrol to gas. The yellow LED will flash slowly, about once a second, if an error has been detected but it stays flashing until you next switch off and restart. Errors are, Lambda sensor broken, Lambda showing lean for too long and Lambda showing rich for too long (although I've never been able to find out how long is too long).

To find out what it is doing and if it has stored any errors, you need to plug in and use the software. Assuming you really do have an OMVL Millennium and not a Leonardo or Pegaso in a Milliennium box, then you need to use the Millennium software. There's various versions but I've never noticed an difference between earlier and later versions. The other OMVL softwares are for the injection systems and won't work. You'll know when you've got the right one as it is the one that will connect to the ECU and do an ECU upload.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
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Re: Advice please!

#68 Post by Pinger » Fri Mar 20, 2020 6:44 pm

Thanks Gilbert - that's me pointing in the right direction.
I'm annoyed with myself for forgetting under what driving circumstance it happened as it would be more info on the table but if it is anything of concern it will likely happen again and I can be more diligent.
I think I want to make all switching between fuels entirely manual and the software is the route to that.
Another thing I want to look at is using other software (Delphi and Wurth) via the OBD port. It should be capable of capture and store and shouldn't be able to tell reading O2 sensor data which fuel so LPG info from there should be possible.
Hopefully next week I'll have a chance to have a look. Recently my focus has been on chassis stuff - wheel bearings and brakes and the vagaries of servo assistance from the PAS pump. Yep, that was new to me!

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Re: Advice please!

#69 Post by Gilbertd » Fri Mar 20, 2020 7:00 pm

Pinger wrote:
Fri Mar 20, 2020 6:44 pm
I think I want to make all switching between fuels entirely manual and the software is the route to that.
Errm why? Set it to switch on deceleration at 1,100 rpm, leave the switch in the LPG position and only bung £20 of petrol in it every 6 months or so. Should you want to run on petrol (if you run out of LPG) then flick the switch, otherwise there's no reason to use petrol.
Pinger wrote:
Fri Mar 20, 2020 6:44 pm
Another thing I want to look at is using other software (Delphi and Wurth) via the OBD port. It should be capable of capture and store and shouldn't be able to tell reading O2 sensor data which fuel so LPG info from there should be possible.
That's fine for checking and I've done the same. The Millennium software will show you in real time what the lambda sensor and TPS is giving as an output and how that is adjusting the actuator. If you check from OBD, you'll only see exactly the same information but due to the lower data rate it will be laggy.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Re: Advice please!

#70 Post by Pinger » Fri Mar 20, 2020 8:18 pm

Gilbertd wrote:
Fri Mar 20, 2020 7:00 pm
Errm why? Set it to switch on deceleration at 1,100 rpm, leave the switch in the LPG position and only bung £20 of petrol in it every 6 months or so. Should you want to run on petrol (if you run out of LPG) then flick the switch, otherwise there's no reason to use petrol.
Current thoughts are that I don't know how the switching is currently configured and I want to know when and that it has changed over. I still have in mind what the previous owner said re 'change over once up to 30-40 mph' and don't want to dismiss what they found out. Maybe they are being overly conservative though.
To my mind, I should be able to look at the switch position and know which fuel is being used. I am though a novice in this and am flexible.
Gilbertd wrote:
Fri Mar 20, 2020 7:00 pm
That's fine for checking and I've done the same. The Millennium software will show you in real time what the lambda sensor and TPS is giving as an output and how that is adjusting the actuator. If you check from OBD, you'll only see exactly the same information but due to the lower data rate it will be laggy.
The appeal of via the OBD is the ability to capture. The Chevrolet is a big 'ol bus and takes all my attention just driving it. Reading live data under heavy acceleration is fraught with danger on the roads round here. I live alone so there's no 'second man' option and in these times, recruiting a helper isn't really an option. What I need to do next though is read from the AEB software and see what I can and cannot find out before going any further. For sure, currently, it is not at all happy above 3000rpm.

I have though restored full throttle (at the butterfly) travel and have a more responsive kick down and although I'm basing my calculation on 'between the lights' on the gauge and only circa 60 miles of running the mpg figure of 18.5mpg (fiscal equivalent of 37) is promising given the way it has been driven. More gentle running should deliver more. Early days.

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Re: Advice please!

#71 Post by Gilbertd » Fri Mar 20, 2020 11:34 pm

Seeing what it is running on is easy. If the red LED only is on, it's on petrol, if the red LED is on with the yellow on flashing (and the level LEDS lit), it's running on petrol but waiting for conditions to be right to change over and when the red LED of off and the yellow one on, it's on gas. A lot of people are cautious of running on gas all the time but the 187,000 miles on gas that my Range Rover has done seems to prove otherwise.

Once you get the software running, then it's very easy to see what is happening. You'll be able to see what the actuator does at idle and check the lambda reading at the same time. Then you can give it some throttle and see what it does when it needs extra fuel. After that a quick drive will be all you will need.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Re: Advice please!

#72 Post by Pinger » Wed Mar 25, 2020 11:22 am

A small amount of progress.
Got the correct software loaded and interrogated the Millennium ECU (but without engine running). Saved the data - or thought I had - but cannot find it on lap top so will have to plug in again.
No obvious errors but some stuff there that agrees entirely with what I'm being told on this forum - and some stuff that opposes - eg, switchover to LPG under acceleration......
Gilbertd wrote:
Fri Mar 20, 2020 7:00 pm
Errm why? Set it to switch on deceleration at 1,100 rpm, leave the switch in the LPG position and only bung £20 of petrol in it every 6 months or so. Should you want to run on petrol (if you run out of LPG) then flick the switch, otherwise there's no reason to use petrol.
.
.....It is that sort of thing that was pushing me toward complete manual control of switchover. While driving I'm lifting the throttle to enact the switchover but the opposite is required.
But, I think I understand better why you (Gilbert) set yours as you do. It allows you to start with the switch set to LPG knowing it will start on petrol and will switch as soon as you do your 1000rpm blip then close throttle. Is that correct? (I've been starting after ensuring the switch is set for petrol but there'll be a day when I forget. BTW, mine starts on LPG when warm - so no minimum rpm? I think I saw switchover rpm set at 1000rpm but I'll have to look again). If I've got this right then, that's a good set-up you have. Makes sense to me (now!)

Which takes me to switching back to petrol when LPG is low (or perceived to be low due to surge). Currently I see no reason for this (with the exception perhaps of pulling out of junctions where there is a risk of it cutting out). There seems to be a setting on my ECU of 243 (units not specified) so it is there. Not sure which direction to go here and need to do more with it but somewhat stymied by being in lock down.

The other figure I gleaned was from Delphi software which shows Vmax from TPS as circa 4.5V. The Millennium software I think showed a maximum value (ie in a settings 'box') of 4.0V. Recall I adjusted the throttle linkage to regain full butterfly travel. Might I have adjusted out what was meant to be capped at 4.0V?

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Re: Advice please!

#73 Post by LPGC » Wed Mar 25, 2020 12:04 pm

The only 'switchover' setting that will see the engine start on gas is 'start on gas', and even then it will only start on gas if gas is selected on the switch.
Other 'switchover' settings will start on petrol until rpms climb / fall past the rpm threshold that's set (switchover on acceleration / deceleration) or until TPS voltage reading falls/rises (deceleration/acceleration on TPS).

Very uncommon to fit a temperature sensor on a mixer system but if one is fitted they can also be set to wait until the reducer is above a certain temperature before switching. Fitting a reducer temp sensor and setting a temperature for switchover may seem a good idea but in practice is a complication you don't need and probably shouldn't want... Better to know you have either full manual control or that it will switch at a certain rpm (in both these cases you'll know when it's going to switch) rather than not know when it's going to switch.

They can also be set to switch back to petrol when tank level sensor reading reflects low tank level but again nobody uses this setting because the tank may still be 1/3rd full when the level sensor reading bottoms out. Better to have full range that the tank can provide and get used to knowing when to switch back to petrol yourself (or maybe set it to switch back to petrol when lambda reads lean for too long) than to set it to switch back to petrol for low tank reading and lose a lot of range.

It doesn't matter if the Millenium reads max TPS voltage as 4V because at 4v and above it will assume high engine load and instead of steering lambda to 0.5v steer lambda to around 0.8v instead (at above 4000 rpm anyway). If TPS isn't connected some AEB175's will steer lambda to 0.8v at 4000rpm and above anyway. Lambda is steered to the higher voltage when the 4 bar block TPS reading is in the block on the right. I believe there are slight differences in how different labelled (Millenium / Pegaso / Leonardo / etc) AEB175s handle TPS but they all do much the same thing.
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Re: Advice please!

#74 Post by Pinger » Wed Mar 25, 2020 1:03 pm

Thanks LPGC.
LPGC wrote:
Wed Mar 25, 2020 12:04 pm
The only 'switchover' setting that will see the engine start on gas is 'start on gas', and even then it will only start on gas if gas is selected on the switch.
Other 'switchover' settings will start on petrol until rpms climb / fall past the rpm threshold that's set (switchover on acceleration / deceleration) or until TPS voltage reading falls/rises (deceleration/acceleration on TPS).
I saw the 'start on gas' option but cannot remember if it was enabled or not. My car will start (when warm - not attempting from cold) on LPG though if the switch is set to LPG. The rpm/TPS combination as per Gilbert's is what I'll configure it to I think - but for.....
LPGC wrote:
Wed Mar 25, 2020 12:04 pm
Very uncommon to fit a temperature sensor on a mixer system but if one is fitted they can also be set to wait until the reducer is above a certain temperature before switching. Fitting a reducer temp sensor and setting a temperature for switchover may seem a good idea but in practice is a complication you don't need and probably shouldn't want... Better to know you have either full manual control or that it will switch at a certain rpm (in both these cases you'll know when it's going to switch) rather than not know when it's going to switch.
.....but for a 40C setting I saw. Don't know if that is reducer or engine block/head temp though. Your last sentence there is exactly how I'm viewing this. Configured as discussed - it will start on petrol even with the switch set to LPG - then do its switchover when rpm and TPS signals are conducive to it?

LPGC wrote:
Wed Mar 25, 2020 12:04 pm
They can also be set to switch back to petrol when tank level sensor reading reflects low tank level but again nobody uses this setting because the tank may still be 1/3rd full when the level sensor reading bottoms out. Better to have full range that the tank can provide and get used to knowing when to switch back to petrol yourself (or maybe set it to switch back to petrol when lambda reads lean for too long) than to set it to switch back to petrol for low tank reading and lose a lot of range.
So I'll need to reconfigure and delete the 'low LPG' enablement. Better I think.
LPGC wrote:
Wed Mar 25, 2020 12:04 pm
It doesn't matter if the Millenium reads max TPS voltage as 4V because at 4v and above it will assume high engine load and instead of steering lambda to 0.5v steer lambda to around 0.8v instead (at above 4000 rpm anyway). If TPS isn't connected some AEB175's will steer lambda to 0.8v at 4000rpm and above anyway. Lambda is steered to the higher voltage when the 4 bar block TPS reading is in the block on the right. I believe there are slight differences in how different labelled (Millenium / Pegaso / Leonardo / etc) AEB175s handle TPS but they all do much the same thing.
I take it that steering Lambda voltages to higher is richening the mixture. Is this to enable more power as lower load settings are on the side of weak or for some other reason (faster combustion?)? (Currently engaged in a conversation on another forum re (petrol) PE (power enrichment) that the 5.7 Vortec is set up for. Kicks in apparently on a shift down into 3rd gear (from OD top) and after 60s of high load running. All to do with cooling. I'm surprised at this level of 'fuel cooling' on an unstressed NA V8 but it is a talking point over there).

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Re: Advice please!

#75 Post by Gilbertd » Wed Mar 25, 2020 7:10 pm

Switching on acceleration can be annoying if the changeover isn't clean. You'd start on petrol and then drive off, as soon as the revs reach the changeover point the gas will be turned on and the petrol turned off (shortly afterwards depending on what delay has been set) so if it isn't a completely seamless changeover it'll cause the car to lurch. With it changing over on deceleration it will change on a closed throttle so even if the delay is too short and it cuts out momentarily you won't notice it.

If the tank has been installed correctly, the slosh should mean that even when the tank is low you won't uncover the pickup tube when pulling away, it'll be uncovered when braking (pickup tube to the back of the car). But, as you'll be on a closed throttle when braking it'll still run at idle if there is only vapour coming out of the tank. I see no reason for setting the automatic changeover when low on gas either because, as you rightly say, a bit of slosh will mean switching back far too soon. The number shown from the fuel sender is a random number between 0 and 255 and will depend on the type of sender you have whether 0 is full or empty. The same goes for the actuator number, again, 0 to 255. Fill the tank, reset the trip meter and wait until you can feel it running out (goes all sick and flat and, as long as Diagnostics are turned on in the ECU, the yellow LED will start to flash slowly) and make a note of the trip meter reading. That way you get a feel for how far you can go on a full tank and fill up when you start to get close to that distance.

As for the TPS voltage it doesn't matter as long as it goes in the right direction. The only thing the Millennium needs to know is if the throttle is closed or not closed. So it will detect the lowest reading and store that as closed, anything above that will be detected as open whether it sees 1V, 4V or 10V, it's above the stored closed voltage (usually around 0.6-0.8V on a 0-5 or 0-4V sensor). I've got mine to cut off the fuel (or at least drop the actuator down to 25 on a closed throttle when the revs are above about 1,500 rpm) which may save a tiny bit of fuel but also gives more engine braking. I've noticed that the stored voltage will alter if I'm on one of my runs through Europe where I can travel for maybe 50+ miles at a constant speed. Once up to cruising speed the throttle opening is only very small with a TPS voltage of maybe around 1.5V or less. As the ECU is seeing that voltage for a long period it memorises that as closed throttle so if I lift off slightly, the cutoff kicks in so rather than gently slowing, it sees it as a complete lift off. All I need do is touch the throttle again and as it has seen a lower TPS voltage it will immediately save that as the closed throttle voltage and not do it again until next time I do 50+ miles at a constant speed. Obviously not something you will every experience in the UK where the possibility of doing 50+ miles at a constant speed is pretty nigh impossible......

Edited to add that Simon replied and you replied to him while I was writing this so it may already be covered (but I can't be arsed to change it all)
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Re: Advice please!

#76 Post by Gilbertd » Wed Mar 25, 2020 7:32 pm

Start on gas is something you might want to use if the petrol system isn't working properly. It may be fine on a smaller engine but on a V8 with a big plenum and inlet manifold you'll find it will crank a lot longer before the gas reaches the combustion chambers. Even when set for any other start method you can force a start on gas by turning the ignition on with the switch set to gas, then switch to petrol and back to gas again. The red LED will go out and the yellow on on steady so it will then start on gas.

If it has a temperature sensor fitted, disconnect it and set the temperature to the lowest (15 degrees) and untick the box so it ignores the temperature (or just untick the box). It will always start on petrol but change over when revs are right. If I start mine on a closed throttle it will still change over as the revs rise on initial start and then drop to idle (625 rpm on a P38) but it happens so quickly if you don't look at the switch you don't realise it has started on petrol.

The woman (yes, it was a woman) that designed the AEB175 (whether badged as a Leonardo, Millennium, Pegaso, Regal, etc) knew what she was doing. As Simon said, at over 4,000 rpm it will set a richer mixture but on a low revving V8 you'll rarely hit that, the rest of the time it deals with fuelling by itself. You open the throttle and more air gets sucked in, as the fuel is being dragged in with the air a correspondingly larger quantity of fuel goes in. Don't over think it. You can set a fixed actuator opening at full throttle where you tell it what TPS voltage it expects to see at full throttle and what actuator opening you want when the TPS hits that, but I've never found a need to enable it. The mixture remains correct at full throttle by leaving it to sort itself out.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Re: Advice please!

#77 Post by Pinger » Thu Mar 26, 2020 4:42 pm

Gilbertd wrote:
Wed Mar 25, 2020 7:10 pm
Switching on acceleration can be annoying if the changeover isn't clean. You'd start on petrol and then drive off, as soon as the revs reach the changeover point the gas will be turned on and the petrol turned off (shortly afterwards depending on what delay has been set) so if it isn't a completely seamless changeover it'll cause the car to lurch. With it changing over on deceleration it will change on a closed throttle so even if the delay is too short and it cuts out momentarily you won't notice it.
Now reconfigured to switchover at 1800rpm (existing setting) on deceleration from TPS.
Gilbertd wrote:
Wed Mar 25, 2020 7:10 pm
If the tank has been installed correctly, the slosh should mean that even when the tank is low you won't uncover the pickup tube when pulling away, it'll be uncovered when braking (pickup tube to the back of the car). But, as you'll be on a closed throttle when braking it'll still run at idle if there is only vapour coming out of the tank. I see no reason for setting the automatic changeover when low on gas either because, as you rightly say, a bit of slosh will mean switching back far too soon. The number shown from the fuel sender is a random number between 0 and 255 and will depend on the type of sender you have whether 0 is full or empty. The same goes for the actuator number, again, 0 to 255. Fill the tank, reset the trip meter and wait until you can feel it running out (goes all sick and flat and, as long as Diagnostics are turned on in the ECU, the yellow LED will start to flash slowly) and make a note of the trip meter reading. That way you get a feel for how far you can go on a full tank and fill up when you start to get close to that distance.
What concerned me was pulling out of a junction while turning - especially turning right - as a safety issue.
My cylindrical tank sits transversely with the multi-valve facing rearward and on the NS. My guess then is that fuel surge (and starvation) is most likely to occur during cornering to the right. Not a safety issue as such but if it occurs how best to deal with it? Lift off the throttle, tough it out, manually change to petrol (if there's time)? Or should I consider enabling auto switchover?
I missed scrolling down the page so missed the settings for this while I had the lap top connected. Switchover lag is 0.4s - acceptable?
Gilbertd wrote:
Wed Mar 25, 2020 7:10 pm
As for the TPS voltage it doesn't matter as long as it goes in the right direction. The only thing the Millennium needs to know is if the throttle is closed or not closed. So it will detect the lowest reading and store that as closed, anything above that will be detected as open whether it sees 1V, 4V or 10V, it's above the stored closed voltage (usually around 0.6-0.8V on a 0-5 or 0-4V sensor). I've got mine to cut off the fuel (or at least drop the actuator down to 25 on a closed throttle when the revs are above about 1,500 rpm) which may save a tiny bit of fuel but also gives more engine braking. I've noticed that the stored voltage will alter if I'm on one of my runs through Europe where I can travel for maybe 50+ miles at a constant speed. Once up to cruising speed the throttle opening is only very small with a TPS voltage of maybe around 1.5V or less. As the ECU is seeing that voltage for a long period it memorises that as closed throttle so if I lift off slightly, the cutoff kicks in so rather than gently slowing, it sees it as a complete lift off. All I need do is touch the throttle again and as it has seen a lower TPS voltage it will immediately save that as the closed throttle voltage and not do it again until next time I do 50+ miles at a constant speed. Obviously not something you will every experience in the UK where the possibility of doing 50+ miles at a constant speed is pretty nigh impossible......
I saw the options but for now have left them. One thing I have noticed during the limited driving I've done is a tendency for the car to feel like it is running away on closed throttle. Long downhills at 50mph I have to check brake to avoid getting too close to the traffic in front. Ditto trying to maintain 30mph on downhills. It feels as if the the throttle is partially open but almost certain it isn't and when I do pick up the pedal, more speed immediately follows. Cruise control definitely switched off. My guess is that this just what a 2500kg truck does (I've been driving 730kg for the past few years!) with little engine braking through a torque converter - unless I'm told otherwise. I'd like to eliminate it if possible though.
Gilbertd wrote:
Wed Mar 25, 2020 7:10 pm
Edited to add that Simon replied and you replied to him while I was writing this so it may already be covered (but I can't be arsed to change it all)
Lots of good info - thanks Gilbert, appreciated.

Pinger
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Re: Advice please!

#78 Post by Pinger » Thu Mar 26, 2020 4:57 pm

Gilbertd wrote:
Wed Mar 25, 2020 7:32 pm
ser_id=1605]Start on gas is something you might want to use if the petrol system isn't working properly. It may be fine on a smaller engine but on a V8 with a big plenum and inlet manifold you'll find it will crank a lot longer before the gas reaches the combustion chambers. Even when set for any other start method you can force a start on gas by turning the ignition on with the switch set to gas, then switch to petrol and back to gas again. The red LED will go out and the yellow on on steady so it will then start on gas.
Starting on petrol it takes a lot of cranking before it fires. The reason for this I suspect is that the injectors are all grouped together and feed the ports via tubes. Filling them adequately creates delay - I think.
The 5.7 Vortec has a very compact inlet manifold lacking anything that could reasonably be called runners. Still wary though of a weak mixture backfire so if I was aiming for starting on gas I would consider another switch which when activated would permit cranking and opening of the LPG solenoids and after a short period I'd turn the key and enable ignition and with the system primed, should be rich enough to avoid backfire, Only if I ditch the petrol tank though and as the current LPG tank is a touch too big (OD) for its space without losing (legally required?) ground clearance - the initial fire-up on petrol is fine for now.
Gilbertd wrote:
Wed Mar 25, 2020 7:32 pm
If it has a temperature sensor fitted, disconnect it and set the temperature to the lowest (15 degrees) and untick the box so it ignores the temperature (or just untick the box). It will always start on petrol but change over when revs are right. If I start mine on a closed throttle it will still change over as the revs rise on initial start and then drop to idle (625 rpm on a P38) but it happens so quickly if you don't look at the switch you don't realise it has started on petrol.
I checked and couldn't see a sensor on the reducer - only a squareish box which looks to be a cut-off solenoid - though I could have got that wrong. In any case, essentially disabled as the temp setting was already at 15C.
Gilbertd wrote:
Wed Mar 25, 2020 7:32 pm
The woman (yes, it was a woman) that designed the AEB175 (whether badged as a Leonardo, Millennium, Pegaso, Regal, etc) knew what she was doing. As Simon said, at over 4,000 rpm it will set a richer mixture but on a low revving V8 you'll rarely hit that, the rest of the time it deals with fuelling by itself. You open the throttle and more air gets sucked in, as the fuel is being dragged in with the air a correspondingly larger quantity of fuel goes in. Don't over think it. You can set a fixed actuator opening at full throttle where you tell it what TPS voltage it expects to see at full throttle and what actuator opening you want when the TPS hits that, but I've never found a need to enable it. The mixture remains correct at full throttle by leaving it to sort itself out.
Enrichment at 4000rpm and over - I take it that's just taking AFR to stoichiometric for best power? No fuel cooling available with LPG in vapour form? (This is still being discussed elsewhere as the yanks never quite gave up on fuel cooling - now it's for the cats - not a cheaper radiator!)

Gilbertd
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Re: Advice please!

#79 Post by Gilbertd » Thu Mar 26, 2020 5:37 pm

Pinger wrote:
Thu Mar 26, 2020 4:42 pm
Now reconfigured to switchover at 1800rpm (existing setting) on deceleration from TPS.
That's a bit high for a V8? You could have a situation where you start and it starts on petrol, you then set off and it's still on petrol and it will change over when the gearbox changes up a gear and the revs drop. I'd be inclined to set it much lower so it changes over before you drive off.
Pinger wrote:
Thu Mar 26, 2020 4:42 pm
What concerned me was pulling out of a junction while turning - especially turning right - as a safety issue.
My cylindrical tank sits transversely with the multi-valve facing rearward and on the NS. My guess then is that fuel surge (and starvation) is most likely to occur during cornering to the right. Not a safety issue as such but if it occurs how best to deal with it? Lift off the throttle, tough it out, manually change to petrol (if there's time)? Or should I consider enabling auto switchover?
If the pickup is no longer picking up liquid, it will still be picking up vapour so the engine will run fine at small throttle openings but be a bit flat if you are giving it some welly. You'll need to try it to see how low (i.e. how many miles you've done since the last fill up) it has to get for this to be a problem (if it is).
Pinger wrote:
Thu Mar 26, 2020 4:42 pm
I missed scrolling down the page so missed the settings for this while I had the lap top connected. Switchover lag is 0.4s - acceptable?
Depending on how it has been installed, that setting adjusts the delay on the yellow wires from the ECU. However, if, as I suspect you have, the installer fitted a pair of Pitagora injector emulators, they have their own built in delay circuit.
Pinger wrote:
Thu Mar 26, 2020 4:42 pm
One thing I have noticed during the limited driving I've done is a tendency for the car to feel like it is running away on closed throttle. Long downhills at 50mph I have to check brake to avoid getting too close to the traffic in front. Ditto trying to maintain 30mph on downhills. It feels as if the the throttle is partially open but almost certain it isn't and when I do pick up the pedal, more speed immediately follows. Cruise control definitely switched off. My guess is that this just what a 2500kg truck does (I've been driving 730kg for the past few years!) with little engine braking through a torque converter - unless I'm told otherwise. I'd like to eliminate it if possible though.
Enable shut off on closed throttle to give you more engine braking. Set the actuator setting to about a quarter of the default and the revs to 1,500 or 1,600 rpm. That way if the throttle is closed and the revs are above this threshold, the actuator closes down until the revs reach the threshold. If the threshold is set too low, when you blip the throttle it can stall before the actuator has opened up enough to keep it running.
Pinger wrote:
Thu Mar 26, 2020 4:42 pm
Enrichment at 4000rpm and over - I take it that's just taking AFR to stoichiometric for best power?
It's running at stoic all the time anyway, it's just that some engines might need a bit of extra fuel under foot to the floor acceleration so it sets the mixture to match a slightly higher voltage from the lambda sensor. Under normal running, stoic will equate to an average of 0.5V (on a standard 0-1V sensor) so at higher revs and under hard acceleration it aims for 0.8V so making the mixture a touch on the rich side. Absolutely nothing to do with fuel cooling though, more to prevent a lean mixture when you are asking for the max.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


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Gilbertd
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Location: Peterborough

Re: Advice please!

#80 Post by Gilbertd » Thu Mar 26, 2020 5:39 pm

In case you don't have it, the manual for the AEB175 is on my Google Drive here https://drive.google.com/open?id=1T6Nuy ... hepjmONRJ5 (English starts on page 20) which may give you a bit more of an insight into how it works.
96 Saab 900XS, AEB Leo, sold
93 Range Rover 4.2LSE, Lovato LovEco, sold
97 Range Rover 4.0SE, multipoint, sold
98 Ex-Police Range Rover 4.0, AEB Leo, daily motor
96 Range Rover 4.6HSE Ascot, AEB Leo, my spare


Proud member of the YCHJCYA2PDTHFH club.

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