Setting up a Stag L Plus

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Gordonjcp
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Setting up a Stag L Plus

#1 Post by Gordonjcp » Mon Feb 10, 2020 10:13 pm

Hi folks, long time no post. I thought that since it's a specifically gas question I'd post here rather than the Pub ;-)

The OMVL Millenium LPG controller in my P38 recently entered an Extreme Failure Mode and while I've bodged it enough to switch the gas solenoids on I really could do with replacing it. Since no-one seems to have it or an equivalent in stock I picked up a cheapy Stag L Plus controller which looks like it does a similar job but is adjusted with a screwdriver rather than a laptop.

It's got a stepper with a power valve on, and a couple of dipswitches to set. The instructions say to screw the power valve out a quarter of the way, then set the dipswitches so it holds the stepper at 200 steps, then adjust the vapouriser so that you can see the lambda switching at idle and the power valve so you can see the lambda switching at 3000rpm.

Here's the question - how could it be switching if the stepper is locked at 200 steps? Are the instructions wrong, or maybe just a bit mistranslated? What am I missing (apart from a working Millenium)?
'97 Range Rover P38, GEMS, OMVL Millenium controller, R90E

I have read the whole Toolless thread.

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Re: Setting up a Stag L Plus

#2 Post by LPGC » Tue Feb 11, 2020 12:23 pm

Hi Gordon,

The Millenium is an OMVL badged AEB175, any other AEB175 will slot in it's place and work properly, such as Pegasso, Leonardo, etc. should be able to buy one of the others if a Millenium isn't available. The stepper motors and wiring looms are all the same for AEB175's too, though possibly with the exception of Tartarini badged stepper motors (and definitely Tartarini Tech99 etc steppers are not compatible with AEB175s).

With AEB175s you can limit the range of stepper motor movement, so for example could set it to close to a minimum of 40 steps open and to open to a maximum of 110 steps open in which case the number of steps would be limited to 110-40 = 70 steps, and with most AEB175s you can set one minimum/maximum for idle conditions and another min/max for off idle conditions.

But with the Stag you can't see readings (stepper position etc) on screen, so it seems the suggestion is that you tune it by limiting the range to 0 steps at 200 position (fixed position for the stepper motor by setting the dip switches), then set the vaporiser to give good mixture with the stepper stuck at 200 position. At this point with any luck you'd effectively have a fairly well tuned open loop mixer system (with the stepper locked at the 200 position it's the same as having a manual valve locked at one position)... So then if you set the dip switches to allow the stepper motor to change position you should have a fairly well setup closed loop system. Another possible meaning for 'hold the stepper at 200 steps' could be to limit the stepper's range to 200 steps but I think the former meaning/explanation is more likely.

There are quite a few simple controllers that don't have a computer/screen interface that are set up similarly to how I've just described... the difference to setting up a Millenium boil down to not being able to see stepper motor position (no interface/screen).
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Re: Setting up a Stag L Plus

#3 Post by Gordonjcp » Tue Feb 11, 2020 3:54 pm

The problem with the installation on the vehicle is that the wiring loom is crumbling, and it's damaged the ECU. I can't find anyone that's actually got the kit in stock right now.
'97 Range Rover P38, GEMS, OMVL Millenium controller, R90E

I have read the whole Toolless thread.

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Re: Setting up a Stag L Plus

#4 Post by Brian_H » Tue Feb 11, 2020 6:00 pm

Gordonjcp wrote:
Tue Feb 11, 2020 3:54 pm
The problem with the installation on the vehicle is that the wiring loom is crumbling, and it's damaged the ECU. I can't find anyone that's actually got the kit in stock right now.
I'd give Tinleytech a try if you haven't already - might be better to either ring or email them to ask as it may be they just don't have it listed on the website as a separate item. They have other AEB 175 bits listed. Though the complete stag controller with loom from them is fairly cheap considering whats there.

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Re: Setting up a Stag L Plus

#5 Post by Gilbertd » Tue Feb 11, 2020 7:25 pm

I've got a complete Leo loom and a dead ECU. The problem with the ECU is that it does everything you expect it to, connects to diagnostics but refuses to change over. It's had a complete reset and been programmed from scratch but still no joy. You're welcome to it if you like if you can get hold of a replacement ECU (or fix this one).

Or there's this https://www.ebay.co.uk/itm/LEONARDO-AEB ... 3754012934
or https://www.ebay.co.uk/itm/Leonardo-AEB ... 4128779220
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: Setting up a Stag L Plus

#6 Post by LPGC » Tue Feb 11, 2020 7:38 pm

The relay has probably burned out in yours Gilbert?

I'll probably have a few new looms... in the past it's been worth me buying complete electronic kits (ECU, loom, stepper and switch) rather than just buy odd ECU's and steppers for repairs.
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Re: Setting up a Stag L Plus

#7 Post by Gilbertd » Tue Feb 11, 2020 7:45 pm

That would be good as one day I intended building a test rig so I could test out ECUs, switches, steppers, etc and wouldn't be able to without a loom. However, if it can help Gordon out, then he's welcome to it rather than fit some dodgy Stag thing.
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: Setting up a Stag L Plus

#8 Post by LPGC » Tue Feb 11, 2020 7:50 pm

I'll have to do some digging to find one then ;-)

TT are showing Bigas Pegaso's in stock. But now Gordon's bought a new Stag ECU maybe he might as well just use that? Like you I'd prefer the screen interface, though there usually isn't much difference in practice as most single point closed loop systems that don't feature an interface link to a PC at least have LEDs etc to show lambda lean/rich etc.
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Re: Setting up a Stag L Plus

#9 Post by Gilbertd » Tue Feb 11, 2020 8:36 pm

On my car the label on the ECU says it's a Pegaso but someone has written Leo on it in felt pen and only the Leonardo software will connect, the Ascot, has a Millennium that will only talk to the OMVL software. the dodgy spare I've got says it's a Millennium too. I always used to keep a spare just in case but I lent that to someone who needed his car and was going to buy a new one from TT and let me have that. Never saw him again......
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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Gordonjcp
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Re: Setting up a Stag L Plus

#10 Post by Gordonjcp » Sat Feb 15, 2020 12:16 pm

I did look on Tinley's website but they didn't appear to have any single-point ECUs or looms in stock. I figured for the 40 quid including postage for the Stag L kit, even if it was shit I could use it for parts - it was half the price of a new Millenium loom alone from eBay and roughly twice the price of just the connectors!

I'm still tempted to devise my own controller, since I never really had the Millenium working well. It was either overfuelling like crazy in high speed light throttle conditions, or lean as a vegan's dog at idle. How Hard Can It Be...?

I got about as far as fitting the Stag's combined stepper and screwy-in power valve yesterday before the horizontal sleet came on. Today the sleet is merely vertical but it is twice as heavy, so I think things can wait.
'97 Range Rover P38, GEMS, OMVL Millenium controller, R90E

I have read the whole Toolless thread.

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Re: Setting up a Stag L Plus

#11 Post by Gilbertd » Sat Feb 15, 2020 5:01 pm

I had similar problems getting the Millennium on the Ascot working properly. It's down to the GEMS 5-0V lambda sensors even though it will work after a fashion if you set them in the software. I ended up locking the actuator default setting (but still allowing it to move 20 or so steps either side of the default) and using the Millennium output to send a 5V square wave to the petrol ECU.
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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Brian_H
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Re: Setting up a Stag L Plus

#12 Post by Brian_H » Sat Feb 15, 2020 6:04 pm

Well you've got it now, so might as well try to use it, but there is a couple of them on here along with the Stag you already have (ecu and loom, but at twice the price of the Stag one listed plus the VAT)
https://tinleytech.co.uk/product-catego ... l-systems/ The Leo is out of stock, but the Bigas and OVML Millenium appear to be in stock, although the later does say you may get a different AEB 175 in place of it.

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Re: Setting up a Stag L Plus

#13 Post by LPGC » Sun Feb 16, 2020 8:26 pm

I did have a bit of a look around for an AEB175 loom but didn't find one.. even though I'm sure I must have some somewhere! But if it helps any of you lot out I'm happy to buy another AEB175 setup and give you the loom so I can keep the stepper, ECU and switch for spares.

Funny moment the other day.. A guy had booked in so I could have a look at his '1973 Jeep with a carb LPG system' because the LPG system had stopped working for a while (when he had a busted radiator) and a mechanic had told him it had stunk of gas when he tried turning it on. When this 1973 Jeep with a carb arrived it turned out to be a P reg 1996 4L Jeep with Stag sequential ECU, MJ reducer and Rail IG injectors! It needed calibration but the only reason it will have stunk of gas would be because the reducer will have frozen up and spitted liquid gas into vapour pipes when coolant level was low due to the busted radiator he'd had replaced by the mechanic. The owner still couldn't see how it was a 96 model not 73 model but went away happy having being given the LPG system's all clear and misfire under load (due to bad calibration, running too rich at high load) sorted.

Said this before... It's seemed to me on numerous occasions that under certain conditions P38 ECU's will pull their own lambda signal wire voltage (open loop cold start, high load, or error condition.. some error conditions can see the engine revert to open loop at idle but still run closed loop off-idle). If pulling lambda signal voltage were to occur with a closed loop single point system fitted it would of course effect mixture when running on LPG (because the AEB175 etc will see the pulled voltage rather than actual lambda voltage). But only if the lambda signal wire hadn't been cut by using the purple wire, if the purple emulation wire is employed and lambda signal wire cut I don't see why an AEB175 would see the pulled voltage or have mixture effected.

Had to work today (Sunday) to convert the engine on a Saab 95 Turbo, the owner's left it with me to convert while he's on holiday but I have another car coming in to convert on Tuesday and the Saab's tank won't arrive til tomorrow (Monday). Finish the Saab tomorrow, start the other job Tues then have lots of repairs customers coming Thurs and have to fix the LPG system on a ski boat near Lincoln on Friday... hope the weather's good on Friday or it's gonna be cold on the water hehe!
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Gilbertd
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Re: Setting up a Stag L Plus

#14 Post by Gilbertd » Sun Feb 16, 2020 9:32 pm

LPGC wrote:
Sun Feb 16, 2020 8:26 pm
Said this before... It's seemed to me on numerous occasions that under certain conditions P38 ECU's will pull their own lambda signal wire voltage
My ex-plod has got a standard 4 wire 0-1V lambda sensor in the RH downpipe purely to drive the Leo (which meant I had to get a boss welded into the downpipe before fitting a new exhaust) so have never had the problem on that. But my second one, the Ascot, has a Millennium wired to the factory 5-0V lambda sensor. I found that it stops giving an output at idle so sits at 5V. Doesn't bother the petrol system as it runs open loop but it screwed the Millennium completely. As it saw 5V it read that as lean so opened up the actuator which shifted the default higher and higher until the default was up to about 230 when running at closed loop under normal driving it needed to be around 120. So I locked the default at 120 with the limits set to +-20 steps. Used the Purple and Grey wires to intercept the lambda signal and then set the Millennium to send the petrol ECU a 0-5V square wave to the petrol ECU. That way the petrol ECU thinks every thing is fine when running on LPG so the trims don't drift off and the default on LPG stays where it wants to be and doesn't drift off. I've thought about using a changeover relay so I can feed the square wave to both of the petrol ECU lambda inputs then there'll be no danger of the trims staying good on one bank but drifting off on the other but haven't got around to it yet.
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: Setting up a Stag L Plus

#15 Post by LPGC » Sun Feb 16, 2020 10:04 pm

On the Ascot, I don't think it's supposed to stop giving an output at idle (which will prevent it idling closed loop on petrol too) because they're supposed to idle in closed loop mode, like I said on thread it may be having it's signal voltage pulled due to detection of some error condition. Your workaround will work fine and may be less hassle than trying to prevent the error condition if the error is due to e.g. fuel trim drift due to running the single point system. Purple wire lambda emulation can help prevent OBD errors when OBD just wants to see fluctuating lambda voltage but can't help fuel trim drift (except for allowing you to decide whether to eventually steer trims to full lean or to full rich)... You'd need something like an AEB426 wired to lambda and OBD to steer fuel trims to zero when running on LPG to prevent some errors when running a single point system but I don't think AEB426's and similar will work on a P38 (except for maybe the last of line 2001+ models with EGR and greater OBD2 compliance).

Not to worry about petrol idle closed loop operation since you run most of the time on LPG... But I can't understand why the LPG system doesn't see actual lambda voltage if you've broken the signal wire to use the purple emulation wire. If you've wired in the purple and cut the lambda signal wire since setting a locked default and small stepper range for idle conditions in the Millenium it might be worth setting a wider range of stepper movement for idle to see if lambda responds properly and closed loop operation on LPG is restored now you've cut the lambda wire?

Although I haven't found an AEB175 loom I'm happy to buy another AEB175 setup and give you or Gordon the loom if it'll be of use? Gordon called me on the phone a few days ago (before he posted on here), I told him then I'd have a look for a loom.
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Re: Setting up a Stag L Plus

#16 Post by Gilbertd » Sun Feb 16, 2020 10:20 pm

It may be pattern lambda sensors or just the way they work on the GEMS engine but on both if I check the lambda output it always goes to 5V at idle and open loop. It only starts giving an output once the revs are up. If I let the Millennium read from the lambda sensor without the default locked, every time I sit idling at a set of lights, the 5V signal says it is running lean so it opens the actuator and progressively shifts the default higher and higher as it tries to tune. By locking the default and restricting the over and under steps, i responds to the lambda output when running normally but doesn't try to adjust the default so, at worst, it is marginally rich at idle but correct the rest of the time. Come MoT time I can reduce the over steps to 0 and give some really impressive emission figures.......
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: Setting up a Stag L Plus

#17 Post by LPGC » Mon Feb 17, 2020 11:31 am

I've definitely seen P38s (you reminded me this would be Gems) run closed loop off-idle but revert to open loop at idle... though IIrc I've usually managed to get them running closed loop at idle too. I generally regard open loop idle on a warm engine as a limp home type strategy on just about anything fitted with a lambda probe that has more than a single wire (just the signal wire, no heater circuit etc).

You know more about P38s than me though! But I can remember years ago on a few different Gems seeing this and managing to get them running CL at idle, had a multimeter connected to the (iirc again) orange and blue lambda signal wires for B1 and B2 front probes at the ECU, had battery disconnected for a while, reconnected the battery then started the engine and held a fast idle while watching lambda flick, gradually reducing rpm while keeping lambda flicking. Besides pattern lambdas I wonder if there's aspects concerning TPS readings? / Fuel trims due to running the single point system? In the early days of fitting sequential systems on Gems I remember wiring to the orange and blue lambda signal wires, selecting 5>0v lambdas in OMVL Dream software and watching lambda voltage flick at idle..
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Re: Setting up a Stag L Plus

#18 Post by CNG » Tue Feb 18, 2020 10:23 am

I read this with interest. Looking to go 'closed-loop' next.

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Re: Setting up a Stag L Plus

#19 Post by Gilbertd » Tue Feb 18, 2020 5:42 pm

Go for the AEB 175 (aka AEB Leonardo, OMVL Millennium, Bigas Pegaso), easy to set up with lots of options compared with some of the other controllers on the market.
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: Setting up a Stag L Plus

#20 Post by CNG » Wed Feb 19, 2020 12:35 am

Thank you. When I get my open-loop nailed will do. I count 3 x Leo which tells it's own story... Used ECU seem easy to find too.

Are the steppers generic?
Will AEB software run them all?
Do they all require same data cable?
Is the loom easy to get?

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