Thanks Orange b for info about recal very reassuring - I do have some problems with ignition leads etc rough running so will wait....
Nice pics Super4.
A bit of clarification on my last post...
I wasn't implying the vehicle will be running 25% rich or lean if actual pressure is different to reference pressure.
Calibration can still be perfect it software (reference) pressure is set to a different pressure than actual pressure, just that behind the scenes the ECU will be applying a more positive or more negative pressure compensation than it would if actual and reference pressures were exactly the same. I added more info on this too , explaining why installers sometimes have good reason for setting reference pressure different to actual pressure.
The info/pic more recently brought to light on Zavoli reducers (MUST having to be set at 1.2 / 1.5bat respectively for N / S reducers) agrees with what I said about Zavoli reducers, unlike the majority of reducers, being far less pressure stable if the allen key adjuster is adjusted to outside of 1.2 / 1.5bar.
The LPG ECU doesn't look directly to lambda readings at all during autocal. Autocal asks you to run the engine on petrol at a set rpm and keep your foot steady on the accelerator even if rpm changes over the whole process of autocal. Under these conditions it first runs the engine on petrol and monitors pinj, then switches to gas and monitors pinj while it adjusts ALL of the numbers in the map (every box in the map) by the same percentage until pinjs when running on petrol and when running on LPG in the ONE box that autocal used as the basis are same.
During autocal, the only reason rpm will fall/rise and/or engine load fall/rise will be due to if there is a different mixture when switching between fuels, however, autocal repeats the process a few times and as it nears correct calibration for the one map box it refers to, engine rpm and load will stay nearer to the same when the switch of fuels occurs, so by the time it reaches it's last comparison rpm and load won't shift when it switches fuels at all - So even though the box on the map that is applied during the early stages of autocal may shift, towards the end of autocalas long as the operator keeps his foot steady on the accelerator, the box that is the basis for the process won't change.
At this point autocal has hopefully set your map so that at least the box on the map that applied to rpm and pinj during the autocal conditions (fast idle maybe 2500rpm maybe 3.5ms pinj) is set properly. This is where it gets a bit more involved and refers to the shortfall in autocal's abilities... Before you ran autocal you will have entered type of injectors in settings, the type of injectors you selected set the default numbers in the map before you even ran autocal and the transition of those numbers across (rather up and down) the boxes in the map is what we refer to as the map 'shape'. Since autocal raises/lowers every figure in the map by the same percentage, autocal doesn't change the shape of the default map. The shortfall with the default map revolves around the fact that at best it's shape could only ever be an average map, where average means best attempt at suiting the average vehicle...but this default shape probably won't suit even one specific model of vehicle. So ultimately having ran autocal the user must then still change the map manually to make the shape of the map suit the specific vehicle... After running autocal, you should still do manual tuning.
TBH I don't even run autocal's anymore except on systems that demand that it is run before allowing normal operation (BRC and ESGI two such examples). It can be quicker to manually select all the numbers in the map and adjust all of the numbers in the map by a percentage (or even not a percentage, I prefer to work with linear changes because in my experience default maps have numbers too low with too great a map slope). 2500Rpm with lower than idle pinj isn't really a much seen real world operating condition, so if I change all numbers in the map by a percentage or figure at all... I might do my first ever switch to gas on a new install under similar conditions to prevent the engine stalling due to a system that at first contains only air but I'm unlikely to get as much insight into how much of the map will look from these conditions - which pretty much says it all as to the value of autocal on a lot of vehicles. P38's / injected Rover V8's are such low demand that you'd probably get away with just running an autocal, but still the results of just adjusting pressure reference and running autocal without doing any further adjustments might mean trims/mixture is less correct than when you started out.
SImon
Gosh Simon - sounds even more complicated than I imagined - for the moment, having done a good road test yesterday where it behaved as normal I'm going to move back to the original problem which caused me to dislodge the gas pipe and stop the LPG from working in the first place. This was the rough running problem but perhaps I have to move to a different topic ? On both petrol and gas as the engine heats up I get rough running and lack of power as if misfiring especially at low revs - changed the coil pack (for a second hand one) - renewed spark plugs but didn't change Magnecor leads (ten years old) yet. Nothing shows up on the basic diagnostic (not a full rovercom thingy) at my local little shed in wilderness garage, good English guy. So I'm going to play around with leads and hope its nothing to do with crankshaft timing sensors or any other sort of clever device !
Chris
You need to give it a good couple of days running on petrol so that the fuel trims can reset themselves. A mixture of round town driving and motorway. I have the Thor engine and a couple of days sorts mine out. I'm not sure if the Gems engine is different.
Once it's running perfect on petrol, then you can begin with the LPG calibration. If there's the slightest problem on petrol, it will be magnified on LPG. The idea is that the car doesn't know it's running on LPG. The LPG system is slaved off the petrol. That's why your petrol fuel trims need to be correct to begin with as the car will always try to adapt and correct the mixture if it thinks it's not right. It can correct the petrol timings, but it cannot correct the LPG system. Which again is why if your petrol side is not right and you calibrate the LPG to it, the car will try and adapt to correct itself which then throws your LPG out and creates rough running. If it's happy on petrol, it will have no need to alter anything. But, you then must ensure that the LPG calibration matches the petrol or the car not knowing that it's running on LPG, will think that the petrol is not right and try and correct itself. You'll be going around in circles.
It's easy enough to do. Just get the petrol right first. Then it's a case of calibrating the LPG and watching the petrol injector timings and fuel trims while it is running on LPG. If they just about match, you've got it right. If there's a big difference in injector timings between petrol and LPG, you'll have problems. All you'll need to do is either make the LPG mix richer or leaner.
LPGC is your man for these sorts of things. I'm just putting down what I've learned from sorting my car out.
I'm beginning to realise that the more I find out the less I understand. I thought that the petrol side of things was completely separate from the gas. And that one adjusts the gas with the software. Does the LPG software make changes to the petrol config as well ? For years it was working fine on both then some months ago I had this misfiring /rough running problem that was common to both systems and got worse when the engine got really hot here. For the last 6 weeks it has been running on petrol because of the pressure sensor pipe leak so if the petrol has to 'settle down' it surely had long enough. Having fixed the gas problem of the leak and made small changes like pressure setting from 1-1 to 1-5 and lambda 2 the car is showing exactly the same fault as before on both systems Are you saying that there are changes necessary to the petrol system and do I set these up through the LPG software and what would they be ? Sorry to be so daft !
The petrol system is separate from the gas, but the gas system takes its injection timing and duration from the petrol engine management system. Very basically the gas system takes the petrol injector timing and the gas ECU just applies a correction factor to account for the different calorific value of petrol and lpg then triggers the gas injectors as well as shutting off the actual firing of the petrol injectors
The petrol management system doesn't know, or care about, the existence or operation of the gas system when the car is running on gas, but continues to monitor lambda sensors, MAF, TPS etc and applying whatever changes are appropriate to the petrol injector timing/ duration. These changes at the petrol injectors are then read by the gas ECU, so if the gas side is not properly calibrated the petrol trims will drift off as the petrol side tries to compensate.
In that situation, when you switch back from gas to petrol, the petrol trims will be off and the engine will run poorly until the petrol side gradually re-trims itself.
In a correctly functioning petrol system, you can't change anything material. It's all done by the engine ECM and its various sensors.
Getting the petrol side right will consist of having all the sensors reading correctly, Injecting the right quantity of petrol through clean injectors at the right time and pressure and firing good sparks at the right times through clean plugs.
Ok - that seems clear - it seems dammed if you do and dammed if you don't !! I notice when I changed the setting to the V8 2 banks lambda the No 1 is up around 4.2 volts but the No 2 is much lower - less than half - is that something I can or should adjust ? On the Modify carb screen I have not touched anything and don't understand it !
So what you are saying is that if everything is right on the normal engine running petrol side it trims itself and then when one adjusts the LPG it matches up and all's well ?
super4 wrote:
So what you are saying is that if everything is right on the normal engine running petrol side it trims itself and then when one adjusts the LPG it matches up and all's well ?
That's right- but you need to sort out your rough running on petrol first. You're wasting your time twiddling the LPG side until you've done that.
Just cos you've mentioned it above, when you switched the setting to 2 banks, that gave you the facilty to balance the gas flows to each bank, similar to balancing the carbs on an old petrol engine but electronically! Not something you should do until after you've at least done an autocal and got the LPG mapping somewhere near right, which of course you can't do until you've sorted your rough petrol running.
Oh I see thanks - I jumped the gun and thought that Blueplastic was suggesting that the rough running was brought on by the Petrol system retrimming to cope with LPG problems - I know its all sort of 'chicken and egg'. I'm happy to pursue the rough running because that seems the root of the problem. Driving along the motorway on gas at 70 is not bad but any of you would sense straight away that there is a problem and it is similar to misfiring - so checking leads next .........
You definitely need to get it running right on petrol before you do anything with the LPG.
If the lambda wires are connected (and they by no means have to be connected) the readings should fluctuate regardless of what fuel you're running on if the engine is running as it should.
This line doesn't over-ride 'running right on petrol first' - I didn't realise you'd adjusted any settings yet. If it previously ran OK on LPG (and we assume LPG calibration really was OK) and the only setting you changed was reference pressure from 1.1 to 1.5 bar (and you haven't run autocal) it might be a good idea to change ref pressure back to 1.1, or calibration on LPG will be richer than before. On an older system setting 2 cylinder banks can affect a bit more than just allowing the twiddle factor for bank 2 but since the thread is probably confusing enough already I'll just say it is necessary to set 2 banks, even if there is the chance of doing so effecting how it runs on gas a little.
Simon
Simon- if I can just jump into super's thread and ask a quick question re the 2 banks thing?
You say:
"On an older system setting 2 cylinder banks can affect a bit more than just allowing the twiddle factor for bank 2"
What else can it affect?
I've just replumbed the LP side on mine (Zavoli Zeta S, AEB2856C, Matrix injectors) to achieve an equal pipe run to each of my Matrix injectors- previously had 1 pipe at 600mm long and 1 at 300mm long from the splitter.
Pinj numbers are now out of balance, as you'd expect, so need to rebalance, but what else will be affected?
Ta
Now back to super!
I think you just apply a 2nd bank corrector %. My pinj were lower on bank 2 so altered the mix on that side to compensate.
**Edit. Don't know why I bothered writing that OB. You already know anyway. lol.
As for the rough running on Super4's car, so far there is everything to suggest that the rough running may have been brought on by the petrol side trying to retrim a poor functioning lpg. That's exactly what it will do. You say it's ok at 70mph on LPG but you are piling the fuel and air into it at that point. It's when you're at idle it'll feel like you're sat on top of a washing machine. You won't diagnose rough running at all whilst you are still using the LPG. You need to just run it on petrol and diagnose from there. Even running it at idle for 10 mins on LPG will alter your trims if you've got problems.
When I got my car, it ran a bit rough on petrol, but fine on LPG. After a couple of weeks the petrol was that bad it was almost undriveable and the lpg was beginning to go the same way. I ran it for 3 days on petrol only and by the 3rd day, it was driving like it had just left the factory. I took it to LPGC and he suspected a leaky petrol injector. Turned out he was right and there were actually 2. By running it on petrol, the car was able to compensate and sort itself out but by switching back and forth from petrol to LPG as multi point does, it couldn't begin to correct and consequently only got worse.
Forget about the LPG for a few days. You know it works now. Concentrate on getting the petrol right. Check for vacuum leaks and compare bank A and B injector timings. Check the spark plugs. These things are free to check.
I bought new coil packs, ignition leads, spark plugs and an Injector to make sure I had all bases covered. In the end, it was only the injector problem that needed fixing. I bought an injector refurb kit and cleaned them all up with carb cleaner whilst clicking them on and off with a home made device and 9v battery. I only changed the coil packs, leads and spark plugs because I had already bought them on the off chance that the injectors weren't at fault as there was no way of knowing for sure until I got in there and had a look. If you have the GEMS engine it's easier to get to all of that to check it than on the Thor engine.
I'm only speaking from my recent experience. I know nowt about cars. Just what I've had to learn to solve a problem. You might just have a loose bulb for all I know.
Hi Blue all makes very good sense - grateful for the logical summary - just wish it was as simple as my Willys Jeep when I was 17 - only had to hit it with the right size hammer .........
Cool pics man!
Couple of Willy's for sale on ebay at the moment. They're not the best family vehicle though. LOL.
Nope, you find out who your true friends are though.....that was my expedition to Tunisia..........3 days before leaving a cog broke off the lay shaft in the gearbox - I took the engine out - took out the gearbox - went into London - Metamet - bought a spare lay shaft - reassembled and we were on our way by the monday ......now I can't even fix a Range Rover !!!
Simpler times.
Man made it, man can fix it! You'll get it sorted.
What a very smart young subaltern you were :)
Smarter than me, that's for sure - but it looks like we shared the kit packing skills!
Orangebean wrote:
Simon- if I can just jump into super's thread and ask a quick question re the 2 banks thing?
You say:
"On an older system setting 2 cylinder banks can affect a bit more than just allowing the twiddle factor for bank 2"
What else can it affect?
I've just replumbed the LP side on mine (Zavoli Zeta S, AEB2856C, Matrix injectors) to achieve an equal pipe run to each of my Matrix injectors- previously had 1 pipe at 600mm long and 1 at 300mm long from the splitter.
Pinj numbers are now out of balance, as you'd expect, so need to rebalance, but what else will be affected?
Ta
Now back to super!
Early AEB systems are not truly sequential, they base fuelling for all LPG injectors on only the blue petrol injector wires (normally front cylinder / same channel as gas injector A and E for banks 1 and 2). Really early systems didn't even have bank trim facility. Later AEB systems are truly sequential (just about anyway!). Some not truly sequential systems can still see firing order, earlier ones can't. Where they can't see firing order firing order is presumed but changing number of banks can change presumed firing order... But since gas injector ABCD still equate to petrol cut wires blu red grn yel, if teh system supports sequential cylinder changeover (which isn't the same as the system being truly sequential) even if gas injector firing order is changed it might still switch between fuels without engine hesitation.
Customer here now, I'll recheck I've replied properly later!
I expect you have all been relieved not to hear about my P38 problems for a while but I think we all gain from sharing information don't we. Well, having at least got it to run on LPG again by securely connecting the pressure sensor pipe on the Matrix injector and without changing any more settings in the diagnostics, I thought I would take a break from it. The misfiring/rough running was as before but I could live with that if it meant not having to think about it for a while. Today I plucked up the energy and changed the 4 Magnecor ignition leads (only ten years old) on the passenger side only for some old used ordinary ones that I kept from my Classic and lo and behold the engine is much smoother and performs more like it's old self when very hot and going up a steep hill. On the basis of this I think I will treat it to a full set of new standard P38 leads. When I spoke to the Magnecor man he told me they were guaranteed for ten years ! To bear out what Lpgc and others have said, when I started as usual on petrol; it did not want to idle so I think it had reset itself to cope with the pre condition of ignition faults etc. I should just say that as usual with my P38 I found the cruise control vacuum rubber lead, which I had replaced before, broken so I rejoined - but the whole thing is perished and despite having loads of din numbers and clever writing on it is crap quality and I suspect made by some underhand company - used it on my Peugeot as well and it just falls apart in a year or so. But here is a question for you- if that vacuum lead is broken does it affect the running ? It has been broken for much of the cars life and running problems have only recently happened.