As a kid I used to go out shooting regularly, usually in an area near local sewage works setting ponds where I'd see how far I could shoot bottles etc from (site was a dump many years ago so plenty bottles etc around). On one occasion some guys were there some distance away shooting shotguns, their Rangerover parked near them. They started shooting in my direction and laughing, likely thinking that would cause me to go away, I could hear the shot going all around me through bushes etc. So I went round the side and shot their Rangerover lights out lol.
Dhallworth txted me, he may be calling on Friday depending on whether I get this Yank pickup converted in time.
With 0.9 bar pressure I would expect even highest flowing Tartarini injectors to need to pulse for more than 3.4ms at idle, so something is amiss. Could be injector fault(s), or banks swapped (injector break plugs swapped, setting 2 banks in software would help to determine that), LPG ECU (not so much firmware but electrical aspects such as injector driving outputs) or pressure sensor problem... or could be that autocal cannot work properly because the engine is running open loop mode (perhaps due to previous attempts at autocal / running on LPG when mixture could have stayed lean/rich for too long / vehicle issue such as failed lambda probe) - autocal relies on the engine's closed loop fuelling system working properly and may continually lean or richen the LPG tuning if that is not the case. Also, the engine needing up to 6ms pinj at idle tells a story about the engine struggling to idle properly on gas (it implies higher manifold pressure necessary due to incorrect mixture on at least some cylinders).
Hope you didn't think I was being arsey or pedantic mate, just thought it better to mention to dhallworth in case it seemed he could just enter same numbers as on yours for instant fix.
Could be that his gas temp sensor hadn't had chance to warm up (either gas temp or picking up under-bonnet heat). At 78c most AEB ECUs (behind the scenes) add zero reducer temp compensation (or about -2% for 60c or +2% for 90c), at 28c most AEB systems behind the scenes will add -2% temp correction up to a max of about +8% at 80c gas and min of -8% for -20c gas). In theory LPG systems don't need any reducer temp compensation because it's only the temperature of the vapour that matters... Besides AEB based systems only a few systems have reducer temp compensation even available to setup as an option but on most AEB systems you can't turn off reducer temp compensation and can't make changes to reducer or gas temp correction (and if you could turn off reducer temp correction you'd probably need to modify gas temp compensation). To me it's always seemed AEB systems compensating for reducer temperature is in a way an acknowledgement that the gas temp sensors are almost as likely to pick up under bonnet heat as they are gas temperature.
He should have a separate reading for bank 1 and bank 2 like you've said. But I wouldn't expect it to make any difference to fuelling because behind the scenes the ECUs run as two banks anyway (all cylinders on a bank get the same fuelling as the front cylinder on that bank). Usually the only way setting one bank instead of 2 banks can mess things up is if the box 'anticipate the injection sequence' is also ticked. Still he should select 2 banks and then we can see if both banks read similar values.
Dhallworth phoned me today and said the pressure reading with the new reducer is 1.4 bar, which is a big improvement to the pressure reading with the old reducer! But he also said that during autocal gas injector pulse length goes down to 3.4ms and stays there... So I advised the 3.4ms will be the minimum pulse duration the firmware allows with injectors selected as Tartarini, so he should decrease physical pressure (if the reducer allows) and set working pressure in software to 1bar. If this doesn't work he should try selecting 'Matrix' injectors in software instead, because the Matrix setting at least won't impose a 3.4ms minimum pulse duration (although this would give mixed results with the Tartarini injectors which probably won't work very well below 3.4ms or even 4ms).. But now you've pointed out that he only has one bank selected and we can't see readings from the other bank, I wonder if he has crossed banks (injector break plugs crossed), which would mean one side of the engine got richer and richer while the other side got leaner and leaner (and could have led to the 3.4ms reading on the bank that was going leaner).
The numbers in the 'modify carb' screen are not the map, they are numbers that are added or subtracted (can enter negative numbers) to the real (underlying) map which we can't see in this version of software. The underlying map starts with a set of numbers (depending on type of injectors selected) all the numbers in the underlying map are changed by the same percentage by autocal... So numbers in the modify carb screen are likely to only be correct for the specific install for which they were entered, because autocal is unlikely to set the same numbers in the underlying map on any 2 installs (even on the same spec vehicle, even with the same spec LPG components fitted). because of variables such as petrol and LPG pressure, injector flow rates. temperatures at the time autocal was run, engine tune/wear etc. Now having said that, if we have 2 ECU's both with the same firmware, same basic settings entered in both ECU's (type of injectors and working pressure) and autocal wasn't run on either ECU then the ECUs would be interchangeable on a specific vehicle and provide exactly the same fuelling, but only because the other aspects (pressures, temps, engine itself) wouldn't change if we're talking about a specific vehicle (otherwise would expect calibration to be close but not spot on). I don't remember if autocal was run on Blueplasticsoulman's install.
Sorry to regress, I've just read the last page of this thread.
Been involved in ongoing discussions (er arguments) about EVs and LPG since before Xmas on PistonHeads. An overview of the way discussion has gone is: Someone started a thread 'EVs does everyone think they are amazing', to which I answered 'No ' and went on to discuss lack of range / long charge time / lack of chargers / cost of the vehicles / battery degradation / problems with electrical infrastructure if EV numbers increase dramatically / etc... which didn't go down very well on the pro EV thread. One poster then started an off-shoot voting thread 'Would you wait 45 minutes to fill up if you could fill up for free' but didn't mention the 45 minutes fillup would be necessary every time since this would be charging an EV. I told them I convert vehicles to LPG which prompted one guy to start the thread 'Five reasons you should never consider an LPG conversion', which kind of backfired on him when I mentioned that he had run LPG converted vehicles for 20 years, some people that I've helped on LPGforum and a guy who's Honda I recently converted joined the thread lol. There's also a '690 miles in an EV' thread, I stirred the wasps nest there by saying for any ice car there wouldn't have been a thread because any ice car could do 690 miles with none of the concerns of having to route around EV charging points etc.
It's mostly the same people over all the EV threads, and 'discussion' has been a bit silly, stale and boring for quite a while now (bit like the infamous LPGforum UKLPG thread) but I keep up with them, especially the 'Five reasons' thread.. I think that thread's proving to have more of a positive effect on how people consider LPG conversions than the negative effect that 'Tinrobot' intended. https://www.pistonheads.com/gassing/topic.asp?h=0&f=247&t=1708145&i=0
Pistonheads wouldn't allow me to use LPGC as screen-name so I'm SimonYorkshire on PH.
Edit, forgot to mention... One guy 'Maxtorque' reckons he's an engineer who was involved with the development of factory conversion LPG systems but has now seen the light and hypes EVs, predicts the imminent phasing out of ice engines, predicts easy upgrades to infrastructure would allow the population to switch to EVs. I'm fairly sure that about 10 years ago I fixed an LPG system for someone called Max who reckoned to be an engineer previously involved in development of factory LPG systems, I asked if that was him but he ignored my question.
blueplasticsoulman wrote:
Lpgc wrote:
may be an option in software to add some petrol to fuelling at high engine loads (and/or switch temporarily fully back to petrol when you put your foot down but resume running >on gas when you lift off the throttle a bit),
I think there is that option Simon. If you remember when we were setting mine up, we had a moment or two where that was happening until you tinkered with the software. I think it's under the "Erichments during acceleration" tab. Which makes sense.
I think you'll be right. Most Tartarini systems have the option but the ECU's change over the years and very early ones won't have the hardware ability to support petrol addition. Unavailable settings are supposedly (and usually) greyed out in versions of software that came out later than hardware but some combinations of software, hardware and firmware can leave unavailable settings looking available... would expect if this were the case then setting petrol addition would just provoke a full return to petrol (with return to gas when rpm falls).
Thanks Miles, I'll try to shift apps to an SD card if you reckon it's possible with the LG?
Off topic a bit, my inexpensive LG phone reports it's running out of storage space, emails no longer work on it. I haven't installed anything, I regularly download and and delete camera pictures etc from it but it came with lots of pre-installed apps that I don't use, many of which have automatically downloaded multiple updates. it's the app updates I believe have sapped storage space but it won't let me delete apps or revert to pre-update versions. A memory card wouldn't do any good as email and apps use internal storage space... Any ideas?
Does the lack of power seem just throttle related or more 50% throttle above a certain rpm? Does it seem to happen at the same time as pressure falls away?
Good luck with the heater matrix problem.
How much stick do you have to give it before it cuts back to petrol? How does it drive on LPG now?
If it drives OK on gas before it cuts back and you have to give it a lot of stick before it'll cut back, some people would be prepared to leave it like that as long as fuel trims / lambda readings are OK. There may be an option in software to add some petrol to fuelling at high engine loads (and/or switch temporarily fully back to petrol when you put your foot down but resume running on gas when you lift off the throttle a bit), where these options are available they can prevent cutting back to petrol because the reducer isn't worked as hard (or even worked at all) when you put your foot down. Not the best setup situation for an LPG system but can mean no further expense on parts and little change in running costs if you seldom boot it to the point the above options are active. You wouldn't want such options set to the point they are applied often or you'd end up saving less money by running on petrol too much.
Adding to Gilbert's point there is likely a liquid phase filter built into the solenoid in the gas feed near the reducer (it's unlikely an installer fitting Tartarini back in the day would be cowboy enough not to fit a reducer filter solenoid). I'd reckon a clogged filter unlikely to be causing the cutting back but it could, it's also possible this solenoid (or the one on the tank) isn't opening fully, though again unlikely.
Unusual to have a high pressure reading after a system has switched back to petrol due to low pressure and 3.2 bar is a very high pressure..Best case scenario - the reducer is set to 2.4 bar above manifold pressure, so when manifold pressure is at atmosphere (1 bar) when you're booting it absolute gas pressure rises to 1+2.4 bar = 3.4bar, since the engine is now switched to petrol and engine is idling manifold pressure is only 0.4 bar so diff pressure (gas pressure less manifold pressure) reads as 3 bar (3.4-0.4, not far from 3.2 bar you're seeing). Middle case - If the reducer gets too cold it can spit liquid gas into the vapour side which then evaporates in the vapour pipes and increases pressure sky high. Worst case - internal reducer fault. But it would seem your 3.4 bar reading is about right after a full throttle switch back to petrol, especially if your reducer solenoid isn't mounted directly on the reducer as the reducer will still be fed with liquid gas from the line between solenoid and reducer when the engine has switched back to petrol (so you get the 1+2.4-0.4 scenario).
Yes it'll be simpler to replace the reducer with the same model. It's an expensive model and no better than some reducers that are half the price but you probably wouldn't quite save half fitting a different model if you had to buy bits of piping etc.
Another check to do before you replace the reducer though... One of the problems is that the system switches back to petrol when you drive on gas (it''ll idle roughly on gas but switch back to petrol as soon as you put any load on the engine)? Assuming that's true, start the engine and let it warm up, switch to LPG while idling, drive the car accelerating slowly on LPG while watching the pressure reading. What happens with the pressure reading (does pressure drop away just before it switches to petrol)?
Daft question Dave but the engine was running on gas when you adjusted the reducer pressure?
It does seem the reducer rebuild didn't work out. You don't need to buy the same (now expensive Tartarini) reducer - Tartarini reducer temp sensors can be an unusual spec but there are ways around any problems arising from less compatible reducer temp sensors such as might be found on a different make reducer. .
Funny how it's possible to watch a spark jump onto your finger/hand and anticipate the electric shock feeling before the feeling has travelled up your nerves lol.
The arcing might not make much difference when running on petrol but could make more of a difference when running on LPG.
How's the weather been Dave? My most recent customer was from Lanark in Scotland, said the weather was OK on his way home until he got close to home, foot of snow there... Foot of snow before he brought his car for conversion last week too, reckons Lanark has a micro-climate lol.
There's a set of miniature relays, one per cylinder, in the older Stag ECU's. If you're getting petrol and LPG to a cylinder at the same time and injectors are OK it could mean a relay is failing to open (closed and off connects the petrol injector to petrol ECU).
To confirm this or other ECU problems you could just swap wiring (affected cylinder's petrol break wiring and another cylinder, also swapping the LPG injector plugs to match) to see if the fault moves with the ECU channel. Seen this happen on loads of Stag installs and years ago had this problem even with a few brand new Stag ECU's.
Even if the ECU cuts the petrol injector it might still have a failed gas injector output, effectively pulsing the affected cylinder's injector for a different duration to the other injectors (too long or open all the time, too short or closed all the time). You've ruled out LPG injectors, which leaves pipe runs (crimped?), wiring, ECU and mechanical (compression?) as potentials. Far more likely there's an LPG problem than compression/engine valve problem. Another thing we could add to the list of potential faults - If the reducer vacuum pipe was connected to the affected cylinder's intake runner and the reducer was leaking gas through it's vac pipe, unlikely it's been plumbed that way on a P38 though.
Orangebean wrote:
As a side issue here, but possibly related, how do you test an AEB025 MAP sensor to ensure it's actually feeding correct data to the ECU?
I mentioned one way above... When the engine isn't running the manifold reading should be very close to 1 bar (atmospheric pressure), when the engine is running and warmed up I'd expect to see around 0.4bar at idle on a P38 that runs well. Software shows gas pressure relative to manifold pressure so If there's only atmospheric pressure in the LPG pipe when the manifold pressure is reading 0.4 bar the gas pressure reading should be close to 0.6 bar and as manifold pressure increases gas pressure should drop correspondingly with manifold and gas pressure always adding to very close to 1 bar (and it's easy enough to take an LPG vapour pipe off to ensure pressure in the gas system is at atmospheric pressure), this check to be done with the engine running on petrol of course. It's only a basic check but is usually a good pointer. But some of us can just swap pressure sensors lol..
@Dhallworth
I believe the pressure sensor is a standard AEB025. If not I'd dare bet it'd be the same spec as OMVL Piro's AEB pressure sensor. If you look at the sensor from the other side where the pipes are connected, does the vacuum pipe or gas pipe attach closest to the wiring connector?
Reducer pressure adjustment is the screw in the middle of the sticky-out bit of the reducer
Valtek type 30 injectors would make for an easy and relatively inexpensive swap (but be sure to order them with 4mm outlet nozzles). Would concentrate on pressure for now, not buy injectors yet.
You could change injectors but you'd still have the issue of pressure being too high, would sort the pressure issue as the first step and then you might find injectors work OK.
Can you post pics of bits of your system (or find same bits on the net and link to them)? Would want a pic of the reducer, injectors and pressure sensor.
Reducer pressure is usually adjusted using an allen key, allen socket is accessible from outside the reducer (no need to remove anything to access it), inside the reducer the allen socket turns threads which screw a plate in/out to adjust compression of the spring which acts on the diaphragm. I'd aim for 1.5bar diff pressure as a start.Got to adjust reducer pressure with the engine running on gas.
Edit - Just noticed this crossed with Gilbert's post.
Gilbert raised another point (bit about 1.2 to 1.5 multiplier), to add to that, the LPG ECU compensates for pressure so where you have 2.3 bar where we might expect 1.5 bar we might expect your 5.5ms gas pulse for 4ms petrol pulse to rise to 8.4ms gas for 4ms petrol when pressure is only 1.5 bar [(2.3/1.5)x5.5 = 8.4], which would imply your injector nozzles are too small for 1.5bar (8.4/4 would mean multiplier of 2.1 which is outside the 1.2 to 1.5 multiplier range Gilbert mentioned), except AEB ECU's have a limited range of pressure compensation and it could be that your system's pressure compensation is maxed out (actually minned out since we're talking about compensating for over pressure). If pressure compensation is minned out it will mean the engine runs richer (or at least fuel trims will be more negative) when running on gas at 2.3 bar compared to running at a pressure that the ECU can compensate for. That's the basic theory but in practice nozzle size makes more difference at idle than pressure does because higher pressures also have the effect of slowing the speed of the injector opening.
What pressure is set in software? This is the pressure at which the ECU applies zero compensation for pressure, the range of pressures the ECU can compensate for is centred around this pressure. None of this affects the fact 2.3 bar is too much pressure for the injectors to cope with.
Diff pressure is the difference in pressure between gas pressure and manifold pressure. The fact that after engine has been off for a while your diff pressure and manifold pressure roughly add up to 1 bar suggests those readings are correct (and also suggests you may have a leak on the gas side, but a leak won't be relevant in this).
But your diff pressure goes up to 2.69 bar when the solenoids first open and to 2.49 bar when the engine is idling on gas, this is far too much pressure and because your pressure readings seem correct this suggests a problem with the reducer.
Can also see that your manifold pressure goes from 0.41 bar when idling on petrol to 0.55 bar when idling on gas.. There are 3 possible reasons for that: