Not long before around 10 years ago most AEB systems didn't feature sequential changeover, also instead of taking petrol injector pulse readings on every channel they would only take readings from the blue wires (front cylinder on each bank) and then the rear 3 cylinders on each bank would all get the same pulse duration as the front cylinder (except for any adjustments due to acceleration enrichment, which was calculated by the LPG ECU).. So an older install could have red / green / yellow wires all mixed up with no consequence on how the vehicle ran on LPG but if a newer ECU was later fitted in place of the old ECU (using same wiring) then the LPG injector pulses wouldn't match at least the order of petrol injection pulses, usually affecting at least smooth idle.

Is the 2.5ms at idle measured when running on petrol or gas? Does it stay the same when you switch fuels? What is ginj when pinj is at 2.5ms? If you drive flat out on petrol, what is the maximum pinj?

Simon

Lambda sensor setting in LPG software won't make any difference to autocal, as said earlier the only reason for the connection at all is to allow the installer to see lambda voltages on screen multimeter fashion, the LPG system doesn't take any notice of lambda readings other than displaying them on screen.

Biagotti Fast is the injector setting you want.

Unless your engine is running closed loop autocal has no chance of succeeding.

You also need to have injector routing correct, i.e.each LPG injector sends fuel to the engine cylinder that it should, so if your LPG petrol injector wiring is blue red green yellow respectively for cylinders 1357 the LPG injectors that fuel those cylinders should be ABCD respectively.

Set overlap to zero... Though stumble on changeover is most often due to incorrect routing and/or LPG calibration - If routing is incorrect and changeover is sequential (thus switches each cylinder separately a brief time apart) then when it turns off petrol to a cylinder and is supposed to start sending gas to that cylinder, what happens is that cylinder gets no fuel at all but another cylinder gets both petrol and gas, result is a misfire on 2 cylinders which will occur at least twice during changeover, and this is if routing on 2 cylinders is mixed up (the minimum possible besides no mix up) , it will be worse if routing is more mixed up than just 2 cylinders. Even with sequential changeover set, the engine can run OK with some mixups with routing, because when switchover is complete all petrol injection is off and all cylinders run on LPG. Depending on ECU firmware version and software the software may have facility to aid checking routing. Incorrect routing would also mess up autocal.

Which version of software are you running? Did you 'Reset the ECU' before running autocal? Did you adjust the pressure setting? When fully warmed up and idling nicely on petrol, what pinj readings are you getting?

Instead of running Autocal, try unticking the 'sequential changeover' box for now and setting all numbers in the map to 140.

Simon

Locks might otherwise be useful for practising jumps? Similar speed limit to rivers... I've skied up the Ouse a long time ago, fishermen wave and you wave back lol...

I still need to pull my finger out and see if I can fix my old speedboat's 3cyl Mercury 70hp 2 stroke engine circa 1982. I rebuilt the powerhead, rebore and new pistons (a pain because the cyl head isn't removable so pistons go in from the crank end and the design is such they're all supposed to go in at the same time while attached to the crank - without the special tool I managed 2 at the same time attached to the crank then attached the 3rd bottom end with the crank just off the main bearings), rebuilt the 2 carbs (yes it's a 3 cyl with 2 carbs), yet it still hardly ever runs right. 2 Stroke fumes didn't bother me much as a kid, they do now, in fact I don't like anything about 2 strokes and especially not messing about with fiddly needle bearings... I've thought about ripping the powerhead off (again) and seeing if I can graft on a 4 stroke car engine instead!

Have seen a few inboard engine'd boats with engine coolant to raw water heat exchangers (engine runs pressurised coolant similarly to a normal car) but I think raw water still runs through the marine special exhaust manifold. Marine exhaust manifolds are another rot spot, not far off the price of an engine and are more difficult to pick up second hand than engines.

Cast iron welding specialist?

Paint it, that'll stop the rust from the outside ;-) A sealed system, especially one that includes something to extract water from it's internal environment, isn't going to rust from the inside? But yeah, if the bit only costs £30odd quid change it. still dunno how much one for the mk2 would cost these days... and considering every bolt on the mk2's tend to seize up including those holding the AC system together I'm not sure I'd want to risk damaging a pipe etc which would then make it necessary to replace other hard to come by and expensive parts of the system.

I didn't know R12 and R134a were similar enough that a universal gas would be possible.

First things first, you will need to remove the brass nozzles from the injector rails (4 on each rail, probably 12mm or 13mm spanner to remove them) and drill the jet in them out to 2.5mm.

The lambda setting won't make any difference to how the LPG system responds but since your system is wired to lambdas the correct setting will show lambda voltage on screen - it is just a facility to allow the user to monitor lambda voltage and is used for nothing else.

OB explained the bank 2 trim. At this point we (or at least I) don't know if your LPG system is wired so that what the LPG system sees as bank 1 is what the petrol system sees as bank 1 or bank 2, adjusting the bank 2 trim could effect what vehicle OBD reads as bank 1. If you have an OBD scanner it can be quite easy to tell if LPG bank 1 matches vehicle bank 1 - In OBD find which bank has the highest trim (ltft+stft), this should be on the same bank that shows the highest pinj in LPG software and adjusting bank 2 trim should mostly effect the vehicle's OBD bank 2 figures. Knowing if LPG bank matches petrol bank can avoid wasting time, because if you set calibration (without using the trim facility to start with) a trim to keep fuel trims correct for bank 1 but the LPG system is wired so it's bank 1 is actually petrol bank 2 and then you realise that you have to set a bank trim, what you'll have to do is adjust the full map and set the bank trim instead of just adjusting the bank trim. Don't set a bank trim from the outset, at least not until injectors have bedded in a bit, and don't calibrate with a bank trim set except as a last resort... need to use excessive bank trim can point to other problems that should be investigated first.

Simon

blueplasticsoulman wrote:

Well I'm glad you're all pleased that I fixed mine. :-)

Pleased already Chris, even more pleased it it's still working in a couple of weeks lol

I wouldn't advise anyone to use the DIY kits if the system wasn't already partially charged - for starters it wouldn't be worth it because you'd need a couple of bottles for a complete charge and that'd cost more than a pro's price, so I think with the air and moisture points factored in the pro method becomes a no brainer for anyone who's had a holed R132 system unless it'd be too inconvenient to visit a pro... but for a top up the bottles can work out cheaper and be more convenient, probably get a few top ups out of one bottle. In these parts Charlie Brown's (there's a chain of them) regas on a no improvement no fee basis, they measure before and after vent temps and if after temp isn't at least a degree colder you don't have to pay. I had a similar discussion to this with my son the other day, his old Mondeo's AC was working a bit but not nearly as well as it had last summer and he reckoned he could tell it wasn't dehumidifying the cabin, he decided to pay £45 for Charile Brown's to do it after considering that his system was probably holed for a long time until he fixed it (scrapyard compressor, condenser and dryer) last year, so a complete discharge and recharge might help clean any crap out of his system and swap some oil for new. However, I did charge the ML up from so low the clutch wouldn't engage using a DIY bottle because I bought the ML at the last minute before using it to go on holiday and didn't have time to visit Charlie Brown's.. One bottle got it working, though I knew one wouldn't be enough to properly fill it. Simple test before attempting to charge that'll at least tell if the system is attempting to hold pressure, see if there's any pressure in the system by depressing the valve on an AC port, easy test to see if the clutch is going to work is to wire it straight to battery, can then tell if the pump is seized or noisy... Only bits now without having had a rudimentary test are the pressure switches, heat sensors and control electronics.

I had the Granada with AC in 1990 when I was 19/20... Back then it was almost unheard of for cars to have aircon except for the likes of prestige stuff and Yank imports, maybe around 1% of mk2 Granadas will have had it. I knew the theory on how it worked but there was no internet, little info available on the subject, main dealers quoted ridiculous prices, indi-pros mostly worked on office AC and didn't know what parts the mk2 would have without 'Bring it in, we'll have a look and probably have to adapt a dryer and pipework to suit, you definitely need to change the dryer or it won't work', any part of at a silly price. I think a lot of people back then didn't know what AC was all about, the term could give the impression of clean air not necessarily cold air, even people who knew it cooled the car probably wouldn't have expected it to cool it by much unless they'd experienced it.. I remember it being an unknown to my mate until a few years later when he got in my AC'd Scorpio, then he said his next car would definitely have it. I wish I'd known a bit more about AC in 1990, especially that propane could substitute R12... Can picture myself rigging up something to try to purge the system of air, maybe bleeding lots of propane through the system while the engine bay, vehicle interior and all AC piping was hot... I would have thought that would just about cover it just leaving the filtering in question, but I'd have rather just trust the existing filter than fork out a few hundred quid in 1990 to change it, reckon filter would still filter even if the bit that takes up water was knackered? I'd probably take the same route today on an R12 system because few AC pros seem geared up to work on R12 these days?

I fixed an R132 system that had a corroded alloy pipe on a Pug306, was corroded by electrolysis where it attached to the metal front cross member and would have cost a fair bit of money and time to fit a new pipe because it was a long one that ran all the way through the bulkhead (dash out job). Fixed with a flexi pipe I had an hydraulics firm make up, proper AC fitting at one end to connect to the condensor but just a bare pipe at the other end with several J clips holding it onto the alloy pipe I'd cut short. Was still working 3 years later when I sold it without being recharged in that time.

Bit of an aside..

I know all AC systems have dryers but what I've never understood is where the moisture in the system is supposed to come from (since the system is constantly above atmospheric pressure even on the low pressure side during operation)?

I've fixed many AC systems on a wide range of vehicles but haven't changed a dryer yet, seemingly had no effect on results.

I've got one of those Halfords DIY R134 recharge kits, has a pressure gauge that connects to the LP side and instructions say to fill until pressure with pump running reads at a certain level below pressure when the pump isn't running. When I've had AC filled professionally and then tested systems using this gauge it always reads a little lower during pump operation than the instructions say it should be, and then when I top up with just a bit more gas from the DIY kit it improves AC operation with engine at idle no end. So I wonder if pro firms tend to short fill systems to save on gas (which would mean their gas weight gauges read high,since I check to make sure pros enter the correct fill weight on machines)?

First car I had with AC was a mk2 Ford Granada 2.8iGhiaX, the AC didn't work for most of the time I owned it, then I thought I'd have a go at fixing it... first problem back in those days was to find an independent AC specialist who could re-gas it economically because the going dealer rate was a ridiculous price. Most pros said I'd need to change the dryer and they could do that for a silly price. I found a guy 20 miles away, he said the dryer wouldn't make much difference and quoted only £30 for a regas so I went to him, he didn't have a vac test machine just filled it from a bottle until the sight glass stopped showing bubbles and it worked.. I couldn't believe how cold AC got, at least for the short time it continued to work lol... But knowing what I (think I) know now, I'd just charge an R12 system on my own vehicle with propane and a bit of AC oil and check for leaks with soapy water.

Simon

Sorry I'm late back to the chat. I'm used to forums that list threads in order of recent activity and usually frequent them often enough to post on relevant threads, while on this forum I've so far left it to luck to keep on top of things because I haven't been using the 'track topic' facility... I've probably seemed ignorant a few times but I'll start using the topic tracker now!

You did remove the injector nozzles and drill the out to 2.5mm?

To stand good chance of proper calibration you'll need temp readings for gas vapour (and for reducer on an AEB based system) to be something like correct, because behind the scenes the system compensates fuelling for temps within a range of about 40%. With a temp sensor disconnected the temp reading will be extremely cold and under such conditions the system may subtract 30odd% of fuelling. You may get it running OK like that but then when the system does read a more accurate temp (when you do reconnect the temp sensor) fuelling will be incorrect and calibration will need to be changed again.

Autocal involves the system running on both fuels, it cannot be done without running on gas, no meaningful calibration can be done at all without running on gas. It simply takes note of petrol injector pulse duration (pinj) when running on petrol at (say) 2500rpm with no engine load, then switches to gas and takes note of pinj when running on gas. If pinj rises when it switches to gas the LPG calibration is lean so autocal increases all the numbers in your map by a calculated percentage, and vice/versa. However, if you ran on gas for a while before running autocal then this could have forced your petrol system to switch to open loop fault mode, in fault mode pinj doesn't change regardless of fuelling so autocal doesn;t see any change to pinj regardless of any changes it makes to the LPG map, so autocal cannot work properly and will likely keep making changes to the LPG map until it reaches the extreme (leaning or richening) of autocal's scope for making changes to the LPG map, which would likely make for worse LPG fuelling than if you hadn't run autocal at all. At this point don't try running on LPG again until after you've cleared any engine fault codes, reset the LPG ECU, re-entered all the basic settings in the LPG ECU and run autocal again.

Loads more to say but best to see the screenshots first. Better if you post screenshots taken after following the above advice.

Simon

I've always used the kids sucker arrow type for grinding valves in too.

None standard head gaskets for marine use Ferryman?

Gilbertd wrote:

Or somebody has tried to jack it up on the front crossmember and missed.

Same theme, or it was parked with front end above something, then air suspension went down?.More than a few Citreons suffered snapped exhausts when parked on uneven ground lol.

Just to add to my last post on this thread...

Agreed with Gilbert's views on setting systems to switch as early as possible because that way you save most money. If you watch fuel trims from cold start on most vehicles they will be different with warming engine (when it first goes closed loop) to when the engine is up to temp, a lot of vehicles (particularly more modern ones) have a different set of trims for during warm up anyway. But how I set changeover on my own cars is a bit different to how I set changeover on customer cars - I know that booting it with cool reducer can lead to problems, while some customers would drive slowly while running on petrol and then boot it as soon as running on the cheap stuff.

Orangebean wrote:

As the aromatics tend to evaporate over time I'd throw in a good dollop of injector cleaner to dissolve any deposits that might be forming..

Chinese stuff, aromatic duck oil? lol ;-) Seriously though I'm interested in just how quickly petrol might degrade, I don't think I've ever seen a vehicle running poorly on even very old petrol even though I know in theory it's supposedly an issue. Maybe if the biggest issue is drop in octane it's more of a problem on higher compression engines, though varnish etc is potentially a problem for any engine?

Simon

Agreed with Gilbert's suggestions, though I doubt it'll be possible to set 1/2 second switching time.

I usually set changeover temp quite low on P38s at around 30C, 2 second changeover from 400rpm. The brand of AEB system, it's age and firmware and software combination can effect the options available but they generally all only allow switching/charging time in terms of whole seconds (and 0 seconds is possible with some) - Some will only allow minimums of 1600rpm and 10seconds, early versions don't allow as wide a range in settings or adjustment of some settings at all without a dongle, later versions usually allow adjustment of temperature compensation in v6.x software and have options such as temporarily switching back to petrol if temps (reducer and/or vapour) fall below additional settings while driving. The latter is useful in allowing a lower changeover temp than otherwise might be necessary, because applying a lot of engine load with temps that might be OK for low engine load can see the reducer and gas temps fall to the extent where they can bring about problems (so such settings can provide a temporary switch back to petrol when gas temp fell below the minimum setting). Some none AEB ECU's have even more settings such as allowing running on gas at low/medium engine loads when reducer and/or gas temp are low (during warm up) but switching back to petrol at higher engine loads at those temps, thereby preventing drop-off of reducer/vapour temps and any problems that might be associated with low temps but allowing running on gas under any driving conditions with normal reducer/vapour temps.

Clive603 wrote:

Restricted space meant I need three spanners out of my collection to undo the unions as the various bends and angles weren't quite right. Finally christened the stubby combination set I picked up "that will be useful" 20 odd years back. If only there had been about 10 degrees more offset angle on the open end that one spanner would have done it all.

Clive

Cut the end of the spanner off and re-weld it with the extra 10degrees... Kind of thing I do fairly often mate ;-) Tools are there to serve a purpose and if they can be adapted to suit purpose better, why not. One of the reasons I don't buy snap-on lol..

Simon

In this area I go to a chain of garages called Charlie Brown's for AC refills, they charge £50 which includes gas and fluid drain, vac test, refill with correct quantity of oil (supposedly) and refill with correct amount of gas (supposedly). If for any reason the aircon doesn't work following their procedure or if the AC vent temp isn't at least a degree colder following the procedure there's no charge, even if it fails the vac test. I say supposedly because in theory they can just enter the reg or make/model of car into the machine and it supposedly knows how much oil and gas to put in but the machine seems set to short-charge... I watch what's going on to make sure the figures on the machine match what it says on the plate on the car and get them to manually enter the correct figures on the machine if they don't match.

I've also got one of those DIY AC charging kits from Halfords, works out cheaper if aircon is working just not as could as it should be (so just doing a top-up) but would need a couple of canisters (bit cheaper on exchange but still expensive) to charge most vehicle AC systems from nearly empty. The charge canisters contain oil but getting oil charge correct is guestimation using this method - Charge with canister upside down and the oil goes in, charge with canister right way up and only gas goes in, in theory... The pressure gauge on these kits is handy for DIY AC diagnostics, can give insight into whether filling with a bit more gas would be beneficial etc.

Simon

That must be similar to the stuff my mates at the local tyre/exhaust place use these days instead of gun gum type exhaust pastes. Had my reservations about it at first (huh using silicone on exhausts...), stuff they use even smells like normal silicone when it's going off (vinegar) - but seems to work well, does retain some elasticity though like normal silicone.

I also got the impression throttle was sometimes being held open a little by adjustment of throttle/kickdown cables, seemed to prevent idle from settling below rpm1000 a few times.

Will have to see what's going on again with fuelling... injectors all seemed to be performing consistently at the time but a bank trim was necessary to balance petrol trims.

Simon

blueplasticsoulman wrote:

Thanks for today Simon. Hopefully it'll behave itself now.

I just remembered the video i watched was a US video so things were opposite way around with regarding numbers i think.

Do you reckon it's likely that injector 6 needs replacing? Could it be the injector seals?

Is there a way to test without stripping down, swapping out and then rebuilding?

No probs Chris, I do think the 3rd pet injector back on drivers side needs changing, number 6, US cylinder numbers are the same as UK numbers... just don't get mixed up between driver and passenger sides lol.

Won't be injector seal(s), not unless seal on cyl 6 is bad and gas injector 6 flows more than others, would be quite a coincidence.

Not really another way to conclusively test.

Martyuk wrote:

I'll give my one a go in a bit, with tweaking the map.

I'll also reply more in my LPG thread to keep from hijacking this one!!

Currently my map sits about 114/116 for the rpm/pinj mark - so increasing 20% would put it about 136-140? I'm not doubting the figures (I worked out about 20% increase aswell) but at idle with a hot engine, I've got figures at 112 around the 3.5-4.0ms mark for the 500/1000rpm section - as I tuned that whilst running to get it as close as I could. Just seems like a fairly bit jump across the table!

Hopefully I'll get a couple of periods where it's not raining and I can pop out and update the map, and then take it for a spin and monitor it again.

Will post results back in my other thread, once I've gotten around to it!

Remember the figures are not really percent, they roughly translate to percent though only roughly. But more importantly, if we increase existing figures by a percentage in the high pinj areas of the map we are likely to see an actual increase in fuelling of around the percentage we entered, not the case at low pinj's where injector latency offsets things to a greater extent. ECU's can also impose a minimum ginj, where this occurs it sometimes doesn't matter much if we enter 10 or 90 / 110 in (say) the 2.5ms box because the ECU will pulse the gas injectors for the minimum duration anyway. Bumping across the table can point to the ECU imposing minimum ginj, or to not very linear LPG injectors on engines that can have low pinj's (not P38's), or to inappropriate nozzle pressure combinations, or may just mean that other areas of the map need to be tweaked.

Simon

Martyuk wrote:

At least it's running better now...

One thing to point though... Cylinder 5 is actually PASSENGER side - 3rd from the front.

The cylinder numbers have bank 1 on passenger side, bank 2 on drivers (so if you are standing at the front of the vehicle, looking towards the engine, 1,3,5,7 are on your RIGHT, 2,4,6,8 are on your LEFT.

My LPG system is also wired so the the red band (usually bank 2) is connected to bank 1 on the engine and vice versa. I figure it doesn't make a lot of overall difference as long as they are all connected to the correct injectors (petrol and LPG) and in the correct order.

I need to finish getting mine tweaked (still) I've got it sitting pretty happy at idle, but it's still a bit out at 70mph on the motorway.. I was reading pinj of between 6.0 and 6.5ms, and when I switched to LPG, it jumped up to between 8.2 - 8.6ms.

One day I'll be able to get it more accurate and get someone else in the vehicle with me who can monitor the laptop and tweak the settings!

Hi Marty, Yeh, doh! Thanks for that, sort of thing I would usually check on to remind myself (and as easily as looking at the back of my garage door where I scratched this info years ago), I did have an inkling but was going on Chris's info so will blame Chris lol ;-) Can still draw conclusions - Now the difference is on cyl6, not cyl5, LPG system bank 1 is engine bank 2, the bank trim difference when running on LPG is likely just due to different machining tolerances of LPG injector rails (because the revelation rules out extra fuel such as due to a leaky Pinj).. It still all points to the Pinj I advised Chris would be at fault (drivers side 3rd back) being the problem causing less smooth idle on petrol. Since trim on bank2 is consistently higher than trim on bank1 on petrol, this actually makes for more compelling evidence that Pinj6 is under-delivering because the under-delivering is constant.. or put in another way - where before the situation would have had to be pinj5 leaking a small amount constantly on top of the fuel that it should have been delivering, the new info implies pinj6 is consistently under delivering under all conditions, while the trims running on LPG can more easily be attributed to a nothing out of the ordinary LPG bank trim being necessary when using this type of LPG injector.

On yours, increase the figures in boxes around the 6ms mark by 15% as a starting point and adjust from there... Also, if this makes the figures in 6ms boxes more than about 20% than figures in 8ms / 10ms boxes I'd expect you'll need to increase figures in those boxes too.

With the old Tartarini system you don't get to see the figures in the actual map, the actual map is underlying and set by type of injectors selected and then by autocal, instead you get to change figures in a map that only acts as an adjustment to the underlying map, so all the numbers in the user adjusted map are zero by default.

Cheers, Simon.

Blueplasticsoulman visited today.

Initial findings - Fuel trims at idle on petrol were close to zero (bank 2 trims a bit higher than bank 1), fuel trims at idle on LPG went a bit more negative on B1 and a bit positive on B2, No entries were made in LPG mapping screen (only autocal would have been done regards mapping), reference pressure set at 1.2 bar but actual pressure was 1.7 bar. Ginj was 4.5ms at idle which is a bit low duration for these spec injectors to work properly at, so at this point I anticipated the need to turn down reducer pressure.

I could correct the bank trim discrepancy at idle quite easily using a positive bank 2 trim figure and entering a slightly negative value in the idle area of mapping to get both banks trims very close to zero when running on LPG. The LPG ECU didn't support switching individual cylinders back to petrol, which would be a way of checking each engine cylinder's response when running on petrol or running on LPG (*later on I temporarily fit another Tartarini ECU that does have this facility). The ECU did feature sequential fuel changeover and the smoothness of changeover between fuels told me injector wiring / plumbing was correct (so input of petrol injector pulse for a certain cylinder results in gas injector pulse to the same cylinder).

Under the bonnet the Tartarini injectors (very similar to V30's) were quiet. The reducer vac reference pipe was simply hanging below the reducer, disconnected from the vac T, and the vac T had the missing pipe connection blanked. I checked the reducer vac pipe for gas leakage, it was fine, sucked on the pipe still fine and gas pressure went down when I sucked as it should. Reconnected the reducer to manifold vacuum and now reducer pressure was near the reference pressure of 1.2 bar - two problems sorted already (autocal wouldn't have worked well with 40% over reference pressure situation and gas injectors wouldn't have worked well pulsing at less than 4.5ms with colder gas).

At this point it would idle a bit more smoothly on LPG than on petrol, also pulled slightly more vacuum at idle on LPG than on petrol, confirmed by slightly lower MAF readings in OBD2 live data on LPG compared to petrol - If any difference at all it should need a bit more airflow to idle on LPG than on petrol with stoch afr. This points to a minor issue with the petrol system such as a dodgy petrol injector...

We went out and calibrated the LPG system, trims on petrol were all decent, matched trims on LPG to trims on petrol and confirmed by Pinj figures staying the same when switching between petrol and LPG. The original calibration won't have been right (as said the original calibration had only had autocal done), I had to enter figures that shifted within a range of around 20% from the autocal figures, it was previously running rich at idle and lean off idle, at least after I'd connected the vac pipe to the reducer, and won't have been running right with the vac reference not connected to the reducer.

The engine still idled better on LPG than on petrol. *I now disconnected the Tartarini ECU and connected another Tartarini ECU which allowed switching of individual cylinders back to petrol (easier to temporarily fit an old Tartarini ECU than a new say King ECU as the old system uses the old Tartarini style switch which other AEB systems are not compatible with), I only roughly mapped this ECU and only for idle conditions. The slight bank trim issue on LPG remained present, thus helping confirm a few things such as issues wouldn't be LPG ECU related. When I switched any cylinder back to petrol (except for what the LPG system sees as channel C on bank 1) Pinj remained the same. When I switched channel C on bank 1 back to petrol PINJ on bank 1 increased, meaning bank 1 ran leaner when this cylinder was switched to petrol. There is no need for the LPG system to be wired so that what the LPG system sees as bank 1 is the same as what the petrol ECU sees as bank 1, but earlier notes (comparing fuel trims to pinj readings) had confirmed that the installer in this case had wired the system so that the LPG's bank 1 is the same as the petrol bank 1. As long as the installer had wired the system so that channels ABCD ran from A at the front of the engine to D at the rear (which they will have) this would mean that channel C on bank 1 would be the engine's cylinder number 5, the 3rd cylinder from the front on the drivers side. Since fuel trims are more negative on bank 1 on either fuel, accentuated when running on LPG, and LPG vapour pressure isn't lost when running on petrol, this could imply that the petrol injector on cylinder 5 is constantly leaking a bit of fuel into cylinder 5 or that airflow into cylinder 5 isn't as high as on the other cylinders (valvetrain issue). Given the poorer idle on petrol compared to LPG it seems more likely that the petrol injector is a bit dodgy and leaky, else if it was a valvetrain issue would expect idle to be worse effected on LPG. It doesn't seem to be burning any oil etc. Chris is thinking about fitting new rocker cover gaskets, I suggested while the manifold is off he could swap pinj5 with one from the other cylinder bank, a test to see if the bank trim situation when running on petrol is reversed. If it is reversed then the real fix would be to sort out the dodgy petrol injector, but while a dodgy injector is fitted on the opposite bank the LPG calibration and bank trim should be adjusted to suit, I advised how to do this.

With hindsight there was one test that we didn't do - could have swapped the Ginj that feeds cylinder 5 with another Ginj (swapping both electrical connectors and both pipes). Perhaps we didn't do this because Chris had already been here for a long time, all seemed pretty conclusive, we were packing up anyway, and my dad's old best mate who's had several strokes and I haven't seen for a couple of years arrived unexpectedly wheel-chaired by his daughter just after we'd done the checks with the second LPG ECU. If the trims on petrol on B1 were not more negative than on B2 on either fuel then this is a test I would have done anyway, but given all the above I'm very confident this wouldn't have revealed a problem with ginj5 and that everything points to a dodgy pinj5. As said the 2nd ECU was only temporarily fitted to allow the injector test, there was no need to sell Chris any parts, all his LPG components seem in good working order and his system is calibrated much better now.

Simon