So last night I left the inline fuse out of the lpg. This morning it drove beautifully on petrol only with just a couple of little judders. Idle was lovely too.

Read diagnostics after 15mile journey and only one is P1319. However, the only live data it will read is O2 bank 1 sensor. No fuel trims, rpm, engine load, nowt!

I stuck the lpg inline fuse back in and fired her up. Still running good (but without turning the lpg on) but now all diagnostics will read. Took if for a spin and ended up briefly getting 0.8v out of bank 2 O2 sensor (first time ever) and the bank 2 fuel trim shot up to 25%.

Does all that sound like the lpg system is conspiring against me?

Just quickly scanned through recent posts, seems to me there's a problem with your LPG system.

I'm just South of Pontefract in case you want to come sometime ;-)

There's a problem somewhere but without having it in front of us it's all theory and speculation. The P1319 code is misfire at low fuel level so that suggests you do have a misfire so it could be the misfire that is causing the apparent lean running. In all honesty, you might be best getting Simon to have a look at it. Far easier to diagnose a problem when you can see it for yourself.

Right. The saga continues....

Carrying on from the last post i wrote above. Where i briefly got a reading from the bank 2 sensors.

I've been working all day and the car's been parked up outside since my last journey this morning. Still with the lpg ecu plugged back in but i've not pressed the button on the dash to turn the lap on. We're running on petrol today. Got in the car at 5pm, stuck realtime diagnostics on and drove 3 miles to pick the Mrs up. Both of the O2 sensors and both of the fuel trims were working spot on and the car drove absolutely immaculate. Not 1 stutter and the idle was that good, it was if the car wasn't even turned on. Picked the Mrs up, drove 5 mile home, again, smashing. I got home and had to go to Aldi so i thought i'd take the opportunity to record some video of the live diagnostics. Drove up to aldi, still on petrol, and still driving like it's just left the factory. How weird is this???

Decided on the way back that i needed to see what would happen when i press the lpg button. So i pulled over and pressed it. Switched over to LPG and everything still the same. Fantastic idle, all sensors working. I made another video of driving home on lpg. Fuel trims were a bit different. Higher % most of the time but i figure that's how it is on lpg? Have to balance the 2 systems together??

I can post video's up if required.

I can't think of anything i've done to fix it. Took the petrol ecu out last night looking for wires and took the lpg ecu out too. The ONLY thing that i can say is that when i put the 15a fuse back into the lpg 12v, i couldn't get it in the little holder. it looks like it's moving around in it's mini plastic housing and i couldn't get the 2 pins in. Got it in there in the end but that would literally be my only observation.

I'm a bit confussled!

You have proved your LPG system needs calibrating. By driving it around on petrol only you have allowed the long term fuel trims to adjust and get themselves correct for running on petrol again. As soon as you changed to gas they should not change at all, they should stay exactly as they are but they aren't doing as the gas system isn't calibrated correctly.

Lets say for arguments sake that at a particular revs, load and throttle opening, your petrol injectors need to be open for 10mS but on gas, as the injectors don't react as quickly and you are injecting a vapour not a liquid, the LPG injectors need to be open for 14mS. In that case the calibration in the LPG controller will be set to add 4mS to the pulses from the petrol ECU (which are intercepted and used to fire the LPG injectors instead). However, if it is only adding 2mS the mixture will be lean, the lambda sensors will tell the petrol ECU that it is lean so it will adjust the pulses to 12mS. So the 12+2 gives the required 14mS. Then when you go back to petrol, the pulses are still at 12mS which is too long and the mixture is running rich. If one of your plugs or leads is a bit iffy the rich mixture causes a misfire. The unburnt air from the cylinder that isn't firing makes the lambda sensor see too much air so the petrol ECU thinks it is still too lean so richens it further and the downward spiral starts until it is in the state that yours was in. Resetting the adaptive values would have done the job at the press of a button but without anything to do that with, you've had to let the ECU learn for itself.

Get it booked in to get the LPG system properly calibrated.

funnily enough i was talking about the car having adaptive values to my Mrs and saying that i wonder if it could be that because i've ran it on petrol today. Then i thought, surely it would take more than a few miles journey to reset itself.

So if i understand correctly.....

The fuel trims learn the petrol side. If then it switches over to gas, it then has to relearn for the gas. then it switches back to petrol and so on and so forth. each time trying to relearn whats going on.

Calibrating the lpg to closely resemble the petrol fuel trims stops this relearning process?

I'll get it booked in for investigation. At least now i know that the sensors are working.

Should i leave it on petrol for now so it doesn't start doing funky stuff again?

blueplasticsoulman wrote:

So if i understand correctly.....

The fuel trims learn the petrol side. If then it switches over to gas, it then has to relearn for the gas. then it switches back to petrol and so on and so forth. each time trying to relearn whats going on.

No, it learns on petrol and the gas system SHOULD be set so it doesn't know it isn't running on petrol, the injector pulses should remain the same and the lambda readings should remain the same so it doesn't have to relearn. Only when the gas system is out will it relearn and cock things up.

It will sort itself out fairly quickly with a bit of varied driving, a mix of low and high speed with acceleration and deceleration in between is ideal.

Great stuff. Hopefully we got there in the end. lol, started off with a bottle of injector cleaner, changed the maf, changed iac valve, changed an o2 sensor, stripped out both petrol and lpg ecu's and all it needs is the lpg calibrating. doh!

How does this explain the o2 sensor reading 0.0 all the time and the fuel trim not moving?

O2 sensor reading 0V because a cylinder was misfiring (as you said it was running rough) and the fuel trims weren't moving because they couldn't move any further.

Glad we got to a conclusion, I've got a ferry to Calais to catch in 3 hours.......

Gilbertd wrote:

O2 sensor reading 0V because a cylinder was misfiring (as you said it was running rough) and the fuel trims weren't moving because they couldn't move any further.

Glad we got to a conclusion, I've got a ferry to Calais to catch in 3 hours.......

Safe journey. :-)

Blueplasticsoulman PM'd asking me to read recent posts here. I agree it seems the LPG system needs calibrating, it is also likely to need some LPG injectors if this is an old system and it must be at least a few years old being Tartarini. I'd get to the bottom of it.

Au revoir Gilbert, have I ever mentioned my sister is a French teacher, brother in law is French... and I can just about remember Au revoir? Lol.

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

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!

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.

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?

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!

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

i'll get hold of an injector when i do the rocker gaskets. No point swapping a potentially dodgy one around, confirming it's dodgy and then having to strip it back down again to change it.

Lpgc wrote:
on engines that can have low pinj's (not P38's),

Simon

HAH, you're not kidding there :)

Having seen Simon last week, i think i've still got a couple of problems at idle. However, i do think it's relating to both petrol and lpg so i'm thinking vacuum leak????

This morning, started up and idled at 1100 or so. Drove up the petrol station on petrol and still idled at 1100. I swapped it over to gas and it didn't change (hence me thinking vacuum leak). Fueled up and set off and everythings normal now. This has happened a couple of times since i've had it. Intermittent. One time, the car idled at 1100 and slowly climbed up to 1300 before it settled down. Simon mentioned in his finding that he thought there might be a problem with injector 6. Could this relate to that or do i have a couple of issues?

I've got some carb cleaner. do i have a bit of a spray around the plenum and manifolds and see what happens??