Right, I've gotten fed up fiddling with the LPG cable. I've no idea why my cable doesn't work despite the pinouts being correct.
As a result, I've just bought the proper cable from Tinley Tech as linked to by LPGC above. Next business day delivery was £2 more then first class so hopefully it'll be here on Tuesday!
David.
V6 software will usually work on anything that V5 does, there was quite a change in terms of compatibility between V4.X and later versions with one of the biggest changes around V4.7 for most AEB stuff. 2005 Is quite old, I'd expect V6 to work but if it doesn't you might need pre V4.7 to work, maybe even V3.X. That said, Tartarini version numbers didn't always follow general AEB trends, the software works in a slightly different way too.
The interface setup you tried may have only 3 wires on the serial side?
The USB > Serial adapter was definitely one of the 4 wire types. The 3 wire ones are useless for console access at work, it needs to be a 4 wire one that we use, it's the same one I'm using for this.
If this cable doesn't work, am I right in thinking you work on these for a living? Fancy doing this one!?
David.
Yes I install and repair vehicle LPG systems for a living, could sort it if you like. But you could be closer to having fixed it yourself already than it seems, hopefully the new cable will work and point to an easy fix such as low reducer pressure, in which case we'd hope turning the pressure adjuster on the reducer will bring pressure back up. That said I wouldn't have bothered rebuilding a Tartarini reducer if the initial problem was low pressure, the kits will repair a leaking reducer but are less likely to repair a reducer that failed on pressure, they don't include all internal bits or the housing... and it seems whatever problem you had before the rebuild was the same problem you're having now?
Two vehicles here for repair at the moment: Supercharged Rangerover with a BRC system just came in which takes a lot of cranking when it's been running on gas, so I'll be looking for a leaking reducer diaphragm / petrol return which continues to dump petrol pressure when the engine is switched off / poor calibration on that one. Merc E500 with LPGTech, Antarctic reducer, V30 injectors with the same long cranking problem, already found the reducer on this one is leaking gas into the manifold and started fitting a new reducer.
that and you're not allowed to jump the queue ;)
Well, my cable has been dispatched, so fingers crossed!
Takes a brave man to run a Supercharged Range Rover on LPG. Those AJV8's have soft valve seats I believe. Is flashlube a total cure for that or does it just prolong the agony?
David.
Lpgc wrote:
and it seems whatever problem you had before the rebuild was the same problem you're having now?
Previously on LPG it would tug or stutter on LPG. Since I've rebuilt the reducer it seems to switch back to Petrol. Previously it just used to stutter and feel as if it was being starved but didn't actually cut back to Petrol.
What pressure would you expect to see when the cable arrives? Is there anything that's worth checking straight away when the cable arrives?
David.
The new cable has arrived, has been tested and let me straight into the ECU. I've metered it out and it's exactly the same as my old cable bar the USB > Serial dongle that came with it. Strange...
Anyway, I managed to get a look at a couple of screens before the laptop battery ran out.
Revs - 760rpm
T.Gas - 5.30ms
T.Petrol - 4.31ms
Temp. Reducer - 74C
Temp. Gas - 43C
Diff. Press - 2.47bar
Man. Press - 0.50bar
Battery Volt - 13.74v
Lambda 1 - 0.5v
I didn't have time to check the lambda was switching before my battery died so I'll do that later. Do the multipoint systems have their own Lambda sensors the way single point do or do they piggy back the cars?
David.
dhallworth wrote:
Do the multipoint systems have their own Lambda sensors the way single point do or do they piggy back the cars?
Generally neither of the above.
They let the cars ECU and systems do all of the hard work and analysis, take the injection timings and durations from the petrol system, apply a fudge factor to suit the different combustion characteristics of LPG and fire the LPG injectors
Which is why it is utterly pointless to try and fix a multipoint LPG system if the petrol side isn't spot on.
That makes sense.
Since I cleared all the fault codes on petrol and reset the adaptive values I’ve not had any errors come back again and it’s running beautifully on petrol so I’m hoping that side of things is ok.
David.
dhallworth wrote:
The new cable has arrived, has been tested and let me straight into the ECU. I've metered it out and it's exactly the same as my old cable bar the USB > Serial dongle that came with it. Strange...
Anyway, I managed to get a look at a couple of screens before the laptop battery ran out.
Revs - 760rpm
T.Gas - 5.30ms
T.Petrol - 4.31ms
Temp. Reducer - 74C
Temp. Gas - 43C
Diff. Press - 2.47bar
Man. Press - 0.50bar
Battery Volt - 13.74v
Lambda 1 - 0.5vI didn't have time to check the lambda was switching before my battery died so I'll do that later. Do the multipoint systems have their own Lambda sensors the way single point do or do they piggy back the cars?
David.
Orangebean wrote:
dhallworth wrote:Do the multipoint systems have their own Lambda sensors the way single point do or do they piggy back the cars?
Generally neither of the above.
They let the cars ECU and systems do all of the hard work and analysis, take the injection timings and durations from the petrol system, apply a fudge factor to suit the different combustion characteristics of LPG and fire the LPG injectors
Some do have a wire to connect though to display the lambda onscreen in the lpg software. Its only used for reference though and doesn't need to be connected. Given you have a 0.5 reading on yours it may be connected.
As Brian says, it's just to make it convenient so you have everything displayed on the one screen rather than having to look at the LPG screen on a computer and check the lambda readings on an OBD reader. Singlepoint systems sometimes use a separate lambda sensor but not always. They work best with a 0-1V lambda sensor but on things like the GEMS P38 with 5-0V sensors there is a setting in the controller to allow them to use those instead. Mine has a separate 0-1V sensor purely to drive the LPG system but the Ascot is using one of the 5-0V ones (as is Gordon's car). What I found is that at idle on LPG the sensor stops giving an output and stays at 5V all the time. This is ignored by the petrol system as it runs open loop at idle but the LPG system sees it as a lean mixture and tries to compensate for it all the time so you end up with a default actuator figure far higher than it should be resulting in it running rich all the time.
Your timings look perfect, petrol at 4.31mS and gas at 5.30mS works out to 1.23x, perfectly in the 1.2-1.5 range they need to be. So the map at idle is right, you need to see what it is like at different points on the rev range and different loads.
Morat wrote:
that and you're not allowed to jump the queue ;)
I haven't forgotten you mate ;-)
@Dhallworth - The differential pressure shouldn't be as high as 2.47 bar, you will have problems if that reading is true. If the pressure is really as high as that it'll point to a problem with the reducer. If the pressure isn't really that high (yet it reads that high) it 'll point to a problem with the pressure sensor, loom or ECU.
What happens to manifold pressure when running on petrol? Were aircon, lights, etc on? In park or drive? I ask because most AEB systems on P38 V8's read just over 0.4bar manifold pressure at idle with warmed engine, if your manifold pressure drops lower when running on petrol it's because the engine is struggling more to run at idle on LPG (ICV opens more to keep rpm at idle). If that's the case it could be that even with half decent calibration and injectors that are in good working order the injectors are still giving inconsistent fuelling due to high pressure (as mentioned above). The pressure sensor is really two pressure sensors in one (manifold / gas), a problem on one sensor may or may not affect the other sensor, as sensors get old they sometimes show slightly incorrect readings but that doesn't always affect good results. As ECU's age the AD converters and/or reference voltage to sensors can see the ECU show slightly incorrect readings, again this doesn't always mean an immediate ECU replacement is necessary.
Lpgc wrote:
What happens to manifold pressure when running on petrol?
I’ll run the laptop up again tomorrow evening and have a look.
Lpgc wrote:
Were aircon, lights, etc on? In park or drive?
Air Con was switched off, lights off, in Park. Engine was hot, had just done circa 30 miles.
I’ll fire Testbook up as well and see if the readings on that resemble whats on the LPG software.
David.
Would expect readings from Testbook to be slightly different to readings from the LPG ECU anyway, not that there are many of the same type of readings to compare between the two. You won't be able to see gas pressure in Testbook.
Whilst at Gordon's this evening, once we'd got his car running again we had a very quick look at the software for the LPG on my VSE.
Starting the car on Petrol and observing the Diff. Press figures we had a reading of 0.65 bar.
Starting on Petrol:
Switching the car to LPG changed the reading, it went straight to 2.49 bar, switching back to petrol from LPG left us with a reading of 2.69 bar.
Switched to LPG:
Switched back to Petrol:
Squeezing the thin rubber tube between the reducer and the pressure switch didn't seem to make any difference to the reading regardless of how hard it was squeezed.
When we waved Testbook at it earlier on I noticed there's a fault logged with both Upstream Lambda sensors now which there wasn't last week. Testbook shows a reading for 4 lambda sensors yet there's only 2 in the exhaust. That surprised me as my old 2000 Discovery V8 definitely had 4 sensors... Has someone removed mine and blanked them off or do the P38's only have 2 sensors?
Readings from Testbook were:
O2 Sns DS - A - 0.447v
O2 Sns DS - B - 0.447v
O2 Sns US - A - 0.261v
O2 Sns US - B - 0.270v
Both of the Upstream sensors were observed switching like you'd expect, I noticed that the DS heater stayed permanently off and the US heater was switching on and off too.
Testbook Readings:
I'll get a few more miles on it and if the fault codes for the lambda sensors comes back again I'll replace them both.
The fuel trims look nice and even on petrol though which is good.
Only US spec P38s had downstream sensors, rest of world only have the two upstream ones. The Yanks worry if the cats aren't doing their job, we don't give a ......
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:
Are the reducers adjustable? The single-point ones seem to have a locknut and screw in the high-pressure side that resembles the adjustment in a normal (old fashioned, not crimped together) gas regulator.