LPG Problems and Theiving Fuckwits
Posted: 30 Dec 2010
I've already mentioned this in my whinge (sorry blog) over on BXC but thought I would have a moan over here too and maybe get some useful advice.
Had a problem with the Discovery over the last few weeks - loss of coolant, rock hard hoses, bubbles in the expansion tank and rough running on gas. Failed HG you might think, but a compression test showed extremely good figures on all 8 cylinders. So then I stripped down the stepper motors allowing gas to be 'injected' into the inlet manifold (1 per bank, each feeding 4 ports) to find there was a significant amount of water in them! So I deduced the problem must lie in the vaporiser which is heatered by the coolant and supplies a constant pressure of vaporised LPG to each stepper motor. I managed to find a rebuild kit for the vaporiser and fully rebuilt it. Result! It ran much better, no pressurisation and more top end power. The slight roughness at idle was still there, I think as a result of me changing one of the stepper motors a few months ago - when they are installed as pairs they should be a balanced pair from the factory as at idle when they are both nearly closed any slight differences in flow are magnified. Open the throttle and it's nice and smooth so I wasn't too fussed. But I thought I would take it to the local specialist (70 miles away!) as we were heading in that direction anyway and were planning to do a lot of towing over Christmas so wanted to ensure things were A1.
They did make it clear to me that they couldn't promise an improvement, and that they would recommend removing the system to fit one of theirs instead. This I declined as it would cost significantly more than an hour of their diagnostic time, so they said that they would do the best they could. All I requested them to do was check that any stepper motor imbalance wasn't causing one bank of the V to run dangerously lean, and to try and increase the idle speed a touch to smooth the idle.
So by the time they finished with the car they tell me they've tried various different maps, and also altered the speed of the self learning setting, but all this made things worse. So my original map was put back in, and it just needed a run on the open road to re-learn parameters for some fine tuning (they were unable to do this due to Christmas traffic).
This I tried, but switching to gas on the move (as advised) many times for about 20 miles just left me coasting with no power. Pulling into a layby we found that it will idle (just) on gas but will not rev above 1500rpm and would backfire if the throttle was pressed further. Upon phoning them back they told me that there was nothing more they could do without substituting parts (which they didn't have) as the gas pressure was too low. But surely if there was an inherent problem with the gas pressure it wouldn't have run satisfactorily for the 100 or so miles after the vaporiser rebuild before I took it in.
I can’t believe I’ve paid money to end up with an LPG system going from working reasonably well, to being useless. It is obviously possible that an unrelated problem occurred whilst in their position, but I’m shafted really. Economically I can’t take it back there for them to try various new parts at my expense without any guarantee of success. I don’t really know what the legal position is - I just want it in the same usable condition it was in before I took it in to the specialist, without being (further) out of pocket.
I discovered that by repeatedly pumping the throttle it was possible to get the revs over 3k rpm, at which point it would rev perfectly normally and hold a steady engine speed from 3k upwards. Drop (even slightly) below 3k though, and the revs would rapidly drop to around 1500 and become rougher. It was possible (just) to drive the car but only below about 10mph as there was no power.
After getting the Disco back home I spotted a split vacuum hose from the inlet manifold to the vaporiser. I think the inlet manifold vacuum moves a diaphragm and allows more LPG into the vaporiser. The hose I know wasn’t split to start with as I reconnected it when I put the rebuilt vaporiser back in - I remember it being a tight fit of the stub it pushed onto which is where it had split.
I initially thought that this would lead to a buggering up of the self learning program, and a simple reset of this would enable it to relearn OK. But now I've found out the self learning is continuous, so whatever fault is present must still be there. The LPG specialist has told me they have no base maps (from which the self learning fine tunes) for the Rover V8 so fuck knows what they have actually programmed it with.
Found another specialist who were the importers for that equipment when it was current (they no longer import that make) so should know what they are on about. Problem is they want the vehicle for several days which is an issue, and fault finding would run into many hours...
Just had an increase on my credit card limit so feel like just throwing money at the problem to make it go away. Even if it comes to a new system, at least then it will (should?) be more reliable, and have better spares availability in the future. I've had some fundamental problems with the system installation pointed out to me (some I knew about like the wiring quality) so maybe that's the best option?
I'm considering giving the second specialist a fixed budget of X hours, so if it isn't a simple fix I won't run into a bill of hundreds of pounds that would be better spent on a new system. One possible thought that springs to mind is that if they adjusted the vaporiser to try and change the gas pressure with a leaking vacuum pipe, the pressure will now be all to cock, and it could just be a simple tweak on a screw?
Oh, and today there was a bang and hiss from the underneath, with a strong smell of gas. Tank contents still OK, so must have been the residual pressure in the pipe leading from the filler port to the tanks. Should be cheap and easy to replace.
Had a problem with the Discovery over the last few weeks - loss of coolant, rock hard hoses, bubbles in the expansion tank and rough running on gas. Failed HG you might think, but a compression test showed extremely good figures on all 8 cylinders. So then I stripped down the stepper motors allowing gas to be 'injected' into the inlet manifold (1 per bank, each feeding 4 ports) to find there was a significant amount of water in them! So I deduced the problem must lie in the vaporiser which is heatered by the coolant and supplies a constant pressure of vaporised LPG to each stepper motor. I managed to find a rebuild kit for the vaporiser and fully rebuilt it. Result! It ran much better, no pressurisation and more top end power. The slight roughness at idle was still there, I think as a result of me changing one of the stepper motors a few months ago - when they are installed as pairs they should be a balanced pair from the factory as at idle when they are both nearly closed any slight differences in flow are magnified. Open the throttle and it's nice and smooth so I wasn't too fussed. But I thought I would take it to the local specialist (70 miles away!) as we were heading in that direction anyway and were planning to do a lot of towing over Christmas so wanted to ensure things were A1.
They did make it clear to me that they couldn't promise an improvement, and that they would recommend removing the system to fit one of theirs instead. This I declined as it would cost significantly more than an hour of their diagnostic time, so they said that they would do the best they could. All I requested them to do was check that any stepper motor imbalance wasn't causing one bank of the V to run dangerously lean, and to try and increase the idle speed a touch to smooth the idle.
So by the time they finished with the car they tell me they've tried various different maps, and also altered the speed of the self learning setting, but all this made things worse. So my original map was put back in, and it just needed a run on the open road to re-learn parameters for some fine tuning (they were unable to do this due to Christmas traffic).
This I tried, but switching to gas on the move (as advised) many times for about 20 miles just left me coasting with no power. Pulling into a layby we found that it will idle (just) on gas but will not rev above 1500rpm and would backfire if the throttle was pressed further. Upon phoning them back they told me that there was nothing more they could do without substituting parts (which they didn't have) as the gas pressure was too low. But surely if there was an inherent problem with the gas pressure it wouldn't have run satisfactorily for the 100 or so miles after the vaporiser rebuild before I took it in.
I can’t believe I’ve paid money to end up with an LPG system going from working reasonably well, to being useless. It is obviously possible that an unrelated problem occurred whilst in their position, but I’m shafted really. Economically I can’t take it back there for them to try various new parts at my expense without any guarantee of success. I don’t really know what the legal position is - I just want it in the same usable condition it was in before I took it in to the specialist, without being (further) out of pocket.
I discovered that by repeatedly pumping the throttle it was possible to get the revs over 3k rpm, at which point it would rev perfectly normally and hold a steady engine speed from 3k upwards. Drop (even slightly) below 3k though, and the revs would rapidly drop to around 1500 and become rougher. It was possible (just) to drive the car but only below about 10mph as there was no power.
After getting the Disco back home I spotted a split vacuum hose from the inlet manifold to the vaporiser. I think the inlet manifold vacuum moves a diaphragm and allows more LPG into the vaporiser. The hose I know wasn’t split to start with as I reconnected it when I put the rebuilt vaporiser back in - I remember it being a tight fit of the stub it pushed onto which is where it had split.
I initially thought that this would lead to a buggering up of the self learning program, and a simple reset of this would enable it to relearn OK. But now I've found out the self learning is continuous, so whatever fault is present must still be there. The LPG specialist has told me they have no base maps (from which the self learning fine tunes) for the Rover V8 so fuck knows what they have actually programmed it with.
Found another specialist who were the importers for that equipment when it was current (they no longer import that make) so should know what they are on about. Problem is they want the vehicle for several days which is an issue, and fault finding would run into many hours...
Just had an increase on my credit card limit so feel like just throwing money at the problem to make it go away. Even if it comes to a new system, at least then it will (should?) be more reliable, and have better spares availability in the future. I've had some fundamental problems with the system installation pointed out to me (some I knew about like the wiring quality) so maybe that's the best option?
I'm considering giving the second specialist a fixed budget of X hours, so if it isn't a simple fix I won't run into a bill of hundreds of pounds that would be better spent on a new system. One possible thought that springs to mind is that if they adjusted the vaporiser to try and change the gas pressure with a leaking vacuum pipe, the pressure will now be all to cock, and it could just be a simple tweak on a screw?
Oh, and today there was a bang and hiss from the underneath, with a strong smell of gas. Tank contents still OK, so must have been the residual pressure in the pipe leading from the filler port to the tanks. Should be cheap and easy to replace.