romano risN on p38

[Gilbertd]

If you've lost two pots, are you sure one of the ignition coils hasn't died? Thought you were taking it to Simon anyway?

[LPGC]

If you've lost two pots, are you sure one of the ignition coils hasn't died? Thought you were taking it to Simon anyway?

Matt did come mate, and we gave it a thorough going over!

Even on petrol the engine was surging a little around idle with the surging getting slightly worse on LPG.. when rpm fell battery voltage went up and vice/versa, so seemed alternator load was the cause of the surge rather than the voltage rise and fall being an effect of the surge. This was so prominent (battery voltage fluctuation, not the surging) that all the dash lights (heater section etc) were very noticeably rising and falling in brightness, with peak voltage well above 15volts... This seems like a voltage reg issue on the alternator and Matt said he was going to consider changing the whole alternator. The rising and falling voltage also causes the temps read by the LPG ECU to rise and fall a little, fluctuating just enough around a point where a little either side can effect fueling by around 2%, this effect will be very slightly adding to the extent of surging that occurs on petrol. The 5v reference voltage to sensors was checked and was holding spot on steady at 5v, so the fluctuating readings could only be due to ECU earth reference changing, but this was checked and found to be as good as possible.

The calibration was found to be far too rich across the entire rpm/load ranges but particularly at higher loads, with some really large and un-intuitive steps between adjacent numbers in the map. We mapped the system properly, which simultaneously sorted the cutting back to petrol at high loads, made idle much smoother than it was, improved all round drive-ability, but still there was a slight surge at idle.

A newer ECU was temporarily fitted to enable comparisons and to enable checking of LPG injectors by switching each individual LPG channel back to petrol at a time. All injectors seemed to be working properly (each effecting fueling by an equal amount, and not effecting fueling when calibration in the new ECU was also made correct to match petrol fueling). I put a bit of pipe to each injector in turn, the other end in ear, to listen for different noises from LPG injectors, was surprised that all the old Romano injectors seemed to be working quietly and properly! With this ECU the read temps were fluctuating just the same as with the Romano ECU, so the main earth and power feed in the LPG loom were checked again, as were other vehicle earths and connections like the main engine earth etc, but all were found to be have good connections.

Some of the switch unit level LEDs were broken (2 + 4 green), but Matt said the gauge otherwise seemed to go up and down as expected with tank level. Matt decided to source and fit his own new switch, so no further action was taken regards the gauge.

Matt phoned to say that the vehicle was now driving and idling much smoother than before he came and continued to run well (not cutting back to petrol) even when driven flat out, but would still run rough after first switching to LPG on a cold morning. I had increased the changeover temp, but with hindsight perhaps this should be increased still further. At the time I didn't want to increase the changeover temp too much because Matt had told me that the vehicle already took over a mile to switch to LPG on a cold morning... I obviously didn't get chance to see the engine warm up and switch to LPG on a cold morning, but in any case the latest V6 version of Romano software doesn't yet allow temperature compensation adjustments, so I would be limited to simply increasing the changeover temp to correct poor running after initial changeover anyway...

Matt called the other day to say that one of the LPG injectors had stopped working, then called again to say that all was well, he had forgotten that he had disconnected it at some point and it ran OK again after he had reconnected the injector.

While I was typing this, by coincidence, Matt called me again to say he had stripped down some of the LPG injectors. I can't remember if he said this was done before or after the injectors stopped working, but would seem another coincidence if they had stopped working at this point of their own accord without being taken to bits! He's going to arrange to come back for some new (different type) injectors fitting, which will of course also involve a total re-calibration. I did have various types of appropriate injectors in stock the other day when Matt visited (and before he came I half expected to be changing the injectors when he visited), but after seeing the vehicle there seemed no point in changing his original injectors as I found them all to be in good (for Romano anyway - not great injectors even when new!) working order at the time and changing the injectors would only add to the bill. He also mentioned the gauge works properly, except when the tank is very nearly empty the gauge again shows full. This can only be due to a problem with the sender unit.. the sender is the individual resistor type so it seems obvious that the earlier tank earth fault has burned out the sender unit's resistor that equates to near empty tank level.

Simon