LPG Rover no longer running

[whitelion58]

Hello
I have a Rover 827 Coupe that I fitted with a single point system about 20k miles ago. Its a Leonardo ECU and a Tartarini Vap - both were second hand when I installed. All has been fine until recently. Refilled the tank and drove a few miles, when it started to splutter and cough and became unusable on gas. Over the next week or so I ran on petrol, attempting to flick to gas now and then, but with no success. Then, suddenly, it worked again and ran perfectly for a couple of days/100 miles. Refilled the tank and again all was well for a few miles, then it died and will not run at all on gas. Fine on petrol though. Not sure if the refills are related or not.

This afternoon I checked the three solenoids are all opening, and plenty of gas arrives at the Vap it seems, so what can be the problem? Knackered vap or dead ECU - what are the thoughts please?
Cheers
Tim

[SimonHobson]

Hello
I have a Rover 827 Coupe that I fitted with a single point system about 20k miles ago. Its a Leonardo ECU and a Tartarini Vap - both were second hand when I installed. All has been fine until recently. Refilled the tank and drove a few miles, when it started to splutter and cough and became unusable on gas. Over the next week or so I ran on petrol, attempting to flick to gas now and then, but with no success. Then, suddenly, it worked again and ran perfectly for a couple of days/100 miles. Refilled the tank and again all was well for a few miles, then it died and will not run at all on gas. Fine on petrol though. Not sure if the refills are related or not.

This is beyond the point where I would hook up the laptop and ask the ECU what's going on. Failing that, hook up a voltmeter to the lambda probe signal and see what the mixture is doing.

A number of things come to mind. First of all, how long since you last serviced it - fitted new filter and drained the heavy ends ?

How old is the reducer ? The diaphragms tend to harden and split with age, and this plays havoc with the mixture.

Lastly, AEB systems have an "interesting" 'feature'. The stepper valve is fine for about a year (ie till just out of warranty ), then it starts sticking when cold. the effect then is that it won't switch over to gas at all, or it will switch over and run weak (poor power and/or backfires) as the stepper didn't move for some of the step signals sent to it - so the ECU thinks it as (say) 90 steps open, while it's actually only (say) 57 steps open. It could be 'fixed' in software and I have told them this - needless to say I had no reply.

[whitelion58]

Thanks for the reply, sorry I took a while to respond. The vap is unknown age and I have never touched it, other than plumb it in initially.

I swapped the stepper motor at the weekend ( found one in my box of bits) - but no effect.

I have acquired a cheap, brand new, Voltran vap - so as soon as my new Olives arrive, it will be fitted and hope it fixes things. The petrol bills are killing me!
Tim

[whitelion58]

Hello again
just spent the morning swapping out the Tartarini vap for a brand new Voltran Major. Still running very rough indeed and undriveable.
Any ideas? It still has the stepper motor I swapped during the week too, so not a whole lot left really!

What is the set up procedure for the new vap, just in case its only a tuning issue now? There is a brass screw at the top and a black plastic on the front - so, what do they do, and how do I twiddle them please?

Running out of ideas and energy now so would really appreciate some help.
Thanks
Tim

[Gilbertd]

My car gave similar symptons when the lambda sensor died because the Leo controller was progressively opening the stepper to richen the mixture. Eventually it did the same thing on petrol too but to start with it was only on gas.

You need to hook the controller up to a laptop to see what the Leo is doing. This will show you if there is an output from the lambda sensor and also what the stepper is doing.

[whitelion58]

Hello
just had the lappy on it. The Lamda reading is staying put at around 0.67 V, on petrol and gas. I seem to remember it used to "bounce" between top and bottom of the scale? I would expect the rover ECU to throw a fault code if it thought the Lambda was out of range, but no sign of that.

The car will now just about run at high revs on gas, but splutters and dies at anything approaching lower revs - fiddle with the Vap? which screw??!

[Gilbertd]

If you've got a reading from the lambda sensor, it seems that it's working. What is the stepper doing? Is it staying at the top or bottom of it's travel or moving around the default setting? At lower revs what is it trying to do. open up or close off? The smaller of the two screws on the vap will be the idle bypass, screw it in to weaken the mixture or out to richen it.

Ideally you want it to run at about 3000 rpm with the stepper at around the default value (which should be anything from 70 to 150) and the same on idle. Adjust the screw to get it into the default zone.

[junkcatcher]

Have you check the voltage readings for both lambda sensors --- the Honda V6 should have a sensor on each bank.

If the lambda sensor output voltages are constant when the engine is at idle on petrol then something is stopping the engine going closed loop. On some Honda engined Rovers you can retrieve the engine ECU fault blink codes by linking two wires behind in kick panel the pasenger (ie left) foot well, but if the fault light isn't on I don't think this will give much clue as to what might be wrong.

Try watching what happens to the lambda sensor output when you introduce a tiny amount of propane from a gas blowlamp into the air intake.