1.9DG/LPG IDLE ISSUES

[JamesKT25]

Once I can, I'll get it warmed and tweaked. And report back I'm so grateful!

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[itchyfeet]

I have learned a thing or two also so thanks to all who contributed.

[JamesKT25]

Thanks again. I hope this can help others.

[ajsimmo]

Good news. Glad you got sorted. It'd still be a good idea to tweak it on a gas analyser.
Oh, just seen you said you'd do that! As you were...

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[JamesKT25]

Does anyone know of a reputable LPG service garage around North East Yorkshire I know there is one in thirsk and hull but would prefer someone I know will get it right. Can a DIY analyser be bought?

[kevtherev]

OK so I tried a little dabble
Warmed the engine.
turned the bias to 0
turned out 8 flats, power valves to 3 turns 1/2 turn on idle bypass
nope...nada would not start
Bias out until engine started 16 flats, no tickover, but ran uneven stuttered at 2000 rpm, would not run until I got to 20 flats (1200 rpm) backed up one flat (19) idle speed 950 rpm.
closed idle by pass. No difference.

Tickover at 950 nice throttle response
Not driven yet, so we'll see

[itchyfeet]

That goes to show all systems are different, I think co setting on carb has an effecton idle too from my experiments.

Worth mentioning a single power valve behaves different from a twin power valve, what do you have?

I found no idle bypass means you need bias and power valve higher and that results in over rich when driving, it's a complicated balance and I'm still juggling with it before putting the closed loop back

I was also under the impression the vapouriser had some sort of 'choke' giving more gas cold but mine struggles cold, if I make it good cold it's over rich warm.

[JamesKT25]

So now I have its idling with a half turn on the bypass.

What's the best procedure to get it running right or as close as. Idle doesn't seem to change as I increase the bias but will drop to a stall if I lower it.

[ajsimmo]

No Paul, the vap has no choke function, and will usually be on the lean side until warmed up. I'm not sure how the CO setting on petrol can affect the lpg running, apart from idle screw may need tweaking if CO is altered. The golden rule is to get it right on petrol first, then make gas work like petrol, not the other way round.
The vap settings with the old pierburg spud ring are very different to with a blos. I really don't like the old mixers, they are weak on draw, temperamental to set up and very prone to even the slightest cross wind. That's why we (used to) remove the connecting hose from the airbox to the corner intake - it all but eliminates the effect of varying air pressure at speed (ram-air making it go lean). We fit Blos almost exclusively now on all WBX conversions (carb and injection) and the vapouriser can be fitted straight out of the box, with little or no adjustment. The Blos draw is much stronger, then once set up, it regulates the amount of gas according to demand, and consequently vap settings make much less difference to the mixture. Positive pressure from the bypass is rarely necessary. It can also be used with a closed loop controller, without any of the lag experienced by some with the traditional setup.

[ajsimmo]

So now I have its idling with a half turn on the bypass.

What's the best procedure to get it running right or as close as. Idle doesn't seem to change as I increase the bias but will drop to a stall if I lower it.

Once you have a smooth idle (same as, or slightly higher than, petrol), rev it. Hold at 3k. Adjust power valve as described. Drive it. If OK on power, leave it until you can get get it checked.

[JamesKT25]

I have found that when I opened the power valve the idle would increase. is that normal?

[JamesKT25]

Whats best practice for setting the idle?

[ajsimmo]

No, it was probably wound in too closed to start with. Vap should be set up with power valve opened right up, and then PV is adjusted last.

[ajsimmo]

Whats best practice for setting the idle?

There are 3 adjustments. Set bias with no bypass. If won't idle, use a little bypass. Will it rev freely? Then rev it and set power valve. Drive it.
That's it.
Then book it in somewhere to fine tune it.
Then try to leave it alone, despite feeling it's not quite right.
Then book in somewhere for a BLOS.
Then enjoy the difference.
Then realise you haven't worried about your LPG for months now.

[JamesKT25]