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[Tezray]

I've recently fitted some new Valtek type 30 LPG injectors and i've been trying to get them set up correctly. I've got the LPG map in a very good place - it's as spot on as it will get in relation to the petrol map and it runs very well.

The problem i'm having is that the power isn't as good as it is on petrol and i've got the error message "Injectors fully open". Looking at the injection times on idle my LPG injectors are at about 4.5ms whereas my petrol injectors are around 3.2ms. The multiplier on my LPG map is mostly around 1.2 also.

I think all this is pointing to the LPG injectors struggling to get enough fuel in... but i've drilled my nozzles to 3.0mm and I don't want to open them out more if it's the wrong thing to do. I'm also not sure how much to open them up to if I do? Is is possible that the nozzle tips that screw into the inlet manifold are undersize?

I don't understand how it isn't fuelling enough if i've got it looking so good on the map? Lots of questions sorry guys 

I've come a long way from where I was with the lpg kit, but I really want to get it running sweet as a nut (if possible on the old Stag 300 bog standard kit) 

[Kevin Wood]

What vapour pressure are you running?

My gut feeling is that more than 3mm won't help. The ID of the tube and the manifold nozzles isn't much more than that and the nozzles might get a bit fragile if you drill them too big.

We have plenty of other V6s running around on 3mm nozzles with no loss of power so I suspect you could do with running them with a little more vapour pressure. I'm running 1.25 bar IIRC.

Kevn

[Tezray]

Thanks for your reply Kevin. I know what you mean about the ID of the tube, I noticed that the nozzles wont go much over 3.0mm either unless you drill out the entire length of the nozzle.

My vapour pressure is also running at around 1.25-1.3 bar. I noticed earlier in the Stag 300 manual that my layout is slightly different; my vapour filter is positioned before my t-piece with the gas pressure and temp. sensors in. Would this make any difference whatsoever?

Maybe the error message should be of no real concern. I'm considering replacing the HT leads in the hope that I may gain some power when running on gas. Generally it's running very well on petrol, on my last tank I got 29mpg (calculated) which I was quite impressed with 

[TheBoy]

I run my MV6 3.0l auto with 3mm, pressure around 1.1 bar, Valteks.

I occasinally get Inj Fully Open, but it never goes lean (you need to check this whilst booting).

They say LPG can be around 5% down on power - I reckon on lpg, in mv6, there is a marginal, possibly noticible power loss.  But then I'm on a multivalve (marginal) and a small evap (marginal).


The elite (3.2), with 4 hole tank and bigger capcity evap, its impossible to tell if petrol or lpg.

[Tezray]

I've made sure it doesn't go lean on the map, but I have noticed that when booting it my lambda readings are around 0.75, is that a tad low?

I do think my evaporator looks a bit weedy, i've seen on V8's they often have 2, 1 for each bank. I would say that my power loss is more than marginal but not significant. What is a 4 hole tank?

I may try replacing the leads, I have no record of them being changed, so it's worth doing from a service point of view.

[TheBoy]

4 hole tan - 4 holes, seperate for filler, feed, pressure relief, gauge.

Multivalve - 1 hole, with multivalve performing all 4 roles

[TheBoy]

I've made sure it doesn't go lean on the map

Most likely not suffering fuel lack then...

[aaronjb]

I've made sure it doesn't go lean on the map, but I have noticed that when booting it my lambda readings are around 0.75, is that a tad low?

0.75 is extremely rich, not lean - that's around 11:1! To give you a rough idea, my turbocharged car is mapped to ~11:1 on boost, while an NA car makes 'best power' somewhere between 12.5 and 13.5:1..

[TheBoy]

I've made sure it doesn't go lean on the map, but I have noticed that when booting it my lambda readings are around 0.75, is that a tad low?

0.75 is extremely rich, not lean - that's around 11:1! To give you a rough idea, my turbocharged car is mapped to ~11:1 on boost, while an NA car makes 'best power' somewhere between 12.5 and 13.5:1..

These aren't wideband lamdas. They are either on or off, so the voltage doesn't matter, its either high (about about 0.6v) or low (below about 0.4v)

[Tezray]

Ok thanks guys, looks like I don't have much to worry about then 

[Kevin Wood]

You might find it's mapped a little rich at full load, actually. Injector times at idle sound about right but you'll find the multiplier doesn't need to be as high at longer injector durations because the long open/close times on those injectors have a bigger effect when the duration is short.

As long as the lambdas are both pegged at rich on a wide open throttle you will be fine.

Kevin

[aaronjb]

I've made sure it doesn't go lean on the map, but I have noticed that when booting it my lambda readings are around 0.75, is that a tad low?

0.75 is extremely rich, not lean - that's around 11:1! To give you a rough idea, my turbocharged car is mapped to ~11:1 on boost, while an NA car makes 'best power' somewhere between 12.5 and 13.5:1..

These aren't wideband lamdas. They are either on or off, so the voltage doesn't matter, its either high (about about 0.6v) or low (below about 0.4v)

D'oh, good point - I'm too used to dealing with wideband sensors, clearly

[Kevin Wood]

D'oh, good point - I'm too used to dealing with wideband sensors, clearly

I keep meaning to put one of those in an LPG'ed Omega. I wonder if I'd be shocked? :-/

[aaronjb]

D'oh, good point - I'm too used to dealing with wideband sensors, clearly

I keep meaning to put one of those in an LPG'ed Omega. I wonder if I'd be shocked? :-/

I know I was surprised how lean the MR2 ran in all conditions with the stock ECU - never lean of stoic, obviously, but it was stoic a lot more of the time than I expected (not anymore with my own tune, though )

[feeutfo]

D'oh, good point - I'm too used to dealing with wideband sensors, clearly

I keep meaning to put one of those in an LPG'ed Omega. I wonder if I'd be shocked? :-/

Interesting. I'd bet on a fair bit of leaning off needed. :-/