Stag 300 isa2 BMW 540 help please

[DanThe]

Ive come to the conclusion the pump at my local LPG suppliers is unreliable, watched 2 other cars now struggle to get a full fill.
I got my steel threaded adapter, 5mm hole down the middle compared to the all brass 4mm hole, 25% bigger/more flow there

Since using the new adaptor I rolled up at my local and it wouldnt fill to capacity, slowed to a halt but no clunk from the valve shutting off. Removing the ball valve there and then made no difference either, it took 0.5 litre then halted again. I refitted the valve drove to a different station about 8 miles away and got another 14 litres in easily at a much more regular speed, no slowing/speeding up on the counter.

Today I connected the laptop up randomly to check how the maps were doing just out of interest



Looks like its teaching itself....!

Just been out and done a bit more messing with the mapping, ive raised the pressure to 1.2bar and re-calibrated/deleted the maps to start again.
Used a route of about 10 miles, lots of uphill foot in floor moments and a nice open sweeping national speed limit road on the way back with hardly any traffic to slow things, took three attempts at altering the multiplier to get this result



Im still getting the "injectors fully open" error but the lambdas are now only showing 0 literally at the rev limiter when holding it just under for a few seconds, should be ok as I rarely rev the engine that high at all.
Very different results now though, feels a lot more like its running on petrol, much more power available.

I might see if I can get some time on a rolling road, I take it its the same as far as setting the multiplier?

[rossko]

Im still getting the "injectors fully open" error but the lambdas are now only showing 0 literally at the rev limiter when holding it just under for a few seconds,

What does the gas pressure do at this time?
I think you can resize your injectors a little yet without getting problems at idle, given a 4.8mS idle time at the moment.

I might see if I can get some time on a rolling road

It's not going to help if something in your system is a bit too pansy for this job. Don't get too hung up on "tuning", this is not a self-contained fuelling needing mapping for all conditions. The petrol system remains in charge of that. The "mapping" here is to find an almost static correspondence factor between petrol and gas.

[DanThe]

You reminded me, at one point the pressure dropped so low that it switched back to petrol, I was pretty much at the rev limiter and for a while. Its set to 0.75 I think as the minimum pressure

[DanThe]

Bit of a thread revival and update/ask for advice from the experts!

Ive now done about 45,000 miles with the setup relatively problem free, only had to change the solenoid coil on the vap as it became faulty.
More recently on cold starts when running on petrol the engine had started to missfire, when it switched over to gas it ran fine so i lived with it for a while, it also started taking a long time to start in the morning after an overnight stand. I narrowed this down to the lpg injectors leaking gas overnight into the intake manifold which meant the spark could not ignite the petrol/air mixture until the lpg had been cleared through.
This meant the injectors had worn the seats away, and were now out of spec which had messed up the lpg/air mixture which in turn adjusted the fuelling adaptions to the point the engine could not run well on petrol until the lambdas were hot/working.
Id seen the rebuild kits but it was going to cost the best part of £100 and remembering the advice given to me previously i decided to buy some Hana injectors.
I bought the Gold variants, now installed ive been having a play with the mapping, I have tried a few different vap pressures 1.2 bar 1 bar and now 0.9 but the multiplier starts in the same place about 1.1
I expect this means i need to fit some nozzles in the hana injectors, I selected the hana green in the gas settings screen as thats the same as gold i believe

Some pictures below, first is after a very brief run second is after about 8 miles with more full throttle time, its a bit messy and i dont think this can be corrected by adjusting the multiplier

[LPGC]

Without re-reading the full thread...

Since you used auto adaption last time with the Valteks, you should reset the ECU or at least go into rpm correction and set all corrections to zero, also delete petrol map and gas map etc.

Wouldn't bother with the auto-adaption but it seemed to work OK for you last time...

Hana Green are supposedly 1.9ohm, Gold are supposedly 1.3ohm. Nevertheless Hana Green setting may be closest match in your settings if you don't see any other Hana setting available.

Looks like autocal didn't do a great job with either Valteks or Hanas. Valtek map had that rise from 13ms which shouldn't be there, with Hanas the map is flat to 6ms, shouldn't be that flat. Even if auto adaption seems to work well on your install, it still won't do a good job for both open loop near closed throttle on over-run / near full throttle operation.

Stag setup usually improves by adjusting temp correction towards a bit positive for cold and towards a bit negative for hot (or over-compensates for temp when Ging is near Pinj).

I don't fit many Stags myself, but do sort out and repair rather a lot!

Simon

[DanThe]

I did delete both maps and start the autocal, I didnt use autoadaption before and havnt used it now, unless you mean auto cal?
Ive looked at the rpm corrections and they were all on zero, i hit the delete button anyway, maybe they reset with auto cal?
Here is the chart for the injectors, I chose the gold 3.0mm 'green' based on this, the engine is approx 290 -300hp



I just went out and altered the multiplier and did about 6 miles, the maps are close but the multiplier is nasty, cant be right can it?



Would fitting the smaller nozzles help the auto cal?

I forgot to take a pic but the deflection map is like a great big S on its side

[LPGC]

I think you've interpreted what I meant correctly.. I did mean don't use auto adaption, autocal doesn't mess things up like auto adaption though some would disagree that auto adaption messes things up!

We can't always go by charts listing nozzle size against bhp per cylinder etc as such charts make lots of assumptions. Having said that, your nozzle size should be good for this engine.

Deflection (I think the very early Stags and similar systems called this gamma, also synonymous with multiplier) map is definitely wrong like you've said - Will need adjustment all the way along

Just so we have a base reference to go by, what are the fuel trims looking like at idle running on gas / running on petrol? I ask because figures suggest your engine is warmed nearly fully up and out of gear with no loads such as A/C etc yet Pinj at idle is still a relatively high 4.4ms. Might expect such figure on some spec P38's but would expect the BMW lump to idle at lower Pinj with warm engine. In which case would expect your fuel trims to be high positive, and since Ginj won't change with correct calibration at idle, correct calibration would therefore mean a higher multiplier at idle and probably a fairly high multiplier all way along... In simpler terms, you may need to increase pressure a bit!

Nearly suggested you attempt calibration with pressure set as it is now but that might involve multiple full remaps, each time after adjusting pressure (in the event full load mixture is wrong). A better/quicker way - Delete all map points after 8ms (leave 8ms in place), this will leave you with straight line between 8ms and 25ms, move 25ms point down until the multiplier line crosses the 16ms mark at multiplier of 1 (16ms because that is around maximum Pinj you'll see on this engine). Repeat: Drive car at full throttle while monitoring lambda (air fuel ratio), Pinj and Ginj. What you want to see is Ginj the same as Pinj with the correct air/fuel mixture. Having the line cross multiplier of 1 at full engine load position should ensure Ginj is same as Pinj at full throttle (which is important) but this likely will not yet have ensured the mixture is correct with those settings... To make sure the mixture is correct for full throttle you need to adjust physical pressure at the reducer and ECU reference pressure to match that physical pressure (increase pressure if lean at full load and vice/versa). Loop until full load mixture is correct with Ginj = Pinj. This has ensured your LPG system can run the engine totally on LPG even up to the red line at full throttle with correct mixture without getting 'injectors full open' errors and without running LPG injectors for less duration than petrol injectors (which can cause less accurate fuelling and lead to hesitation when you put your foot down suddenly etc). Now you can note the pressures you just used, run Autocal if you wish to use it (after autocal make sure autocal hasn't changed your set reference pressure), do the rest of your mapping with the confidence that you've already set pressures correctly so won't have to make changes to pressure.. Obviously during the above, you need to make sure mid range and idle multiplier are not too far from correct but you don't need to adjust such points in detail until you come to calibrate them properly.

Most people start with autocal, then move onto light/medium loads, then move onto high loads. Sometimes this will lead to Ginj being quite different from Pinj at full engine load with all the implications that involves (some listed above)... At which point some of those people would adjust pressure and then need to re-calibrate from scratch again to ensure engine will run correctly on LPG at high loads, but it seems a majority of people would check to see Ginj is in the same ball park as Pinj and then simply leave calibration at that... After all, they spend all that time calibrating idle and mid range points so engine runs nicely during normal driving - seems they'd hate to have to restart calibration from scratch and maybe mess up what they just did or have wasted that time just to ensure engine will go up to red line with correct mixture without injectors full open errors etc, maybe thinking customer will hardly ever drive it like that, or maybe just not knowing any better!

Simon

[DanThe]

You know now you mention it and looking back to previous pages the pinj times were about 3.5 before, and ive just realised I always leave the AC on permanent, might help if i turn it off i suppose! Maybe this would bring the pinj times down a bit, will have to investigate it more.

First time round it became much easier to map once the pressure was raised, and the map shows it leans out at full throttle so will lift it up again for that reason, the ininitial full throttle response is poor at the moment, lags and then gets going, I took a pic of the deflection map earlier while checking the maps again



Thanks for the advice

[LPGC]

You're welcome.

Wouldn't think AC compressor was in on first pic as map was only .3 bar.

Definitely need to sort that map out, shouldn't raise again at top end like that for starters.

No autocal can sort top end of map.

Simon