Simon, I've tried to answer your questions & comments below, this is the first time I have been able to access
http://www.lpgforum.co.uk (not sure why) since last Monday, thanks:
LPGC wrote:Recently fixed some obvious mistakes on several vehicles from a certain installer mentioned in the thread (not from anyone who's posted but mentioned in the thread). As others have said in other threads recently, shame because they used to do decent installs that didn't have these problems - Same company name, different people doing the installs.
What company's sticker is on the front of the AEB2568? The brand will tell us which injectors can be selected.
(photo added)
You've noticed your Beemer ticks over with around 2.5ms petrol injection. What do those petrol injection figures go up to on cam (4000rpm-ish) at full load? Not sure if they're the same but the Ultragas injectors I've seen look like Valtek type 30, which isn't a very fast opening, linear or great flowing injector - Wouldn't be happy fitting them on most Beemers for reasons related to that 2.5ms tickover which I'm going to explain. Even with those injectors though, we can get you running OK but the system might need to do a petrol addition or switch back to petrol at high loads/revs.... Explanation: LPG injectors need to inject enough gas to properly fuel the engine at full power and maximum revs. At 6000rpm petrol injectors have a possible injection window of 20ms. In this window they must be able to open, flow fuel into the engine and close again in time for the next injection cycle, and because of this most petrol injectors go up to 16ms open duration on an engine that does a bit over 6000rpm. Most engines tickover with around 3m/s petrol injection. There are a few reasons why your BMW might tickover at 2.5ms, including (a) it might tickover efficiently (they do with that forced air tickover system), (b) it might do an extra injection pulse, (c) the petrol injectors might flow more or be fed with a higher pressure than most manufacturers would fit on the same size engine. If c is the only one true out of abc then your maximum petrol injection pulse won't go to 16ms and you won't have as much of a problem with poor injectors if it calibrated differently. LPG injectors that aren't great need to have large nozzle sizes and run at high pressures to be able to inject enough fuel within the 16ms at high loads, but this can mean they don't need to open for as long as the petrol injectors at low loads. For an LPG system to accurately measure gas into an engine, LPG injectors need to open for at least as long as the petrol injectors. But, on top of the last point, if LPG injectors are too slow to open or close, then it becomes difficult to accurately dose LPG into the engine at low LPG injector open durations. If you have Valtek type 30's, they won't work well at low injection pulse times. If the last two points are true, the way to improve matters is to lower pressure and/or reduce nozzle sizes. This might mean the LPG system won't flow enough fuel for top end power, but with your system you can add a petrol addition or it will switch back to petrol when LPG injection time exceeds the injection window time.
This is how it looks at ~4000 rpm, full throttle.
'Lambda error' can mean many things. If the car was running ok on petrol, no MIL light before the conversion, then unless the 'lambda error' was due to the lambda probe heater circuit, I suspect you've changed the lambda probes in vain.
Yes, I should have at least kept them so I could test them. It wasn't the heater circuit code, it was something like "out of range".
You've changed the 2.0ms load figures to 0 across the entire rev range. This won't be correct - If it runs better with the zeroes, I suspect one or a combination of the following: you have the extra injection filter set wrong / pressure too high / nozzle sizes too large / injectors not linear enough for vehicle / wrong injectors selected in software.
I knew this wasn't correct, but it did allow the "idle on petrol" setting to catch the idle before it stopped. I have since changed this, I have enriched to 130 in the 2.0 & 2.5 boxes for 500 and 1000 rpm. I also clicked the "ignore extra injections" box on the last page. This does make the petrol times even lower (~2.3 ms), but, it doesn't stall anymore. It does still miss on idle though.
Connecting the lambda probes to the LPG system won't change anything.
I just wanted to see if it was running rich or lean, I know it isn't part of the control (except through the car ECU).
You mention the diagnosis window. I think that the 6:0, 3:3 and 0:6 that you mention is you switching individual cylinders between LPG and petrol. On the last setting you tried, you turned all cylinders back to petrol.. Since it runs OK on petrol there's no wonder it ran better on 0:6 !
Sorry, I didn't write that clearly, I know it that 0:6 was all petrol, but just trying to explain that it got progressively better the more cylinders were on petrol, no matter which ones they were.
First thing to check: As someone else has said, the first thing to do is check to see where they've installed the manifold injector nozzles (spuds). If they're too far up the manifold, you will always have problems at low rpm, especially if your Beemer has the forced tickover air system.
I think they're about as close to the head as possible, but the hoses after the injectors are fairly long. Photos now added.
Second thing to check: A lot of BMW six cylinders (including yours from memory) are managed as two banks of three cylinders - like a V6 they have two primary lambda's. The software should therefore be set to two banks. Being a straight 6, this is sometimes overlooked and the installer leaves the setting at one bank. If overlooked there will always be fueling problems. Check in the 'Lambda' screen for 'number of banks'.
This was set to 2 banks. "bank 2 trim" was set to "6". One day it needed me to change this to "15" to make the 2 petrol injection times even. The next day it needed "-20". In the end I just changed it back to "0" and actually it seems to sort itself out pretty well. Sometimes they are different, but usually about the same.
Regarding the MJ injectors, just so we know, what nozzle size do they have (if not sure, what vehicle were they fitted on before)?
The MJ injectors I have are 3.0 mm drilled, they were on a 3.0 mk III Supra, then 4 of them were on a 318is.
What is the set working pressure of the system?
It changes depending on load, on idle I think 1.2 bar... I shall double check.
What injectors are selected?
I-PLUS injectors (whatever they are!)
Where is the extra injection filter indicator? Start with enabled and in middle.
Where is the 'acceleration injection enrichment' indicator? Start with fully to right.
My car hasn't got an OBD2 port, don't I need this for the "acceleration enrichment" control?
The "extra inj filter" was set one notch left of the centre. Now switched off.
Thanks again,
Ross
