Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: BigCat on 26 August 2011, 23:33:10
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My 3.2 V6 has an LPG conversion which I had put in about 3.5 years or 45K miles ago. For sometime now it's been hard to start after running on LPG.
If I start it within a few minutes of stopping it starts ok, otherwise it requires at least 20 seconds of cranking, even after a few days of having last used it.
If I remember to turn off the LPG say 10 or 20 seconds before stopping the engine (and then turn it on again) it starts straight away.
If I run it on petrol only, the problem doesn't occur.
I had a misfiring issue which has now been solved (oil in the plug wells), but the hard starting issue is still with me.
Does anyone have any suggestions?
Dominic
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Coil packs not as healthy as they once were ? :-/
Showing any codes ?
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Coil packs were new just before the conversion.
I've only just got the car back for the oil-in-the-plug-well thing, so haven't had a chance to check codes yet.
What I don't understand is why running it on petrol for a few seconds (10 -20) before shutting it off makes a difference. Either way it starts on petrol.
I have this wild idea that the system leaks LPG into the plenum after shut down which then "floods" the engine at startup. The logic being that by changing back to petrol before shutting it off, I'm purging the leak out.
Does that sound plausible?
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BTW: I'm not getting e-mail notifications for my posts. :o
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Coil packs have been soaked in oil, which does them no good at all. LPG is much more sensitive to HT weaknesses than petrol. :-/
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Any codes? Pedal trick? Lights on dash? Fuel trims ok? Did it get progressively get worse over time....?
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LPG is much more sensitive to HT weaknesses than petrol.
I accept that, but whether I do my trick or not, the system starts on petrol.
Surely that rules out the HT system?
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Any codes? Pedal trick? Lights on dash? Fuel trims ok? Did it get progressively get worse over time....?
I've just picked it up from my mechanic to correct a misfire which was down to oil in the plug wells, so haven't had a chance to check for codes.
It does suffer from the V6 pre-cat problem so the emission light is normally on (reset at the moment).
What are fuel trims? is that the offset in the LPG ECU?
It did progressively get worse, although it now seem to have stabilised i.e. at first, it didn't happen every single time , but now it does - unless I do my trick.
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LPG is much more sensitive to HT weaknesses than petrol.
I accept that, but whether I do my trick or not, the system starts on petrol.
Surely that rules out the HT system?
Petrol doesn't need as strong a start to ignite so it doesn't rule it out... However, it should start on petrol before switching to LPG anyway so I don't think it's a HT issue with regards the starting.
Your theory of an injector flooding the cylinder is possible but I'd start off looking for a petrol leak. Although that would probably occur regardless of fuel system when switched off :-/
What LPG system is it?
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Fuel trims are the amount of positive or negative duration applied to the fuel injectors on each firing cycle. The engine ecu adjusts the duration according to the mixture that the o2 sensors are seeing in the exhaust. If it's rich it trims back the injector duration giveing less squirt per firing cycle giving negative fuel trim. Lean it applies positive fuel trim to give more fuel. Fuel trims.
With LPG, if the set up has an issue, causing the excessive fuel trim on gas only, then when it switches to petrol it immediately has to go back to the correct fuel trim which takes time as the trim level is worked out as an average over a period. This is long term fuel trim. Which, if it has say +25 % of lt fuel trim on gas will bring the engine light on, and will run very grumpy on first stater up on petrol first thing.
Switching the gas off 5 mins from home will bring the fuel trims in line enough to make petrol running better. Although it takes longer for the trims to be correct due to it's average learning.
It's possible the trims are far enough out to cause a starting issue IMO. It needs a look at live data and codes on petrol, then see how the gas affects it and adjust accordingly.
Work to do. Sortable though.
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my thought is maybe an injector too, sticking open when shut off? dropping fuel into the pot making it harder to turn over? :-/
Or is it trying to start on LPG, not petrol? :-/
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Might be worth getting your mech to get a code reader on it. See what fuel trims and codes are doing first. Clear codes and see how it goes, assuming the faults are fixed.
There are other threads from the op discussing other issues iirc...?
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Switching the gas off 5 mins from home will bring the fuel trims in line enough to make petrol running better. Although it takes longer for the trims to be correct due to it's average learning.
It's possible the trims are far enough out to cause a starting issue IMO. It needs a look at live data and codes on petrol, then see how the gas affects it and adjust accordingly.
Yep, I'd go along with this. It means the fuelling on LPG is wrong, either due to a fault in the LPG system or because the system just needs mapping again. The problem is, the software, lead, dongle, etc. needed to talk to the LPG ECU will be required to get much further although you could confirm this by checking the fuel trim values in the petrol ECU using an OBDII cable. Do you know what LPG system is fitted?
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Yes, I can see what you're saying and it sounds quite reasonable. When I had the LPG installed, they did ask me whether I wanted it set up for power or economy; I chose economy reasoning if I wanted more power I could simply switch to petrol.
So, just freethinking here: I guess my LPG ECU is setup lean, the Engine ECU compensates by richening the mixture; therefore when it stops on LPG and then starts on petrol, it's running rich...
...except, despite everything I said earlier, I have just realised it doesn't start as though it "has the choke out", rather the opposite. Perhaps it's all the inverse of what I said, which still points to fuel trims.
I forgot to mention one other thing, As it starts, warms up and changes to LPG, it progressively runs rough and nearly stalls (the engine light flashes). If I immediately change back to Petrol then back to LPG, it runs smooth. If I don't interfere it eventually sorts itself out.
Definitely sound like fuel trims.
I'll do a pedal check on my way to work tonight.
Next step: Are there other readers that can read fuel trims live or just a Tech II?
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I think your LPG installer is either being lazy, or know full well the kit has an issue they can't be arsed to sort out. If driving reservedly a slightly lean mixture will bo covered no problem.
Something is amiss. Certainly. It needs checking and mapping correctly so the lambdas never go lean, but so it's not rich either. LPG injector nozzles may very well need re sizing.
There are cheap code readers capable if code reading and live data. Most basic function of which is lambda readings/fuel trims.
But once again...WHAT KIT IS IT? :)
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Yes, I can see what you're saying and it sounds quite reasonable. When I had the LPG installed, they did ask me whether I wanted it set up for power or economy...
This rings alarm bells. ::) There's only one way to set up an LPG system. The correct way. ;)
If they have tried to set it up lean, it will trim the mixture back and this could well be what is causing a problem.
You really need the software to talk to the LPG ECU to try and set it up better but a chat with a Tech 2 or other code reader capable of live data will confirm if the fuel trims are going awry.
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Possibly not much help as the OPs EML is on anyway with Cat codes, but it would appear that, on a 3.2, a code gets stored (thus pedal trick or code reader will display this) in the ECU when Long Term Trims go up to 20%, BUT do not actually bring on the EML until 25%.
See, GayBoyGixer, I did learn something today, no matter what gormless state my friggin mind was in ;D
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...but it would appear that, on a 3.2, a code gets stored (thus pedal trick or code reader will display this) in the ECU when Long Term Trims go up to 20%, BUT do not actually bring on the EML until 25%.
Yes, I would agree with something like that. The EML hasn't come on permanently since the last reset, until this morning.
(I'm working night shift at the moment hence the starnge timing of my posts.) I drove home this morning and had a very rough drive, the engine was misfiring all the way on both LPG and petrol and nearly stalled a few times, towards the end (15-20 min drive) the EML started flashing and then came on permanently.
I disconnected the battery and re-connected it tonight. EML is reset and a much smoother run in. Off-idle performance is a bit rough, but runs smooth and idles reasonably.
UPDATE:I just performed a pedal chack and got the following codes:
0300 Random/multiple cylinder misfire detected
0302 Cylinder 2 Misfire Detected
0304 Cylinder 4 Misfire Detected
0173 Fuel trim malfunction (Bank 2)
0173 Fuel trim malfunction (Bank 2)
No, those last two are not a misstype, I checked it three times, it definately gave two lots of 173, although I realise why I'd had so much difficulty before; The third flash on the first 173 code is very brief and not the same timing as the other two.
.
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...but a chat with a Tech 2 or other code reader capable of live data will confirm if the fuel trims are going awry.
I bough a couple of code readers a few years ago, including a EBDII one which cost me a few hundred quid, but it wouldn't talk to my car. I sent it back to the distributor who checked it out and sent it back saying there was nothing wrong with it. I lent it to a colleague who said it worked fine for him.
I'll have to ask him for it back and have another go...
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...but a chat with a Tech 2 or other code reader capable of live data will confirm if the fuel trims are going awry.
I bough a couple of code readers a few years ago, including a EBDII one which cost me a few hundred quid, but it wouldn't talk to my car. I sent it back to the distributor who checked it out and sent it back saying there was nothing wrong with it. I lent it to a colleague who said it worked fine for him.
I'll have to ask him for it back and have another go...
Don't bother... The Omega isn't EOBD2 compliant ;)
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I think your LPG installer is either being lazy, or know full well the kit has an issue they can't be arsed to sort out. If driving reservedly a slightly lean mixture will bo covered no problem.
Something is amiss. Certainly. It needs checking and mapping correctly so the lambdas never go lean, but so it's not rich either. LPG injector nozzles may very well need re sizing.
There are cheap code readers capable if code reading and live data. Most basic function of which is lambda readings/fuel trims.
But once again...WHAT KIT IS IT? :)
?
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Indeed... One more time!
[size=20]What kit is it?[/size]
:-? :-?
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Don't bother... The Omega isn't EOBD2 compliant ;)
A 3.2 should be. ;)
But.. handheld code readers are often pretty poor IME.
Cheapest way is probably to buy a generic ELM327 diag. cable on Ebay and then install one of the freebie applications that do code reading and live data - if you have a laptop. Worked nicely for me. :y
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Don't bother... The Omega isn't EOBD2 compliant ;)
A 3.2 should be. ;)
But.. handheld code readers are often pretty poor IME.
Cheapest way is probably to buy a generic ELM327 diag. cable on Ebay and then install one of the freebie applications that do code reading and live data - if you have a laptop. Worked nicely for me. :y
good point :-[
Although being ex plod I wonder if there's some butchered wiring stopping it working :-/
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Although being ex plod I wonder if there's some butchered wiring stopping it working :-/
Could even be one of the LPG kits that talks to the ECU using the OBDII wiring, but then I'd expect it to be working better in that case. :-/
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The LPG kit is "Pick and Mix". All I know is when I had to have the multivalve replaced in Italy (it failed whilst I was away last year), I took it to a few places and they all commented that the tank and multivalve were BRC and the ECU wasn't!
I understand that there are two major Italian brands, and that the ECU is the other brand i.e. Not BRC. Any ideas where to look?
Code Scanner: The 3.2 is apparently OBD II AND CAN BUS II compliant, and that's what model of reader I bought from these guys: http://www.opel-scanner.com/. It is supposed to give me all sorts of info via laptop, including fuel trims. See here http://www.opel-scanner.com/index.php?pid=7
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The 3.2 doesn't support CAN diagnostics but does support the older OBDII protocols. That device says it can support all Omegas, though, so it must also support the earlier pre-OBDII protocols.
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Have a look around for the ecu (Probably easiest to follow some of the injector wiring back to it) and hopefully there'll be a sticker on it with the make. If we can get software then one of us with some LPG experience may be able to help out :y
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There are cheap code readers capable if code reading and live data. Most basic function of which is lambda readings/fuel trims.
But once again...WHAT KIT IS IT? :)
I have borrowed a simple code reader, but I don't think I'm going to get my comprehensive one back. Can you point me in right direction for an inexpensive reader that will also do fuel trims?
BTW codes today are:
300, 302, 306 (always the same two cylinders)
725 Is this something to do with gearbox?
156 O2 Sensor Circuit High Voltage/Slow Response/No Activity/malfunction (Bank 2 Sensor 2)
150 O2 Sensor Circuit High Voltage/Slow Response/No Activity/malfunction (Bank 2 Sensor 1)
As for the kit, well I can't get to the ECU, but the injectors are OMVL (and the tank is BRC). It has a MAP sensor, but I guess both OMVL and BRC use those. The only other thing I can note is that the wiring harness seems to match the injectors well, so quite likely its OMVL.
(BTW:Note to any Admins reading this, I'm still not getting e-mail notifications)
(http://i117.photobucket.com/albums/o54/ddichiera/OMVLInjectors.jpg)
OMVL Injectors
(http://i117.photobucket.com/albums/o54/ddichiera/LPGEngineBay.jpg)
Engine Bay
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If it's a BRC system we're buggered. They don't allow fiddling with their software as it needs a dongle to alter the parameters which they don't sell to Joe public. Can you see any makers name on the ecu?
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Thnaks for everyone's help so far.
I've been working 12 hour shifts continually, so haven't had time to search for the LPG ECU, but hopefully will next Friday.
I've been running on petrol for the last day and a half and absolutely no codes.
Post modified by Admin Team to remove discussion on acquiring copyrighted stuff.
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.... youmay find admin will delete related posts due to op com copyright issues.
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.... youmay find admin will delete related posts due to op com copyright issues.
This just gets more complicated by the minute. What are the op com copyright issues, or can't we discuss that?
Is that why I'm not getting e-mail alerts to this thread?
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It isnt legally available in this country. ;)
Normally is referred to on here as "a chinese code reader". ;)
From the admins viewpoint, they could run into trouble for allowing their forum to breach copyright legislation. :(
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OK 0301 0302 0304 is the passenger bank coil pack
Check plugs first
Also use some decent petrol not supermarket crap
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What about this software: http://www.opel-scanner.com/index.php?pid=4 is that legal, or verboten?
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I think that one is OK as it is to the licensed supplier ... but just compare the price to the ebay copies ... :(
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That's a relief, I already own that. Just have to see if it'll work with the different hardware.
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.... Although it's handy to have live data capability, I wonder how much use it will be ultimately?
Seeing as we still don't know how to read or adjust what ever kit it is? Or if it's even possible.
Pointless spending a penny until we know. May even be a case of finding an approved LPG installer and paying him to sort it.... Live data or not!
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Unfortunately I have to agree with Chris. Unless you can talk to the LPG ECU and adjust it, which I don't think you're going to be able to do, it's going to make more sense to visit an installer. :(
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Just checked back throug this thread... If it's got OMVL Dream injectors then it's probably an OMVL Dream kit (although there are several versions) so you may be able to get the software and lead to be able to look/change the setup. :-/
The misfire codes need looking into though, check the coil packs and plug wells for oil contamination.
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This thread has become quite long and confusing, particularly as much has changed since I first posted it, so once I get access to the LPG ECU I shall start a new thread.
ON the OMVL lead thingy, I found this: http://www.tinleytech.co.uk/acatalog/Software_and_leads.html I can only hope as it's a company and not an ebay item, that there are no copyright issues here (possibly available cheaper elsewhere legitimately).
For anyone who has managed to follow the thread accurately (you deserve a medal :D) , I've been running on petrol for a few days now and have not had any problems; no misfiring, no hard starting; although the eml has finally come on again (pre-cat issue surely).
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Yep all sounds like the usual LPG issues. LPG has a much narrower "window" for ignition. So any spark, timing, or lambda issues on petrol... or jet size issues on LPG... will show up far more readily. Correct set up is key. And a good strong ignition system of course.
If you start a new thread, include a link to this one so we don't get fuddled. ;D
Re sparks, vx are far cheapest for plugs, ESP if you have a trade club card, see FAQ.
Coil pacs Bosch only. Should be able to pick one up for £60 to £65 from a factors or google. See Vauxhall parts warehouse.(?)
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This thread has become quite long and confusing, particularly as much has changed since I first posted it, so once I get access to the LPG ECU I shall start a new thread.
ON the OMVL lead thingy, I found this: http://www.tinleytech.co.uk/acatalog/Software_and_leads.html I can only hope as it's a company and not an ebay item, that there are no copyright issues here (possibly available cheaper elsewhere legitimately).
For anyone who has managed to follow the thread accurately (you deserve a medal :D) , I've been running on petrol for a few days now and have not had any problems; no misfiring, no hard starting; although the eml has finally come on again (pre-cat issue surely).
Tinley are a reputable OMVL distributor so all OK there... Good customer support from them most of the time too :y :y
As for running fine on petrol, that doesn't rule out a HT fault... LPG is very demanding on the HT side of things and will highlight any weaknesses long before they show on petrol.
Give us a quick recap... What's the age of Plugs and Coil Pack? Have you checked the plug wells for oil (cam cover gasket leaking?) or have they been leaking in the past?
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Recap:The car has been hard to start after running on LPG, for some time now (although it starts on petrol).
On a return trip from southern Italy three weeks ago, the car developed a severe misfire and engine knock on both petrol and LPG. Mechanic found oil in plug wells and replaced camshaft gaskets, after which it ran much, much better.
In the last two weeks, LPG has been getting progressively worse and generating lots of codes (misfire consistently on 302 and 306 as well as various lambda sensor errors), following which I've been running only on petrol and no codes for three days, until today. 430 and 420 which is the pre-cat issue.
At the moment, it runs perfectly on petrol, no misfire, no hard starting.
As I'm working constant 12 hour shifts, I haven't had time to locate and identify the LPG ECU, but I suspect it's OMV Dream XXI as per the injectors.
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Oh and the LPG system has been in for three or four years and the coil packs were replaced just before. Plugs were replaced 4 months ago.
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Sounds to me like it's building up a large fuel trim on LPG which is making starting on petrol harder. It starts on petrol always, so why else would it not start easily if it was previously running on LPG?
Get some live data from the engine ECU, on both petrol and LPG, which I suspect will show fuel trims going awry on LPG then see if you can find some software to talk to the LPG ECU.
If the LPG system previously worked fine, then I suspect something has gone wrong. Either a filter clogged, vapouriser problem or some other restriction causing the fuelling on LPG to have changed from the state when it was set up.
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...Either a filter clogged, vapouriser problem or some other restriction causing the fuelling on LPG to have changed from the state when it was set up.
The multivalve failed whilst I was away last year, and I had it replaced at the local BRC agent (the tank is BRC).
The new mulitvalve had two problems: it reads incorrectly on the motorway i.e. if the fuel is consumed fast (it only drops to two out of four green leds when the tank empties) and it regularly gives false "trips" (sets off the empty buzzer) even when full.
I took it to the original LPG fitter in Battersea and asked them to change it. They maintain they did, but I still get exactly the same symptoms >:(
Could this be the cause of an LPG metering problem?
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...Either a filter clogged, vapouriser problem or some other restriction causing the fuelling on LPG to have changed from the state when it was set up.
The multivalve failed whilst I was away last year, and I had it replaced at the local BRC agent (the tank is BRC).
The new mulitvalve had two problems: it reads incorrectly on the motorway i.e. if the fuel is consumed fast (it only drops to two out of four green leds when the tank empties) and it regularly gives false "trips" (sets off the empty buzzer) even when full.
I took it to the original LPG fitter in Battersea and asked them to change it. They maintain they did, but I still get exactly the same symptoms >:(
Could this be the cause of an LPG metering problem?
We might be onto something here. :y False trips occur when the vapour pressure falls too low for the engine to continue running on LPG.
Give that the multivalve is what caused this problem it would make me wonder if it's not capable of flowing enough liquid to feed the engine. If this is the case, it might well be causing the engine to run lean, and hence trim the fuel to the point where starting becomes awkward.
Gauge readings could well be because a different multivalve has been fitted without the display being calibrated to suit it.
Issues if the fuel is consumed fast make me wonder if the pickup has fallen off the multivalve. In this case, the valve will be delivering vapour instead of liquid. This restricts the flow of fuel causing a loss of pressure (see my first paragraph!) and, if the gas is being consumed quickly, the temperature of the tank can fall so low that the gas can't boil off vapour any more, so the system behaves as if the tank is empty while the liquid level (as shown by the gauge) remains high.
If you take it for a decent run (say a couple of junctions up the motorway at a decent cruising speed) then get out of the car and feel the tank, is it cold, and perhaps showing signs of condensation or frost on the outside? (it should stay at the same temperature as its' surroundings).
It would also be worth checking the temperature of the vapouriser at this point, to make sure that it is piping hot.
Kevin
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Or it's just a crap multi valve...? Ime they do trip out to Petrol at the slightest jolt. Cats eyes, bumps, corners even.
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Or it's just a crap multi valve...? Ime they do trip out to Petrol at the slightest jolt. Cats eyes, bumps, corners even.
The original multivalve work perfectly, until it stopped completely. I never had any of these problems with it.
We might be onto something here. :y False trips occur when the vapour pressure falls too low for the engine to continue running on LPG.
Give that the multivalve is what caused this problem it would make me wonder if it's not capable of flowing enough liquid to feed the engine. If this is the case, it might well be causing the engine to run lean, and hence trim the fuel to the point where starting becomes awkward.
That's what I'd wondered.
Gauge readings could well be because a different multivalve has been fitted without the display being calibrated to suit it.
Yes, I'd reached the same conclusion.
Issues if the fuel is consumed fast make me wonder if the pickup has fallen off the multivalve. In this case, the valve will be delivering vapour instead of liquid. This restricts the flow of fuel causing a loss of pressure (see my first paragraph!) and, if the gas is being consumed quickly, the temperature of the tank can fall so low that the gas can't boil off vapour any more, so the system behaves as if the tank is empty while the liquid level (as shown by the gauge) remains high.
The only thing that changes with motorway driving is the gauge reading. LPG performance is the same.
I don't think the pickup has fallen off, only because the behaviour hasn't changed since they "changed" it. They took the tank out of the car and re-fitted it a few days later. I suspect they took the multivalve out, couldn't see anything wrong with it and re-fitted the same one, but I do have my suspicions about the multivalve. The BRC chap in Italy muttered something about "might have to find a secondhand/reconditioned unit" when I first spoke to him. (it's not the usual size/type they use down there.)
If you take it for a decent run (say a couple of junctions up the motorway at a decent cruising speed) then get out of the car and feel the tank, is it cold, and perhaps showing signs of condensation or frost on the outside? (it should stay at the same temperature as its' surroundings).
It would also be worth checking the temperature of the vapouriser at this point, to make sure that it is piping hot.
Chance would be a fine thing, although I have done the vaporiser test and it was very hot to the touch.
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Ok, the LPG system is an OMVL Dream XXI. You wouldn't believe where I found it... :-[
(http://i117.photobucket.com/albums/o54/ddichiera/OMVLDreamXXI.jpg)
(http://i117.photobucket.com/albums/o54/ddichiera/OMVLDreamXXIb.jpg)
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Better than in the airbox.
BTW I was threatened with legal action for mentioning the installer. BTW the Police warned him off me for threats.
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Better than in the airbox.
It's not too bad actually. They moved the main ECU over and wedged it in Goldilocks snug ;)
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Better than in the airbox.
It's not too bad actually. They moved the main ECU over and wedged it in Goldilocks snug ;)
Well who'd of thought, an ecu in the ecu compartment :o ;D
Sadly I don't thing the stag ecu, which we use on here, will fit in there... Never thought to look ;D