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PostPosted: Sat Dec 12, 2009 7:40 am 
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Hi I've recently had my BMW E46 330 converted to LPG (BRC senquential), but have noticed problems on a cold start, the colder the worse.

Basically my car will drop to 400, often lower in RPM's after dropping the clutch or coming to a stop and almost stall out, then will surge to around 1000 the either come back to normal idle RPM's (~700), or do a few more cycles or dropping and surging. I often have to stabilise the revs myself for fear of stalling at a junction.

This will not happen when running on petrol, so i think vanos problems are unlikely. The same issue on non LPG 6 cylinder BMWs 3 series is often due to the idle control valve getting gummed up and sticking, but why is this happening with LPG and not petrol?

Once warmed up its fine, although perhaps my LPG is in general a little more jerky than when running on petrol.


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PostPosted: Sat Dec 12, 2009 11:45 am 
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You can still have a slight problem on petrol which does not show that can amplify as a bad problem on lpg causing each ecu to conflict with each other and cause running problems.
It could also be there is something wrong with the install.
Seeing as you will be under warranty I would not touch it , just take it back and let the installer take a gander should be the first port of call.


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PostPosted: Sat Dec 12, 2009 12:12 pm 
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Sounds like a coolant flow through the reducer problem, the reducer isn't getting enough warm coolant flow to supply to evaporate to the liquid lpg,

The evaporation of the lpg has freezing effect exactly the same as the evaporation of the gas in in a fridge freezer.


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PostPosted: Sun Jun 06, 2010 5:10 pm 
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Just thought i'd post an update. Still have the idle drop and surge until the engine warms up though not as bad at the moment cause its not as cold. Also when going on the accelerator when cold the engine does jerk slightly. But i recently removed my cars strut bar and noticed the following:

Image

Injectors are to the left, but it looks like the metal cylinder with "flow" written on it is connected up the wrong way round!! Can anyone tell me what it is? A valve or filter of some kind? And does it simply need turned round or does it need replaced seeing as the car has been running like this for 9 months now?


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PostPosted: Sun Jun 06, 2010 5:50 pm 
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thats the gas filter and looks like it is the wrong way round.

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PostPosted: Sun Jun 06, 2010 7:00 pm 
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I don't think there's anything in that particular filter that causes a problem through being run backwards.

But what you musn't do now is 'correct' it - that would just flush anything it has caught straight into the delicate injectors. Really, you ought to fit a brand new one (the right way round of course!) but that is unlikely to fix the cold running issue.

Not completely impossible though ... one of the functions of the vapour filter is to act as an expansion trap to catch wax present in cold LPG until the injectors have warmed up enough to pass the warm and runny wax. Might not do this so well in reverse.

In the same vein, it can help if the injectors are angled downwards towards the engine so that they don't trap warm oil in use - which would be cold wax at the next cold start.

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PostPosted: Mon Apr 07, 2014 2:06 pm 
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Its been a long time since i visited the forum but thought I'd post an update, in case it helped other people.

Since then its slowly gotten worse, I've been getting the check engine light with P0171 and P0174 codes, over the last 20-30k miles, with it gradually coming on more frequently. Initially only on LPG, but gradually started to come on with petrol running as well. However with petrol although i might get the codes and engine light, it will never have the uneven idle, like this:

[url="http://www.youtube.com/watch?v=9DuAt5p3Wnw&list=UUl4kj0pLPCOfCEdtg6qGWCA&feature=share"]http://www.youtube.com/watch?v=9DuAt5p3Wnw&list=UUl4kj0pLPCOfCEdtg6qGWCA&feature=share[/url]

Initially the light only came on in winter and on a cold start and even then not straight away, often after several days of the same conditions. But gradually the light comes on sooner, the colder the weather the sooner it comes on. If temps are above 15 degrees C, although the codes come up, the "check engine" light will not even on LPG.

I have a BMW specific Peake code reader and it gives me:

Table 19
E3 is O2 sensor adaptation limit Cyl # 1-3
E4 is O2 sensor adaptation limit Cyl # 4-6


There was delay in getting the service (about 10k miles over!) and its definitely better since then. Its plumbed in parallel. But as the codes come up on petrol with the light occasionally as well, i think I've narrowed it down to the DISA (throttle adjuster valve) or the Oxygen/lambda sensors.

Lastly when i first started getting the problem, only P0174 came up, but gradually P0171 started popping up as well. This is what makes me think its O2/Lambda sensors rather than the DISA. I'll keep this updated as and when i get more info. My order of repoacemante at the moment will be, replace O2 sensors, plumb the system in parallel as mentioned elsewhere on this forum, then the DISA


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PostPosted: Mon Apr 07, 2014 4:45 pm 
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Bloody hell OzStriker, have you lived with these problems for nearly 4 years? Wonder if that's a record between posts on the same thread! :lol:

Does the BRC filter have a circlip at the end which you can remove to access the filter element? Will want this filter and the reducer (liquid phase) filter changing now after 4 years if they haven't been done already. Filters are unlikely to be your direct problem but could have indirectly caused your current symptoms by creating injector problems, dirt and 'heavy ends' can cause injector problems. Classicswede (forum member) sells injector cleaner which is claimed to revitalise injectors in some cases - in case it is found injectors are your problem.

I suspect bad mapping was the original issue, maybe with too low a changeover temp, but might also have been spud (manifold nozzle) placement, especially if your 330 is a later model with secondary air? I don't think your model has secondary air because I can't see the 'air rail' that runs across the top of the manifold on such models.

I wrote much of the following having forgotten your fairly techy level of understanding, so forgive any lessons in sucking eggs!

The issue has got worse, so if we were approaching this as an LPG system related issue (and LPG related issues can cause check engine lights to come on when switched to petrol if, for example the short term fuel trims need to over-stretch because long term fuel trims have adapted to incorrect LPG calibration) then now maybe look at plugs, then injector issues etc, to get it back to the same situation that it was in 4 years ago. Whenever injectors are messed with a re-calibration is usually in order in any case, but if you get the car back to how it was before you'll then be looking at calibration as said above.

Don't under-estimate plugs when it comes to LPG, I've had no probs with BMW's regarding plugs but it's worth remembering that an engine can run fine on petrol but have all sorts of problems on LPG with in-appropriate (for vehicle model for LPG) plugs, damaged plugs or too big a plug gap (like with worn plugs). Appropriate for LPG doesn't mean specific LPG plugs - many of us find those are best avoided. To me, generally but not for all models, appropriate LPG plugs are single electrode nickel plugs, slightly colder running (maybe), same protrusion, same electrical characteristics, obviously same fitting. Since your car ran well when warm for 4 years on the existing plugs, maybe get the same plugs, maybe close the gap a little? Assuming you haven't changed the plugs fairly recently and had no problem until very recently of course.

To approach this as a general vehicle problem I'd first look at things like the air flow meter, PCV valve (which may be under the inlet manifold and a pig to get to), cracked breather pipes, even the oil filler cap which is notorious on BMW's for air leaks.

Simon
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PostPosted: Mon Apr 07, 2014 7:21 pm 
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I would presume you have checked all the common suspects. The little elbow that goes to the iac valve.
Split or blocked oil drain back tube / Cvv valve and associated hoses ?


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PostPosted: Mon Apr 07, 2014 8:03 pm 
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Has the system been serviced over the last 4 years? Any initial running issues should have been sorted at the first service and checked at each one since.

Contrary to popular belief, changing a vapour filter does not constitute a gas service. There is a lot more to it.

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PostPosted: Tue Apr 08, 2014 2:47 pm 
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lpg-cars wrote:
Has the system been serviced over the last 4 years? Any initial running issues should have been sorted at the first service and checked at each one since.

Contrary to popular belief, changing a vapour filter does not constitute a gas service. There is a lot more to it.


Would agree entirely with that mate, and expect most of the installers on the forum would too.

The problem is that customers often don't bother servicing LPG systems. Often when they ask for a service it is because their is a problem with their system and sometimes such problems can be brought on by lack of a service (causing injector and other issues). So by not having a service earlier, when they think they want a service what they actually need is parts replacing, parts that would have been protected against wear and other accumulative problems by having a service much earlier. Among the things we look at when we service a system is the calibration, but calibration shouldn't need to be adjusted much over the life of the system if it was set properly in the first place. The need for a big change in calibration points to it not being set properly in the first place, or wear to injectors (which might have been prevented with earlier servicing), maybe a reducer diaghpram issue, a sensor issue or something more general vehicle related like spark plugs. All of which might have been prevented with earlier LPG and/or
vehicle servicing, all of which now require something beyond the scope of just an LPG service.

I have lost count of the times a customer has paid another LPG pro to 'service' their LPG system, then come to me after the service hasn't put right any of the issues which prompted them to have the service. In such cases the other LPG pro must have been fairly sure that the service wouldn't put the issues right, but got themselves the easy job of the service and knew the customer would be paying again to have the more involved job of rectifying the problems done. I had a potential customer on the phone this morning with a Jeep 3,3, didn't know what system it was but I knew it would be sequential on the 3.3 and I got the impression AEB based given his description of the switch. He'd just bought the vehicle and was advised the system would need a service by the seller. He wanted to come straight in for a service and I could have just said OK bring it in, but I advised him over the phone that a service probably wouldn't correct the very poor running problem he wanted sorting and given the symptoms it might need a part, but a service wouldn't be a bad idea either. I didn't want him coming thinking he'd likely just be paying just for a service and then going home unhappy if the service didn't sort the issues. I know of many installers who would have happily charged for the service and gone on to charge over the top to remedy the problems later. The problem with being honest in this way is that people think the other guy might just charge for a service and fix the problem, when in reality they are likely to be paying the other guy more when they realise the service hasn't fixed the problem and have to return for the fix.

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PostPosted: Tue Apr 08, 2014 8:28 pm 
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That's the first thing I always say when people rung up for a "service"
"Is it exhibiting any running problems ?"
To which they generally reply "oh yes it's lumpy ticking over and keeps putting the EML light on"
Hmmm.....


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PostPosted: Sun Apr 13, 2014 8:37 pm 
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Thanks for the replies.

I did take it back to the installer for the 1st check, but every time I tried to get him to troubleshoot the cold running problems, he'd give it a once over, say it was because I had it remapped or something else. He did change the switch over temp to the highest allowable by the software, about 49 deg C I think. Eventually I lost confidence in him so just had the filters changed, apart from the last service which was done after over 20k :shock:

But usually March - Oct it was never an issue really, I even drove the car to Italy 18 months ago and it was all good, no CEL. October 2011 I drove to Berlin, and it was pretty cold there that time of year, and although I didn't check for codes, I had no running issues and no CEL. If I think back, in winter 2011, outside temps probably had to be around or below freezing at a cold start to give the surging/dipping revs and throw the CEL.

Although eventually the light got triggered in warm weather on petrol in summer 2013 (but ran fine) this stopped after I replaced the CCV/PCV and all associated hoses. After install, I went over it all again, to check all hoses and pipes were connected properly..... yes it is a PIA to do! Whilst this was being done, the ICV and throttle body were cleaned, and the latters gasket/O-ring was replaced. Everything ran good, and so I waited........ for winter to set in! And then about November, the saga starts again!

The only time I've had the surging and dipping revs as in the link I posted, whilst running on petrol, was when there was a big split in the intake elbow, that runs from the MAF to the throttle body and ICV. When this happened, the codes and engine light would come on straight away.

With daytime temps much warmer now, here's where things currently stand:
If temps are above 15 deg C, running on petrol-------- > No CEL, no codes. Long term fuel trims were at about 5-7%
If temps are below 10-15 deg C, running on petrol ----------> No CEL, but codes above will come up.

If temps are above 15 deg C, running on LPG -------- > No CEL, codes as above will come up.
If temps are below 10-5 deg C, running on LPG ----------> CEL will come on fairly soon, as will codes above

The folks over at E46 fanatics don't think its O2 sensors, but more likely to be some sort of vacuum leak, as under cooler conditions rubber gaskets will shrink slightly, hence letting in unmetered air. As far as my basic understanding goes, the BRC ECU just replicates what the BMW ECU is doing with regards to fuel injection, mixture, mapping etc Except that the stock BMW ECU perhaps is just better able to compensate for whatever the underlying problem is, except for when it gets colder.

I'm going to do some idling tests in the coming days. Start the car up from cold when outside temps are < & > 10 deg C, on petrol and LPG, and let it warm up and see if codes &/or CEL come on. I read somewhere if it comes on at idle it wold more likley point towards a vacuum leak.

I checked my service records and the plugs were last changed at 76k, around the same time as the LPG install. So they could do with replacing, assuming Bosch 4+ platinum's have a service life of 60k. But I'll go for single electrode perhaps this time.

Another thing to note, the car has a valve cover leak, very minor at the moment, it only drinks about 500-700 mls of oil per 1000 miles of city driving (up to a litre is within the range of normal for a 330). When I drove to Italy, it didn't take a drop of oil for the whole 1800 mile round trip!


Last edited by oz striker on Tue Apr 15, 2014 8:42 am, edited 1 time in total.

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PostPosted: Mon Apr 14, 2014 10:11 am 
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The life expectancy of O2 sensors is not limitless
http://www.ngksparkplugs.ca/tech-info-o ... ensors.cfm
"NTK generally recommends checking your oxygen sensor at every 60,000km"
but there would be clues for the observer from aged sensors - slow to begin working from cold, slow to swing output when hot.

I still wouldn't rule out waxing at the root of some of your problems, and this would be amplified if the system fails to get stinking hot - many short journies or engine thermostat failure, or poor water flow to the regulator.

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PostPosted: Tue Apr 15, 2014 9:06 am 
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rossko wrote:
The life expectancy of O2 sensors is not limitless
http://www.ngksparkplugs.ca/tech-info-o ... ensors.cfm
"NTK generally recommends checking your oxygen sensor at every 60,000km"
but there would be clues for the observer from aged sensors - slow to begin working from cold, slow to swing output when hot.

I still wouldn't rule out waxing at the root of some of your problems, and this would be amplified if the system fails to get stinking hot - many short journies or engine thermostat failure, or poor water flow to the regulator.


Cool I'll bear that in mind. I think there prob a few things causing my issues, i suppose electric components like O2 sensors and MAF's can have soft failures?

The car is going into a LPG gaage tomorrow, (same folks who serviced it in Jan, they seemed very genuine & friendly), leaving it with them overnight, so they can do a cold start in the morning and see how it goes.

BUT the plot thickens, i did some idle tests on petrol and heres what happened:

Car not driven cold start at 10 deg C. Engine left to warm up at idle on petrol. Within a few mins, idle became very rough, like misfiring (assume this happened after the cars automatic choke cuts out,). Engine left to warm up to normal temps, then shut down and codes read.

Peake tool, BMW specific
E3: O2 sensor adaption limit Cyl # 1-3
E4: O2 sensor adaption limit Cyl # 4-6
CA: O2 sensor control limit Cyl 1-3
EE: Misfire Cyl # 1
FO: Misfire Cyl # 3
EF: Misfire Cyl # 4
C6: Catalytic convertor efficiency Cyl # 1-3

Genereic OBD codes:
P0171 & P0174 – lean banks 1&2
Crankshaft position sensor code
Misfires on numerous cylinders

Tested like above. Car not driven, cold start but at 17 deg C. Engine left to warm up at idle on petrol. Within a few mins, idle became like above. Codes as follows:
E3: O2 sensor adaption limit Cyl # 1-3
E4: O2 sensor adaption limit Cyl # 4-6
CA:
FO:
EF:
C6:

Generic OBD codes as above.


The day before this test, heres how it ran on LPG:

6 miles city driving from cold start, at 10 deg C:
Check Engine Light came ON in 4-5 mins, idle surged and dipped when coming to a stop until engine fully warmed up, then ran fine. Following codes pulled at the end of drive:
E3: O2 sensor adaption limit Cyl # 1-3
E4: O2 sensor adaption limit Cyl # 4-6

P0171 & P0174 – lean banks 1&2


6 miles city driving from cold start, at 17 deg C:
Check Engine Light came DID NOT COME ON, car drove fine, But following codes pulled at the end of drive:
E3: O2 sensor adaption limit Cyl # 1-3
E4: O2 sensor adaption limit Cyl # 4-6

P0171 & P0174 – lean banks 1&2


And 1 week prior to this i did 200-250 miles on petrol of mixed city and motorway driving, with outside temps > 10 deg C and there was no CEL or codes.

The idle tests really had me stumped, but then i guess I've never started the car up from cold and just sat there, I'm usually rushing to work!! So people place your bets....... what's going on? No prizes if you're right I'm afraid, just a smug feeling & forum respect :wink:


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PostPosted: Tue Apr 15, 2014 6:40 pm 
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Crank sensor code stands out as odd and unexplained. Are you clearing codes between tests, or accidently looking at historic logs?

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PostPosted: Tue Apr 15, 2014 9:16 pm 
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The little rubber elbow on the bellows going to the throttle body that feeds the iac valve is a bit perished.
There is a little rubber bung on a vac nipple on the back of the manifold that has gone hard and cracked.
The map is badly adjusted on LPG.
That's my 3 guesses.


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PostPosted: Tue Mar 24, 2015 11:17 am 
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Hello folks didn't realise i hadn' updated this, so here's what happened after the above:

I replaced the petrol fuel filter and spark plugs after which the the car ran fine on Petrol. The spark plugs looked like they were past their best, i understand they probably wont last their usual 60k mile lifespan on an LPG car, but instead last about 45-50k. I should also say, the fuel filter return hose that returns fuel vapour had a small 5mm hole in it, which i fixed. It code have cause unmetered air entering the system, triggering lean codes.

Image

I then had and LPG service (this was overdue) and after the filters were changed, LPG running essentially returned to normal (the occaisonal lean code would come up if temps were less than 14 deg C, but not idling issues.

So around Sept/Oct last year, the idling issues & codes returned, when temps went less than 12 deg C but only on LPG. I then replaced the precat Oxygen/Lambda sensors after which LPG ran normally, but only until temps stayed above approx 8 deg C.

I then did a lot of reading, and read about coolant freezing in the vaporizer. So i applied some very basic fireproof insulation around the vaporiser and around the pipes coming off of the vaporiser. And guess what? No more lean codes, and it runs fine on LPG, but I've only mananegd to test it down to 2 deg C. I can get the occaisonal uneven idle when temps are that low, but only when it first switches over and only for a few secs, after which the revs stabilise.

Hope that helps others with any issues. And I'll update if next winter i manage to drive it in lower temps.


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