rikpy04ghg

rikpy04ghg · Jan 2nd, 2009, 20:43

I have a W reg V20 2.4 which I had converted to lpg last september. I now have the persistent orange engine light coming on, on the dash. Each time I have a diagnostic device attached the fault code is P0171 which indicates 'lean burn' but I understand that this is a requirement for running on LPG. This has only recently started happening, for roughly a month now. Is it something to do with the cold weather or is the bandwidth for the oxygen sensor too small now I am running on LPG. The light when cleared in the diagnostic does not come on immediately, but generally after 3 or 4 days minimum and anywhere up to a fortnight maximum. Is there anyway to stop this from reoccuring?

I also have a V50 which has alos been converted but I have had absolutely no problems with this at all.

Thanks in anticipation,
Rik

GavinC · Jan 3rd, 2009, 10:57

I understand that the 'lambda' light is often, if not always, disconnected by fitters so as to avoid this problem. Mine was but it is a singlepoint (old technology) conversion. Your situation may be different - particularly if multipoint. Mike Brace - the forum's resident LPG expert - would know for sure.

John_C · Jan 3rd, 2009, 11:21

A multi-point lpg injection system should only cause the lambda/emissions light to come on if something is wrong or it hasn't been set up properly in the first place. Since yours was fine I would say something needs tweaking, or it may be a fault with the lambda sensor itself as they don't last forever.

How long since your sparkplugs have been replaced as if they're still the same ones since last September they are probably on their way out? I'd check them first if you haven't already.

Cheers,
John

rikpy04ghg · Jan 4th, 2009, 14:15

I hasd the oxygen sensor replaced earlier in the year for an unrelated fault before the lpg was done. I had the car serviced and a new cambelt fitted and on picking the car up the engine light was on all the time - on taking it back I was under the impression the garage had maybe knocked the lead by accident but this was not the case and I had to have new sensor, and a Volvo original part also. This then cured it, so is it likely it has failed so soon? I cannot have done more than 5000 miles since I had it done and maybe no more than 3000 miles as this car is used primarily by the wife, and we use it for holidays in this country. The V50 is the workhorse that does in excess of 18000 miles a year with my job.

Cheers,
Rik

capt jack · Jan 4th, 2009, 17:40

LPG is no more likely to make the Lambda light come on than petrol. If it comes on it's because a fault has been registered.

When my LPG conversion was done 4 years ago, the Lambda light came on within a few hundred miles. Turned out it was the camshaft position sensor, and was just coincidental to the LPG conversion.

The first step is get the codes read by a dealer. This will then identify the what the system believes is the source of the problem. It could be a genuine fault, or it could be a faulty sensor.

If the O2 probe was replaced only a few K miles ago it's possible it's faulty, but probably not. If it is you've got a claim against the dealer who supplied and fitted it. Get this dealer to tell you what the codes are. If they worked on the car only recently then they should in all fairness do this for free I would have thought.

Cheers

Jack

davew · Jan 5th, 2009, 10:28

your car will be running lean, which is not good. (unless you want to burn your valves.)

What is happening is your long term fuel trims are slowly adjusting until it gets to the critical point (20%) I think and then it throws a code as it cant compensate any more.

When you get your codes read and the light reset this resets the fuel trims back to 0. Then slowly (over 4 days as you suggest) the trims creep up again and and throw the code.

You need to go back to you LPG guy and get them to go on a run with you whilst they have there equipment connected. They will adjust the lpg / air ratio on the move until it is stable.

rikpy04ghg · Jan 13th, 2009, 20:06

A big thank you to davew. Iemailed my installer and copied the reply you gave me about the 20% and needing to reset the system, and lo and behold it was sorted out today. We drove up a long straight road and on petrol the ratio was 8.9% but on gas it was 22%, hence the light. The engineer increased the amount of gas going to the injectors by a small amount and the ratios were then comparable with petrol. He was quite suprised that as a layman I knew so much about how the system worked etc.
I suppose being an engineer in my own right, albeit a multi-skilled one in a factory envoroment, I do have the ability to grasp the fundamentals easily, and must have sounded quite convincing when talking it through. Hence no trying to pull the wool over my eyes again hopefully.

regards,
Rik

John_C · Jan 13th, 2009, 22:42

Glad you got it sorted.

davew · Jan 14th, 2009, 08:05

No Probs, Glad I could help.

Lets hope it stays stable for you now.

Jan 2nd, 2009, 20:43	#1
rikpy04ghg New Member Last Online: Jan 13th, 2009 20:07 Join Date: Jan 2009 Location: Kettering	rikpy04ghg I have a W reg V20 2.4 which I had converted to lpg last september. I now have the persistent orange engine light coming on, on the dash. Each time I have a diagnostic device attached the fault code is P0171 which indicates 'lean burn' but I understand that this is a requirement for running on LPG. This has only recently started happening, for roughly a month now. Is it something to do with the cold weather or is the bandwidth for the oxygen sensor too small now I am running on LPG. The light when cleared in the diagnostic does not come on immediately, but generally after 3 or 4 days minimum and anywhere up to a fortnight maximum. Is there anyway to stop this from reoccuring? I also have a V50 which has alos been converted but I have had absolutely no problems with this at all. Thanks in anticipation, Rik

Jan 3rd, 2009, 10:57	#2
GavinC GavinC Last Online: Oct 13th, 2012 18:51 Join Date: Dec 2003 Location: Harrogate	Get the light disconnected? I understand that the 'lambda' light is often, if not always, disconnected by fitters so as to avoid this problem. Mine was but it is a singlepoint (old technology) conversion. Your situation may be different - particularly if multipoint. Mike Brace - the forum's resident LPG expert - would know for sure.

Jan 4th, 2009, 14:15	#4
rikpy04ghg New Member Last Online: Jan 13th, 2009 20:07 Join Date: Jan 2009 Location: Kettering	LPG engine light woes! I hasd the oxygen sensor replaced earlier in the year for an unrelated fault before the lpg was done. I had the car serviced and a new cambelt fitted and on picking the car up the engine light was on all the time - on taking it back I was under the impression the garage had maybe knocked the lead by accident but this was not the case and I had to have new sensor, and a Volvo original part also. This then cured it, so is it likely it has failed so soon? I cannot have done more than 5000 miles since I had it done and maybe no more than 3000 miles as this car is used primarily by the wife, and we use it for holidays in this country. The V50 is the workhorse that does in excess of 18000 miles a year with my job. Cheers, Rik

Jan 4th, 2009, 17:40	#5
capt jack VOC Member Last Online: Yesterday 19:15 Join Date: Jun 2006 Location: Selby, North Yorkshire	Lambda light LPG is no more likely to make the Lambda light come on than petrol. If it comes on it's because a fault has been registered. When my LPG conversion was done 4 years ago, the Lambda light came on within a few hundred miles. Turned out it was the camshaft position sensor, and was just coincidental to the LPG conversion. The first step is get the codes read by a dealer. This will then identify the what the system believes is the source of the problem. It could be a genuine fault, or it could be a faulty sensor. If the O2 probe was replaced only a few K miles ago it's possible it's faulty, but probably not. If it is you've got a claim against the dealer who supplied and fitted it. Get this dealer to tell you what the codes are. If they worked on the car only recently then they should in all fairness do this for free I would have thought. Cheers Jack

Jan 5th, 2009, 10:28	#6
davew Senior Member Last Online: Jun 16th, 2011 15:27 Join Date: Sep 2008 Location: Nelson	your car will be running lean, which is not good. (unless you want to burn your valves.) What is happening is your long term fuel trims are slowly adjusting until it gets to the critical point (20%) I think and then it throws a code as it cant compensate any more. When you get your codes read and the light reset this resets the fuel trims back to 0. Then slowly (over 4 days as you suggest) the trims creep up again and and throw the code. You need to go back to you LPG guy and get them to go on a run with you whilst they have there equipment connected. They will adjust the lpg / air ratio on the move until it is stable. __________________ S80 - 301 Bhp - 450Nm

Jan 3rd, 2009, 11:21	#3
John_C Allons-y! Last Online: Jun 8th, 2020 15:32 Join Date: Dec 2004 Location: Winchester	A multi-point lpg injection system should only cause the lambda/emissions light to come on if something is wrong or it hasn't been set up properly in the first place. Since yours was fine I would say something needs tweaking, or it may be a fault with the lambda sensor itself as they don't last forever. How long since your sparkplugs have been replaced as if they're still the same ones since last September they are probably on their way out? I'd check them first if you haven't already. Cheers, John

Jan 13th, 2009, 20:06	#7
rikpy04ghg New Member Last Online: Jan 13th, 2009 20:07 Join Date: Jan 2009 Location: Kettering	LPG engine light and fault code. A big thank you to davew. Iemailed my installer and copied the reply you gave me about the 20% and needing to reset the system, and lo and behold it was sorted out today. We drove up a long straight road and on petrol the ratio was 8.9% but on gas it was 22%, hence the light. The engineer increased the amount of gas going to the injectors by a small amount and the ratios were then comparable with petrol. He was quite suprised that as a layman I knew so much about how the system worked etc. I suppose being an engineer in my own right, albeit a multi-skilled one in a factory envoroment, I do have the ability to grasp the fundamentals easily, and must have sounded quite convincing when talking it through. Hence no trying to pull the wool over my eyes again hopefully. regards, Rik

Jan 13th, 2009, 22:42	#8
John_C Allons-y! Last Online: Jun 8th, 2020 15:32 Join Date: Dec 2004 Location: Winchester	Glad you got it sorted.

Jan 14th, 2009, 08:05	#9
davew Senior Member Last Online: Jun 16th, 2011 15:27 Join Date: Sep 2008 Location: Nelson	No Probs, Glad I could help. Lets hope it stays stable for you now. __________________ S80 - 301 Bhp - 450Nm

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