Misfire with my BMW - Please help me diagnose my fault!
Discussion
Hi guys, firstly apologies for the long post, I want to ensure I paint the whole picture. Would be very grateful if someone can help, as I am starting to lose patience with my car!
I drive a 2000 BMW 530iA. Bought it a year ago with 142k on the clock and been trouble free for a year. At 161k I booked it in for a LPG conversion.
The day before it went in it packed up and was recovered home. Seems the alternator had gone, and a new Bosch one was fitted.
I ran it for a day or so and it was fine again so definitely do not think this is connected.
It went in for its LPG conversion and got it back and again all was ok, except a slightly lumpy idle. Could hardly notice it.
I drove it for a week, 500 miles, and all seemed ok on the move, full power etc.
It went into BMW for a service and 30 miles after this it started to go wrong. The emissions light came on and it ran very lumpy indeed. Idle at around 500rpm, down on power, and vibrating whilst accelerating. It did this for a day or so then light went out and all seemed ok again.
I posted these symptoms at it was suggested to replace the spark plugs.
I did this, with NGK's and again all was fine for a week. The light them came back on and it was running rough. After 100 miles it started running ok again but the emissions light stayed on.
Over the next week I contacted BMW (to see if anything went wrong at the service) and the LPG fitter.
BMW took it in, checked it over and all seemed ok to them. The bad vibration was not present at this point. The LPG fitter said at the 1000 mile service he will remap it and all will be ok, as it was previously mapped to the old spark plugs.
After another few days I took it in for its 1000 mile service (at 1400 miles). He spent an hour going over everything and remapped it and gave it the clean bill of health. The next two days were a joy, it has NEVER driven so well!
However, the light them came back and down on power. Once again I called the LPG guy who suggested it could be the coil pack on cylinder 1 as the diagnostics has originally found a slight misfire. I changed it on the weekend and again it was ok for 100 miles (although the light stayed on) before the fault appeared again.
Since then the emissions light has stayed on and the fault has been on and off, normally for a day or so at a time.
Where do I go from here? Are there any suggestions?
It is worth noting that there was always a slight misfire on petrol ONLY when I moved the car say off the drive then left it over night. The next day it would misfire until it had some heat into it. Not sure if that is connected.
When the fault is present and it is down on power it will not switch back to petrol (according to the gauge) and I struggle to get gas into the tank at some stations. Again may not be connected.
The LPG guy, wrongly so, is losing patience, convinced its a petrol issue, BMW say the opposite.
Is it worth disconnecting the battery to see whether it resets the ECU's. Will that be ok considering it is on gas?
It is booked back into the LPG fitter next Wednesday but have 500 miles to do before then and keen to try a few things as it is a pita getting the car over.
BMW will have one final free look on the diagnostics week after but lots of faults that showed up last time they believed to be purely down to normal running of gas and different pressures etc.....
I am at my whits end as to what is wrong. Changed all the bits I thought, all plugs and coil pack on cylinder one but it continues. The problem is intermittent aswell so it does run ok at times. And when it is rough it stays rough for a few days before being ok for a day or two.
Any help MUCH appreciated....and sorry for the ramble
I drive a 2000 BMW 530iA. Bought it a year ago with 142k on the clock and been trouble free for a year. At 161k I booked it in for a LPG conversion.
The day before it went in it packed up and was recovered home. Seems the alternator had gone, and a new Bosch one was fitted.
I ran it for a day or so and it was fine again so definitely do not think this is connected.
It went in for its LPG conversion and got it back and again all was ok, except a slightly lumpy idle. Could hardly notice it.
I drove it for a week, 500 miles, and all seemed ok on the move, full power etc.
It went into BMW for a service and 30 miles after this it started to go wrong. The emissions light came on and it ran very lumpy indeed. Idle at around 500rpm, down on power, and vibrating whilst accelerating. It did this for a day or so then light went out and all seemed ok again.
I posted these symptoms at it was suggested to replace the spark plugs.
I did this, with NGK's and again all was fine for a week. The light them came back on and it was running rough. After 100 miles it started running ok again but the emissions light stayed on.
Over the next week I contacted BMW (to see if anything went wrong at the service) and the LPG fitter.
BMW took it in, checked it over and all seemed ok to them. The bad vibration was not present at this point. The LPG fitter said at the 1000 mile service he will remap it and all will be ok, as it was previously mapped to the old spark plugs.
After another few days I took it in for its 1000 mile service (at 1400 miles). He spent an hour going over everything and remapped it and gave it the clean bill of health. The next two days were a joy, it has NEVER driven so well!
However, the light them came back and down on power. Once again I called the LPG guy who suggested it could be the coil pack on cylinder 1 as the diagnostics has originally found a slight misfire. I changed it on the weekend and again it was ok for 100 miles (although the light stayed on) before the fault appeared again.
Since then the emissions light has stayed on and the fault has been on and off, normally for a day or so at a time.
Where do I go from here? Are there any suggestions?
It is worth noting that there was always a slight misfire on petrol ONLY when I moved the car say off the drive then left it over night. The next day it would misfire until it had some heat into it. Not sure if that is connected.
When the fault is present and it is down on power it will not switch back to petrol (according to the gauge) and I struggle to get gas into the tank at some stations. Again may not be connected.
The LPG guy, wrongly so, is losing patience, convinced its a petrol issue, BMW say the opposite.
Is it worth disconnecting the battery to see whether it resets the ECU's. Will that be ok considering it is on gas?
It is booked back into the LPG fitter next Wednesday but have 500 miles to do before then and keen to try a few things as it is a pita getting the car over.
BMW will have one final free look on the diagnostics week after but lots of faults that showed up last time they believed to be purely down to normal running of gas and different pressures etc.....
I am at my whits end as to what is wrong. Changed all the bits I thought, all plugs and coil pack on cylinder one but it continues. The problem is intermittent aswell so it does run ok at times. And when it is rough it stays rough for a few days before being ok for a day or two.
Any help MUCH appreciated....and sorry for the ramble
Having run a few lpg vehicles in the past, the symptoms you describe are familiar.
IME most symptoms like that with lpg are ignition related. Lpg is very sensitive to spark strength and in particular less than perfect HT leads - I suspect a new set of quality leads like Magnecor will fix it and it may also be worth checking the condition of your lambda sensor.
IME most symptoms like that with lpg are ignition related. Lpg is very sensitive to spark strength and in particular less than perfect HT leads - I suspect a new set of quality leads like Magnecor will fix it and it may also be worth checking the condition of your lambda sensor.
OnTheOverrun said:
a new set of quality leads like Magnecor
BMW have been running Coil Over Plug for quite some time now, so no real leads to speak of in the common sense, but the coil packs are a weak link.I'd try to borrow a set /short term swap and see if the problems cross over between the cars.
It's a little expensive to buy a new full set just to see, but also it's hard to actually test them, so a try before you buy would work out best.
musclecarmad said:
Sorry to hear your predicament - good on BMW and the lpg guy looking at it for you.
I do have to say (sorry to be an a
hole) that you bought a ten year old 142,000 mile 3 litre BMW and it now has over 162,000 miles on it and is also LPG'd so it was never going to be trouble free motoring. As with big old cars like this with big mileage there is a risk so it looks like you will have to shell out big time.
I do wish you luck though and hope you get it sorted.
to try and be helpful why don't you disconnect the lpg?
I appreciate your point, but the car proved trouble free for a year and ran my last BMW up to 230k. Hoping once the issue is sorted to have lots of trouble free driving again!I do have to say (sorry to be an a
hole) that you bought a ten year old 142,000 mile 3 litre BMW and it now has over 162,000 miles on it and is also LPG'd so it was never going to be trouble free motoring. As with big old cars like this with big mileage there is a risk so it looks like you will have to shell out big time.I do wish you luck though and hope you get it sorted.
to try and be helpful why don't you disconnect the lpg?
Edited by musclecarmad on Tuesday 25th May 18:43
OnTheOverrun said:
Having run a few lpg vehicles in the past, the symptoms you describe are familiar.
IME most symptoms like that with lpg are ignition related. Lpg is very sensitive to spark strength and in particular less than perfect HT leads - I suspect a new set of quality leads like Magnecor will fix it and it may also be worth checking the condition of your lambda sensor.
The issue is where do you stop. New leads, new lambda sensor, new coils thats best part of a grand. Which may not fix it!IME most symptoms like that with lpg are ignition related. Lpg is very sensitive to spark strength and in particular less than perfect HT leads - I suspect a new set of quality leads like Magnecor will fix it and it may also be worth checking the condition of your lambda sensor.
Anyway to determine whether there is indeed a fault with any of them?
useyourdellusion said:
Blimey! I would start from the ground up on this one. Earthing connections for one (although I suppose this would throw up various diagnostic codes).
Dodgy connectors on your Lambda sensors and/or Mass air flow meter maybe? Could account for the intermittent issue.
Most definitely intermittent, and also only occurs on gas. Runs fine on petrol (although I cannot switch back to petrol once on gas)!Dodgy connectors on your Lambda sensors and/or Mass air flow meter maybe? Could account for the intermittent issue.
matt21 said:
OnTheOverrun said:
Having run a few lpg vehicles in the past, the symptoms you describe are familiar.
IME most symptoms like that with lpg are ignition related. Lpg is very sensitive to spark strength and in particular less than perfect HT leads - I suspect a new set of quality leads like Magnecor will fix it and it may also be worth checking the condition of your lambda sensor.
The issue is where do you stop. New leads, new lambda sensor, new coils thats best part of a grand. Which may not fix it!IME most symptoms like that with lpg are ignition related. Lpg is very sensitive to spark strength and in particular less than perfect HT leads - I suspect a new set of quality leads like Magnecor will fix it and it may also be worth checking the condition of your lambda sensor.
Anyway to determine whether there is indeed a fault with any of them?
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