Hi
I had my 07 Merc A150 converted to GAS by Birmingham Autogas as recommended by forum uses.
I'm having poor running, it idles ok but when you press the gas pedal it burbles and seems to hunt for revs, I took it to mercedes and they reprogrammed the whole ECU as they said lots of the peramiters were out, but I called the LPG garage and they said that the system has its own ecu and they could not mess with the cars ecu.
When I got the car back from Mercedes it ran ok on petrol, like it should. But the moment I changed to Gas it started to misfire, when I try to pull away the revs are just erratic, then as im driving and put my foot down it jerks alot. This is what gets me when I put it back to petrol it runs the same idles ok but revs are erratic and the same jerks when driving.
Could the LPG be causing the problem?
Has anyone got a Merc and had a similar problem?
The Merc garage has ask how did the LPG garage get around the oxygen sensor?
Any help would be most gratefull.
Merc A150 LPG rough running
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tommo2009
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Has it always been like this or has it recently started to do it.
If it has only recently started then it may well be the gas system. what system is on the car.
it may well be fine on petrol and rough on gas, but if the ecu picks up a problem it may go into limp mode.
run it on petrol, go to gas and get it to run rough, switch back to petrol and if it still runs rough, turn the ignition off and restart the car. Does it now run fine on petrol, if it does then it is definetly something to do with the gas.
Most LPG systems don't need Lambda connections as the car doesn't know its on gas so it is still adjusting the fuelling via the petrol ecu.
The closed loop system is still in operation and adjusting the petrol injection timings which are fed into the gas ecu.
If it has only recently started then it may well be the gas system. what system is on the car.
it may well be fine on petrol and rough on gas, but if the ecu picks up a problem it may go into limp mode.
run it on petrol, go to gas and get it to run rough, switch back to petrol and if it still runs rough, turn the ignition off and restart the car. Does it now run fine on petrol, if it does then it is definetly something to do with the gas.
Most LPG systems don't need Lambda connections as the car doesn't know its on gas so it is still adjusting the fuelling via the petrol ecu.
The closed loop system is still in operation and adjusting the petrol injection timings which are fed into the gas ecu.
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billynoband
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Thanks for the quick replies.
The car is booked in at Mercedes tomorrow to fault check with their star diagnostic equipment. I have booked it in at the LPG Garage next wednesday, he told me after I collect from Merc and is running ok on petrol to keep it on petrol until next wednesday for him to check, he said it may be the spark plugs are incorrect, but it's just been serviced a week before conversion.
It should run fine after Mercedes has reprogrammed the ECU again. It ran ok last night when they delivered it back to me, again it was ok this morning but then pressed the gas button and fault came back, only thing is when I go back to petrol the problems are still there.
Will keep you all posted of my progress.
I would like to say the Mercedes dealer has been great, this will be the 3rd time in. 1st they reprogrammed the throttle body, problem still there so they took it in and thurther inspection noticed the whole ECU had to be reprogrammed. Was all working until i WENT TO GAS, this time I wont until the Gasman has had alook, I'd rather run on petrol with a smooth engine.
My other car runs great thats a Renault Grand Scenic 2.0l Auto on LPG.
The car is booked in at Mercedes tomorrow to fault check with their star diagnostic equipment. I have booked it in at the LPG Garage next wednesday, he told me after I collect from Merc and is running ok on petrol to keep it on petrol until next wednesday for him to check, he said it may be the spark plugs are incorrect, but it's just been serviced a week before conversion.
It should run fine after Mercedes has reprogrammed the ECU again. It ran ok last night when they delivered it back to me, again it was ok this morning but then pressed the gas button and fault came back, only thing is when I go back to petrol the problems are still there.
Will keep you all posted of my progress.
I would like to say the Mercedes dealer has been great, this will be the 3rd time in. 1st they reprogrammed the throttle body, problem still there so they took it in and thurther inspection noticed the whole ECU had to be reprogrammed. Was all working until i WENT TO GAS, this time I wont until the Gasman has had alook, I'd rather run on petrol with a smooth engine.
My other car runs great thats a Renault Grand Scenic 2.0l Auto on LPG.
Thanks rossko
went to collect the car today still not perfect on petrol, then when they tried again to reprogramme the ECU it now won't let them.
He said the diagnostic came up with incorrect mixture, so he is sure it is when the ECU detects the switch over from Petrol to LPG thats causing the fault code and going into some kind of limp mode he said, I said but surely when I change back to Petrol it should run normal, this is where we are both stuck, he also said it should.
The Mercedes garage said when they try to connect their star diagnostic and reset the parametres it just says failed, they to reset again failed again, he said he will contact Mercedes Directly to open a case.
Anyway they still have my car.
The LPG guy said he would look at it on Wednesday, and maybe be the plugs, don't know anything about this, it's just been serviced last month.
Anyone got any ideas? I don't understand the car was ok on petrol, then I go to GAS this is were is packs in all jerks, loss of power when I try to gas it, I had trouble getting above 70 on a straight flat dual carraige way. Then I switch back to Petrol same thing happens.
Its like the gas upsets the car ecu then it doesn't want to go back to normal wether on gas or petrol.
went to collect the car today still not perfect on petrol, then when they tried again to reprogramme the ECU it now won't let them.
He said the diagnostic came up with incorrect mixture, so he is sure it is when the ECU detects the switch over from Petrol to LPG thats causing the fault code and going into some kind of limp mode he said, I said but surely when I change back to Petrol it should run normal, this is where we are both stuck, he also said it should.
The Mercedes garage said when they try to connect their star diagnostic and reset the parametres it just says failed, they to reset again failed again, he said he will contact Mercedes Directly to open a case.
Anyway they still have my car.
The LPG guy said he would look at it on Wednesday, and maybe be the plugs, don't know anything about this, it's just been serviced last month.
Anyone got any ideas? I don't understand the car was ok on petrol, then I go to GAS this is were is packs in all jerks, loss of power when I try to gas it, I had trouble getting above 70 on a straight flat dual carraige way. Then I switch back to Petrol same thing happens.
Its like the gas upsets the car ecu then it doesn't want to go back to normal wether on gas or petrol.
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junkcatcher
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- Joined: Mon Apr 21, 2008 4:54 pm
It sounds like the mixture while running on gas is well out which has upset the adaptations in the petrol ecu.
To put it in laymans terms the cars petrol ECU learns the best settings for your engine and driving conditions as you drive and stores these corrections in memory as adaptations to the injection durration. When the car is running on LPG the petrol ECU still thinks the engines is still running on petrol so if anything is wrong on the LPG side it can confuse the petrol ecu and cause the stored adaptations to be wrong making the car run badly.
As the fault is bad enough to cause a misfire on gas or petrol the petrol ECU will store a fault code which apparently on your model triggers limp home mode.
The Merc dealers aren't really reprogramming the ecu but clearing the adaptations and fault codes.
I am also wonder if the root of the problem might be HT related --ie plugs, plug gaps & coil packs.
To put it in laymans terms the cars petrol ECU learns the best settings for your engine and driving conditions as you drive and stores these corrections in memory as adaptations to the injection durration. When the car is running on LPG the petrol ECU still thinks the engines is still running on petrol so if anything is wrong on the LPG side it can confuse the petrol ecu and cause the stored adaptations to be wrong making the car run badly.
As the fault is bad enough to cause a misfire on gas or petrol the petrol ECU will store a fault code which apparently on your model triggers limp home mode.
The Merc dealers aren't really reprogramming the ecu but clearing the adaptations and fault codes.
I am also wonder if the root of the problem might be HT related --ie plugs, plug gaps & coil packs.
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junkcatcher
- Member
- Posts: 637
- Joined: Mon Apr 21, 2008 4:54 pm
I have been thinking about this --- eventually I remembered something I had read some time ago about the A class ECU having the MAF sensor (Mass Airflow sensor) built into it. So I looked at the BBA remanufacturing web site a good source of info
http://www.bba-reman.com/content.aspx?c ... er_and_ecu
also see
http://www.ecu-repairs.com/tag/a-class-hesitates/
http://www.bba-reman.com/content.aspx?c ... er_and_ecu
also see
http://www.ecu-repairs.com/tag/a-class-hesitates/
How would this affect the running of the car, as the car runs fine now on petrol after merc did something, if it was the maf would i not need a new one, but merc seems to have fixed the problem, on petrol anyway.
You see it runs poor on gas then i revert back to petrol and still i get the poor idle, hesitance, loss of power and the rest of it.
The dealer was asking how did the LPG fitter get around the oxygen sensor, as he said this would send a different signal when running on gas that is giving false reading.
You see it runs poor on gas then i revert back to petrol and still i get the poor idle, hesitance, loss of power and the rest of it.
The dealer was asking how did the LPG fitter get around the oxygen sensor, as he said this would send a different signal when running on gas that is giving false reading.
Updatejunkcatcher wrote:It sounds like the mixture while running on gas is well out which has upset the adaptations in the petrol ecu.
To put it in laymans terms the cars petrol ECU learns the best settings for your engine and driving conditions as you drive and stores these corrections in memory as adaptations to the injection durration. When the car is running on LPG the petrol ECU still thinks the engines is still running on petrol so if anything is wrong on the LPG side it can confuse the petrol ecu and cause the stored adaptations to be wrong making the car run badly.
As the fault is bad enough to cause a misfire on gas or petrol the petrol ECU will store a fault code which apparently on your model triggers limp home mode.
The Merc dealers aren't really reprogramming the ecu but clearing the adaptations and fault codes.
I am also wonder if the root of the problem might be HT related --ie plugs, plug gaps & coil packs.
Is it true the car does not know it is on gas. If so when I change to gas and the mixure is incorrect which starts all the problems does this mean the car ecu will store the adaptations to try and run better, then when i change back to petrol, in which case the car still does not know the difference it runs poor on petrol.
the dealer did say it comes up with a mixture problem when on the star diagnostic.
Well I'm hoping this is the problem.
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junkcatcher
- Member
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- Joined: Mon Apr 21, 2008 4:54 pm
An LPG injection system simply piggy backs onto the the petrols system.
The wires that normally go to the petrol injectors are diverted to the gas ECU. The gas ECU has wire connections to both the petrol injectors and the gas injectors.
Running on petrol the signals from the petrol ECU to the petrol injectors are passed straight through the gas ECU to the petrol injectors.
Running on gas the gas ECU intercepts the signals from the petrol ECU to the petrol injectors stops them going to the petrol injectors and sends a modified version (longer pulse to allow extra time required to inject the gas) to the gas injectors.
As the Meerkat says simple ! --- at least it sounds simple
The wires that normally go to the petrol injectors are diverted to the gas ECU. The gas ECU has wire connections to both the petrol injectors and the gas injectors.
Running on petrol the signals from the petrol ECU to the petrol injectors are passed straight through the gas ECU to the petrol injectors.
Running on gas the gas ECU intercepts the signals from the petrol ECU to the petrol injectors stops them going to the petrol injectors and sends a modified version (longer pulse to allow extra time required to inject the gas) to the gas injectors.
As the Meerkat says simple ! --- at least it sounds simple
UPDATE A150 MISFIRE
Car is running great and perfect now.
Went to LPG in birmingham on Wenesday morning, on petrol was running normal, plugged in diagnostic and went for a test drive, whilst monitoring the car we changed to Gas and the problems came back, judder and misfire, found the problem the car was too rich put back to petrol but the car would not re-adapt the car ECU had locked the petrol trim level.
At this point I booked it in at Merc sameday (4th time, by now they now just to upload the original settings) Took 45 mins then I returned to Birmingham.
The nice chap there new what the problem was and changed the LPG ECU as he thought it was letting Petrol and GAS in at the same time causing the misfire, ( Very rare problem). Anyway after new ECU had been fitted we took it for a test drive, whilst I was driving he was mapping the LPG ECU on his laptop in the passenger seat. After the drive it was working perfectly.
I have done 230miles since Wednesday night without any problems. I must say the lpg guy was great sorted the problem in 1 day, although I orignally thought it was the Petrol ECU that had played up. He told me he offered a money back guarantee if the system did not work.
I had great experiences with both garages, Merc never charged me for the 4 times it went in to reset the petrol ECU.
Well I would like to thank all who have left replies. If anybody has a problem with converting an A Class (169 model) just remember the Petrol ECU might lock out it the fuel trim is way out, even after driving on petrol for a day it won't relearn, you have to take it to a dealer to upload the correct files again.
Thanks Guys
Car is running great and perfect now.
Went to LPG in birmingham on Wenesday morning, on petrol was running normal, plugged in diagnostic and went for a test drive, whilst monitoring the car we changed to Gas and the problems came back, judder and misfire, found the problem the car was too rich put back to petrol but the car would not re-adapt the car ECU had locked the petrol trim level.
At this point I booked it in at Merc sameday (4th time, by now they now just to upload the original settings) Took 45 mins then I returned to Birmingham.
The nice chap there new what the problem was and changed the LPG ECU as he thought it was letting Petrol and GAS in at the same time causing the misfire, ( Very rare problem). Anyway after new ECU had been fitted we took it for a test drive, whilst I was driving he was mapping the LPG ECU on his laptop in the passenger seat. After the drive it was working perfectly.
I have done 230miles since Wednesday night without any problems. I must say the lpg guy was great sorted the problem in 1 day, although I orignally thought it was the Petrol ECU that had played up. He told me he offered a money back guarantee if the system did not work.
I had great experiences with both garages, Merc never charged me for the 4 times it went in to reset the petrol ECU.
Well I would like to thank all who have left replies. If anybody has a problem with converting an A Class (169 model) just remember the Petrol ECU might lock out it the fuel trim is way out, even after driving on petrol for a day it won't relearn, you have to take it to a dealer to upload the correct files again.
Thanks Guys