Mercedez Vito - Fuel Delivery Issue - Please Help!
Discussion
Hello everyone,
I am a taxi driver and have a 2014 Vito, I have joined the forum as I am desperate for any advice or similar experiences relating to a suspected fuel delivery problem.
The vehicle has 130,000 miles on the clock and about a year ago started to lurch and judder intermittently when accelerating under load.
Covid has hit my industry hard in the year since and I have so far spent approximately £4,000 trying to get this issue resolved with no success.
Please if anyone has any advice or suggestions any help would be very much appreciated. I've described the issue below and also listed all the steps that have been taken already to try and resolve the problem.
Issue Description
When accelerator pressed while under load, eg going uphill the power to the engine seems to cut out intermittently. This results in the loss of all acceleration for a moment, while foot is still down, before the power kicking back in. As a result of this issue the issue lurches and kangaroos forwards and can give the impression to passengers that I am driving dangerously.
Also when idling in neutral the vehicles shakes more than usual and the engine noise is erratic.
I think it is a fuel delivery problem, but the engine management light does not display so no one seems to be able to diagnose the issue.
Steps to try and fix
I've taken the vehicle to multiple garages, a Mercedez specialist, taxi specialist, diesel engine specialist and mobile mechanics.
After each of these steps there is a brief improvement in the issue, but within 48 hours the issue starts again.
- Mass airflow sensor replaced x2
- EGR replaced
- Replaced air filter
- Replaced oil filter
- DPF cleaned
- Catalytic convertor cleaned
Each time I visit a garage they investigate, think they have identified the fault, then repair and I pay for the labour, parts and VAT only to find the issue is still there within a few days.
Any and all suggestions would be really helpful.
Thanks
I am a taxi driver and have a 2014 Vito, I have joined the forum as I am desperate for any advice or similar experiences relating to a suspected fuel delivery problem.
The vehicle has 130,000 miles on the clock and about a year ago started to lurch and judder intermittently when accelerating under load.
Covid has hit my industry hard in the year since and I have so far spent approximately £4,000 trying to get this issue resolved with no success.
Please if anyone has any advice or suggestions any help would be very much appreciated. I've described the issue below and also listed all the steps that have been taken already to try and resolve the problem.
Issue Description
When accelerator pressed while under load, eg going uphill the power to the engine seems to cut out intermittently. This results in the loss of all acceleration for a moment, while foot is still down, before the power kicking back in. As a result of this issue the issue lurches and kangaroos forwards and can give the impression to passengers that I am driving dangerously.
Also when idling in neutral the vehicles shakes more than usual and the engine noise is erratic.
I think it is a fuel delivery problem, but the engine management light does not display so no one seems to be able to diagnose the issue.
Steps to try and fix
I've taken the vehicle to multiple garages, a Mercedez specialist, taxi specialist, diesel engine specialist and mobile mechanics.
After each of these steps there is a brief improvement in the issue, but within 48 hours the issue starts again.
- Mass airflow sensor replaced x2
- EGR replaced
- Replaced air filter
- Replaced oil filter
- DPF cleaned
- Catalytic convertor cleaned
Each time I visit a garage they investigate, think they have identified the fault, then repair and I pay for the labour, parts and VAT only to find the issue is still there within a few days.
Any and all suggestions would be really helpful.
Thanks
Sounds like another one of those incompetent garage threads that are all too common.
The fact you say it does not run correctly, potentially off a cylinder at idle...should be the first aspect to investigate if it is a fault that is always there, rather than something that requires driving to find it which will be more difficult.
Although certainly various live data parameters should be logged whilst driving, to see what is happening when the cutout is occurring to see what is amiss.
For the idle/shaking as you call it, find out which cylinder it is first, check fuel pressure, check injector operation, do a compression test. ( and I'm ignoring ensuring basic service items are all in good order like filters etc which should already have been covered )
Throwing parts and doing silly things which seems have already been done, do not make a lot of sense.
If it is not reporting any problems relating to MAF, EGR or DPF, there probably wasn't any point at all changing any of those parts, at least without through diagnosis of their operation first to justify it.
The above also assumes it has not had some dodgy remap, potentially removing the ecu's ability to report some faults and that the CEL does indeed actually work.
The fact you say it does not run correctly, potentially off a cylinder at idle...should be the first aspect to investigate if it is a fault that is always there, rather than something that requires driving to find it which will be more difficult.
Although certainly various live data parameters should be logged whilst driving, to see what is happening when the cutout is occurring to see what is amiss.
For the idle/shaking as you call it, find out which cylinder it is first, check fuel pressure, check injector operation, do a compression test. ( and I'm ignoring ensuring basic service items are all in good order like filters etc which should already have been covered )
Throwing parts and doing silly things which seems have already been done, do not make a lot of sense.
If it is not reporting any problems relating to MAF, EGR or DPF, there probably wasn't any point at all changing any of those parts, at least without through diagnosis of their operation first to justify it.
The above also assumes it has not had some dodgy remap, potentially removing the ecu's ability to report some faults and that the CEL does indeed actually work.
YJCouls said:
Thank you for your comprehensive advice, I will get the checks down as you advise. Just wish garages were not so greedy and just stop trying to fleece me. It’s been a tough as it is with no work.
Fingers crossed we will get to the bottom of the issues.
Greed is perhaps one aspect....but largely it's incompetence to diagnose.Fingers crossed we will get to the bottom of the issues.
Proper diagnosis can often take some time ( and can be difficult ), and often time that never gets fully paid for. Oddly, randomly throwing parts at something they've no hesitation in charging for though.
It's usually a case of trying to find a competent technician who can diagnose faults properly, but they are a rarity.
Last vehicle I had with a similar problem that others couldn't fix turned out to be a black slimy water jelly like substance (seen before on diesel vehicles) blocking the fuel inlet pick-up pipe in the fuel tank swirl pot it would lose power on occasion 
hard acceleration and exiting large roundabouts would change from week to week but got more frequent near the end on a late Focus , yes it was a pain I at to drop the tank but when you get a feeling about something and your seeing an historical fault code for fuel pressure you have to act 
and the owner was getting to the end of his tether with the car 
dont go or allow prodding the parts pinata if your not able fix it yourself get someone competent enough to monitor real time data and interpret fault codes correctly etc and just a good visual inspection often always pays off too
hard acceleration and exiting large roundabouts would change from week to week but got more frequent near the end on a late Focus , yes it was a pain I at to drop the tank but when you get a feeling about something and your seeing an historical fault code for fuel pressure you have to act and the owner was getting to the end of his tether with the car dont go or allow prodding the parts pinata if your not able fix it yourself get someone competent enough to monitor real time data and interpret fault codes correctly etc and just a good visual inspection often always pays off too YJCouls said:
After each of these steps there is a brief improvement in the issue, but within 48 hours the issue starts again.
The answer might be in this little nugget. I'm wondering if there is air getting drawn into the fuel system - the fuel filter would be one of the 1st things many mechanics would look at for the complaint. They remove, they look, they refit & they bleed, removing the air that may be causing the issue, vehicle the runs OK for a short period & air ingress then slowly gets you back to where you started.Just a thought.
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