R58 inconsistent fuel rail pressure on 2012 car
Discussion
The EML has been coming on and going off. Putting a code reader on shows occasional misfires and low fuel pressure.
I thought this meant the high pressure fuel pump may be at fault but pressure according to the IBD II readout is generally between 4800-11000 kPa. It very occasionally drops suddenly to 400 kPa.
If there was an issue with the HPFP then surely the pressure would regularly be low but does the occasional drop suggest some sort of temporary blockage?
I thought this meant the high pressure fuel pump may be at fault but pressure according to the IBD II readout is generally between 4800-11000 kPa. It very occasionally drops suddenly to 400 kPa.
If there was an issue with the HPFP then surely the pressure would regularly be low but does the occasional drop suggest some sort of temporary blockage?
It's the N18. I thought the HPFP failure issue was only up to about 2010 cars and I'm wondering if some HPFP failures have been misdiagnised on the later cars.
Surely if the pump was failing, there would be consistently low pressure?
I'm seeing 4800kPa as a minimum with just the very occasional drop to about 400kPa as if the pump may be seeing fuel starvation?
Surely if the pump was failing, there would be consistently low pressure?
I'm seeing 4800kPa as a minimum with just the very occasional drop to about 400kPa as if the pump may be seeing fuel starvation?
I think its just a common problem, my N18 pump finally gave up last year, i say gave up i got fed up with it. It would occasionally go into limp mode but you could stop it and restart and it would be fine for weeks. It got towards the stage where it would missfire and run like a bag of nails so i bit the bullet. There was always a fault code in for low fuel pressure. I don't believe there is a fuel filter in line, there may be one in the tank though.
So replacing the HPFP has resolved the fuel pressure issue?
In that case it wouldn’t be a fuel filter problem. I wonder if there is a pressure regulator in the pump and that is sticking open?
What I can’t understand is why it would be full pressure for most of the time and occasionally drop to such a huge extent.
If it was an electric pump, you’d think it was an intermittent cut out.
Surely mechanical pumps either work or don’t.
In that case it wouldn’t be a fuel filter problem. I wonder if there is a pressure regulator in the pump and that is sticking open?
What I can’t understand is why it would be full pressure for most of the time and occasionally drop to such a huge extent.
If it was an electric pump, you’d think it was an intermittent cut out.
Surely mechanical pumps either work or don’t.
Specs from an N18 HPFP manufacturer below.
The note about minimum fuel pressure before the HPFP can work may be relevant; 400 kPa is 4 bar, and below the stated work pressure. Might be worth checking the other pump and fuel filter, as the N18's pre-HPFP pressure is specced as 5.0 bar.
Note: please check your vehicle's fuel pump work pressure(at least 5Bar) first before replace our "HPFP", because HPFP need at least 5 bar work pressure start to work. check below chart.
Fuel pump standard parameters:
voltage range: 6V-16V
nominal voltage: 12V ±0.1V
petrol work pressure: 5.0bar---5.9bar
diesel work pressure: 3.6bar----5.9bar
temperature range: -40---85?
Brand New High Pressure Fuel Pump Compatible with the following:
Mini R55 Clubman - All Cooper S & JCW models with N18 engine
Mini R56 Hatch - All Cooper S & JCW models with N18 engine
Mini R57 Convertible - All Cooper S & JCW models with N18 engine
Mini R58 Coupe - All Cooper S & JCW models with N18 engine
Mini R59 Roadster- All Cooper S & JCW models with N18 engine
Please note, this will not fit pre 2010 Cooper S models with the earlier N14 engine or pre 2012 JCW models with the earlier N14 engine.
The note about minimum fuel pressure before the HPFP can work may be relevant; 400 kPa is 4 bar, and below the stated work pressure. Might be worth checking the other pump and fuel filter, as the N18's pre-HPFP pressure is specced as 5.0 bar.
Note: please check your vehicle's fuel pump work pressure(at least 5Bar) first before replace our "HPFP", because HPFP need at least 5 bar work pressure start to work. check below chart.
Fuel pump standard parameters:
voltage range: 6V-16V
nominal voltage: 12V ±0.1V
petrol work pressure: 5.0bar---5.9bar
diesel work pressure: 3.6bar----5.9bar
temperature range: -40---85?
Brand New High Pressure Fuel Pump Compatible with the following:
Mini R55 Clubman - All Cooper S & JCW models with N18 engine
Mini R56 Hatch - All Cooper S & JCW models with N18 engine
Mini R57 Convertible - All Cooper S & JCW models with N18 engine
Mini R58 Coupe - All Cooper S & JCW models with N18 engine
Mini R59 Roadster- All Cooper S & JCW models with N18 engine
Please note, this will not fit pre 2010 Cooper S models with the earlier N14 engine or pre 2012 JCW models with the earlier N14 engine.
Yes. It’s logical to start from the tank.
Reading online though there seem to be loads of pumps changed with the same symptoms as me but no detail answer as to what has caused the failure.
Worn mechanicals? Faulty electrics? Pressure regulator?
This isn’t just the odd pump, it sounds like there’s thousands affected.
Reading online though there seem to be loads of pumps changed with the same symptoms as me but no detail answer as to what has caused the failure.
Worn mechanicals? Faulty electrics? Pressure regulator?
This isn’t just the odd pump, it sounds like there’s thousands affected.
BMW are keeping quiet about the cause, but it got so bad in the US they extended the warranty on the pump to 10 years and did a recall on over half a million vehicles. (https://hausofminis.com/2015/07/bmw-high-pressure-fuel-pump-issues/ )
Problem is that it would need a good number of failed pumps being stripped down before the cause is known, and most pumps are still being replaced within the dealer network. This means we're speculating, but...
The fix included a remap that may have reduced power (anecdotal and "my friend's" before/after dyno tests), indicating the pump can't achieve the designed peak pressure or flow rate without damage. (Or the pump is still being damaged, but the lower pressure mitigates this and extends the apparent life.) It being such a problem in the US might be due to their using bio-ethanol more widely, which is more aggressive on seals. The failure appears to be unaffected by driving style, chipping or transmission type, again indicating a chemical rather than mechanical or overload failure.
It would need a side-by-side look at the original and redesigned pump, and several failed pumps, to suggest the cause.
Problem is that it would need a good number of failed pumps being stripped down before the cause is known, and most pumps are still being replaced within the dealer network. This means we're speculating, but...
The fix included a remap that may have reduced power (anecdotal and "my friend's" before/after dyno tests), indicating the pump can't achieve the designed peak pressure or flow rate without damage. (Or the pump is still being damaged, but the lower pressure mitigates this and extends the apparent life.) It being such a problem in the US might be due to their using bio-ethanol more widely, which is more aggressive on seals. The failure appears to be unaffected by driving style, chipping or transmission type, again indicating a chemical rather than mechanical or overload failure.
It would need a side-by-side look at the original and redesigned pump, and several failed pumps, to suggest the cause.
I can't believe I've had this problem since June but I've been hoping it would get worse to confirm it is HPFP.
It hasn't!
The car has been into a Mini independent and they say "our best guess is HPFP".Even they say it would be easier to be sure if the situation got worse.
What I don't get is that the problem is only there at cold. I start the car up without difficulty. It clearly runs badly and the code reader says low fuel pressure.
Let the car warm up - reset the EML and everything is fine again.
If it was HPFP then why is the pressure fine once the car is warm?
Could the fuel rail pressure sensor be at fault which puts the ECU in tizzy?
Neo Bros do the pump for £410 but I'm reluctant to throw even that at it without confirmation that it will fix it.
It hasn't!
The car has been into a Mini independent and they say "our best guess is HPFP".Even they say it would be easier to be sure if the situation got worse.
What I don't get is that the problem is only there at cold. I start the car up without difficulty. It clearly runs badly and the code reader says low fuel pressure.
Let the car warm up - reset the EML and everything is fine again.
If it was HPFP then why is the pressure fine once the car is warm?
Could the fuel rail pressure sensor be at fault which puts the ECU in tizzy?
Neo Bros do the pump for £410 but I'm reluctant to throw even that at it without confirmation that it will fix it.
Thanks for all the responses here.
I fitted a new HPFP from Neo Bros this morning. Great service from them.
It was a very easy job. After moving a few pipes and cables out of the way it was 3 setscrews, a couple of pipe fittings and done.
I also tried using the Laser fuel coupling tool but that was more of a hindrance than a help.
I'm really not impressed that this part has failed on a car with less than 40K miles and 6 years old.
I fitted a new HPFP from Neo Bros this morning. Great service from them.
It was a very easy job. After moving a few pipes and cables out of the way it was 3 setscrews, a couple of pipe fittings and done.
I also tried using the Laser fuel coupling tool but that was more of a hindrance than a help.
I'm really not impressed that this part has failed on a car with less than 40K miles and 6 years old.
MrC986 said:
BMW Mini haven't treated UK owners of R56s well in regard to the HPFP debacle and I think it lost them a few customers from the brand - there's been lots written on forums about this and it's not necessarily a mileage based problem as the OP has found out.
I totally agree. I had cold start misfire (R57 with N18 engine), no conclusive diagnosis, eventually renewed the HPFP as codes suggested and no other option. Fault fixed. But BMW know they have a duff design, admitted and warrantied in USA (10years?), but in UK they ignore and let customers face extortionate cost for a part that should not fail. First and last BMW product I will buy. (unless a good early M3 comes along...) Also surprised there is no recognised specialist doing a replacement refurb service- there must be an opportunity there). German reliabilty myth is just good marketing, not related to product- in my opinion.
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