New to forum. 2008 MCS 65k miles. Well maintained. Car sat for 2 weeks. Now stalls and or misfires on cold start
requires 4 attempts then idles and runs perfectly with no loss of power or misfires and no excess fuel consumption. Only codes were multiple cylinder misfires. I checked vacuum, cleaned MAF sensor checked air filter all good. Took to mechanic. He checked and rail psi only at 39 during rough idle. He did not check lpfp but said he had to replace both lpfp and hpfp and wants $3000 to do it. So I am going to do it myself. Here is the kicker. After successful start, if I shut down and restart with 4 hours, no problem. If I go longer than 4 hours the problem returns. So I'm thinking most likely culprit is fuel system check valve leaking down. I cannot understand how the hpfp can work perfectly once a good start but then just is bad if I go over 4 hours driving? Any thoughts would help before I spend money needlessly. Thx.

 

Problem with the N14 high pressure pumps is they seem to go bad without much warning. Do you have a tool to collect out the DTCs?

If you're at the point of throwing parts at the car, I would start with the low pressure pump in the tank, as this one is much less expensive. If the problem goes away, great. If the problem persists, then replace the high pressure pump.

 

Dtc codes for multiple cylinder misfires.
I know if it is a bad check valve I have to change lpfp. I thought if I cycled the start button 3 or 4ctimes with foot off brake I could pressure the line but tha5 did not seem to help. T9 check it with a guage I have to buy the guage and adapter and pull off the air filter housing etc. I can do that but I would rather not if unnecessary

 

Sounds like what my HPFP did when it was going out. Come out after work and would barely want to start, rough idle, no misfire codes though. I could rev it to 1500-2000 to get it to smooth out and then after it got warm, would run fine. I did notice that after about a month of this, if I were to do a pull to pass someone or anything like that, it would throw a half CEL and wouldn't go away until I shut it off and restarted it. About that same time, it started running really rough whether I left it overnight, or fueled up. Didn't matter on a timeframe or how warm it was. Replaced LPFP first, didn't do anything. Replaced just about everything that I could think of before biting the bullet on the HPFP. Haven't had the issue since.

 

Ive had the same problem and Ive been shotgunning parts at my mini for almost 3 months now with little success. My mini had similar starting issues and then it would cut off if I did WOT from a stop here and there. One day if wouldnt idle correctly and the sound was horrible. People kept telling me it was my HPFP, but I looked for a leaks among other things. I found a cracked PCV hose on the passenger side which I replaced, changed plugs and coils, double checked and then double ziptied all vacuum line ends. My idle got alot better I was still having fueling issues. I replaced LPFP and my HPFP twice, as the first and now second ebay/used HPFP didnt seem to help as I cant get past 126psi for fuel rail pressure....

Im waiting on a FCPEuro HPFP and crossing my fingers that this actually solves the problem...If not then my R56 is being sold off.

 

Out of curiosity, to all, what brands did you use for the two pumps, and did you replace the two fuel lines to/from the hpfp? The genuine mini parts are WAY more expensive than the other brands, except Delphi? Thx. Will do lpfp snd fuel filter first and cross my fingers.

 

Oh yes, this reminds me, I used a ebay pump too and it lasted a week. Then I found a used one off this forum and it hasn't skipped a beat in the 3 years it's been on. So get genuine.

 

If I had an N14 and needed a pump today, I would get this one:
https://www.ecstuning.com/b-oes-mini...517588879~hud/

 

I got the FCPEuro HPFP in today and installed it, it fixed the fuel pressure issue for sure. Im reading over 1000psi at idle, previously it would get over 126psi even when driving. Im still having the issue with the machine gun popping after 4k rpm though but I think thats a vacuum leak, flapper seal, or diverter valve issue. Im currently replacing the diverter valve since I have an extra on hand...hopefully it fixes the issue...

 

Sport mode you get the pops and bangs when you come off the throttle stock. Also if someone every added a tune it makes that machine gun noise after down shift or come off the throttle fast.

 

Its quite different than a normal pop and bang, normally it happens when you release throttle...Im having it happen with throttle applied after 4k rpm along with a loss in power.
Also, the new Diverter Valve did not help. I may be changing the plugs and coils again and doing a leakdown test.

 

Mine is not like that at all. The only problem is low rail pressure and stalling or misfiring after car sitting for 4 hours. Takes 3 shutdowns or stalls then on the 4th try fires right up like normal and then drives and accelerates like normal. Once in a while during start attempts I will get codes for multiple misfires. How long does it take the lpfp to charge and pressurize if the check valve has a leak?

 

In any event I will change lpfp and filter first because it is easiest and less expensive, although it does not appear that it would take more than a couple of hours to swap out the hpfp...

 

I changed the filter and the LPFP I got was less than $55 HERE. It seems to work pretty well.
The LPFP and Filter takes a few hours, the HPFP takes literally 10 minutes to swap out if you have the correct tools - the fuel line DQ was probably the most annoying part.
You can test the LPFP with a multimeter, if it shows 12V output like mentioned in Pelicans tutorial then you know its not that, leaving the Relay or HPFP...most often times being the HPFP unfortunately. If you have a scanner or ultragauge you can check rail pressure.

Im starting to think my issue is with the spark side of things now that my fuel problems are fixed.

 

UPDATE: After replacing coils once again and the Lambda O2 sensor, my car is driving again!

 

Update on my issue and request for assistance.

Mini R56 S 2008 with ~65K miles. About 3 months ago began with hard cold starts. Multiple attempts before car would idle and run right. With first attempts, either the car would start and immediately stall or would start but rough idle at <500 rpm with multiple misfires. Only codes for the misfiring. Once running, would be totally normal v-v gas mileage, acceleration, etc. IF I drove the car and then let it sit for less than 2-3 hours, would restart normally. Beyond 3 hours, and certainly overnight, the stalling, misfires, etc. would return.

Took to mechanic. All he checked was the high-pressure pump. Said that the pressure in the hpfp was around 147 while the pump was commanding 1400 or so. Also told me he "had" to replace the lpfp as well, to the tune of $3000. So, I opted to fix myself.

1. Cleaned the MAF sensor.
2. Checked air filter clean.
3. Added Sea Foam to the gas tank.
None of these helped.
4. Replaced lpfp and in tank filter. No improvement.
5. Bought a pressure gauge and measured low pressure to the hpfp. Results:
a, As soon as I open car door, pressure jumps to 4.8 bar. This tells me that the fuel pump fuse (which I had already checked anyway) and the fuel pump relay and the lpfp is working fine.
b. the pressure at the gauge came up to 5 bar with attempted start and stayed that high regardless of whether the start was normal or the usual stall and misfire.
c. Pressure on the gauge fell about 0.2 bar after 15 minutes with car off. It dropped about 1 bar after 1 hours, 2 bars after 3 hours, and was down to 2.5 bar by the next morning. All this tells me is that the check valve and the pressure regulators are fine.

Prior to putting the gauge on the low-pressure size, I swapped out the hpfp. It actually was harder to start and never had any power with the "new" pump, which was an OEM new pump I bought on-line. Talked to my mechanic, he said I got a bad hpfp and should exchange it.

BEFORE I throw more parts, can anyone reading this come up with any other suggestions before I spend the $ on the pump? It just seems weird that after 3 months, the only problem is starting. I would think there would be some other symptoms, like stalling at a stop sign, bad fuel economy, smoke out the tial pipe, hesitation when acceleration, etc. THERE ARE NO OTHER SYMPTOMS.

Also, for those who have had to replace their hpfp themselves, any recommendation as to specific brand would be appreciated. I don't want to have to keep sending back defective units.

Thanks in advance.

 

Which HPFP did you go with? From where online? OEM is the best and the only thing that will work from what I have read. My personal experience is, again, a cheap one I bought from eBay lasted a week before the symptoms came back. Once the symptoms came back, I actually put my original one back on because the eBay one was so much worse. I then got lucky and found a low mileage used one and I haven't had a problem since. I have read posts that cheap ones can last up to 6 months if you are lucky, but in the end, everyone ends up replacing it with an OEM one and not having a problem. So as far as "brands" that you want recommendations for, I would go with what was linked above, go to the dealer and get one, or see if you can find a OEM one online (like ECS). Did you have your mechanic test the new pump and tell you what the psi was reading?
And as far as other symptoms, I remember NOT having a problem with stalling, bad fuel economy, smoke, or anything while driving. My issues were mainly startup until later on when it didn't like it when I would get on it and do a pull.

 

I got the OEM HPFP fr9m ECS Tuning.
no the m3chanic did not check the replacement but I was able to read the freeze frame with my OBDII reader. It was 107 got up to around 120 with 4000 rpm.
I won't buy a mini logo one because they are. Double the others. Will likely get a PSG since the r56 engine was actually made by Peugot.

 

Only thing i could think of is bad injectors. Rare the OEM HPFP goes bad out of the box. It happens, we had some genuine ones bad. I guess if the pump sucks up some grime from the old pump connection or something inline as part of all the repair and removal it can happen. I also seen people complain about when they ran the fuel tank low it sucked up some fine dirt and got past the filter into the pump. I know the HPFP are very sensitive to the fuel.

 

Doubt injectors. I got misfires on all 4 cylinders. Lpfp pressures are spot on but rail pressures way low...until I finally get it running then everything 100% normal till engine cools down for 2 to 3 hours. Including hard acceleration . And. Lpfp recharges to 5 psi in 1 second. I don't understand...