A few weeks ago my 07 mini s started having trouble idling on a cold start. The rpms jump around from as low as 400-1k. For a split second when first started it's fine but then the rpms drop. And no throttle response once they drop. I can give it gas when starting it'll rev up fine but starts to backfire and eventually the rpms fall super low. Eventually it'll pull itself out of the issue and run perfect. And when running theres never an issue even at a stop. My first thought was MAF sensor. Because when I unplug it it starts up and runs fine. There was never a CEL before unplugging the MAF but obviously after there was. Ordered a new MAF sensor but the problem presists. Any help is greatly appreciated.

 

When is the last time you cleaned your intake valves?

 

I've only owned it for about 5 months so I'm not really sure. Could've been just before I bought it. Could've been never

 

Pull off your intake manifold and look at the intake valves.

 

Going to check the intake this weekend. I've also decided to replace the ignition coils. They looked pretty corroded when I replaced the spark plugs will update later. Thanks for the input so far guys

 

It's a good idea to replace the coils, when they go, they just go.

 

The biggest reason I'm thinking it could be the coils is I got a misfire CEL on cylinders 1 and 3 which were the corroded ones. Here's hoping

 

That's likely the cause, I had the same deal. 1 and 3, they weren't corroded but they were the culprit AND it's an easy fix. Change the plugs with them.

 

so changed the coils and the plugs. issue still persisted. decided to clear the codes and start it up. almost instantly the limp mode/half engine light popped up along with a new CEL. ran the codes P3091 (HPFP) which was my first thought weeks ago when the issue first came up. and of course my car being an 07 is just one year too old for the warranty. so i plan on checking it again in the morning to see if any other codes pop up. and ordering a new fuel pump.

 

No need to go further, it's your HPFP for sure. I've the exact problem. And I bought one from Pelican parts for 300 bucks. I also bought the fuel lines to and from the pump because the factory service manual says to replace those if you ever loosen up those connections. Well, when I had those lines out, I also decided to pull all the injectors and ran then through with pressurized carb-cleaner solution (rigged up my own electrical switch, pumping line) and sprayed the injectors until the patter is all the same. Then I also had new gaskets and seals put back in with the injectors.

Of course, while the intake manifold has to be removed, I also checked the intake valves to see if there are oil deposits (I did walnut blasting 1 oil change ago), and on this check, I can see some oily wet valves already, so I lightly walnut blasted the valves again.

After everything's done and put back together, car starts and runs like a champ!

 

So I replaced the HPFP a week ago. Ran great. Good as new. Yesterday I decided to have a little fun with her and really push it. Car went back into limp mode and didn't wanna start right a few hours later. Same symptoms. Ran OBD2 came up with the same code again. Is there anything else that can throw that code or did I just get a lemon for a fuel pump

 

Did you replace the fuel rail, too? You're supposed to get a new fuel rail when you're doing the HPFP.

Anyways, other than the above, it's possible you've gotten a lemon pump. Where did you buy the pump from? See if you can return it for a new one.

Also, depending on model/year of your car, dealership may be able to replace it out of an extended factory warranty on these pumps. Apparently, even Mini realized that they put a shitty pump in our car, and I'm glad they stand behind it to upkeep with a warranty.

 

I also might point out that my OBD2 ready fuel rail pressure at 120ish

 

Could the issue be the hard fuel line? I didn't replace that one. I did replace the soft line from the tank though

 

I was informed from my local dealership when I was buying the associated parts from them to do the HPFP change. They said that if you ever open up that hard line either end, you will need to replace it completely because that rail has special sealing thread and once it's set, you shouldn't re-use it. It will leak sooner or later. If you get high pressure fuel error code after that HPFP replacement, chances are you do have a leak with that connection. Of course, this is just a suspicion, I could be wrong. And if you do replace that fuel line and it's still same issue again, you probably do have a lemon pump.

One other thing I did when I did the HPFP was I also replaced the fuel filter (my car was around 100k, and my hunch is it's never been replaced before). I did it just so to prevent any flow restriction to the fuel line. When I pull out the fuel filter, it was very dirty, black particles, but no gunk. So I was glad to be doing that replacement. (If you are going to do that, too, do it when you have 1 or 2 blocks of fuel left on the guage) It'll make a mess to do it with tank full of gasoline. Hope this helps.

 

so i replaced the high pressure fuel line and while i was at it removed the HPFP just to make sure everything was bolted up properly. put everything back together. drove less than a mile up the road to test everything. limp mode came on again with same code. so i contacted the seller on ebay about getting a replacement HPFP. fairly certain i got a lemon. fingers crossed.

 

 

2Cati, your motor is different than the OP's. He's after the HPFP which on your N16, I don't think you have such device.

 

 

 

Sorry for never following up. But yes I replaced the HPFP along with the high pressure and low pressure fuel lines. Runs perfect now

 

 

What makes the high pressure fuel line so expensive? Looks like a brake line. Anyone tried bending their own line?