HPFP or injectors, best way to tell?

jleckenby · Post by **jleckenby** » Wed Dec 27, 2017 10:49 pm

Evening all,

Car has been idling a bit rough for a while. Wondering if anyone can help identify whether it’s HPFP or injectors.

- No check engine light and only interesting code is a historic misfire on cylinder 6
- It often has a long crank (3-5 seconds), and the idle is a little rough (usually 650-750)
- Sometimes it works up to revs on start, sometimes it starts 1.5k-2k and drops down
- If I hold throttle steady below 2k there’s always a slight wobble, higher is constant
- Warm startup is always good, no long cranks
- Doesn’t really seem any power reduction (though it’s been a few months so could be wrong)
- Changed spark plugs and coil on cylinder 6
- No petrol comes out of exhausts
- HPFP idles 695-730
- Very ocassionally the start is very rough and engine light comes on. Restarting car sorts the issue.

The length of time the car is left doesn’t seem to make the crank longer. Ive been away for a fortnight and it started straight away (though on high revs). If the injectors were leaking would the length of time make it worse?

Any help appreciated!

Z4M-2006 · Post by **Z4M-2006** » Thu Dec 28, 2017 9:18 am

No,

If the injector drips then it will drop fuel pressure in the fuel system, the fuel pressure sensor will detect the low pressure and the car will be held in "non start" until correct pressure is maintained.

Hence elongated cranking times

Sounds like you have no6 injector at fault

jleckenby · Post by **jleckenby** » Thu Dec 28, 2017 3:20 pm

Hmm, interesting! I expected a long crank after leaving it for so long and there was no fuel thrown out the exhaust, hence wondering. Think I’ll take the injector out tomorrow and have a look at it!

mcbutler · Post by **mcbutler** » Thu Dec 28, 2017 4:43 pm

Z4M-2006 wrote: ↑Thu Dec 28, 2017 9:18 am No,

If the injector drips then it will drop fuel pressure in the fuel system, the fuel pressure sensor will detect the low pressure and the car will be held in "non start" until correct pressure is maintained.

Hence elongated cranking times

Sounds like you have no6 injector at fault

I would expect a strong smell of unburnt fuel if this were the case.

Timdon · Post by **Timdon** » Thu Dec 28, 2017 8:17 pm

I had long crank, strong smell of fuel and irregular tick over .

ph001 · Post by **ph001** » Sat Dec 30, 2017 1:57 pm

All those symptoms point to injectors from previous history. The long crank is usually as a result of loss of compression in one or more cylinders due to bore wash from the unburnt fuel on the piston rings.

dario · Post by **dario** » Sat Dec 30, 2017 7:35 pm

If its like this.....

Then its likely the injectors.

regards

Glad i had extended warranty!

jimbo1958 · Post by **jimbo1958** » Sun Dec 31, 2017 3:04 am

dario wrote: ↑Sat Dec 30, 2017 7:35 pmIf its like this.....

Then its likely the injectors.

regards

Glad i had extended warranty!

Ditto......3 grands worth of work for the injectors and module when mine went. Thank f*ck for the Warranty.

HillWalker · Post by **HillWalker** » Sun Dec 31, 2017 2:59 pm

What year and what mileage were these cars that had the problems with the injectors and the hpfp, I think it was a noted problem on the early 35 models, just hoping it was all sorted by the 2015 model.

dario · Post by **dario** » Sun Dec 31, 2017 5:19 pm

HillWalker wrote: ↑Sun Dec 31, 2017 2:59 pmWhat year and what mileage were these cars that had the problems with the injectors and the hpfp, I think it was a noted problem on the early 35 models, just hoping it was all sorted by the 2015 model.

2011 /25k miles

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