All Things Mk5 > How to Guides / Troubleshooting
One reason why fuel-rail pressure may be low....
ROH ECHT:
--- Quote from: rich83 on May 02, 2022, 07:39:23 pm ---Great info. Shame it’s impossible to measure without stripping the chain cover.
--- End quote ---
Right...measuring of it, might just be something to add when doing the timing chain, tensioner, and oil containment ring job.
breeze:
I think the drop of actual vs specified fuel rail pressure at around 3,500 RPM is the big giveaway. At that point it is likely to something on the high pressure side of the fuel system because that is mechanically linked to engine speed.
You can remove the HPFP to check plunger and follower fairly easily. If they look OK then there is a good case for removing the chain cover and measuring the cam.
Taking the opportunity to measure when replacing the chain would also make sense.
LC5F:
Great information.
I was thinking you could remove the HPFP and use calipers to measure the depth from of lobe to shaft.
- or -
Would whipping just the vacuum pump off give enough room to measure?
it would make an ideal time to re-new the pump seals at the same time
ROH ECHT:
--- Quote from: LC5F on May 03, 2022, 09:47:54 pm ---Great information.
I was thinking you could remove the HPFP and use calipers to measure the depth from of lobe to shaft.
- or -
Would whipping just the vacuum pump off give enough room to measure?
it would make an ideal time to re-new the pump seals at the same time
--- End quote ---
That is a really good idea. I think it is definitely something worth attempting, if to avoid removing the chain cover. Some calipers may make the reach while some may not, but....so long as cam lift measuring is achieved; 8.75mm - 3.50mm = 5.25mm
pudding:
Or you could use a vernier caliper's depth measurement from the machined surface of the HPFP hole, to the peak of the cam. We would of course need a known good measurement as a reference first.
Regarding K04 cams, apparently only the CDL (plus all 265hp derivatives) shows a different intake cam on ETKA. AXX, BWA, BYD etc all share the same cams.
Cam wear certainly makes a lot of sense for explaining fuelling short falls. But it's not quite as clear cut as that unfortunately as there have been several revisions of HPFP over the years. Some can support Stage 1 and higher with ease, and some are borderline even on stock fuel demands.
If it were me, personally I wouldn't waste my time just replacing 1 cam. This is a far better option, and everything is new. Cams, guides, valves, VVT gear, the lot. Slap it on and move on with your life :happy2: It's a similar price from VW directly last time I enquired.
https://tornau-motoren.de/en/NEW-Cylinder-Head-complete-for-Seat-2-0-TFSI-BWJ-06F103063PX-240HP-177kW/p/detail/10015215
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