NowForThe5th wrote:When the pressure i the rail exceeds the limit of the valve the excess is bled off and returned to the tank. A sensor detects this and shuts everything down. You will know all about it, believe me. It will feel like you've just hit a brick wall and the engine will go into lump mode. A restart will usually reset it but a code will be logged.
It would be quite rare for a remap to result in rail pressure so high that it goes above the limit of the valve. With a piggyback chip though it's quite common, especially for the higher performance tunes.
Interesting, i'll have to post a video of a few sensors worth of data on a histogram when i get a chance to do a pull up hill and wife records.
In most cases, my peak pressure can reach 23,000psi, sometimes it spikes to just over 26,000psi. When in tiptronic and manually shifting and flat-footing throttle, SOMETIMES rail pressure gets stuck around 15,000-16,000psi, sometimes around 7,000psi and only quickly letting off throttle and going back on on gets it past it.
No rail pressure errors or SCV errors, and no limp or sudden "hitting brick wall" feeling like the P1298 overboost error. Fuel filter is new sakura (11 microns from memory) and new donaldson post filter (3micron) and SCV is new + each tank gets 50ml fuel doctor. It feels like the time i had a blocked fuel filter, but that happened all the time on load, this only happens sometimes and letting of throttle fixes it instantly unlike a blocked filter.
I did at some point a couple of months ago try the longer SCV which from some research here indicates its diesel pump specific to the new models, this ended up peaking my rail pressure to about 30,000psi whilst cranking and made loud squealing noises (end scv fault error), at which point i removed it and put the old one back on until i could get a short model replacement.
Was wondering if this episode could have busted my pressure relief valve the same way the system gets overpressurised whilst pressure testing with the chip etc. Its been slightly harder to start in the mornings and get white smoke on startup (glow plugs and fuse ok)