Engine swapped Jetta won't start unless ignition is left on for 5 minutes first!

[Rynny]

Hey all, so as some backstory, I have a MK5 Jetta TDI that put a 2.0T FSI into with a K04 and all the mods you'd expect for that sort of upgrade.

I've adapted everything from the body harness, to the fuel system, and I still just have one issue, the car has immo off, and drives perfectly fine, but when it's been sitting for longer than an hour, or the engine is cold, it just cranks and cranks and cranks.

It starts up perfectly fine if I leave the ignition switched ON and run a 5 minute timer, then it cranks and starts as normal.

I've changed the Fuel pressure sensor, the crankshaft sensor, the fuel pump control module, coils, coolant temp sensors and more (either to fix this, or to fix other issues with the swap.) and no luck. Checked with VCDS and the fuel pressure on the low and high side are perfectly normal, it's priming, it's got fuel pressure, the HPFP is functioning as expected and the coils receive power.

The only things I've got left to potentially test would be injectors, something software related, or the high pressure fuel sensor or fuel rail sensor, although they seem to read perfectly normal when the car IS running smoothly. Doesn't seem to be anything that's clogged since as I said, ignition on for 5 minutes, and it starts like NOTHING is wrong...

Thanks for any help, if anyone else has experienced this please help me shed some insight on the issue, it's doing my head in because this is such a wicked project, it just takes so long to start!

[Rynny]

Another thing of note to anyone reading into this, when the car is running, it runs perfectly healthy, the idle is smooth, there's no sputtering, and even at WOT there's zero issues to fuel, spark, or timing.

[MIG]

Who did your IMMO off? A timer like that feels like some countdown happening.

Try making a measuring block channel map, before and after the 5 minutes and comparing the results Ross-Tech: VCDS Tour - Controller Channels Map

[Rynny]

Who did your IMMO off? A timer like that feels like some countdown happening.

Try making a measuring block channel map, before and after the 5 minutes and comparing the results Ross-Tech: VCDS Tour - Controller Channels Map

My Immo work was sorted out by Redline Tuning in Geebung, which recently shut down due to management issues, so I can't return to them for any questions.

Since the channel map was taking quite some time, I just ran one of Channel 01 Engine, and Channel 09 Central Elec.
Channel 09 was identical throughout every single measuring block, so I removed it from my spreadsheet, although I've put all the measuring blocks of Channel 01 into a spreadsheet with a condition showing whether the values match (true) or don't match (false) between the first turn of the key, and after waiting 5 minutes with the ignition on.

I wonder if there is anything of major note to be interpreted through this information:
VCDS - Google Sheets

Since the channel mapping takes quite some time, if I were to do the entire can network, anything scanned in the second half would have been scanned towards the end of the 5 minute timer, meaning we would probably not be able to see any difference between the values, but I can wait a few hours, and scan another module if it's important to compare again.


Also regarding the fuel pressure, I know in blocks 103 and 106 it shows the rail pressure sitting at 7 bar, but I can confirm during crank it immediately pressurizes to 50-70 bar and instantly starts, then it will hold that pressure for hours, it also reaches the expected 110-130 bar at WOT, I suspect there is a slow overnight rail leak, but it does not affect starting when, as usual, I leave the ignition on for 5 minutes first...

[Rynny]

Who did your IMMO off? A timer like that feels like some countdown happening.

Try making a measuring block channel map, before and after the 5 minutes and comparing the results Ross-Tech: VCDS Tour - Controller Channels Map

The only thing in Channel 01 that really seems of major note would be 3,3 Throttle Valve Angle goes from 1.2% to 6.3%, and 247 and 252, that temperature reading going from the negatives into the positives, which seems to play no roll in starting from my tests.

[MIG]

Thanks for uploading that, yer those measuring blocks you mentioned are weird; I don't think they are necessarily a temperature reading. It might be just VCDS thinking the value reported is temperature.

Maybe someone else on here with a similar ECU can compare that block?

[Passat my07]

Will it start with aerostart to prove the ignition side is fine?
Are the injectors leaking when it’s turned off?

[Rynny]

Update to my no-start/long-crank situation:

I may have found a problem to look into, so I just opened my passenger door and disconnected the fuel pump (so I could read the rail pressure without it priming), and turns out my rail was at 1.02 bar and low side at 1.06 bar after sitting overnight. I would also like to note that my 103-2 (Fuel Pump Adaptation Value) is -4000, while the VCDS site says spec should be +/- 1000, is this an issue?

Priming it sent them up to 5.06 and 5.28 (high and low sides respectively)

Then disconnecting the fuel pump again, the high side slowly leaked down to 4.2 bar over the period of 2 minutes while the low side stayed at 5.2

I am now suspecting that I have a bad fuel pressure regulator and/or leaking injectors, I will be testing for wet cylinders tomorrow. I really want to fix this issue because waiting over 5 minutes just to hope it catches sucks, I want this build to be ready for cruises haha