Cold start issues - LPFP, HPFP, Injectors replacement - Results

[ZoliWorks]

My Mk5 GTI cold starts sounds the same as on your videos every morning...

I still dont think it's fine but it is what it is, I gave up. As long as it starts, it's ok I guess...

Earlier today, 12c outside, it started like a diesel at -20: It started cranking, puffed about twice, died again, then cranked for a bit more and finally started. Take a look at this video on reddit. It was basically that but 2x longer

https://www.reddit.com/r/GolfGTI/comments/1al3gxc/mk5_bwa_rough_cold_starts/

[mjmallia]

That does not sound right for sure.

[ZoliWorks]

Okay I did not think it'd do it again, but surprise! it did... It's 16 degrees celsius outside and you've been sitting in a garage! Why cant you just be normal?!

I gave you brand new injectors, brand new high pressure pump, brand new low pressure pump, new n80 valve, new o2 sensor, the cam chain was done with all new INA parts, including the VVT adjuster and solenoid! and you've been carbon cleaned last year...

[mjmallia]

Are you sure the timing is good still on the chain and belt?

If a tooth out on either one, that would def make a hard to start scenario

[ZoliWorks]

At idle, the chain is sitting quite happily at 1.0 KW when warm but the adjuster is at 26-27 KW even when the requested is 28 KW. The belt hasn't been checked since last year but back then we checked 3 times and both marks were on spot.

I need to take a look at those VVT adjuster ring seals. Those wren't changed and they are rubber/plastic on this engine as far as I know.

[dennis10]

I've been chasing the same cold start issues on my Edition30.  After trying various fixes, late last year I replaced the rubber o'rings in the vacuum pump on the side of the head and that seems to have done the trick.  For a couple of months now it has been starting on the button, no extra cranking, no shaking and rattling into life - just a normal engine start.  Try that if you haven't already?

[ZoliWorks]

I've been chasing the same cold start issues on my Edition30.  After trying various fixes, late last year I replaced the rubber o'rings in the vacuum pump on the side of the head and that seems to have done the trick.  For a couple of months now it has been starting on the button, no extra cranking, no shaking and rattling into life - just a normal engine start.  Try that if you haven't already?

Do you mean the VVT adjuster seals? If yes, then yeah, that's the next thing on my list. I already have the 3 rubber rings and the gasket for the cover, just didnt have time to do it yet.

If you mean the internal seals in the vac pump itself, I'll likely be replacing the whole pump as it's leaking and I haven't had much luck with rebuild kits.

[dennis10]

I mean the vacuum pump seals - seems to have done the trick for me.  I think it is a pretty sensitive engine with regards vacuum etc.

I actually tried to check and replace the 3 plastic o'rings on the VVT housing myself on the weekend because I have an ongoing slight idle misfire.  I also needed to replace the cam cover gasket too - Annoyingly I didn't get the whole job done, I just couldnt get the housing cover off of the VVT/timing chain area.  I started to button it back up and consulted my guide again and realised that I had left 1 black bolt in the housing at the bottom and had removed a silver bolt that was right next to it in an area with no visibility, thinking I'd taken out the right one.  Only realised my mistake after buttoning most of it back up, but the day was getting long and I'd had enough so I gave up - something for another day.  At least it should be a shorter job in the future as I don't need to remove the cam cover again to do this job.  Good luck with yours!