Stumbling start (intermittently, so that's fun [still not fixed, apparently])?

[Anthony3o55]

I changed my battery from a n advance auto parts duralast to an OEM VW battery from the dealer. The moment I put the new battery the car starts up super quickly. VW Battery seemed to fixed my issue

 

[avenali312]

Welp, this has returned after being problem free since April. Super long crank before starting on Saturday. Did eventually fire and stumble up to proper RPMs. Of course this happens right after I stop researching what my next vehicle will be and decide to commit to it for the long haul haha.

 

[avenali312]

But hey, I managed to finally get a video of it! This was after my 35 minute commute to work and then letting the car sit for a bit over an hour and a half. The video does have sound, but it looks like Imgur mutes by default.

http://imgur.com/YOvaEtk

 

[avenali312]

@Diggs24 Any thoughts? I know at one point we were discussing HPFP. No codes thrown in the last two times this happened in the past few days.

Also, recommendation on the dongle for SimosTools. I've got a birthday coming up haha.

 

[Diggs24]

https://www.sparkfun.com/products/17493

 

[avenali312]

Bumping this back up. I saw my trusted indie mechanic in January for some regular maintenance and he diagnosed it as the HPFP. We decided to let it ride until it got worse. Well, it has gotten much worse, so I have an appointment on Friday for a new T revision HPFP.

 

[OceanJack]

Bumping this back up. I saw my trusted indie mechanic in January for some regular maintenance and he diagnosed it as the HPFP. We decided to let it ride until it got worse. Well, it has gotten much worse, so I have an appointment on Friday for a new T revision HPFP.

I had your exact problem, replaced my hpfp and the issue has not come back. It only threw a rich code once, that was really random while just driving in traffic. Not when it was stumbling around 20 mph

 

[avenali312]

I had your exact problem, replaced my hpfp and the issue has not come back. It only threw a rich code once, that was really random while just driving in traffic. Not when it was stumbling around 20 mph

Yup, I've only ever gotten the one evap code in this whole thing making it super hard to track down.

 

[avenali312]

New T revision HPFP installed this morning. Now only time will tell ?

 

[Mk7noob85]

I've got a similar but different issue. No cold starting issues, however if I do a medium drive (45min+) then shut it down, wait 10-30min and try a hot restart I have an issue. Instant restart then after 10 seconds it will nearly stall out. if I'm in gear or moving it will fully stall. Long cranking restart after then its fine. No codes. The only other time it will show similar issues is a long drive then long idle it will stumble and act like it wants to stall every 2-3 min. I'm thinking maybe lpfp or hpfp or combination.
Lots of maintenance upcoming.

 

[avenali312]

I've got a similar but different issue. No cold starting issues, however if I do a medium drive (45min+) then shut it down, wait 10-30min and try a hot restart I have an issue. Instant restart then after 10 seconds it will nearly stall out. if I'm in gear or moving it will fully stall. Long cranking restart after then its fine. No codes. The only other time it will show similar issues is a long drive then long idle it will stumble and act like it wants to stall every 2-3 min. I'm thinking maybe lpfp or hpfp or combination.
Lots of maintenance upcoming.

Yeah, my issues were entirely hot starts. Get car up to temp, stop by the grocery store or something for 15 minutes, go back out and the car didn't want to start. Just crank and crank. The way my indie explained it (he may be simplifying it for me, so the terminology may not be exactly correct haha) was that there's some sort of check valve in the HPFP that wears out (specifically the early 2014-2015 early revisions) and that lets rail pressure bleed off when it's hot. The cranking is basically the car trying to build that rail pressure back up. Once my car would start, it would never have an issue while driving.

 

[Mk7noob85]

I guess that's why it's confusing to me, because it'll start just fine then stumbles after a few seconds. I wonder if my LPFP is doing what your HPFP was doing. I watched it happen on VCDS once and the fuel pressure on the high side did drop but it was parallel with the drop in engine RPM. Since it's driven off the cam that makes sense.

I'll have the car up on the lift for a bunch of other maintenance soon so I'll check what I can check then try to log the issue on my next long drive. If nothing solid shows up I'll likely just install new pumps.

 

[Parabola]

New T revision HPFP installed this morning. Now only time will tell ?

Did you replace cam follower also? How much was the pump?

 

[avenali312]

Did you replace cam follower also? How much was the pump?

I haven't replaced a cam follower in the 10 years since I sold my FSI MKV haha.

Pump was a little over $600.

 

[OceanJack]

I haven't replaced a cam follower in the 10 years since I sold my FSI MKV haha.

Pump was a little over $600.

I paid 288 plus 50 for a new cam follower from fcp