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Very hard cold starts

DeepBlue

Ready to race!
Location
NYC
Started noticing this lately...

Car is a 2008 GTI (FSI) with 75k miles. Door is showing open on MFD but I don't hear the fuel pump priming. In all honestly, I am not sure if I ever did.

So far the only thing done was a gas filter replacement. My shop took a look and they tell me that its showing clean with no codes. Carbon cleaning was done 10k ago and I have been running on shell exclusively for a while.

Just trying to get a sense of what this is about before I let my shop do a deep dive and probably spend all sorts of money trying to fix whatever this is.
 

gti2slow

Go Kart Champion
Location
NH
The micro switch in the drivers door is known to go bad, mine failed int he same manner (door stuck open on MFD).

This will stop the LPFP from prime on initial start.

If this isn't an issue a worn LPFP might be the cause, if you have access to a vag-com you can log fuel pressure and get a good understanding of where any issue may lie.
 

larcic

Ready to race!
Location
Tampa, FL
I think turning the key to on with out turning the car on (electrical only) primes the fuel pump as well.
 

DeepBlue

Ready to race!
Location
NYC
To clarify, I meant to say that MFD accurately reflects the status of the door open/closed.

I usually wait about 5 beeps after turning key to on, and before turning the key start. Actually, I think i show that in the video.
 

larcic

Ready to race!
Location
Tampa, FL
must not be a priming issue then. could be old spark plugs? old coil packs? have you had your battery inspected?

edit: sorry just read carbon cleaning 10k ago
 

DeepBlue

Ready to race!
Location
NYC
must not be a priming issue then. could be carbon deposits? old spark plugs? old coil packs? have you had your battery inspected?

Thats whats puzzling...

Carbon cleaning was done less than 10k ago. Same for new set of red coil packs and plat plugs. Battery is about a year old and car starts just fine when not cold. Right before I swapped the battery last time I was seeing signs of power management which are missing now.

Its also up to date on all general maintenance. Babied, really. In fact, I just had timing belt done and swapped out the cam follower which was just beginning to show signs of finish wear after 10k.
 

larcic

Ready to race!
Location
Tampa, FL
that is puzzling. you should log your fuel pressures just like gti2slow said
 

GIACUser

Master Wallet Mechanic
Location
SoCal
Thats whats puzzling...

Carbon cleaning was done less than 10k ago. Same for new set of red coil packs and plat plugs. Battery is about a year old and car starts just fine when not cold. Right before I swapped the battery last time I was seeing signs of power management which are missing now.

Its also up to date on all general maintenance. Babied, really. In fact, I just had timing belt done and swapped out the cam follower which was just beginning to show signs of finish wear after 10k.

Colder weather can exacerbate an existing condition. My car has just under 75K miles and I had to replace the LPFP. Typical sign is that starts are taking longer but car turns over at normal speed (not a weakened battery).

If it were me I would pull all of your sparkplugs first and check gap (don't assume it was done right, best to check it yourself). Also confirm they put the right temp range in. I have found that a lot of folks are under the misconception that they come gapped from the factory. Something as simple as too wide a gap combined with with some decrease in ambient temps could easily be the problem.
 

GIACUser

Master Wallet Mechanic
Location
SoCal
Thats whats puzzling...

Carbon cleaning was done less than 10k ago. Same for new set of red coil packs and plat plugs. Battery is about a year old and car starts just fine when not cold. Right before I swapped the battery last time I was seeing signs of power management which are missing now.

Its also up to date on all general maintenance. Babied, really. In fact, I just had timing belt done and swapped out the cam follower which was just beginning to show signs of finish wear after 10k.

Colder weather can exacerbate an existing condition. My car has just under 75K miles and I had to replace the LPFP. Typical sign is that starts are taking longer but car turns over at normal speed (not a weakened battery). Check plugs, and fuel filters first of course.

If it were me I would pull all of your sparkplugs first and check gap (don't assume it was done right, best to check it yourself). Also confirm they put the right temp range in. I have found that a lot of folks are under the misconception that they come gapped from the factory. Something as simple as too wide a gap combined with with some decrease in ambient temps could easily be the problem.
 

DeepBlue

Ready to race!
Location
NYC
Colder weather can exacerbate an existing condition. My car has just under 75K miles and I had to replace the LPFP. Typical sign is that starts are taking longer but car turns over at normal speed (not a weakened battery). Check plugs, and fuel filters first of course.

If it were me I would pull all of your sparkplugs first and check gap (don't assume it was done right, best to check it yourself). Also confirm they put the right temp range in. I have found that a lot of folks are under the misconception that they come gapped from the factory. Something as simple as too wide a gap combined with with some decrease in ambient temps could easily be the problem.

Does the above still make sense if I say that everything has been running fine for about a year after plug/coil packs (and everything else mod wise) was done.

What would a good service interval for plugs on a heavily modified Mk5 running a K04? By the way, everything was professional done in one shot by a very reputable shop.
 

Qwoz

Roflcopter pilot
Location
Redmond WA
Car(s)
08 GTI
I am interested to hear what the culprit ends up being for you. I have been having the same issue with the hard starts when the engine is cold. I have new plugs, coil packs, and I just replaced the battery which helped but didn't solve it. Haven't had a carbon cleaning and im at 77k, so I was thinking it might be that. Since you have had the carbon clean and are still running into the issue I bet that it might be the LPFP. I now suspect this might be what is wrong with mine because I have been getting a check engine light for a while indicating that I have low fuel pressure. P9023 is the code I am getting, or something like that. I don't get fuel cuts at all, but I throw this code maybe 3 times a week. It will happen more often when stepping on it. I'm APR stage 2+ with a "HPFP Upgrade" pump.
 

DeepBlue

Ready to race!
Location
NYC
I am interested to hear what the culprit ends up being for you. I have been having the same issue with the hard starts when the engine is cold. I have new plugs, coil packs, and I just replaced the battery which helped but didn't solve it. Haven't had a carbon cleaning and im at 77k, so I was thinking it might be that. Since you have had the carbon clean and are still running into the issue I bet that it might be the LPFP. I now suspect this might be what is wrong with mine because I have been getting a check engine light for a while indicating that I have low fuel pressure. P9023 is the code I am getting, or something like that. I don't get fuel cuts at all, but I throw this code maybe 3 times a week. It will happen more often when stepping on it. I'm APR stage 2+ with a "HPFP Upgrade" pump.

No codes at all here. I have APR K04 with all supporting mods including HPFP.

I'm going to leave it overnight at same shop where I had all mods done. Hopefully they can narrow it down some. Really not looking forward to a protracted/expensive witch hunt. Then again, I don't need this thing to strand me someplace. Otherwise, car runs just fine. I haven't noticed any fuel cuts which is not saying much since I rarely go WOT.

I did notice that start gets particularly bad when it sits for more than two days. One day and the choke is half as bad as one in video.

Fuel pump doesn't look that bad. https://www.ecstuning.com/Volkswagen-Golf_V--2.0T/Engine/Fuel/Pump/In_Tank/ES2179061/

If thats what it is. If not, well... just more reasons to upgrade to Golf R sooner rather than later. Would have to do a feasibility study on whether or not it would be worth it to offload mods separately.

Getting a bit ahead of myself. One step at a time.
 

DeepBlue

Ready to race!
Location
NYC
UPDATE on root cause

RSW says that my in-tank fuel pump is on its way out. Seems like its been just hanging on for a while.

Will have them swap it out and see what that does.
 

Eric6014

Ready to race!
Location
Brooklyn, NY
Car(s)
2 Door 2008 GTI DSG
Mine does exactly the same thing. My plugs and coils only have a few thousand miles on them. I replaced the fuel filter and it helped for a while but it's back to rough starts again. Doesn't matter if it's hot or cold out. Always does it on the first start. In for updates to see if the in tank pump is the culprit.
 

larcic

Ready to race!
Location
Tampa, FL
when mine went out I was getting fuel cuts not cold start problems. but hopefully that fixes your problem. its an easy and relatively cheap replacement job
 
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