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Hard Start When Cold

Jerome81

Autocross Newbie
Location
USA
the problem is a leaky check valve between the hpfp and the lpfp. it doesn't maintain enough pressure over several hours of being parked. it's fine as is, the lpfp runs when you open the door for a reason. just takes a few extra revolutions to get good pressure at the injectors.

Interesting advice. Anyone else have this as well? Repaired?
 

whitemkv

Passed Driver's Ed
Location
Medford NY
Car(s)
2006 gti
check the battery, they shut down when its really cold. average life of a battery is around 4 years so yours is getting close. bring it to an auto parts store and have them do a load test.
 

kirkbar

Mod til I drop
Mine just started doing this too. Can happen right after I shut off - go for milk - and come back. Engine just about starts then sputters off. It's cold here 30F and wet. I have VAGCOM and no codes thrown.

I have an 09 with 25K miles.
 

GTIWV

WV VW
Location
WV
Hell, you should be in mine when I start it up. Of course it sits a lot now, but it starts rough. lol. i figure part due to sitting, weather the s3 injectors, k04, tune and other factors. But as long as it starts, i am fine with it.
 

Jerome81

Autocross Newbie
Location
USA
I'll resurrect this thread a bit.

I'm still curious if this leaky check valve is indeed the problem? Has anyone had success after having this replaced?

Is this something that I could replace myself? I have a feeling, as others have had too, that when I leave it at the dealer, the hard start will not happen. I'm tempted, if the part isn't too expensive and can be easily replaced at my house, that I may just try putting a new one in and see what happens.

I do know that when I open the driver door, I DO have that priming sound, so I know it isn't that problem.

Any other way to somehow test the lpfp with vagcom or have the dealer look, etc? Or is this one of those just-start-replacing-parts-and-hope-you-get-the-right-one kinda problem?

I just find it really really really really frustrating that this seems to be a pretty common problem on our cars, yet I just still cannot seem to get anything that indicates that XYZ is the problem part. Everyone still seems to be taking shots in the dark. It so odd. Most other problems this common have at least 1 or 2 known causes. This hard start is a ghost.
 

ecoterragaia

Ready to race!
Location
Richmond, VA
I'm not saying to go out and try this, but I added good dose of Chevron Techron Fuel System Cleaner to my tank and it greatly improved my slow/stuttering cold starts. HOWEVER, the reason I added it was because I was getting cold start misfires and was looking for a last-resort cure without replacing the injectors. The stuff did get rid of my misfire CEL's, but I don't know the long-term effects for the start condition or the misfires 'cause I sold the car 2months later.

Just thought I'd throw it out there. If you do try it, be sure to change the oil afterward, it turns pretty ugly and the cleaner reduces the effectiveness of the oil's additives.
 

Jerome81

Autocross Newbie
Location
USA
I'm not saying to go out and try this, but I added good dose of Chevron Techron Fuel System Cleaner to my tank and it greatly improved my slow/stuttering cold starts. HOWEVER, the reason I added it was because I was getting cold start misfires and was looking for a last-resort cure without replacing the injectors. The stuff did get rid of my misfire CEL's, but I don't know the long-term effects for the start condition or the misfires 'cause I sold the car 2months later.

Just thought I'd throw it out there. If you do try it, be sure to change the oil afterward, it turns pretty ugly and the cleaner reduces the effectiveness of the oil's additives.

I threw a bottle of Techron Concentrate in the tank yesterday. Not the Techron Injector Cleaner. Will see how it goes.

If no improvement, then I'll try a bottle of the Techron Injector Cleaner. If still nothing, then I'm gonna have to start going deeper....


SIDE QUESTION: Can leaking / leaky injector cause this cold start problem? Any way to test?
 

JoeyGTI

Touring Car Champion
Location
San Diego, Ca.
I have also used the Techron Concentrate Fuel System Cleaner and it works amazing !! Cured my cold rough starts. I will be using this every 5000 miles from now on !!
 

DeepBlue

Ready to race!
Location
NYC
Oh man... my car has been doing this for about 5 years!

No big deal. Checked and re-checked by everyone I could get to dig into this problem for me. Last thing I did was leave it with a highly reputable VW spec for 2 weeks. Could not find anything wrong with it. Car runs perfect otherwise.

After giving it a lot of thought, I decided that this is due to car sitting too much. Admittedly, I do not drive it nearly as often or for as long as I used to.

I now have a cold start procedure that is an effective workaround. It is as follows :

1. Get in car
2. Close door
3. Insert key / NOT turn
4. Tap gas pedal a few times (sometimes I tap brake too, sometimes I hold brake while starting)
5. Quickly turn key from off to start without any delay or stops in between

Car starts fine!
 

ROH ECHT

K04 PLAY
Location
PDX OR
Car(s)
2007 MKV GTI
The primed fuel pressure bleed off is what should be checked when it takes longer time cranking than it should to start.
 
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