Hard starting when cold, for the 10,000th time!

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
If this was an issue, would it throw a code?
I'm following another thread that "could" be fuel temperature related but doesn't include any codes. Wonder if it could be subtle enough, like a marginal MAF, such that it doesn't produce crisp results and it doesn't trigger codes?
 

Technician!

Veteran Member
Joined
Apr 12, 2011
Location
Jackson, Michigan
TDI
None, currently
As this is my first winter with this vehicle...it is only getting worse as it get colder.
Never had this problem with my B4.
Since it is temp related, I am going back to the glow plug system to check more. I have voltage at the harness to glow plug connectors, and what seems to be the correct ohms readings per glow plugs 101. Crazy. This Am @ 35 F I had to crank 3 times at about 7 - 8 seconds each (plus pre-glow each time) to get it to start. And when it does....crazy gray diesel exhaust smelling smoke.
 

Technician!

Veteran Member
Joined
Apr 12, 2011
Location
Jackson, Michigan
TDI
None, currently
I actually believe my injectors are leaking down, and when it's cold this problem is worse than when it's warm outside.
I went out this AM (30 F out) and cracked all the lines at the injectors and got no drips at all. (8 hour cold soak, not cranked over yet.)
I think this also explains all the gray smoke when it finally starts.
Anyone got any intelligent, experienced thoughts on this?
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
I'm curious as to what happens after the engine is shutdown. Could it be that fuel is bleeding off via the fuel return lines? (or perhaps that's not possible, per design)
 

Rob Mayercik

Veteran Member
Joined
Dec 19, 2001
Location
NJ, U.S.A.
TDI
2002 Jetta GLS, Baltic Green/Beige
I don't believe a CEL is guaranteed if the MAF is failing but not failed. Hopefully someone with more MAF experience can chime in here?
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
MAFs have a LOT to do with a properly running TDI (unless one has one set up to not use one- that's a whole different story).

Unplugging the MAF is not a "trick." I think that nearly everyone in these forums knows to do this as a means of diagnosing possible MAF-induced problems.

I've had a MAF completely trash out, such that the ECU did NOT default. Don't recall whether there was a CEL or not (in my mind I didn't need an idiot light to tell me something was wrong). Engine was bucking like something was REALLY trashed: one could readily guess it was a failing IP or a bad CPS. With the car still running I (stopped on the road- country road), popped the hood and unplugged the MAF- INSTANTLY the car settled down (running on default "safe" map). Popped in a known "OK" (spare) MAF and done!

Just installed a new MAF in my car even though VCDS had shown it to be within spec. Instantly saw what looks like a 2mpg improvement along with a bump in power.
 
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