Interesting Cold running, not starting, running IDI

[Smokey Eddy]

Lately it's been a little colder than usual and i let the glow plugs warm up really nice (like 10 seconds min.) and the AAZ starts just fantastically with a new starter. But when I give it some pedal it's like the timing gets messed up (or something) and runs on possibly 3 or even 2 cylinders and sometimes dies and becomes very difficult to start again. Burns very white/blue BUT here is the kicker...
If i never touch the pedal and just let it idle, it idles just fine, and wait for the oil to get to at least 100F it will drive normally...
What is going on here?
something to do with the pump? timing? im really lost with this one.
The injection pump is not loose.

[maxfax]

IS it something it does only after the engine is cooled down several hours, or does it take longer (say like overnight) for it to happen..  That kinda puts me in mind of some sort of air in the fuel or fuel priming issue..  Say after it sits it get an air bubble in there..  When left idle it works out and all is fine, but when you rev it the bubble gets sucked though to the injectors, or something like that..   I'd think something like that would show up under other driving situations though...   

[Settings]

Reminds me of the veg-oil forums...as the temperature drops the viscosity drops magnifying any restriction in the fuel system. You might get enough fuel to idle, but can't meet the increased demands of acceleration. Letting it come up to temperature lowers the viscosity allowing it to flow freely. I assume you're not using veg-oil 

Have you checked for any restriction between the tank and the IP? If you starved the IP you would first lose power, then stall if you kept it up. Depending on the restriction you might have to crank quite a bit to prime the system before it would start again. Perhaps MityVac your way back from the pump to check from restrictions.

But, as Max points out, it seems that would occur under any conditions. That it works fine once the engine is to temperature lends itself to a problem on the other side of the pump. I'm not as versed in injector behavior and its relationship to temperature. I can only think of injectors clogged with something that breaks down at higher temperatures.

[Toby]

It sound like air in the fuel system. Try looking at the clear line for air bubbles before you light it off in the morning.

It might be that the compression is down in one or 2 holes and these need to be good and warm to fire when the temps are lower. It could also be a hazy injector or 2 as well. Try this next time: After it starts hit your glow plug button and then see if it will rev up then. If it does you know its not air in the fuel. BTW: Why would anybody do away with the glow plug timer except to get you back home to fix it? This strikes me like converting automatic chokes to manual or bypassing the radiator fan switch.

[Smokey Eddy]

I'll check for air. That's what im thinking also.

Toby, i still have the stock glow plug system, i can just force them to stay on longer if i choose with a switch.

[R.O.R-2.0]

I'll check for air. That's what im thinking also.

Toby, i still have the stock glow plug system, i can just force them to stay on longer if i choose with a switch.

just cycle the key off and back on, it will keep your glow plugs lit.. if you dont feel like a complete dual glow, just hit the key a few seconds into the second glow cycle and then it will kill the plugs (power to the plugs)

[Smokey Eddy]

i like switches! it's not going away!
plus i was  really referring to keeping them on once the engine has started

[R.O.R-2.0]

why would you want to burn your plugs after its running? the second it fires up, its building more heat in the combustion chambers than those little plugs could ever produce..

if you gotta glow it again once you get it running, just to smooth it out, then you got low compression or something..

[Toby]

That is not exactly true. The Ranger diesels and the GM diesels (and probably others) keep the glow plugs cycling after start for a short time. It is claimed to aid in warm up and reduce start up smoke. In a VW a rough start up just means that something is not up to snuff. That could be IP, glow plugs, injectors, or compression.

[R.O.R-2.0]

mind i say "LOW COMPRESSION OR SOMETHING"

i kinda have the feeling that you know everything and are not afraid to tell people about how much you know, and that you are NEVER EVER wrong?

thats kinda what i thought..

you have good things to say, but you go about it wrong. it seels like its either your way, or no way. andrew is one of the smartest users on the forum, and you argue with him.. good job!

maybe if you came across as a little LESS RUDE?

this is sad, that I OF ALL PEOPLE, are pointing this out. cause i almost got booted for being a dick to everyone..

that is all..

continue nit-picking, class dismissed 

[Toby]

If you reread my post you will see that the "not exactly true" part was referring to the glow plug issue posted by ROR2.0, not to your post about "compression being low, or something".

[Vincent Waldon]

Just as a data point... AAZ glow plugs in the A3 and B3 chassis run for several minutes *after* the car starts...for drivability and emissions.

TDI plugs in the AHU/1Z and ALH engines do the same... even in the summer when they didn't come on initially to start the engine.    Catches folks by surprise when they get a glowplug Check Engine Light in the middle of the summer.  

[Smokey Eddy]

I love you Vince. No homo.

[maxfax]

Ed, you make anything out with this issue?   I'm kinda curious as to what you find...

[Smokey Eddy]

Nadda... im kind of stumped.
No air in the line from the filter...
I plugged my block heater in for over an hour and when i started it then i was able to just leave. definitely effected by temperature...