76 fuel injection super beetle problem

[convertible john]

I have a 76 super beetle with EFI, and I can't seem to keep it idling. It will start high idle for about 2 minutes, then it just dies. Ran good about 2 months ago, then just started having issues. All help appreciated!!!

[Marc]

First thing to rule out is an induction leak - the symptoms you report are consistent with that problem. Any air that can sneak into the intake tract downstream of the airflow sensor will lean the mixture (high, thready idle typical) as well as not help hold the flap in the airflow sensor open far enough to keep the fuel pump relay closed...if it closes too far, the pump shuts off.
Look for vent hoses that have come loose and cracks in the convolutions of the intake air elbow between the airflow sensor and the throttle body. The latter can usually be patched temporarily with RTV while you locate a new part.

[convertible john]

Thank You, I will double check all those. I'll let you know. Thanks again

[convertible john]

Checked all the lines and can't seem to find any air leaking into the intake track. Went as far as replacing all vacumn lines in the engine compartment.

[ainokea]

This is probably not your problem but, check the connector at the air box and the pins for anyhing bent or broken. There must be solid contact at all points in that connection. As suggested already, check all hoses and connections that may be allowing unregulated air to enter the system.

Ainokea

[Marc]

...check the connector at the air box and the pins for anyhing bent or broken...

Yes, as well as the ground connections (every place a white FI-harness wire attaches to the engine) and the head temp sensor inline connection. If the resistance is too high, the computer will see it as a stone-cold engine and richen the mixture 'way out; as the engine warms up it's too rich to run, much like a carb'ed engine with the choke stuck shut but the L-Jet gets some extra air for a while via the Aux Air Valve. I've seen corrosion between the head temp sensor and the head cause enough extra resistance to richen the mixture (merely removing/cleaning/reinstalling takes care of it).
It'd be enlightening to see what the emissions figures are. Even a basic 2-gas (CO and HC) should tell the story. Does it run long enough to drive to a shop or is it stranded at home?

[convertible john]

Basically stranded at home. I can use an idle set screw and get the idle wound way higher than it should be, but at soon as it gets turned down, it dies. I'll start checking all electrical connections. Thanks again!

[Marc]

Not saying this'll be of any use right now, but file it away in your memory. Most OEM airflow meters have a popoff valve in the flap that's intended to prevent damage if the engine "sneezes" through the intake. Unfortunately these are made of some kind of pot-metal and the stem of the valve often breaks off, leaving you with a gaping hole in the flap that causes the same symptoms as an induction leak. The most common cause of a sneeze is lean running, so the typical scenario goes like this: the crankcase vent hose backs out of the intake air elbow, or some other small intake leak (or even an almost-empty fuel tank) causes a lean condition and the engine sneezes. The flap in the airflow meter slaps shut and the popoff valve breaks and falls out. Now, even if the original vacuum leak is located and corrected, or gas is added, the hole in the flap keeps it from opening far enough to energize the fuel pump relay and you're dead on the side of the road (or worse, in the middle of an intersection). To get the car running again, at least well enough to move to a safe spot or the next offramp, remove the aircleaner. Look in to verify the problem, then try to locate the disk and stem of the valve and its spring - don't want these bits being drawn into the engine. Find a long, slender object (a coat hanger, a stick, a Slurpee straw); push the flap open a little and stuff the stick in far enough that it keeps the flap from shutting (so the fuel pump will stay running after you stop cranking), wedge it so it can't fall out - tie it in place with a shoelace if nothing else works - and go start the car . The mixture's going to be all wrong but you should be able to find a throttle position that'll make it run well enough to limp away.
No need to replace the AFM just yet if it's working otherwise, simply epoxy/JBweld the valve back into the flap and make sure that whatever caused the initial sneeze is corrected.