TheSamba.com :: View topic - cold start problem on 79 fuel injectd super beetle

Tue Sep 07, 2010 1:05 pm

Hi guys, I am having a cold start issue on 79 EFI super beetle convertible. The car idles very rough and will cut off at times when first started cold. After the car warms up the idle is rock solid.

Does this EFI have a cold start valve or injector that could be faulty? What about a possible engine temp sensor?

Any advise or info is greatly appreciated.

Tue Sep 07, 2010 1:59 pm

Suggestion....

You can download this troubleshooting guide for free...

http://manuals.type4.org/ljet/

Although I am loathe to replacing any FI part until it tests bad, make sure you have one of these new in your tool box at all times.....

http://www.busdepot.com/details.jsp?partnumber=0280130012

Also you may want to have a look at the AAR to see if the little door is opening and closing correctly.....

http://www.itinerant-air-cooled.com/viewtopic.php?t=6867

Tue Sep 07, 2010 2:14 pm

Thanks I will check those out.

Tue Sep 07, 2010 2:47 pm

Take a look at this diagram:

Basically, the cold start valve gets its power from terminal 50. In other words, when the starter is operated, the cold start valve receives +12V. It is grounded through the thermo-time switch. Contact with ground is made when the engine is cold or when the starter has been operated less than 15-20 seconds. These things can be tested with a VOM, or even a test light.
You can also remove the cold start valve from the plenum; leaving the electrical and fuel connections intact and observe the spray pattern (into some kind of container) while someone operates the starter.
The Bentley manual has a very good chapter on the fuel injection system.
The temp sensor noted above will vary its resistance with temperature. Before you replace it, make sure the connector is clean and tight; as a bad or intermittent contact will "corrupt" the signal sent to the brain.
Good luck, Mondshine

Tue Sep 07, 2010 8:48 pm

Check the wiring connection at the cold start valve. Sometimes the tab which keeps brass wire spade captive inside the plastic connector folds back. This will cause the wire feed to back out of the connector when it's pressed into the cold start valve. I had this happen on my 79'.

Wed Sep 08, 2010 5:22 am

Thanks for the help guys. This is some good info on where to start.

Wed Sep 08, 2010 10:52 am

If the car is very hard to start but eventually does the 1st thing I'd check if it is in good tune is the temp sensor screwed into the left cylinder head.

Wed Sep 08, 2010 3:07 pm

My 77 does the exact same thing.
On cold starts, it will fire right up, but the idle is very low and rough.
Once warmed up it's smooth and steady.

On Hot or warm restarts, does the exact same thing. Very low poor idle.
Once driven a touch, idle is smooth and steady again.

Wed Sep 08, 2010 4:09 pm

cfvwtuner wrote: My 77 does the exact same thing.
On cold starts, it will fire right up, but the idle is very low and rough.
Once warmed up it's smooth and steady.

On Hot or warm restarts, does the exact same thing. Very low poor idle.
Once driven a touch, idle is smooth and steady again.

That says "I need to have a look at the AAR valve".