Fuel/air ratio, CO & HC level problems


sandor feher

New member
85 Westy, went through on all checks from computer and everything reads out normal on the sensors according to the Bently's manual, but the car running very rich. Spark plugs and the exhaust is black, smokes at idle when reving it up, at cruise it surges and puffs black smoke and loose power, have very high fuel consumption.
Can find the right sensor that tells the engine to run so rich.
Any suggestion, please?
 

Capt. Mike

Moderator
Although the Vanagons were originally planned for a computer analysis plug (usually hanging on the alternator), it never came to pass so attempts to use a computer analysis will not give proper responses. [I'm surprised your dealer even still has that one!] You have to do the basic check-outs with a volt-ohmmeter.

Although the '85 was not Digifant and didn't have the classic Vanagon Syndrome caused by the air-flow meter wiring problem, the air-flow meter (intake air sensor) can still not work properly and cause your symptoms. First check it (24.28), then I'd say the next most likely are temp sensor II (24.32) and the complex and inter-related set of throttle switches (24.33-34).
 

sandor feher

New member
I did the check by removing the harness at the computer. All checks were within specifications. I have checked also the aux. air regulator and have the same experience with it as one of you previous post on an 84 Westy. The only check I did not done is the fuel pressure regulator and the injector test. Since all four plugs are fouled up I have ruled out the injectors. They would't fail all at once.
For the air temp & air flow sens. I have a spare substitute, and it did not change.
The idle sw. and the throttle enrich sw. is functioning OK.
I just would like to diagnose the problem to order the rigth part to fix the problem.
 

Capt. Mike

Moderator
Transferred from another post to consolidate similar topics.

Black Smoke from tailpipe all the time.

walsky, Junior Member, 05-16-2001 11:18 PM

I have an 1990 Vanagon, it blows black smoke from the tailpipe whether it is a cold start or fully warmed up,(fouls plugs, runs rough because it's so rich). It has the "fix all plug" on the vane air flow meter, and I have also done the checks for the plug,fuel pressure and regulator,ctsII, also it has new plugs,wires,cap,rotor,o2 sensor. This conditon just started out of the blue, no specific time or reason,would apreciate any insite into this problem.
 

Capt. Mike

Moderator
The fact that something has been replaced does not automatically preclude it was done right. If this is something that has started overnight, it's probably a sensor that has failed or something was disconnected such as a vacuum hose.

See the Vanagon Syndrome thread about the harness fix. They are not infallible, though if it was that, it would expect more indications than just running rich.

There is a thread posted elsewhere about trouble-shooting the FI system with a volt-ohmmeter. I'd start with a timing and ignition advance test first, then move on to a systematic check of the FI.
 

sandor feher

New member
I have had the same problem on 84 Vanogan. All four cylinders fouled up and running reach all the time.
I have changed the aux. air regulator (about $65), adjusted the idle speed screw and now running fine.
The aux. air regulator may be not working properly even if all test indicate OK which was in my case.
To easy acces the auxt air. regulator, use a ¼" drive only with a 10mm socket, remove the air filter and the airhorn and the rest is just a peace of cake.
 
Last edited by a moderator:

Vanawaggin

New member
how to enrich fuel mixture

Does the computer regulate the fuel mixture or is it adjustable on an a/c 2.0l FI Vanagon?
 

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