79 FI Westy won't idle

[justgimmecoffee]

Been driving this bus since April 2009. Went on a long trip to Klamath Falls last week and at some point it developed a problem. It won't idle steadily and dies frequently. Driving it is near impossible- it dies at stoplight and signs, so I have to do a rolling stop.
Today, I really went at it.. and failed.


The upper hose is actually two hoses with a connector in between.


The lower end connects down there. Disconnect to replace..


This is is the fixed version. The braided cloth hose replaced the two part kludge.



The big double clamps and brass fitting are still there. The Auto stores don't stock the large size and finding another fitting to go from that size to the EGR valve has been difficult. Despite its ugliness, I don't suspect it as part of the problem.



The new braided hose has a slight kink in it.. but doesn't appear to affect the function.


While tightening all the connections, I saw a crack in the S boot.



Upon removal, I found a lot of brown liquid in the bottom..



Fortunatly, I had another (thanks, Hal!)


Unfortunately, despite running oil around it and being verrrry gentle, I cracked the replacement. Glopped some permatex form a gasket on the interior and exterior of the new crack. Let it dry a bit, then tightened the clamp.



All connections checked and double checked. All the smaller vacuum hoses were replaced last summer and have been working fine; they're still new.
In desperation, I checked the Cold Temp Sensor II, up near #3 cylinder. Bentley says replace it if its signifantly different from 2500 ohms. Mine read 1475.. so I replaced it. New one tests at 2175.... closer, at least.
Engine was rebuilt by Trafton's and has maybe 3000 miles on her. Colin paid me a visit three weeks ago and when he left, she was running better than ever. Also, whether its the frequent restarting or what, she's getting terrible mileage.

It will start up, but struggles to idle. Its not really safe to drive as it dies all the time. I hear a sharp air sound, but I can't tell if that's just normal air going through the system or what. Here's a movie:

http://spot4m.com/images/sp/engine.mov

[bretski]

I know you said that you checked all the vacuum connections...but...just for me...check your AAR vacuum line, particularly the elbow.

[Ritter]

I dunno sh!t but would strongly suspect a vacuum leak. Checked your timing? (don't know how to do this if the engine won't stay on, but maybe you do!)

[vdubyah73]

vacuum leak(s). check everything. intake to head torque, as trollfromdownbelow just found. take a look at valve cover gaskets, if one leaks only when shut off and the gasket looks sucked in that is a vacuum leak.

[justgimmecoffee]

just for you, Bretski... i checked. All good. Pulled my hair out for a few more hours. Finally took it back to Trafton's for a little more hands on help.

Turn's out it was the AFM meter. The little wiper had rubbed off all the contact surface, which prevented the engine from idling properly.. thus causing the 'hunting' behavior.

all fixed and running like a charm again. Thanks, Bill!

-Barry

[bretski]

just for you, Bretski... i checked. All good.

:) Good to hear it. Last time I had symptoms like yours (dying at idle...ie at a traffic light), this is what I found:

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Pulled my hair out for a few more hours. Finally took it back to Trafton's for a little more hands on help.

Turn's out it was the AFM meter. The little wiper had rubbed off all the contact surface, which prevented the engine from idling properly.. thus causing the 'hunting' behavior.

all fixed and running like a charm again. Thanks, Bill!

-Barry

Hooray!

[hambone]

Most excellent. It's amazing those wiping surfaces last as long as they do. What happens when a finite supply of AFMs run out?
Hope to see you at Hambone!