Continuous popping while idling - lean ? rich ?

[prebordao]

I'm having trouble adjusting the mix / pressures:

Latest symptom: while idling and stopped there's a continuous popping from the exhaust... Indicates rich or lean condition ?

Car was not fully warmed yet.

[kodioneill]

Year/model/miles?

[prebordao]

1974/S/many

[Bob Kontak]

Is it a popping or "puffing" backfire? I had puffing which was like a mini backfire but not noisy when I had an air leak at the base of one of my intake runners. Happened all the time.

[prebordao]

It's really a pop-pop-pop similar to the small backfires you can have when your decel valve is not connected and you lift suddenly. But here it was continuous.

[Bob Kontak]

Before I start rambling, did this symptom start after you made some adjustments to pressure and mixture?

[prebordao]

Yes, after.

But now I know its rich. The wur heating element isnt working so it takes a lot of time to reach oper temperature, so mix remains too rich too long.

Back to the gauges again.

[Bob Kontak]

Try a hair dryer on it to warm it up quicker. just a thought.

[docrodg]

Double check timing too. A retarded timing can cause a small amount of the pop as well but be hard to detect at high rpm. Reason is fuel burn not complete when exhaust opens giving a pop or huff.

[prebordao]

I have the grandaddy of WURs - the 001
I just opened it and it's a bit different inside from the newer ones.
Later I'll post pics and a probable explanation.

This one has an additional resistance inside that seems to cut power to the element when it heats...

From a german Bosch document I get this description:

einsteckbarer elektrischer Anschluss aus kunststoff mit Zusatzwiderstand 3 ohm

Google translates it as:

insertable plastic electrical connector with additional resistance 3 ohm


Any better translation out there ?
Luckily, the heating element tests ok with the multimeter.

[rpc356]

Can you post photos of the -001 wur internals and describe how you disassembled (and presumably will reassemble) it? My -001 works, but the warm control pressure is a bit low. Have thought about opening it up to see if a general cleaning might help. And maybe there's some way to make modest adjustments to the WCP.

[prebordao]

I just opened a new thread for the disassembly.
They're fully adjustable for warm and cold.

Warm - screw on bottom
Cold - pin