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12V at Warm Up Regulator

4K views 16 replies 8 participants last post by  nobby 
#1 ·
Does 12V power go to the WUR full time or is it controlled by the thermo switch / fuel pump relay and shuts off once operating temps are achieved.


Currently it starts cold at 1500 rpms and stays there.

Turn off the car and re-start 5 minutes later? Perfect 800 rpm idle.
 
#2 ·
Talked to Larry at CIS and he says power to the WUR is a full time thing.

He also says that I've got an "air" problem. Too much or something is hanging up.

Something??? Only the AAV would do that and it's new and it works.

I guess.
 
#4 ·
On a quick reference in the 110 manual, 07.3.2 11a-140/9, looks like the fuel pump relay supplies power to the warm-up compensator off pin 7 via a 0.75 black/green/white wire...

does that help???

RC
 
#7 · (Edited)
reading....

I've thought immediately to check 2 other things besides the WUR voltage supply

1. Thermovalve is operational (50ºC) and the little one-way valve.

Mercedes-Benz Model 116

http://handbook.w116.org/Engine/110/07_3-125.pdf

http://handbook.w116.org/Engine/110/07_3-500.pdf

Section 'D' in the 07_3-500 PDF. The other culprit *may* be the decel valve..
Wiring is section E
There should be 2 little valves on the firewall with vacuum ports. to test the decel valve you disconnect the top lines from the valves and plug the lines together while the engine is running. if the engine stalls then the decel valve should be working OK.
You can remove it and spray it with carb cleaner, then spray a bit of silicone lube in it to make sure it works OK. or mity-vac it to test..

http://handbook.w116.org/Engine/110/07_3-140.pdf
http://handbook.w116.org/Engine/110/07_3-150.pdf


just a thought..
 
#9 ·
Whats the cold control pressure and whats the warm control pressure? As someone stated, WUR is powered by fuel pump relay. Is your control plunger sticky? What about vacuum leaks? And pinching AAV hose like djenka said when cold is good way to knock that off suspect list.
 
#10 ·
WUR is only going to change the mixture. If the mixture is off the idle speed will most likely go down or possibly up by no more than 10%. Sounds like air is getting by somewhere.

Try eliminating external air sources by pinching off vac lines.

Power booster
Charcoal canister
Especially any vacuum lines controlled by relays or thermo switches.
 
#11 ·
Thanks for the suggestions, everyone. Obviously you can't possibly have been following my whole history on The PIG's issues so I'll just say....been there and done all that.


I changed the plug end on the WUR harness and idle dropped in 150 seconds (as per).

Then it stalled. I had it WAY leaned out to overcome the WUR.

I'll see tomorrow when it's back to cold....but for now....it seems like it is right.
 
#13 ·
9 years ago I did my first PIG tune up.

Plugs, wires, cap rotor, belts etc.

upon first start up it was coughing and belching black smoke. ran like shit.

Double checked all my work....everything was correct.

Still ran like shit.

Put the old cap and rotor on.

Still shit.

Old plugs.

Shit.

Wires.

Shit.


Turned out to be a bad WUR and the plug end disintagrated in my hand.

New WUR and plug end.....VROOM.


Skip ahead a bunch of years and I'm spinning my wheels with EVERYTHING new and / or tested serviceable and a wonky idle.

Turned out to be the WUR harness plug.

Again.

Ho Hum.
 
#15 ·
Silver lining?


Fuel and air delivery systems are all brand new....and ignition 75% done.....still have the original distributor.....but I have 2 spares to muck around with.

Good for another 25 years. Hopefully.:)
 
#17 ·
Not really. If it looks good and it has 12V...then why bother?

I replaced that plug end 7 years ago because it was rotten. It lives in a bad place on the M110...subject to more abuse than if it was on top of the engine.

7 years later it was rotten again and only working intermittently.
 
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