rough slow idle ? Testing Warm up regulator ?
 

On a 1983 SC starts right up but runs low idle and surges. Runs well with good power while driving. The WUR was changed by prior owner ? I took it off and blew are through it. Ohms test shows 10.5 ohms resistance ? Car was not used much in a few years. New spark plugs, fuel and air filters, distilled cap and rotor plus oil filter change. The fuel mixture screw plug was still intact. I drilled the plug but did not turn the screw.
Any ideas. Thanks .

Find the part number on he WUR and post it.

You should have an -090 regulator. They are just over 25 ohms.

Unscrew that dime sized screw head on the drivers side of the intake unit when the car is warm. That should give you a touch of relief on the low idle by bringing a little more air into the ntake mixture. All you are doing is adding or reducing air depending on which way you turn. NOTHING to do with fuel.

Do not touch the 3mm screw yet. Thank your lucky stars you have a un-pimped CO screw.

Read "Mike in FL" post regarding his WUR..........
 

Keyla,

Your WUR-090 is out of spec. Not until you install a good working WUR, the erratic cold idle problem will always be there. Check and read "Mike in FL" post about the same problem you are having now. The culprit was easily identified and confirmed.

I could lend you a newly rebuilt and calibrated WUR-090 for you to use and test in your car. You are not obligated to buy it. It is just a loaner for you to experience how a good working WUR feels like. PM me if you are interested in the loaner.

Tony

Thank you very much Bob,
If you are referring to the large idle screw. I did adjust that and had to turn it in as the idle rose quite a bit when warm. The regulator I have is marked 916 ? The car is very stock. I hope to have a picture to show soon.

Tony are you referring to the resistance reading I am getting ? Thank you for your kind offer of a test unit.

Identifying your WUR.........
 

Keyla,

916 is not the WUR identification number. This is the cast number for WUR made in France. The other cast number is 086 or 980 depending how your read it are made in Germany. 916 reads the same 916 inverted.

If you look closely at "France" characters on top, next to it is the Bosch logo followed by 0 438 140 xxx. The last 3 digits which are stamped on the body is the WUR ID number. And you should have 090 if you have the correct WUR.

Tony

Number should start with 0438 140 XXX Look patiently for it. Maybe a little mirror? (Edit: Overlap with Tony's post)

I would set acceptable idle right now at warm temps just for driving pleasure. Just struggle though the warmup in exchange for normal op when warm.

Keep us informed as it's your surest route to proper closure.

Yes it is 090. Thank you. cast and stamped by the vacuum tube.

Then your WUR is "broken"

26 - 26.5 ohms is where it should be as to resistance through the coil wrapping the bi-metallic arm. The arm dictates control pressure. Less resistance = less bending of the bi-metallic arm arm via the electronic warm up process = rich mixture.

Talk with Tony. You could have this dialed in by the end of next week.