WRD woes continue

[FresnoBob]

Now that I've improved my fuel flow, I've returned to my WRD in an attempt to increase my cold idle. 

I checked the lever inside the IP, which is actuated by the WRD.  It moves freely, and surprisingly has travel of at least 15 mm. 

I now have the original 0.745 mm of oval shims below the WRD.  It frankly doesn't seem to matter how many shims I have, the car just doesn't run when cold. 

When cold starting the car, the air / fuel ratio is 30, far too lean and I have to manually apply pressure to the accelerator pedal to keep the car running. 

I've confirmed air flows through the WRD air filter unimpeded and also shuts off when the car is fully warm.  I'm still not comfortable with the bolt and lock nut on top of the WRD insert.  I see no way to unlock and adjust this bolt unless I take the roll pin out of the WRD and remove the insert.  When I attach the WRD to the IP, I can feel the compression of the lever inside the IP.  It feels like I have several mm of compression, and I've been advised by Benz Dr. that my WRD version should only have 1.1 mm of travel. 

All suggestions welcomed!

[mrfatboy]

If I remember correctly your car runs well at operating temp and CO is within spec (750-800   RPM CO  3.5 - 4.5  =  AFR 12.80 - 13.20)

Correct?

[FresnoBob]

That is correct.  Between 12.5 to 13 A/F ratio when warm. 

[mrfatboy]

And when you do split linkage test and just add fuel the rpms shoot up to 2000 as I remember. Correct?

[FresnoBob]

My observations so far:

At the first start, the split linkage rpms increase with additional air and the A/F ratio hovers around 14.  I know I measured 30 A/F yesterday at cold idle, but today the car is behaving differently. 

After a few less cold starts, the car barely runs and no addition of air or fuel seems to keep it running.  I have to increase both fuel and air to keep it from stalling. 

Once the car is warmer, it won't idle at all until it reaches 80ºC, at which point it idles smoothly. 

Strangest darn thing...

[mrfatboy]

I think your Gas analyzer has a warning about testing when engine is cold. You are not supposed use test on cold engine. You can foul up the sensor tip and you will have to buy a new one.  It happened to my friend.

Check the manual to verify.  This might be why you are getting sporactic readings when cold.

[wwheeler]

At the first start, the split linkage rpms increase with additional air and the A/F ratio hovers around 14.  I know I measured 30 A/F yesterday at cold idle, but today the car is behaving differently. 

After a few less cold starts, the car barely runs and no addition of air or fuel seems to keep it running.  I have to increase both fuel and air to keep it from stalling. 

Once the car is warmer, it won't idle at all until it reaches 80ºC, at which point it idles smoothly. 

The first part sounds perfectly normal to me. These engines run rich for the first while and adding air should cause a RPM increase.

I guess I don't understand what "a few less colds starts mean". But I can tell you what happens to my engine from a cold start. It starts great (I have a CSV cabin button BTW) and runs well until the thermostat opens for the first time @180F. That is when you can see you gauge rise up and then fall just a bit. From that point, my engine runs lean and at lower RPMs until it completely warms up and maybe five more minutes. Why? I couldn't tell you, but trust me, I have tried everything I know and have settled on great cold running, lean warm running and great hot running.

I am not surprised that these WRDs are not perfect from cold to hot, but yours sounds odd for sure. What about getting a used WRD and seeing if that makes a difference? Maybe someone has "tweaked" the one on your car. You would need the housing, air valve, plunger and the aluminum base below that for a good test. Not sure what else to suggest.

[FresnoBob]

Thanks Wallace, that is a great suggestion.  I'll contact Bud's to see if they have a spare around.  Any other places you suggest I contact? 

[wwheeler]

Possibly EBay? You have a few scrap yards in your area. Problem is most want to sell the whole pump, not just one part off of it.

Another better suggestion would be Pacific Fuel and Fairchild injection. Both of which rebuild the pumps and both are in CA. They should have parts laying around.