WRD and cold idle

[FresnoBob]

I've read all the posts regarding WRD tuning and operation.  My WRD is not increasing cold idle.  As Stickandrudderman notes, the air does flow into the WRD via the air filter and removing or inserting the filter doesn't change idle speed when cold and there is little or no air detected when the car is warm.   Jumping my enrichment solenoid stalls the engine as well as jumping the CSV. 

However, the car idles at 600-700 rpm when cold, and then idles at 800 rpm when warm. 

I have 3 oval shims: .5 mm, .145 mm and .1 mm totaling 0.745 mm.  Removing all the shims didn't change the WRD function. 

I placed my WRD thermostat in boiling water and the plunger extended several mm and then returned once I cooled it. 

I note my WRD doesn't look like the others pictured.  Without removing the press fit pin, I can't remove the insert and I have no idea how to adjust the rotating pin which limits the insert travel.  I also assume adjusting the screw (with lock nut) on top of the insert will affect WRD function, but I can't loosen the lock nut as the insert spins.   In my understanding, as the thermostat becomes hot, it pushes down on the insert and reduces WRD function.  Therefore, more oval shims and/or further inserting the insert adjusting screw should increase WRD function.  Is this correct?  I note as I back off the WRD thermostat tower screws the car increases idle and runs better.  How do I increase my cold idle?  Any suggestions are most welcome. 

I don't have a way to measure CO.  Does anyone know where can I buy a reasonably priced CO meter? 

Thanks!

[ja17]

The rotating pin is for test purposes only. Normally it is left in the down position so as not to limit the travel of the piston. The WRD increases cold idle by allowing additional air through from the small air filter on the WRD. In addition the WRD also enrichens the fuel mixture when the heat feeler is cold and contracted. Try doing the split linkage test when the engine is cold running. With the linkage split, increasing the air by opening the venture should increase the idle.

[mrfatboy]

My friend has one of these that we use on my car for A/F mixture.  You would also need the bracket.

Innovate Motorsports (3837) LM-2 (BASIC) Digital Air/Fuel Ratio Wideband Meter incl. Bosch LSU 4.9 https://www.amazon.com/dp/B001S7W836/ref=cm_sw_r_cp_api_i_aOD4Cb7EV12D4

Innovate Motorsports 3728 Exhaust Clamp Cast-Stainless https://www.amazon.com/dp/B000CO9MF8/ref=cm_sw_r_cp_api_i_eQD4CbFQEZ9K7

Search for best price.



My other friend has this type that we use also.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F162003793729


I would suggest making sure the hot running CO and idle are correct before messing with the cold start/warm up idle.

[FresnoBob]

Hi Joe,

Just to ensure I understand the split linkage test in this instance, if I increase, through the injection pump linkage, greater fuel while the WRD is letting in air as observed, the engine should increase in rpm.  This would seem to indicate the that fuel to air ratio is wrong in the WRD during cold operation.  How is this adjusted?  Shims inside the insert?  I have no idea how to remove the insert or adjust the black bolt and lock nut on top of the insert; they just spin. 

[ja17]

Before the engine is warm, start and let idle. Split the linkage. Open the venturi a little and see if the idle increases. Next let the venturi close and move the lever going to the IP. Let me know which action increases the cold idle.

[FresnoBob]

I'm in Chicago this week, but will try this on Friday and report back.  Just for my understanding, how do you increase the fuel / air ratio as I clearly have lots of air coming through the WRD air filter? 

[ja17]

The WRD air passage should(shut-off (or nearly close) after the engine reaches 180 F. Check this first.

[FresnoBob]

Hi Joe,
I have checked that the WRD shuts off when warm and I can't detect any air coming through the air inlet. 

[Benz Dr.]

Assuming that the sliding valve is free to move up or down I'd say it sounds like you're too lean. If you can't move your idle mixture knob in much farther you could try adding a very thin shim under your barometric compensator. A half turn out could make all of the difference.

[wwheeler]

 I have been reading this and I think I understand what you are wanting. It sounds like the air flows into the WRD air filter when cold and shuts off when hot. That would mean to me that the air slide valve is moving and that the thermostat is also functioning.

Is what you are wanting to change is only at idle when cold? It sounds like it runs fine when warm? If so, the oval shims under the housing will do that. Add shims to make more rich and less to lean. But first as Joe mentioned, you need to know if it is rich or lean now. Do the linkage test when cold and at idle. Once you know that, hopefully changing oval shims to get you where you want to be. If the shims have no effect, there is something else wrong. Changing shims of .005” to .008” thick in the right direction, should have a noticeable effect.

Good luck

[ja17]

Yes, the oval shims change mixture during warm-up. But if your mixture is not correct when warm, the Dan is giving you the solution which changes mixture with a cold and/or hot engine. Until we understand if your engine is running rich or lean, hot or cold, we cannot prescribe which one of these or both fixes are needed.

[Benz Dr.]

Yes, the oval shims change mixture during warm-up. But if your mixture is not correct when warm, the Dan is giving you the solution which changes mixture with a cold and/or hot engine. Until we understand if your engine is running rich or lean, hot or cold, we cannot prescribe which one of these or both fixes are needed.

I agree. Not rocket science but not something that's simple to fix either. Check all of your ignition system first before you get too far into this job. Ignition affects everything.

[jeffc280sl]

Don't want to complicate the rich and lean running condition discussions but I had a failed barometric compensator on my FIP.  The compensator varies fuel mixture as altitude is changed.  As Joe and Dan suggested there are many things to check and adjust. 

I would leave the barometric compensator for last.  I got pretty deep into this subject years ago and wrote about it here.  You can read about this device in the tech manual, fip, altitude compensator.

I also wrote about very fine and difficult tuning of the fuel injection pump. This is very challenging and probably beyond most owners patience.

Once everything else is near perfect one can take tuning to the next level.

[FresnoBob]

The split linkage test was exceptionally clear - I need more air.  Increasing throttle opening dramatically increased rpm, while adding more fuel didn't increase idle at all.  I obviously need to lean my cold start fuel mixture.  There is lots of air flowing through the WRD filter, so how do I change the mixture?  The car idles well when warm. 

On a separate, but related note, I received my A/F ratio meter today and can begin testing.  Any suggestions as to what I should test first?  Per Mrfatboy's suggestion, I purchased:
 https://www.amazon.com/dp/B001S7W836/ref=cm_sw_r_cp_api_i_aOD4Cb7EV12D4

[jeffc280sl]

Have you read this section of the tech manual?  Its a good start.

https://www.sl113.org/wiki/Fuel/Injection#Pump

The A/F ratio tester you purchased is very capable.  I used one to interface with the car and report measurements to my laptop.  There is a ratio test you can run at idle which is straight forward.  With your device you can measure A/F ratio at multiple rpms under load to see how your FIP compares the on road dyno tests established in the BBB.

[FresnoBob]

Thanks Jeff,

The A/F at warm idle hovers between 12.5 and 13.0.  Mrfatboy suggested a target of 12.5, but I haven't found that number on the forum.  Do you agree? 

[mrfatboy]

Bob,

My memory did not serve me well. But close   Take a look at this chart.

https://www.mgexp.com/article/co-afr.html

Here are the specs from the BBB

Idle       
750-800   RPM CO  3.5 - 4.5  =  AFR 12.80 - 13.20

Lower partial   
1500      RPM CO  1.5 - 3.0  =  AFR  13.40 - 13.95
3000+  RPM CO  0.2 - 1.5  =  AFR  13.95 - 14.50

Full load   
3000+  RPM CO  2.0 - 4.0  =  AFR  12.85 - 13.20

[FresnoBob]

Thanks Mrfatboy,

I am now hovering between 12.5 and 13.0 at warm idle, so I'm satisfied with that.  I need the proper clamp to test above idle as I don't want to damage the O2 sensor tip. 

I know I need to lean out my cold start mixture, but I'm waiting for Joe A to give me some advice regarding the thickness of my oval shims, which now total 0.745 mm. 

[mrfatboy]

I would think shim thickness will be different for every car.  Mine is. 3mm now. 

You will just have to experiment.  The problem is you have to wait for the car to cool for each test. 😀

[jeffc280sl]

I think your idle measurements are close to ideal.  Mrfatboy gives you most of the dyno test specs you want to meet if you go that far.  Its far easier and maybe cheaper given your labor rate to send your FIP out for calibration on a flow bench.  For those with unlimited time and frustration levels you can try and do a similar calibration test on the road.  The BBB gives us the specs to meet.   Like I said do everything else you can think of first.  Your LM-2 is capable of collecting and storing on road test data like rpm, MAP sensor data (need to install a sensor on the SL intake manifold, like a modern car) and A/F ratio.  Basically at specified RPM and load levels you should have desired A/F ratio.  To achieve the correct A/F ratio the FIP can be adjusted.  Please don't try this without giving the entire process serious consideration.  You have to be a little nuts to play with the FIP.  See my write up and pictures in the tech manual

[wwheeler]

Since your cold idle is rich and your warm idle is fine, you obviously don't want to mess with the mixture for all of the ranges. Just focus on the mixture at idle when cold. Removing oval shims could do the trick. But, .745 mm isn't a lot to work with. I have .711 mm now and my mixture is good. So you can remove those and hopefully that will be enough. Not sure what combination of shim thicknesses you have, but removing a .20 mm shim should produce a difference.   

Looking at your picture on the first post, it would appear that your thermostat has an adjustment on the tip? I know that exists, but I do not have one and not sure how to adjust it. If the shims are not enough and you have an adjustment on the thermostat tip, you can extend the tip and that will be the same as removing shims.

[ja17]

Yes start by removing an oval shim.  When the barometric unit fails, the mixture usually becomes much more lean.

[FresnoBob]

Thanks Joe - is the target then a split linkage test where increasing throttle or IP both increase rpm in a balanced way? 

[ja17]

Doing the "split linkage test" when the engine is warm and cold will give you a good overview of the fuel mixture. Opening the venturi with linkage split should increase idle 100 to 200 rpms. In this way the air adjustment screw on the intake will have some range of adjustment after the engine has warmed.

[FresnoBob]

I've tried every combination of shim, from no shims and adding the 0.1 mm or 0.145 mm and the 0.5 mm, but the car still won't idle when cold.  As the car runs so well when warm, I'm thinking I've missed something in my WRD function. 

As the car sputters along at cold idle, I tried increasing both the throttle and IP, and either one would stall the car.