Any Gunson CO Tester Volunteers out there?

[glenn]

re:Air/fuel ratio during start/warmup.   The Bosch/MB fuel management(FIP, WRD, CSV, TTS, relays, butterfly, idle air screw, idle fuel knob, etc....) cannot accurately control the air/fuel ratio to optimum.   Plot air flow versus fuel flow.  At start the air flow is idle air plus WRD air.  The WRD air is gradually reduced to zero as the coolant heats.   At start the fuel flow is massive-FIP max for a sec or two, CSV max.  After starting, the FIP is reduced to WRD influence, CSV squirts until TTS times out.  Seems air and fuel are out of sync........ The additional air from the WRD supports the additional fuel from the FIP and the CSV.   How is the correct ratio maintained during warmup???.......
All gurus are invited to explain....

[wwheeler]

I just started the engine tonight before I take the car down for a rear axle rebuild. Eventhough it stayed in the garage, I was able to get the temp up to 180F.

To lessen the lean period, I added a .008 oval shim for a total of .036" and it was just too much fuel when cold. In fact for the first time, it made my eyes water :'( So I took out .004 (.032 total) and the difference was amazing. Yes it was still a bit rich when totally cold, but ran pretty well when nearing 150F. More importantly, the lean period was almost insignificant. It was a tad lean but ran OK.

The other thing I did was to remove the WRD air filter and check the flow. When the engine entered the lean period (160F), there was still a slight air flow. I took a few minutes, but the temp rose to 170F and still a tiny bit of air flow. Finally after a total of 10 minutes, the temp rose to 180f and guess what; the air flow shut off. When that happened, the rpm rose by 100 and the idle smoothed out and the mixture was then correct.   

So I guess I am a believer that the fuel rod hits the stop first before the air valve completely shuts off. Because the fuel rod spring is heavier, it takes a while before the thermo plunger gets hot enough to overcome the spring and shut off the air flow. Like was said, if you drive the car and not let it sit, it will totally warm up faster.

     

[mrfatboy]

Because the fuel rod spring is heavier, it takes a while before the thermo plunger gets hot enough to overcome the spring and shut off the air flow.

I believe it is the opposite. The fuel rod spring is lighter or weaker than the thermostat spring. When the thermostat heats up it is exerting upon both springs. Since the fuel rod pin is weaker it compresses first. Once compressed 18mm (fuel rod at its stop) the thermo pin moves its final .5mm to close off the wrd aux air.

There is still room for the thermo pin spring to compress in case the car heats over 180 degrees.   Again, the fuel rod pin is already at is stop and is not affected.

[wwheeler]

I was calling the fuel rod spring the actual spring on the fuel rod. The other spring is in the FIP itself and is lighter than the spring on the fuel rod. So we are saying the same thing just a difference in nomeclature.