Hi all,

I have a Carter YFA 1bbl carb Ther is a device attached to it I think it is called a feedback solenoid or a mixture control solenoid either way what do I have and what does it
do??

My problem is I failed emissions from to much CO 55 limit
63 actual passed all other tests. If I am right this would indicate a rich mixture so I went to lean out the mixture
went out 1 whole turn (i understand with this carb out is lean in is rich) went and restested and got almost identical results.hence my question above as i think that part may be my problem my chiltons does not describe my carb enough
to be of any help anything you could suggest would be helpful

Thanks JEFF
Oh 1984 Ranger 2.3 liter carter yfa carb 1bbl feedback or not I do not Know

 

The mixture control solenoid allows the computer to control the mixture. Even ignoring the computers actions, the mixture screw you adjusted only affects idle mixture. With the computer ("MCU" in your case) in the loop, you don't get to adjust the mixture.

Check your plugs, plug wires, dizzy cap and rotor, O2 sensor, and cat.

 

Hmmmmm, here's a little work around to consider. My neighbor (who's a mechanic) informs me that when he's working on a car that failed emissions for CO (like yours, not WAY over) he runs the gas down to about 5 gallons and adds naptha to the tank (either a pint or a quart, I can't recall). The naptha warms up the catalyst more than normal and therefore reduces CO. After you leave the emission test, promptly go fill the tank to dillute the remaining fuel.

Myself, I'd inspect the suggested items along with the timing, air filter and evap emission system (including the seal on the gas cap and make sure it's on tight). Save the naptha trick but be aware of it too

 

I failed to mention I used the denatured alchol trick on the second pass 1 gallon to six of fuel no help what i guess i an looking for is what else could be the culprit??
i have new plugs wires cat is fine(tested with a non contact thermometer) evap passed, new air filter, new pcv valve,checked timing the truck runs great other than the co
i need help dont want to pay an emissions shop to {diagnose}

thanks

 

Denatured alcohol is not the same chemical as naptha. In fact, I believe alcohol burns cooler and could aggravate the condition. Naptha on the other hand will heat up the converter more, therefore enabling it to burn off remaining hydrocarbons in the exhaust.

 

That thing on the carb is commonly called a dithering valve. It constantly switches back in forth between rich and lean depending on the computer input. Failure mode of the dithering valve is if they fail in the rich mode, you fail emissions, but the engine runs good. Failure mode in the lean mode is that it passes emissions and runs weak with more spark knock then normal. Years ago, mine failed in the rich mode, so for every emissions test I would replace it with a spare good valve until the test was over then switch it back. I sold the 84 and gave the new owner the spare dithering valve. Sorry.

 

Careful with that naptha. That stuff is extremely volatile. Not to mention it stinks, bad.
CRC makes a product called "Guaranteed To Pass." It usually works for emission tests.

 

Yuppers, naptha is very volatile stuff. I talked to my neighbor today and you want to use 1 quart in ~ 5 gallons of gas. I also like what ranger pat had to say; I have a TransAm that uses one of those valves and you can hear it working before you fire the engine up and when it's idling and you have the top of the carb exposed. It's a very noticible ticking sound. I'm not sure if the Ranger makes the some noise but maybe someone else in here knows. I'm always a fan of fixing things before using a band aid to cover em up anyway.

 

First off thank you all for your replys


I am with cowboy billy on this one I would rather repair
the problem than bandaid it. Is there any way to test the operation of this valve??

 

If it is like the control solenoids they use on the 2 bbl carbs, you can remove it from the carb and test it with a 12 volt source. No power applied, it should be in one position. With power, it should snap to the other position. You can also test it with an ohm meter - it should be somewhat low resistance.

 

ok Update:

I tested the solenoid by it self it operates
then I monitered the power supply to the solenoid
and started the engine and let it run {14 volts} even after the choke dropped to normal idle.

My booksays
the initalization mode occcurs when the mcu system is activated by turning on the ignition on and persists for a brief moment after the engine is started during this mode the a/f ratio is maintained at a rich condition for easy starting
In the open loop mode the a/f ratio output signals from the mcu module are held at a fixed level adjusting fuel to assure good response and performance
In the closed loop mode the mcu system leans out the a/f ratio so that suffecient air is present in the mixture for nearly complete combustion of the fuels hydrogen and carbon

When the engine is running at its normal op/temp and under light load part throttle conditions the mcu system is in the closed loop mode when thee engine is acclerated to wot, decelerated or standing at idle the mcu system switches to open loop mode

In addition to the three operating modes the mcu has the built in capability for testing itself for any mode malfuntion.

Q#1in order for the solenoid to switch modes the power should pulse either on or off to switch? ie 14v no v

Q#2could the mcu know its rich and trying to compensate
ie 14v all the time?

Q#3 I have an after market ignition {mcu} 1 in the same if it can test itself how can I get the results I have no cel
no hook up for eec obd obd1 or obd11 no way to pull any
codes that i know of

Q#4would I have to load the engine to get the solenoid to switch modes

Q#5 Am I just missing something stupid

sorry for the long post but I am startin to go bald from pulling out my hair j/k but my finger hurts from typing this thanks all jeff

 

With the 2bbl carb, the solenoid always has battery voltage at one terminal. The computer selectively grounds the other terminal. Not grounded, the carb runs rich. Grounded, it is lean. (Your application might be the opposite.)

Note, the solenoid doesn't "switch" modes. Instead, the computer alters the duty cycle of grounding the solenoid. The computer is probably cycling between grounded and not about 10 times a second. You won't be able to see this on a voltmeter!

If you have a test light, you could put it in the circuit in place of the solenoid. The brightness of the light should change at different conditions.