passing smog......

[YeLLowBoaT]

I just want to make sure I am going to right direction with this.....
84 ford bronco XLT 351W(5.8l) 2 bbl carb is running way rich( very high COx #s and you can smell it too.) if this was a normal carb I could fix it in about 2 secs... but this vehicle has a 02 sensor on it that can actaully control the metering of fuel.
It has a about 115k miles and runs really really nice( should have known that it would not pass smog... always have to make them run like shit to pass)
I am unformilar with a computer controling fuel mix with a carb. Now I know normally on a EFI car when its runing rich its a 02 sensor. So my Q is... Is swaping out the 02 sensor a good place to start??? or should I look some where else?( all of the vacum lines are in good condtion and in the right spot.)
I must say the #s made me proud.... almost 2 x the "Gross Polluter" level for COx, every thing esle was fine. :crossx:

[Big Kahunaa]

didn't the smog guy tell you the o2 sensor is bad i would replace that and mabey go up one heat range on your plugs

[YeLLowBoaT]

He said It might be bad... Reason why I am asking is its a PITA to get too... have to remove the head pipe and some other shit to get to it. I just want to make sure I am going in the right direction b4 I go blow $100 and 3 hrs of my time( changing plus smog test)

[buzzaro]

sometimes just running premium fuel w/ octane boost clears the emissions right up. At least long enough for the smog test.

[YeLLowBoaT]

Not when your almost twice the gross polluter level.....

[FOUNTAINATLAST]

Most of those older Fords have an air pump system which I'm sure you have. The Pump systems are very critical to those old Fords to get them to pass. Check and make your the pump is working and your divertor valve is working properly, thats were I would look first. Follow the vacuum routing making sure its correct and those solenoids for the system are working, mixed up lines will send air to the wrong places during operation making the system not function like it should.

[76ANTHONY]

if you want i can ask my smog tech tomorrow about how to do it. he is top notch and very cool. i might need to see your failure papers though. pm me if you need his help...

[YeLLowBoaT]

Heres the #s
15mph / 25mph
rpm 1493 / 1453
CO2 13.5 / 13.6
O2 0.0 / 0.0
HC 99 / 93
CO 2.70 / 2.59
NO 460 / 412
That and my gas cap failed the test... big whoop.

[Kachina26]

Don't go changing parts willy nilly. That's not to say that after a period of running too rich that your O2 isn't fouled, but, many things can cause a vehicle to run rich. If you cannot diagnose the computer controlled carb system, you might be money ahead to pay someone who can. And I don't mean Pep Boys! I've seen too many people come into my shop after spending literally hundreds on unneeded repairs only to find out they need a $40 purge valve and $120 worth of diag and repair. My .02

[76ANTHONY]

Don't go changing parts willy nilly. That's not to say that after a period of running too rich that your O2 isn't fouled, but, many things can cause a vehicle to run rich. If you cannot diagnose the computer controlled carb system, you might be money ahead to pay someone who can. And I don't mean Pep Boys! I've seen too many people come into my shop after spending literally hundreds on unneeded repairs only to find out they need a $40 purge valve and $120 worth of diag and repair. My .02
i have to agree with this, i see it everyday. people diag theyre own shiat and have no idea and no tech to do so. on comp controlled vehicles you gotta get it to a pro. pay the 90 bucks and it diagnosed corrcetly. its worth it in the end..

[76ANTHONY]

Heres the #s
15mph / 25mph
rpm 1493 / 1453
CO2 13.5 / 13.6
O2 0.0 / 0.0
HC 99 / 93
CO 2.70 / 2.59
NO 460 / 412
That and my gas cap failed the test... big whoop.
i'll ask if there are any parts that fail alot on your vehicle and i'll give him your numbers...

[Maxey]

It has been awhile since I worked on a Bronco of that vintage, but if it has a
variable venturi carb, the diaphram (at the rear of the carb) that controls the
venturi size and metering rod position is probably deffective. Another problem with them was the enrichment rod "hanging up".
If your engine has the more conventional 2v 2150 feedback carb, it may have problems with the air mix solenoid. As someone said earlier, the proper operation of the air injection system is critical. If it is continuing to pass air (O2) passed the O2 sensor, the sensor will "tell" the ECA that the engine is lean, and will send a "rich" command to the carb air solenoid.
Try to find a tech in your area that has experience with the Ford EEC system. Hope this helps.
Dave