Hi,

I bought a used 1996 Bronco XL 5.0 and now I need help passing emissions test.

First air test, I blew a 10.0 CO when 1.0 is passing. I added catalytic converter since I had none. (I bought this used where emissions testing wasn't required.)

Second air test, I blew about 6.25 and HC was down around 35%. I am sure the O2 sensor is bad due to engine light coming on so I am replacing that today.

While I was down there I noticed the dangling air tube. I believe it may have hooked into a cat at one point and I may have had 2 cats. IDK if I need to suffer the expense of adding that air tube tube back (new cat has no air connector) and/or another cat.

Appreciate any feedback.

 

Do you have an air pump or place for one?

EFI motor, right?

You are probably OBD 1. Here's how to get the codes:

https://www.freeautomechanic.com/dia...blecodes7.html

What about visual test? Or are you sniffer only?

 

Sniffer only. I think it is EFI. It may even say it on the block.

 

EFI:

http://broncozone.com/uploads/monthl...1341227600.jpg

 

Thank you for codes and the image. It is 5.0 EFI.

The new O2 sensor went in but check engine still goes on.

I noticed oil in the air filter case when I replaced the air filter just now too.

I'll check the codes.

 

Anyone know if the 93 5.0 PVC valve has a filter?

 

That link shows no filter. AFAIK, the only filters were for '70s era vehicles that drew air out of the air cleaner housing, outside the filter. The system illustrated draws air out of the upper air manifold, so the air has already passed through the air filter.

 

Is this a 1993 or 1996 Bronco?

1993 would be OBD-I with one O2 sensor.

1996 would be OBD-II with three O2 sensors.


A 1993 Bronco has a dedicated PCV filter below the main air filter in the filter box.

A 1996 Bronco draws air from the air intake after the MAF meter. There is no dedicated PCV filter.

I know the 1996 Broncos with 5.8L engine does not have an air pump or the associated air injection tubing. The 5L may have all of this just like the 1995 and earlier Broncos.

 

This is a 1993.

That dedicated PCV filter is the source of the oil. But thanks, I didn't realize what is was for. On my way to get a new valve/filter now.

 

If oil is coming out of the filter, your PCV is either not working right or is overwhelmed due to excessive blow by or other issue.

That filter should be filtering air going into the engine block via the valve cover usually.

The PCV pulls that air out of the engine, usually on the other side or some other distance from the intake, and that air goes into the manifold to be sent into the combustion process.

 

I replaced PCV and O2 sensor but I still fail by a mile. I tried adding 64 oz rubbing alcohol and running at high RPM prior to test as was suggested by the guys at NAPA.

Check engine light wasn't even on during the test although it turned on the drive home.

I do not know what an engine with worn rings handles like but this Bronco has lots of acceleration to about 60 mph.

I am off to AutoZone this evening to get a read but w/ 800 HC and 10 CO, I may need a major repair.

 

Worn rings will give you blue smoke, and plenty of it.

Do you get black smoke at all?

Temperature sensors, failed t-stat, idle control valves will all cause a rich condition.

Does your temp gauge work? If so, does it show the engine warming up and staying in the normal area?

 

No smoke. I used to see a puff of whitish smoke in the morning but that stopped happening.

All the gauges work and temperature is dead steady in the normal range.

Autozone is not able to do an OBD-I.

I have an appointment on Thursday w/ a shop that could perform a real diagnostic. I was hoping the new PCV would do it since oil was pushed into the air filter. It seems strange that there was no change in the reading. It was not a motorcraft replacement but still.