Need Help to pass emission

[jpprock]

Hi,

I have a 1995 ford bronco that has about 200000 miles. I can't seem to get it to pass Colorado air emission.

It fails the CO test (too High). I have change the oil, oil filter, all air filters and the spark plugs. The bronco is running fine. What should I

change next?

Thanks

Jim

 

[92broncomann]

May need to get some new catalytic convertors, could need an O2 sensor maybe run some denatured alcohol thru it to clean stuff up.

92BM

 

[Broncobill78]

Does the truck have A/C ? Turning it on during the test loads then engine & drops the emissions (that's why they tell you to turn it off for the test) The tester may or may not notice & may or may not look the other way but I did it more than a few times when I lived in Mass.

 

[BroncoJoe19]

That's interesting.. if your emissions are off your CEL should be lit.

I do not dissagree with the previous two posters, esp about the Cats and possibly the O2 sensors.

I would give her a tuneup.

Plugs, cap and rotor, PCV, and air filter.

Depending on the miles on the plugs I might just clean and regap them.

Check for vacuum leaks.

Make sure the coolent level is topped off.

WHether it is lit or not, I would pull codes. All you need is a 4 inch piece of wire and the ability to count to ten.

Pull Diagnostic Trouble Codes (DTCs) From your onboard computer.

Your engine and transmission are computer controlled.

The computer uses sensors to tell it a number of different things and it controls actuators that push or pull mechanical levers (kinda). If one or more sensors aren't working properly, the computer goes "blind" and doesn't know what to do. If the computer can "see" but one of the actuators is broken and therefore can't follow the commands of the computer; the engine won't run correctly. The computer is preprogrammed with set values for each of its sensors, and each of its actuators. It will run a self check of all systems, like the space shuttle; it will compare its set value(s) to the value(s) it recieves from its sensors, and actuators. If any sensor or acutator is out of the "normal" range the computer will generate a "code." It will generate some codes on the fly, and others will be stored while you are driving. There is a simple method to "pull codes" out of the computer for one to use for diagnostic purposes.

Earlier versions of On Board Diagnostics OBD 1983-1995 can flash the error code to the dash board and can be pulled in one's driveway without any special tools.

Later versions of On Board Diagnostics OBDII some 1995, and pretty much all 1996 and newer, require one to use a code reader or scanner tool.

Some auto parts stores will scan your engine codes for FREE, you may want to call around. Some will scan OBDII but not the older (prior to 1996) OBD systems.

SO here you go...

How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway

Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more