my 87 bronco is dumping fuel??

[famousguy_fsas]

so i have a 1987 ford bronco with a 5.8 electronic fuel injected motor. at 45 mph and mostly at 65 mph the check engine light will flash on and off. off for like a second and on for like a half of second. whenever it flashes on my engine will kinda cut out just for the fastest second. like a little hickup. and when its doing that i can smell the gas. i had the computer hooked up to it and i think it was code 42 maybe. it said something like "lack of heated 02 sensor" or something along those lines. the place said what its doing is dumping fuel on to my catalytic converter. but why its doing that... well they wouldnt tell me. they said i need to pay them $100 and they will take my truck for an hour and then tell me. does anyone have any clue as to why my truck would be dumping fuel or why my engine light flashes and truck hickups when it does? any help would be awesome. thank you

 

[BroncoJoe19]

Here is a thread on how to pull codes yourself, all you need is s 4 inch piece of wire.

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

IF you get 42 when the engine is running

No HEGO switching detected always rich (right side).

IF it is in continuous memory

HEGO sensor circuit indicates system rich (right side).

 

[famousguy_fsas]

yeah i had codes ran on it at a shop and im almost positive it was 42 but not sure. i just remember it said something like " lack of heated o2 sensor" sorry im new to fords and fuel injection. does that mean i should change my heated o2 sensor?

 

[BroncoJoe19]

You're not sure, that's why I posted a link to teach you to pull codes so that you can be sure.

When one pulls codes there are three kinds.

On demand... created on the fly, the PCM checks some sensors and actuators.

Continuous memory, it checks its memory of codes that were created and stored while in use.

KOER key on engine running it tests some sensors while the engine is running.

I posted the continuous memory, and KOER verbal meanings of code 42 above.

neither says there is a "Lack of O2 sensor"

regardless, codes only point in the direction one should look, they rarely tell one exactly what is the cause.

O2 sensor issues can be caused by poor connection to the O2 sensor itself, degradation of the sensor (it my understanding that they may be cleaned, but they are pretty sensitive, and if they have never been replaced in an '87 they are due). Vacuum leaks, and exhaust leaks may also cause a rich code. A faulty MAP is another, but there is a code for MAP (which may or may not get set).

Unfortunately running rich on one side may also mean that the fuel on that side, (at least in one cylinder) may not be fully combusted. If you have a missing cylinder raw fuel may be getting dumped into the exhaust. You mentioned that you can feel a miss ocassionally. So I guess it is time for a good tune up.

I hope this helps.

 

[BroncoJoe19]

Checking for vacuum leaks.

Some of the sensors and some of the actuators either read the amount of vacuum, or use vacuum to move controls, therefore it is important to the proper functioning of the engine that your vacuum system is fully intact. Otherwise one may get codes falsely indicating that there is a problem with a controller/actuator, or a sensor when in reality it is caused by a lack of vacuum.

Look at your rubber vacuum hoses (they are about 1/4 - 3/8 inches in diameter, if they are dry rotted or cracked, replace them. IF they slip on/off of their connectors too easily, they may have stretched out a little bit, cut the ends off, and put them back on.

You may listen for a leak. Sometimes using a cut off piece of garden hose is a good aid to listen with. Sometimes a cardboard tube (like from gift wrapping paper) is helpful. Just remember that whenever you stick your head inside a running engine compartment, that you are not wearing any loose clothing or jewelry that can get caught.

Another suggestion is to use a spray can of carb cleaner and spray around the bottom of the intake manifold, and the base of the throttle body assembly. IF there is a leak, you should hear a change in your engine.

Keep a fire extinguisher handy, or use water instead of carb cleaner (it works, but not as well.) Be aware that if you use water and the wires get wet and it runs worse... your wires may be bad, and the water is allowing them to arc instead of jump the gap of the spark plug.

Another suggestion is: to take a propane torch, turn it on (but don't light it) and move it over the vacuum hoses and connections. The engine RPM's will increase if there is a leak and the propane gets sucked in.

Also check the PCV valve, hose and grommet, and the line to the vacuum booster for power brakes.

 

[Seabronc]

If you already know you had a code that said no O2 sensor, then change it. The O2 sensor is what tells the computer if you have the correct fuel to air ratio. The computer probably thinks it is running too lean and is attempting to enrich the mixture causing the gas odor since it over does it.

Probably the O2 sensor is bad or the connection to it is bad.

Good luck,

>-

 

[BroncoJoe19]

Seabronc,

To my knowledge, there is no code that says... no O2 sensor.

 

[Seabronc]

Seabronc,To my knowledge, there is no code that says... no O2 sensor.

Broncojoe19 In his initial post he said this, "i had the computer hooked up to it and i think it was code 42 maybe. it said something like "lack of heated 02 sensor" .

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[famousguy_fsas]

yeah a shop hooked up a computer to it and i looked at it when thay walked away and it said something about a heated o2 sensor. lack of heated o2 sensor is what i beleive it sait. and to my knowlege the o2 sensor in front of the cat is called a heated o2 sensor. so ill try that. thanks for all the help. if none of it works. ill prob be back

 

[famousguy_fsas]

sorry i dont know terms.... whats "hego"

 

[Seabronc]

sorry i dont know terms.... whats "hego"

That is a heated O2 sensor. It is located in the exhaust system and has an input to the computer. It is relatively inexpensive and easy to change. Sorta looks like a spark plug. On your truck it is probably right close to the exhaust manifold. It looks at the oxygen level in the exhaust to tell if the engine is being supplied the proper amount of fuel. If there is a problem with it, the computer can not properly adjust the amount of fuel being injected into the cylinders. I'd fix that before going any further.

Good luck,

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