KOEO Fault Code 179 - What does it really mean? See my Sympyoms and g

[dwildey]

Hello,

I have a 1990 full size with the 351 EFI. I am having problems when I do a cold start. It runs fine for about two minutes when cold and then the RPM's drop real low and it runs rough or dies. If I keep my foot on the pedal and let it worm up, it then runs great once warm. I put the code reader on and get a code 179 which says "HEGO (HO2S) sensor fault unable to switch / rich during part throttle". I am not sure what this mean and had replaced the O2 sensor along with a few other things about 6 months ago. What I do know is that I get terrible mileage even on the high - 8mpg. Being so, I thinking once it's warm it is rich. It smells rich as well.

Any ideas? I hate to start guessing........ I've been reading and wondering about the fuel pump / pressure. Not sure if that's related to the symptoms, but it does have an audible whine. It always had, but I don't know if that's "normal".

Any help on what to look at would be great!

 

[Krafty]

how long has this problem been happening since the new O2 sensor?

 

[dwildey]

It just started - I hss been running fine up until the last month when the temperatures dropped. The gas mileage has never been over 8 and on the last trip, I got 8 as well which seems a little low for highway.

how long has this problem been happening since the new O2 sensor?

 

[Krafty]

you'll have to do some tests, if you get a fuel pressure test done then you can rule out anything mechanical. that just leaves a bad sensor or controller somewhere.

just because your getting a code from the 02 sensor that means its actually doing its job. if the sensor was bad then it would be running rich and not telling you about it.

the computer uses the O2 sensor to slightly adjust the amount of fuel given to the engine within a certain amount once its outside the range of the computer to adjust then it sends you the code.

what it is is something that adjusts the fuel based on A. Temperature sensor (based on engine temp) B. MAP sensor which adjusts for Air density and altitude. ( Air density is also affected by the Temperature of outside air).

or C you computer is malfunctioning. the computer has programed fuel charts that are set for combinations of signals from those 3 sensors.

less likely but still a possibility.

 

[miesk5]

yo!

From the Ford VECI Label (is the same as the Label on the Radiator core support) I see 2 O2 Sensors on your 90 5.8; which sensor did you replace if you have 2?

From the DTC description I see "]Bank #1" which would be on passenger side.

179 Fuel system at lean adaptive limit at part throttle, system rich (Bank #1)

How did the old sensor look? black soot?

Contaminated Oxygen Sensor pics w/Diagnosis, General

Source: by Tomco http://cds.activant.com/C2C/C01/68/541/824663110.pdf

--

There is a TSB 9237, JAN 92, EVAP System - MIL ON/Codes 171/173/179 Set ... but for 1991 Ford Truck E 150 Van V8-302 5.0L. and some other F series in diff years, but none apply to your year Bronco; I can't retrieve the TSB right now.

maybe someone else can get it posted-up here for you soon.

A long shot;

You could pull the Red vacuum line off of the rfuel pressure regulator (FPR); any gas or odor in the vac line then the FPR is bad

Read more: http://74.125.93.132/search?q=cache:Ozrtpc...s#ixzz0ZUJZmaL7

Also,

All of the following items will cause a HEGO code:

 

[dwildey]

Thanks for the info. Today I changed out the plugs, wires, cap & rotor which all needed anyways. The plugs were all clean but all parts were due for a replacement. I re-pulled the O2 sensor to check and this is fairly clean as well. It was a little dark, but the vehicle has been running rich.

What is more bizarre is now everything seems to be worse! I won't even stay running unless I keep my foot on the gas even when warm. I did notice when it's cold if I pull off anything vacuum related and it can breathe better, it runs better. When I hook the vacuum backup, it starts to spitter and sputter and dies.

I was wandering about the Throttle Position Sensor and/or Coolant Temperature Sensor. I know in reading that the TPS can cause it to run rich and waste gas but it won't run worth a darn when cold right now and dies and seems to have a IDLE with an RPM that is way to low.

yo!From the Ford VECI Label (is the same as the Label on the Radiator core support) I see 2 O2 Sensors on your 90 5.8; which sensor did you replace if you have 2?

From the DTC description I see "]Bank #1" which would be on passenger side.

179 Fuel system at lean adaptive limit at part throttle, system rich (Bank #1)

How did the old sensor look? black soot?

Contaminated Oxygen Sensor pics w/Diagnosis, General

Source: by Tomco http://cds.activant.com/C2C/C01/68/541/824663110.pdf

--

There is a TSB 9237, JAN 92, EVAP System - MIL ON/Codes 171/173/179 Set ... but for 1991 Ford Truck E 150 Van V8-302 5.0L. and some other F series in diff years, but none apply to your year Bronco; I can't retrieve the TSB right now.

maybe someone else can get it posted-up here for you soon.

A long shot;

You could pull the Red vacuum line off of the rfuel pressure regulator (FPR); any gas or odor in the vac line then the FPR is bad

Read more: http://74.125.93.132/search?q=cache:Ozrtpc...s#ixzz0ZUJZmaL7

Also,

All of the following items will cause a HEGO code:

 

[dwildey]

Update - Almost fixed - Progress REPORT - High Idle:

Today, I pulled the throttle body off and replaced the TPS (Throttle Position Sensor), cleaned the Throttle Body and inside manifold, replaced the coolant sensor and fluid lines, put new gasket and installed new Intake Control Sensor (IAC). My theory was that I might as well do all of it if I had to take to mechanic, it was all new and clean.

Anyways, now it starts right up and runs great cold or warm. The only problem I am having now is the RPM is hanging out at 1500 which is obviously high. I played around with the TPS one more time to make sure I had it on correctly which I believe I do. I am going ot have the Timing checked because it might be fudged for when it was running poorly or worse.

Other than that, I can at least drive without it dying! If anyone has ideas on the high idle, let me know!

Forgot to mention that Key On Engine Off passes with no errors. Key On Engine On give 411 and 412.

Thanks

 

[miesk5]

yo

411