For first time CEL come on and Stang running lean , need quick help

[Slow5.0]

Today I start my Stang and after a few seconds CEL come on , I been driving with CEL about 15 min when CEL goes off , than I go in AutoZone to free testing CEL , they find two codes 172 and 176 , than they tell me 172 code is HEGO sensor unable to switch cyl bank #1 and 176 code is HEGO sensor indicates lean condition bank #2 , after that I go home I take my "94-99 Mustang Haynes repair manual book" and I find this 172 code is HEGO sensor indicates lean contition ,right side (same like from AutoZone) and 176 code is HEGO sensor indicates lean condition ,left side
So which one is right
Guys I have to tell you this , last weekend I was rebuild my T5 tranny and before that I never have problem with CEL , never come on before ,never , guy who did redbuilding tranny tell me I runn rich because O2 sensor on left side is black inside(he have to take off that sensor so he can easy take out bell housing) , after that sometime on red lights idle is funny goes up and down 1250-650 a few times and engine turn off , I have Autometer air/fuel ratio gauge where I read lean in lowers rpms ,but if I punched over 4500 led goes up to stoich
SO what a heck is wrong , do I need just new O2sensors or what

 

[Joes95GT]

My guess would be the O2 sensors. What is your fuel pressure set at? Did that guy mess with your fuel pressure at all? He may have leaned it out too much, but then again, that wouldn't cause a CEL if it was done manually.

Joe

 

[RIO5.0]

back when i added LTs the car was wayyy rich...the o/2s were caked with black soot....anyway, they were like a yr old...i took a torch and lightly heated them, cleaned of the soot as best i could...threw em back in and all was cool...that was 2 yrs ago...
may be worth a shot versus replacing them??? clean them up...reset the ECC and give it some time??? is it running like ass??? minus the vibration thing, thats new anyway..

if the lights on then off...thats better than on all the time and running chitty??

 

[Slow5.0]

RIO5.0 how I can clean o2 sensors I mean with kinda sprey /cleaner

 

[RIO5.0]

RIO5.0 how I can clean o2 sensors I mean with kinda sprey /cleaner

The only thing i have seen is the heat method,so i tried it...i never attemped any type of cleaner, nor have i seen any mention of it...can't answer that one???

 

[Slow5.0]

So you take a torch and lightly heated them than wipe with something righr!

 

[RIO5.0]

So you take a torch and lightly heated them than wipe with something righr!

Yup..I used a fine bristle wire brush to clean em...dont get them to hot...a heat gun would work too..

 

[Slow5.0]

RIO5.0 today I take out both o2 sensors , and they are black , I use torch and wire brush , than I install and same thing , I don't know did I tell you I have autometer air/fuel ratio gauge and when I start car in morning led is on 2nd on left side(lean) than after 10+ min in crousing led came up to 2nd on stoich , and on red light led is on 2nd in lean again and sometimes on red light idle gors up and down 2-3 times and engine turn off , I check stock fuel pressure regulator and I change with my old one same thing , so fuel pressure is good, when I take out o2sensors I find a low snow and ice on conector and I clean that ,but nothing and I didn't find ant wather inside conectors
So maybe O2 is bad , I gonna buy new on in friday and try again , I will let you know whats happening

Ernie

 

[Slow5.0]

Here is what I do today , I spend 150 bucks on new O2 sensors (Bosch) than I install new one and reset the ECC , start car and same thing , on A/F ratio gauge reade lean very lean but when I rev up a few times over 3-4k gauge show stoich and rich than when I leave engine on idle led's on gauge come back to lean again , I take some videos and pics about that but I have to upload them on net

 

[Slow5.0]

Yesterday I return new O2sensors , I install old one back and gess what I finf , problem is cold weather , when is realy cold my O2sensors read lean ,but when I leave my car in garage a few houts and when I start a car O2 works good , mey be something else is bad or mey be not

 

[PRO50SC]

Been my experience if you have codes for both o2's at the same time it's generally not the o2's at fault. Something else is probably wrong. I would check a little deeper into it.

 

[Slow5.0]

Been my experience if you have codes for both o2's at the same time it's generally not the o2's at fault. Something else is probably wrong. I would check a little deeper into it.

Like what

 

[PRO50SC]

Have you done anything to the engine recently to cause a problem? Is there excessive black smoke coming out of the exhaust. What temp is the engine running at? If it's running too cold, the computor is going to command a rich condition, this would be a problem on a warm motor. possibly ect, engine coolant temp sensor malfunctioning, not the one for the gauge, the one the ecm reads. How does the car run, idle, cruise? Idle rough? Possible vacume leaks. Have you pulled a plug to see what color it is?

 

[Slow5.0]

Damn , I mess with all that , but I never had problem with o2 sensors untill I rebuild T5 tranny , and f****** CEL come on

 

[Slow5.0]

I FIXED, I FIXED my O2 sensor problem , I had blown HEGO fuse , damn i'm an idiot , today on job I been thinking what the hell is wrong b/c I check everything : MASS,IAC,IAT,ECT,EGR and a few more and I beed whatching my Haynes book and in Chassis electrical system "Typical 5.0L engine control system" when I saw HEGO fuse #10 20A , in same minute I ran to my car and check that and I find blown fuse , this fuse drive me crazy last 3-4 weeks , I never check that fuse before until today
And I'm happy now
And here is bastard

<img src="http://forums.stangnet.com/attachment.php?attachmentid=18259&stc=1">

 

[Yung Than]

Where is this HEGO fuse located at? Is it under the steering column or under the hood?

 

[Slow5.0]

Under steering column/ under dash

 

[Slow5.0]

Yung Than here is one pics about HEGO fuse location

<img src="http://forums.stangnet.com/attachment.php?attachmentid=18315&stc=1">

 

[hiattwl]

wtf is a hego fuse?

 

[mo_dingo]

wtf is a hego fuse?

It's a regular fues. He means it's the fuse for the HEGO O2 sensors.
Scott