New o2 sensors bad? or??

Discussion in '94-95 5.0 - Specific' started by B.mad, May 9, 2014.

  1. B.mad

    B.mad Well-Known Member Preferred Vendor

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    Ok so a while back my check engine light would go on when it would either be 50+ MPH or 3k RPM. So i thought the O2's are going out. I bought a pair from AM the NTK's. Got them installed the same time i got my O/R h-pipe installed, and......check engine light still turns on. Not as often but still did. So ok i thought it was my IAC/TB that were dirty. So i cleaned them out with some TB cleaner. Now check engine light goes on even more. Ran the code and it came up with the o2's reading lean on top end. Can it be just bad O2's? or can it be something else? Because the o2's are reading but i doubt its the reason it runs lean. Any suggestions? After cleaning out the IAC/TB the car seem to be less responsive throttle wise. And i didnt clean the Air filter and the MAF.
     
  2. RichV

    RichV Well-Known Member

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    GT or Cobra? Any engine mods? What timing do you run?

    Have you checked plugs? It could be a fuel delivery issue as well. FPR, fuel filter, fuel pump, injectors.
     
  3. VooDoo95Cobra

    VooDoo95Cobra Active Member

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    Its def not your O2 sensors. I second Rich.. Tell us a little bit about the car and we can help you pinpoint it. Check for vacuum leaks first. Clean your MAF or at least inspect it. Have you recently installed any new items or done any service to the intake or manifolds? Check for exhaust leaks before the o2 sensors, this can cause a lean condition. If all of that is sound do a fuel pressure test and then test the fuel pump to make sure its not crapping out slowly.
     
  4. B.mad

    B.mad Well-Known Member Preferred Vendor

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    Its a GT. Motor wise i havent done anything to it besides clean out the IAC/TB. I recently installed magnapack catback and BBK O/R H pipe. It was throwing codes before the exhaust. As far as i know the timing is stock. Havent checked and dont know how to. I got it from an older couple who had it allllll original. He changed the distributor some years ago, so its possible the timing isnt correct. Im almost 100% sure the wires and plugs neeed to be replaced. As well has the fuel filter, more than likely the filter is factory. I dont know what FPR stands for lol. Fuel pump and injectors i dont know either how can i check? and how do i run a pressure test? I will take a look at the MAF and air filter by this weekend. And it doesnt seem to have an vacuum leaks from what i can see. And i believe it threw 176, 181, 186, 189 engine codes.
     
  5. B.mad

    B.mad Well-Known Member Preferred Vendor

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    oh and it did idle kind of rough. the RPM would fluctuate from about 900ish to about 600ish. Once in a while the car would turn off when i would come to a stop (its a 5 speed btw). but it hasnt done that in a while and only did that once. Since I cleaned out the IAC/TB it hasnt been running as rough, but definitely still rough. I will post up the link to youtube of the videos i took with my new exhaust and hopefully you can hear how it idles.
     
  6. B.mad

    B.mad Well-Known Member Preferred Vendor

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  7. RichV

    RichV Well-Known Member

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    So how did you come upon this issue? Did it turn on the CEL (Check Engine Light)?

    You should be able to borrow some tools to check the timing and fuel pressure. Check with your local part stores, they will typically have loaner tools.

    For the timing you'll need a timing light. Hook it up according to instructions, disconnect the 'spout', and aim the light at the harmonic balancer which is below the water pump pulley on the alternator side. Lots of YouTube vids on how to do this. You're looking for the timing to be 10* BTDC, can be as high as 14* for a little performance but no higher or lower than 10.

    Fuel pressure just needs checked at the rail. You can get a permanent gauge which goes into your rail's schrader valve, or a test gauge which you'll install for the test, then remove when done. You want to do the test with the vacuum line removed from the FPR (fuel pressure regulator), it sits on the passenger side of the fuel rail closer to the firewall. You're looking for about 40psi with the vacuum removed, will be less with vacuum connected.

    Definitely check the vacuum as well. If you have a leak somewhere it can definitely cause the issues you're seeing. Biggest leaking spots are PCV, cracked plastic connectors/tree, brake booster, and the intake manifold.

    Hope this helps!
     
  8. darinmasse

    darinmasse Member

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    If u got a lean code it one of 3 things number one being the 90 percent of the time cause

    1 vacuum
    2 lack of fuel
    3 o2 sensors

    Sent from my Huawei-U8665 using Tapatalk 2
     
  9. toyman

    toyman Active Member

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    Since it appears that you haven't had the car for very long and it's maintenance history is sketchy I would start with some basics. First do a tune-up (Plugs, wires, rotor, cay, fuel and air filters, clean the MAF sensor element and remove and clean the battery to engine and engine to chassis grounds). This will give you a base upon which you can attempt to diagnose various issues. When reporting on data trouble codes (DTCs) tell us the code value as well so it can be linked back to a particular sensor. The way things are right now you are going to get many different responses of which none may be relavent to the issue at hand.
     
  10. B.mad

    B.mad Well-Known Member Preferred Vendor

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    The o2 problem i decided to do it on my own terms. After the engine light went on, I pull the codes and it came up with 176, 181, 186, 189. I will check the PCV, brake booster, and intake. and i do not know what is/ what you mean by cracked plastic connectors/tree.
     
  11. B.mad

    B.mad Well-Known Member Preferred Vendor

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    it isnt number 3. at least it shouldnt because i just replaced them. I would need to check the fuel pressure. Can i check the fuel pressure on each injector? or does it not work that way?
     
  12. B.mad

    B.mad Well-Known Member Preferred Vendor

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    i am going to do a tune up once i get a little money. and as far as code value, i think i would need to go to a shop for that. Gotta make some phone calls
     
  13. toyman

    toyman Active Member

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    I was referring to the DTCs which I see you now have posted. Fuel pressure is checked at the schrader valve not the injectors. The reference to the cracked plastic piece is the vacuum tree that splits the single vacuum source at the intake to other components such as the brake booster, HVAC controls, cruise control, etc. You can make your own tree with tees and short pieces of vacuum tubing. Vacuum tubing and tees come in many diameters and can be purchased by the foot at most parts stores.
     
  14. B.mad

    B.mad Well-Known Member Preferred Vendor

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    awesomeness, hopefully before or after work on wednesday i can take a look at it. But i also noticed that when its warmed up i.e. been driving for a while, the throttle response sucks, and my exhaust note isnt the same. Also i noticed on the highway around 70ish MPH, a weird smell come up, kind of smells like burning oil. And smoke come out my exhaust i can see it in my drivers mirror. but doesnt last long. Oh and my windshield wiper decides to work randomly. Its happened like 3 times where im driving and they just randomly wipe. only one wipe though. And i didnt touch the switch btw.
     
  15. the5.ohh

    the5.ohh Legend

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    Smells like your burning oil and what colors the smoke coming out of the exhaust?
     
  16. B.mad

    B.mad Well-Known Member Preferred Vendor

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    cant tell if its blue or white. And also if i go into about 3k+RPM i can feel like it doesnt have enough power for that range, like i can feel it have less power. so definitely a fuel/air problem. or not strong enough spark for the amount of gas. Also, dont know its the O/R H-Pipe or not, but it does smell alot like gas.
     
  17. the5.ohh

    the5.ohh Legend

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    Well the bad smell comes from having no cats, but if your O2's are shot, it will smell even worse since it'll be running rich or lean iirc.. My O2's were done for, blacker than burnt charcoal from a bbq. Installed new ones, and shit, the thing don't even smell anymore! And I'm running longtubes, x pipe, no cats, no smog pump etc.. Check your radiator cap and see if the coolant looks milky, if it is, you may have a blown headgasket(s)
     
  18. CC'S95GT

    CC'S95GT Legend

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    90% of the info in this thread can be found in a Haynes/Chilton manual. BUY ONE.

    As already stated, give it a fresh tune up and look closely at the battery cables for loose connections and broken wires.
     
  19. B.mad

    B.mad Well-Known Member Preferred Vendor

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    i just replaced the o2 when i did the h pipe. Coolant still is green not milky. Im sure it isnt a head gasket problem especially since im not over heating. It kinda seems like the ECU is lagging on giving fuel at higher speeds/RPM.
    Like it gives to much fuel and it just smells like gas. Reminds me like my other mustang thats carb and runs super rich. But it doesnt always smell like gas fumes, just once in a while.
     
  20. the5.ohh

    the5.ohh Legend

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    Ah okay your good then as far as headgaskets wise. Check your injectors for leaking o-rings