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NEED HELP Had one code now have two.

Discussion in 'Vortec 4.2L I-6' started by pell, Jun 6, 2017.

  1. pell

    pell Member

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    Bought a 06 TB with 194,000 miles on. Owner said the CEL was on. He reset the code via battery disconnect. The only code I pulled was p0107. So after some research I come up with 1. Replace the MAP, 2. Clean the Air flow sensor, 3. Clean the Throttle body.

    Now I have codes P0106 and P2431. I truck is now very sluggish when first hitting the pedal and hard starting. Before it would start right up and drive fine. I did notice when cleaning the throttle body the butterfly did not close completely. Not sure if this is normal. Did check the MAP connector voltage. The ground is good and reference voltage is 5 volts. Any help would be great. I did double check the clamps and connectors everything seems OK.
     
  2. AtlWrk

    AtlWrk Well-Known Member

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    The throttle body is spring loaded to a partially open position--this is normal.

    The P0106 and P0107 basically say the MAP sensor data doesn't match what the PCM is expecting under certain operating conditions. This can be because the data is wrong (bad sensor or wiring issue) or a physical problem is causing the pressure in the intake to deviate from normal (restrictions in the exhaust, leaks in the intake, clogged MAP sensor, etc). The P2431 says the secondary air injection system (SAIS) pressure is not as expected but since it relies on the MAP sensor for reference if you figure out the P0107/P0106 it will likely take care of the P2431 too.

    Either one of those scenarios can lead to poor engine performance/sluggishness.

    What are you using to get codes? Can you get MAP sensor live data?

    With the ignition on and engine off you should be reading ambient barometric pressure (about 101 kPa or 14.7psi at sea level or 0 vacuum, depending on how your scantool reports).

    If you disconnect the MAP sensor you should get a reading near 12kPa (1.7psi or 13psi vacuum). With the engine idling you should get a little above that.

    Perform an exhaust backpressure test (or have a shop do it) to verify the exhaust system isn't restricted (clogged catalytic convert) though this isn't something that would show up suddenly.

    Also, did you reset the PCM after cleaning the throttle body? It shouldn't be so bad as to cause codes but may impact the performance/responsiveness.
     
  3. pell

    pell Member

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    I checked the live data key on engine off 14.2 psi, disconnected 1.5 psi. At a standing idle in park 3.6 psi @ 700RPM. Being a ford guy I thought clearing the codes via scan tool would reset the PCM. After problems I did disconnect the battery for 30 min. Thanks Pell
     
  4. AtlWrk

    AtlWrk Well-Known Member

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    I forgot one check:
    If you disconnect the map and short the 5V terminal to the signal terminal you should get ~15-15.1psi, but no less than 14.9.

    I suspect you have a problem with the MAP signal wire (poor connection/high resistance) causing lower readings than true.

    P0106 says the signal is out of the expected range (too high or too low) but the P0107 you had originally says the signal was so low that it could only be caused by an electrical fault--I should have caught this earlier.

    Adding this to the readings you provided:
    10.6psi (14.2-3.6psi) vacuum or 21.6 inHg is on the higher end of "normal", if not slightly beyond. Do you have a vacuum gauge you could use to compare? This supports the idea that the PCM is getting erroneously low readings.

    Now to find the source of the problem: Could be the terminal(s) on the MAP connector itself. Any signs of corrosion, looseness? Try moving the harness at the sensor and at the PCM and see if it has any impact on the live MAP readings. Remove and reseat the MAP and PCM connectors (sometimes this enough to cleanup the contacts). Do you show any resistance between battery ground/negative terminal and sensor ground ("low reference" terminal)? Anything over ~5ohms indicates a problem.
     
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  5. pell

    pell Member

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    So I shorted the reference to the signal wire 15.1 psi. Checked the ground I got 50 ohms. I did pull off the Map and PCM connectors. For the heck of it I put the old map sensor back on and that code P0107 came right back. Changed it back no more P0107. With the 50 ohms do you think there is a broken wire in the circuit? Thanks Greg
     
  6. pell

    pell Member

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    Does anyone know what connector on them PCM the ground wire to the MAP is in? I opened up the one closest to the fire wall and it has what looks the orange with the one black stripe. Just trying to confirm that is the one. Thanks Pell
     
  7. Mooseman

    Mooseman Moderator

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    You'd have to look at the schematics for that.
     
  8. Sir ffeJ

    Sir ffeJ Well-Known Member

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    When you cleaned the TB, did you take it off and clean the back side or just cleaned it while attached to the engine?
     
  9. pell

    pell Member

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    I did pull the Throttle body off the engine. Is there a thread that might get me to the wiring schematics. Thanks
     
  10. Tiggerr

    Tiggerr Gold Supporter

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  11. pell

    pell Member

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    Yes I was able to find that thread. It was very useful. Think I might jump that ground from the PCM to the map to see if I get a better ground. Will let you know how it goes.
     
  12. pell

    pell Member

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    So I have been very busy at work. Had time today and I jumped the wire from the PCM to the MAP. Took it for a ride now I have P0068 and P0106 and the truck runs very poorly.
     
  13. limequat

    limequat Well-Known Member

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    Jumped which wire, the ground? Regardless, something's not right. I would suggest starting over and measuring resistance between MAP and PCM for all 3 wires.
    50 ohms does sound too high to me, if you're still getting that.
     
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  14. pell

    pell Member

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    So here is the latest with my trailblazer. After putting in the old sensor in P0107 came back with no P0106. I put the new sensor and P0106 came on the truck ran poorly. So on a hunch I decide to spend a little money and buy another sensor. I bought an american made sensor made by BWD Automotive at Advanced Auto Parts. The truck runs like brand new but as things go I now have P0014. What to do now?
     
  15. Mooseman

    Mooseman Moderator

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    P0014 is probably the CPAS, located just behind the power steering pump reservoir. Pull the plug and check for oil in the plug. If there is oil, needs to be replaced (ACDelco or Delphi). If it looks good, you could try cleaning it:
    How To: Clean The Camshaft Position Actuator Solenoid (CPAS) Picture Heavy
    Unfortunately, PhotoBucket screwed us again with the pics. Description is pretty good though.
     
  16. pell

    pell Member

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    Yes, thanks for the link on the thread, Hopefully get it done tomorrow. Still can not believe the problems the replacement sensor caused me. Did like a 100 mile drive with this truck today and it ran great. This looks like a good fix for the P0014. Thanks Greg
     
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  17. pell

    pell Member

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    So I am doing what I need to do to clean the CPAS, and it seems like my fan is ready to fall off. I heard some squealing thought in might have been an idler or tension bearing. Is this a common issue with these rigs? Thanks
     
  18. Eric04

    Eric04 Silver Supporter

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    The fan clutch is a common issue, yes. Idler/tensioner no more so than other platforms, IMHO. In the early stages of fan clutch failure on my rig the noise wasn't very loud and therefore not easy to pinpoint. Putting an ear up to the grill nailed it down for me as it was very clear from that angle.
     
  19. Mooseman

    Mooseman Moderator

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    There's 4 ways they can fail. The most common is when the fan freewheels and doesn't speed up when commanded (most common). Next is the clutch is locked up and the fan roars non-stop (second most common). Then there is bearing bearing failure (what you're experiencing) and internal electronics failure where it screws up the 5V reference line and affects the throttle body and pedal sensors. These last two are rare but do happen.
     
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  20. pell

    pell Member

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    When the bearing fails does the fan fall off? I ordered a new clutch assembly, still would like to drive it to reset the monitors to get an emission test on this truck. Does the water pump really have to be done? I would see coolant leaking if it had a bad seal? Thanks Again Pell
     
  21. pell

    pell Member

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    On a better note I did drive this about 150 miles yesterday and NO CODES! Thanks guys. Pell
     
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  22. Eric04

    Eric04 Silver Supporter

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    You don't have to swap the water pump, no. The thing is, it can be kind of a pain getting the fan clutch and shroud out, but once you're there it's really easy to then pull the water pump. Given that the clutch rides on the end of the water pump shaft, in all likelihood you won't have long before it takes a powder on you too. It's one of those "in the neighborhood" deals and the pump is cheap so you save yourself the hassle of probably going back in the near future and doing most of the job over again. You can find a lot on this topic if you fish around the forum.
     
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  23. Mooseman

    Mooseman Moderator

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    Just be sure it's the clutch and not the pump going wonky on you. Take the belt off and grab the end of the fan to see if it's the clutch or the pump bearing that's going.
     
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  24. pell

    pell Member

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    Once the fan is off I should be able to see if it is indeed the clutch I am assuming. I know it sounds foolish but I just don't have the time to pull the pump, mainly dealing with the drainage of the coolant ect. Is there any way just to change the clutch bearing?
     
  25. pell

    pell Member

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    How long does it take to clear EVAP on the ML. Whats better highway or city driving.
     
  26. djthumper

    djthumper Administrator

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    Admin Post
    highway
     
  27. Mooseman

    Mooseman Moderator

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    No, it's a sealed unit.

    But do check the water pump just to be sure and save yourself some time if it is it.
     
  28. pell

    pell Member

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    Great news the truck passed inspection running like a champ. Had one issue with the plate light in the back not working. Torn apart the whole interior of the lift gate to find the wire broken between the gate and the body. Reminded of my 95 escort wagon which had the same problem many years ago. Still waiting for the fan clutch to show up. But I would say problem SOLVED. Thanks everyone.
     
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