coolant temp sensor?

Discussion in 'General Motoring' started by Randy Pape, Nov 21, 2007.

  1. Randy Pape

    Randy Pape Guest

    can a coolant temp sensor be bad and make my car run lousy once it warms up,
    even if there aren't any codes? I know how to test the sensor with my
    ohmmeter,when its cold and then hot,checking the resistance. I just thought
    if it was going that I should get some kind of code. thanks Randy
     
    Randy Pape, Nov 21, 2007
    #1
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  2. Randy Pape

    Bill Putney Guest

    What year and model vehicle?

    Some vehicles have a single temp. sensor that controls the engine
    temperature (by controlling the engine cooling fans) *and* drive the
    temperature gage (thru the computer). If that's the case, you can get
    some indication of what's going on with that sensor by how the
    temperature gage is operating during and after warmup (in conjunction
    with other observations, such as operation of the cooling fans, actual
    engine temperature as measured by another known good source, etc.).

    Bill Putney
    (To reply by e-mail, replace the last letter of the alphabet in my
    address with the letter 'x')
     
    Bill Putney, Nov 21, 2007
    #2
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  3. Randy Pape

    damnnickname Guest

    Yes it can, a scan tool would be better so monitor what the temp is
    actually reading. What is the year, make and model?

    Glenn Beasley
    Chrysler Tech
     
    damnnickname, Nov 21, 2007
    #3
  4. Randy Pape

    Randy Pape Guest

    this car is running bad now ,once it warms up. 1998 dodge stratus es 2.5v6.
    I think the cooling fan always ran more then I thought it should. I'll
    check it out with my scan tool. thanks


    well, now with new plugs,wires,fuel pump, fuel filter, the car still does
    not run right. it misses and acts like it's not getting fuel when you step
    on it . could it be the coils shorting out under load? I know my repair
    manual says I can check the coils with my multi meter but how do you
    simulate it under load, if this is the problem. note: there are no codes of
    any kind coming up with this problem. I don't want to be a parts hanger but
    I had 2 distributors that were bad before,and the last one was changed in
    Feb 07. any ideas or checks I can do. would the dodge dealer find the
    problem on his expensive equipment? my mechanic friend did the fuel
    pump,filter, this weekend and the last distributor in feb 07 and he thinks
    it's an ignition problem. I thought I read somewhere if the voltage isn't
    right ,then the fuel won't pump? thanks for any info Randy
     
    Randy Pape, Nov 21, 2007
    #4
  5. Randy Pape

    maxpower Guest

    If you had a scan tool you would be able to read what the intake air
    temperature is and probably find out it is way to hot once the engine warms
    up. This is because your EGR valve is stuck open and allowing hot exhaust to
    enter the intake and causing a really lean condition. On a carbureted engine
    this would have caused a bad idle, since this engine is fuel injected
    directly into the cylinder all you may notice is a higher idle. Disconnect
    the EGR valve vacuum line and see if it makes a difference, If the Spring
    inside the valve is broken, disconnecting the hose may not make a
    difference. You want to take a shot at it? toss an EGR valve on it.

    Glenn Beasley
    Chrysler Tech
     
    maxpower, Nov 22, 2007
    #5
  6. Randy Pape

    bllsht Guest

    Introducing exhaust gas into the intake does not cause a lean
    condition. The exhaust gas, being inert, dilutes the air/fuel mixture
    and it'll idle like shit whether the engine is fuel injected or not.
     
    bllsht, Nov 23, 2007
    #6
  7. Randy Pape

    maxpower Guest

    It will not idle like shit, it may have a slightly higher then normal idle,
    Map sensor will compensate for this leak. Take the EGR valve off and the
    engine will run at a high RPM. Not a rough idle.(It isn't a carbureted
    engine) The pcm will think that the throttle blade is open and
    compensate.What do you think the purpose of the IAT (intake air temp) sensor
    is used for????? Incoming cold air will cause a richer mixture, now suppose
    you have the intake Temp at 180 to 200 degrees from a stuck open EGR valve?
    Very lean condition with a possible hesitation an or ping on accel. The
    vehicle will run good until it reaches operating temps.

    Glenn
     
    maxpower, Nov 23, 2007
    #7
  8. Randy Pape

    bllsht Guest

    Run good until it reaches operating temps? With a leaking EGR valve?
    Nope!

    Taking the EGR off is not the same as the valve leaking exhaust gas
    into the intake. Removing the EGR will leave a large vacuum leak that
    will cause a high idle, and the PCM will add fuel because of the low
    vacuum sensed by the MAP sensor. Leaking exhaust gas into the intake
    will cause a shitty idle or stall, because the fuel/air charge will be
    too diluted by the exhaust gas to burn properly.
     
    bllsht, Nov 23, 2007
    #8
  9. Randy Pape

    maxpower Guest

    Yup, The intake air gets to hot, causing very lean condition
     
    maxpower, Nov 23, 2007
    #9
  10. Randy Pape

    bllsht Guest

    With the engine idling, hot or cold, if you pull the EGR open it will
    stall. Likely before you're even able to detect an IAT sensor temp
    change with your DRB. High temp is not the problem. Lack of oxygen and
    fuel is.

    You obviously have no idea what EGR does.
     
    bllsht, Nov 24, 2007
    #10
  11. Randy Pape

    Randy Pape Guest

    well i got the car back and it ran fine until i got almost home. then loss
    of power, idled rough, and was hard to start once i shut it off. i do have a
    new EGR valve assy, i'll put on tomorrow.
     
    Randy Pape, Nov 24, 2007
    #11
  12. Randy Pape

    maxpower Guest

    Install the EGR valve, it will take care of the problem.
     
    maxpower, Nov 24, 2007
    #12
  13. Randy Pape

    maxpower Guest

    Tomorrow has come and gone long ago, when are you gonna tell us it fixed it?

    Glenn
     
    maxpower, Nov 30, 2007
    #13
  14. Randy Pape

    Randy Pape Guest

    well glenn ,
    its not fixed. i have a question for you . when using a spark tester and
    turning the engine over,should there be continuous spark at the gap of
    tester? when i do it on my #2 plug i can make a one count between sparks.
    is this normal?
    i thought it spun so fast that it should almost continuous? i also don't
    think it's real blue in color. thanks Randy
     
    Randy Pape, Dec 2, 2007
    #14
  15. Randy Pape

    maxpower Guest

    Is this vehicle a no start? I thought it was a hot drivability problem?
     
    maxpower, Dec 2, 2007
    #15
  16. Randy Pape

    bllsht Guest

    What you're describing sounds about right. The spark will not be
    continuous. You will only get a spark at one cylinder every other
    revolution of the crankshaft. Example: If the engine is cranking at
    300 RPM you will see a spark every 2.5 seconds at each plug wire.

    If it starts & runs, you're probably not going to determine the
    problem by looking at the spark. If you suspect an ignition problem,
    you really need to connect a scope to see what's going on.

    Or you can keep throwing parts at it.
     
    bllsht, Dec 2, 2007
    #16
  17. Randy Pape

    Road Runner Guest

    An engine cranking at 300 rpm rotates 5 times per second.
    Therefore spark will occur every .4 seconds on a single fire and .2 seconds
    on a double fire ignition system.
     
    Road Runner, Dec 3, 2007
    #17
  18. Randy Pape

    Randy Pape Guest

    this was suppose to be a warmed up car issue now its a no start car issue.
    the plugs were wet and looked fouled so i'm putting in new ones. this went
    from just a bad fuel pump(so i was told ) to a host of other issues. first
    it ran then after a while it ran lousy ,so mechanic friend suspected bad
    coil,so reman distributor was put in. then car ran ok until 3/4 of the way
    home and it had no power and acted like it was starving for gas. once i
    turned it off ,it was hard to start again. this has been a frustrating
    ordeal and i'm not, nor do i like parts hanger mechanics. but once my friend
    said he wouldn't have given the car back to me if it was bad and i'm on my
    own now , i will find the problem through trouble shooting etc. thanks for
    all the input and sorry if it seems like i'm going in circles here on my
    posts. Randy
     
    Randy Pape, Dec 3, 2007
    #18
  19. Randy Pape

    bllsht Guest

    Yes, I should have said 2.5 times per second.
     
    bllsht, Dec 3, 2007
    #19
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