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    Cooling fans no blow

    On Sis in law's 1998 protege with 1.5L DOHC engine. The fan does run when AC is on, but do not run otherwise, even when the engine is approaching over temperature.

    Sis in law replaced fan relay in fuse box on LH side of engine bay. There is +12 at one side of the relay coil, and +12 at common of relay throw. Energizing relay coil on bench throws relay.

    The engine coolant temperature sensor is replaced, before replacement engine temperature gauge did not move, now it warms up rapidly.

    This car does have two radiator/condenser cooling fans, I'm not sure which/both should run on engine temperature, and which/both should run on AC on.

    Thank you so much for any wisdom here. This is one of those jobs where compensation is good will/love, so we've got that going.
    Last edited by Slim; 01-22-2018, 10:02 AM.

    #2
    Oops, my problem looks a lot like this one: http://www.wihandyman.com/forum/show...ns-not-working

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      #3
      Can anyone say if PCM error codes will indicate which if not both O2 sensors are fouled? It would be good to know which if not both are malfunctioning. Thanks in advance....!

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        #4
        Update - after new water pump, new radiator, new T stat, new T sensor/sender, new hoses, car starts, temperature gauge reaches Hot very quickly. T stat opens only when gauge is reading H.
        Top tank is quite hot to touch, lower tank is cool to touch with fans running.

        Looks like gauge is reading high, car does not seem hot, with radiator cap off coolant flow is observed, no boiling over etc. Sender is AZ cheapie. Are there multiple sender applications for this car? Anyone had issues with T gauge reading high?

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          #5
          i would get the right sender from the junkyard. or mazda OE
          ---Has ClubProtege helped you in someway? show your support by Contributing--- Click Here---

          1992- project FE3..... 313 WHP @ 9.3psi




          I pet my dash when I get into the car..."good car"
          he actually has a mazda tree, parts grow on it

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            #6
            I have AZ cheapie and it ran great.

            I did however make ABSOLUTELY sure I got a dual stat. There are two temperatures that will open, instead of one. I also got that from AZ.

            I think if you get a single it will open much later, like yours. The dual is for heat in the cabin.
            1991 Protege LX 5MT, P/S, A/C, NOW Sun Roof!

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              #7
              To answer your O2 sensor question, I'm not sure if there any any specific codes for each sensor (at least I've never had any). You'll usually get P0420 (I think) "Catalyst efficiency below threshold" which points you to the catalytic converter, but it could also be a bad O2 sensor. If you have an OBII reader and can view the data while the car is running you should be able to see something like O2 sensor 1 and O2 sensor 2. Sensor one if before the converter, in the exhaust manifold, and sensor 2 is after the converter, under the engine.

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                #8
                Thanks so much for the assistance. Next problem: car runs pretty well when cold, except slight stumble when throttle is abruptly opened, for example in neutral, punch the throttle there is a perceptiple miss or two, then engine revs up fine. After warm up, same conditions cause engine to rev partway up, then begin to die as if ignition is suddenly and completely removed. Letting off throttle results in engine picking up and running again. If throttle is not released, engine will bog down, and die. Fuel rail pressure looks good, 39 psi at idle, jumps up to 49 psi when throttle is opened, returns to 39 at idle. Fuel rail pressure remains stable even as engine bogs and dies.

                CEL is off part of time, comes on while driving, last I checked it was off.

                Since fuel pressure looks good, I suspect ignition. Tonight I'm going to read CEL codes, and inspect distributor. It looks like crank pos sensor and ignition module in distributor are the primary ignition components. Has any one seen a similar failure in components act like this?

                Thanks so much. This is one of those in law jobs, good works situation.

                Thanks.

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                  #9
                  have you covered the basic ignition tune up components yet/already??

                  have you checked for vacuum leaks as well? light spray bottle around the intake hoses/manifold?
                  ---Has ClubProtege helped you in someway? show your support by Contributing--- Click Here---

                  1992- project FE3..... 313 WHP @ 9.3psi




                  I pet my dash when I get into the car..."good car"
                  he actually has a mazda tree, parts grow on it

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                    #10
                    No CEL codes presented. Distributor cap has a little oil and dirt in it, Ignition rotor is cracked. I can hear spark snapping inside cap when engine misfires, so I think fresh cap, rotor and plugs. This car has 350K miles, so no surprise. Sis in law can afford little, so a charity job here.

                    Odd is why it idles well, then misfires under open throttle. I suppose PCM is changing ignition timing so that arcing is more likely, and the pressure in the combustion chamber goes up. I know that electrical energy follows path of least resistance. I don't really understand the physics, but it seem as if misfire is worse when engine is under load.

                    So I think basic tune up parts will solve it. Thanks again to all who help.

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