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vtec wont engage at normal temperature

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    vtec wont engage at normal temperature

    I've yet to find answers to this problem. I have found some posts with the topic but none answering the problem.

    Basically, on cold start up, once my engine begins to warm up, vtec will engage once or twice, and it pulls nice!

    but shortly after the engine has reached normal operating temp, vtec will not engage.

    I do regular oil changes, and my vtec was engaging beautifully before. It just all of a sudden decided to stop. I think it could have something to do with the summer? I unno... cause winter it ran fine all the time, and now it is only working when the engine has sat for a while enough to cool off for a bit. if its warm, it wont engage.

    i have an h22a swap with m2b4 lsd and the stock ecu from the prelude that the motor came from.
    Everyday is one day closer to completing my cb7 <3

    #2
    are you getting any CEL's? check/diagnose those first.

    could be lack of oil pressure. also could be knock sensor signalling the ECU to not engage it. do you have a working knock sensor wired in?
    RIP '91 LX.

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      #3
      I do have a cel but it is only the egr cel. BUT it has never stopped my vtec from engaging. I have no idea what knock sensors are for or are. So im going to have to research that. But why would it tell it not to engage?
      Everyday is one day closer to completing my cb7 <3

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        #4
        So now i know what a knock sensor is. Is there a quick way to disconnect it and see if it solves my problem? Juding by your post, im assuming its possible to wire your car with out it
        Everyday is one day closer to completing my cb7 <3

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          #5
          Did you do your swap yourself? Yeah i'm running my h22a without one. But if your knock sensor detects knock (detonation) it won't engage. It's a sensor on your block under your intake manifold by the intake port for cylinder #2, above the water pump to thermostat pipe. I think it's either pin D3 or D4 on your ECU but i'm not 100% sure so study an OBD1 pinout.

          Is your car going into limp mode by any chance? You say you have an EGR code. It could have something to do with the MAP. I fixed my homeboy's h22a cb7, his VTEC wouldn't engage and his car would stay in limp mode cuz his vacuum n wiring was all messed up. He got it done at a shop that didn't know what they were doing..
          RIP '91 LX.

          Comment


            #6
            no i didnt do it myself. I bought the car as is. and the vtec was running fine prior to all of this. it still works, but once warm temperature it stops. so im asuming some kind of sensor. vaccume lines I assume would be fine, otherwise vtec would not engage at all. I will try disconnecting the knock sensor and see what happens. could this be harmful to the engine though? and wont the ecu throw a code once disconnected?

            on a side note... I did manage to find this last night as I was searching, http://honda-tech.com/showthread.php?t=2613546 I'll try cleaning it and see if I can get my hands on a new pressure switch, and/or solenoid.
            Last edited by trinistylez; 07-24-2012, 07:00 AM.
            Everyday is one day closer to completing my cb7 <3

            Comment


              #7
              Originally posted by trinistylez View Post
              no i didnt do it myself. I bought the car as is. and the vtec was running fine prior to all of this. it still works, but once warm temperature it stops. so im asuming some kind of sensor. vaccume lines I assume would be fine, otherwise vtec would not engage at all. I will try disconnecting the knock sensor and see what happens. could this be harmful to the engine though? and wont the ecu throw a code once disconnected?

              on a side note... I did manage to find this last night as I was searching, http://honda-tech.com/showthread.php?t=2613546 I'll try cleaning it and see if I can get my hands on a new pressure switch, and/or solenoid.
              your solenoid is obviously working if its engaging before its fully warm. my guess could be get a new screen or just clean that one, change your oil and see if that helps, what type/weight oil are you running, as the motor warms up the oil gets thinner and could be causing not enough oil pressure

              Comment


                #8
                Ive always used castrol 5w-30 non synthetic high mileage oil. I really want to clean the screen but i want to do it while the motor is cool, my days are just too busy. The motor stays warm until i go to sleep -_-
                Everyday is one day closer to completing my cb7 <3

                Comment


                  #9
                  I did an oil change, vtec seems to have come back, somewhat. I think it may be because the oil pan has a dent, Going to try that in two weeks when I get the funds.
                  Everyday is one day closer to completing my cb7 <3

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