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Cold Weather Problems

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  • dmaljunkdmaljunk Posts: 160
    sequoiasoon, thanks in advance. I am in Brooklyn, NY. Thanks
  • dmaljunkdmaljunk Posts: 160
    div2, I got the electronic tester and attempted to measure the Engine Coolant Tempreture Sensor resistence manually. I got reading on a warm engine, which seemed to fit the graph of normal readings in the manual(0.67 kOmhs at about 125F) but with the cold engine I couldn't get clear readings. I was expecting to see something like 2 kOmhs but didn't get anything at all. Some numbers came up for a second and then nothing. Is this an indication of a problem? Is it possible that the sensor works fine and gives off proper resistence when antifreeze is warm and doesn't work at all when antifreeze is cold? It sure seems that it's doing just that based in the symptoms... I am kind of ready to throw another $27 at this problem and see if that is it but I am not 100% sure.
  • div2div2 Posts: 2,580
    For $27 I'd say that it's worth a try. Better than letting some doofus at the dealer replace every mega-dollar part they can unbolt...
  • alcanalcan Posts: 2,550
    Anyone with a scan tool can access datastream and get live, accurate readings of the coolant temp sensor input to the engine control computer. Would take about 5 minutes from cold startup.
  • dmaljunkdmaljunk Posts: 160
    true but dealer did already and they said they can't find anything. These bastards don't even know how to use their $6,000 Consult-II computer. They look for a code and if it's there they replace the part, if there is no code then they are not gonna spend any time looking at voltages, resistence, pressure readings and making any intelligent conclusions... I have yet to find a descent mechanic...
  • dmaljunkdmaljunk Posts: 160
    I will let you know how it goes, I want to get down to the root of this problem as a matter of principle now :) If it's not this sensor then I will keep digging. By the way, I got the FSM for my car and it's amazing how many things you can do yourself, it's my new hobby
  • dmaljunkdmaljunk Posts: 160
    div2, your original suggestion on Engine Coolant Temperature Sensor being the cause of cold weather stalling symptom was correct!!! Thanks a lot. I bought the sensor, replaced it myself and I didn't get any stalling or shaking symptoms today on a cold morning and evening. I think the car is cured and only for $27, well a $5 3/4 wrench, which I needed for this repair as well... Thanks again.

    I'd like to quickly describe how the car behaves now after the sensor replacement. Can you let me know if this is normal or am I just paranoid now:
    1. Cold Start-up - engine revs to about 2200 rpm and immediately comes down to about 1300 at which it idles for some time, may be 30 seconds or so.
    2. Engine attempts to drop rpm to normal operating idle of about 700 or so. There is no hesitation or shaking, it drops the rpm, then it feels that engine is still cold and it bumps the rpms back up to about 1300 again and continues to idle. This step may occur two or 3 times before temperature guage climbs up about 1/4 of the way.
    3. Finally rpms drop to normal 700 or so and engine idles perfectly.

    Now, before I replaced the ECTS, at step two the car would start shaking real bad and stall, the only remedy was to hold foot on gas pedal. This doesn't happen now. But is step 2 necessary, do the rpms need to go down and then back up once it feels that temp is still too cold? Is this normal or an indication of a problem? Please let me know.

    Thanks again for your help or to anyone else who might reply to this post.
  • div2div2 Posts: 2,580
    I don't think the car should be doing that. Does it have an Idle Control Valve? If so, it may be dirty or sticking. I know that a wonky ICV can cause similar problems on BMWs.
  • dmaljunkdmaljunk Posts: 160
    actually, it got colder and the old original problem came back. It's stalling as I described before when the temp is below freezing. So, I flushed my coolant but it didn't help at all. As far IACV, the dealer supposedly replaced it along with my computer. This was when I had an engine service soon light for IACV but he also determined that the computer itself is bad and he only charged me for IACV and computer was replaced under Nissan good will. So, I don't know, supposedly IACV was replaced. Should I try taking it off and washing it? May be they just lied to me and never touched the volve?
  • cslicsli Posts: 1
    Hi dmaljunk -

    I have a 1996 Nissan Maxima and it has the same cold start problem. You mentioned that by changing the ECTS actually fixed it. I wonder if you can tell me where is the ECTS located and how can I change it?

    Thanks a lot!
    csli
  • dmaljunkdmaljunk Posts: 160
    It didn't fix it unfortunately, seemed to improve it but the symptoms came back on a really cold morning. Mine is a 2000 model and so 1996 should be different but basically, look for the main hose coming out of your radiator and as it enters a pipe, the sensor should be right on that pipe because it's inner part needs to be dipped into your antifreeze. There is a harness connected to the outside of the sensor. I needed to remove part of the air duct to get to it and a 3/4 wrench is required.
  • div2div2 Posts: 2,580
    The best thing to do would be to swap your IACV with a known good one. In any event, it can't hurt to look the thing over.
  • dmaljunkdmaljunk Posts: 160
    just disassembled the air duct today and got a good look at IACV - it's brand new, the whole part. The dealer didn't lie to me, they did replace it just a month ago. So, I am lost here again. What the... Logic doesn't work any more :) Hey, just a thought, can this be in any way related to oil? Suppose I have an oil leak and a gasket or seals are leaking or even worse - oil is leaking inside one of the cylinders, would that cause such symptoms on cold starts and go away as the car warms up? If not oil leak then let's say low oil pressure? Would that cause such symptoms? I am kind of dismissing this because I would have symptoms with warm engine as well but hey I am not the mechanic. Please let me knwo. Appreciate your help. Thanks
  • div2div2 Posts: 2,580
    If anything I'd think that it's a vacumn leak somewhere downstream from the HFM.
  • dmaljunkdmaljunk Posts: 160
    div2, vacuum leaks is something I heard about a lot and it definitely may be the cause. Can you explain what is a vacume leak and where do I look for it and how do I fix it? Is it like a cracked air hose or loose clamp? Oh ye, what's an HFM?
  • div2div2 Posts: 2,580
    HFM=Hot Film Mass Sensor=Air Flow Meter
    Check every hose connection between the HFM and the cylinder head. The ECU bases its computations on the air flow as measured by the HFM. Any unmetered air downstream from the HFM throws off the computations.
  • My '99 neon has an engine knock (fairly loud) when I start it up when it's cold. Sometimes it does it when it's been sitting over night and isn't very cold. It has 110,000 miles on it and I'm wondering if this means that it's about to die or if it's something I shouldn't really worry about. Otherwise the car seems fine for it's age...
  • If it's a real "knock", that's a pretty "heavy" sound---not a tick, tick.

    But if it is actually knocking, then the end is near, yes, unless you are just talking about a faint "piston slap" which could linger on for a while longer. Also wrist pin noises sound worse than they might be....but really, any knocking sound is not a good sign for the future----so plan for the worst.
  • Thanks for the response and being honest even though it's not what I'd like to hear.
    I'm not really sure how to describe the sound, but it is pretty loud. From what I hear about first generation neons I don't really think it's a minor problem. I also don't expect much from a car with so many miles on it.
  • If the rest of the car is nice you could always consider a good low miles used engine.
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