Naylor2006 Posted September 11, 2012 Share Posted September 11, 2012 (edited) Last monday when I started the car I was most frustrated to find that it started fine for a second then the revs plummeted and it barely ran at all, it stayed this way until the car was warm however it still didnt idle great at times. Given my history with idle issues I just thought that my new idle control valve had failed and researching my problem didnt seem to throw up lambda sensor issues as they are apparently ignored during a 'closed loop startup' So I ignored that it could even be an issue and blamed my pattern part ICV Well like many times before I was wrong, after fitting a gen ford valve my cold start issue was as bad as it always has been, so then everything was inspected and there it was, my lambda sensor had like 1 wire in tact going into it and the others as broken, given the proximity of this to the Air Con pump and the fact that my problems occurred technically 2 days after I had my system re gassed I could be forgiven blaming the air con guy. My mate a few months back had identical symptoms in his escort when his wires all broke off. New sensor and my idle is back to normal and so was his, as well as the other issues common with faulty lambdas which I kinda didnt notice so much given how bad the cold start was. So the reason im posting is that why has this caused these problems, I can understand why I was getting the other issues whilst the car was run up as the lambda would confusing things but why on a cold start when many people say it doesnt get used until the car is warm? Edited September 11, 2012 by Naylor2006 Link to comment Share on other sites More sharing options...
Stu Posted September 11, 2012 Share Posted September 11, 2012 So what exactly are the conditions where you think the oxygen sensor is causing you a problem? Link to comment Share on other sites More sharing options...
Ahmotorsport Posted September 11, 2012 Share Posted September 11, 2012 Modern lambda sensors have heater elements which only take a minute or two (most likely quicker than that now, i'm a bit out of date) to warm up, so your lambda starts working quite quickly, without the element, they take a lot longer. They're probably down to a matter of seconds these days. Link to comment Share on other sites More sharing options...
Stu Posted September 11, 2012 Share Posted September 11, 2012 How can you be out of date? Oxygen sensors have been heated since you were in nappies. Link to comment Share on other sites More sharing options...
Ahmotorsport Posted September 11, 2012 Share Posted September 11, 2012 How can you be out of date? Oxygen sensors have been heated since you were in nappies.Because the majority of cars i work on them either don't have them i.e classic cars/race cars or had only just come in at the time. Link to comment Share on other sites More sharing options...
Naylor2006 Posted September 11, 2012 Author Share Posted September 11, 2012 (edited) So what exactly are the conditions where you think the oxygen sensor is causing you a problem? It isnt anymore, its sorted now with a new one. Stone cold start after sitting all night or similar, start the car and initially for a split second you get the initial burst of revs then plummets straight after and the car barely idles at all, doesnt cut out but runs lumpy as hell. In hindsight I had more than cold start issues but it was easy to focus on this as it was the most dramatic and considering I thought the lambda does nothing at this time I ruled it out causing the general poor idle and running, havent been booting it around to feel it holding back etc which you can associate with lambda too so I thought wrongly I have an idle problem thats most poor on cold start, blamed the wrong part, tis what idiots do. Modern lambda sensors have heater elements which only take a minute or two (most likely quicker than that now, i'm a bit out of date) to warm up, so your lambda starts working quite quickly, without the element, they take a lot longer. They're probably down to a matter of seconds these days. Were talking less that a second, as soon as ive taken my hand of the key, once the initial burst of fuel is burnt it plummets, well it did. Edited September 11, 2012 by Naylor2006 Link to comment Share on other sites More sharing options...
Stu Posted September 11, 2012 Share Posted September 11, 2012 The HEGO sensor isn't used that quickly on cold start. If your ECT sensor was mis-reading, perhaps the engine thought it was in warm running mode when it wasn't? Who knows. Link to comment Share on other sites More sharing options...
Ahmotorsport Posted September 11, 2012 Share Posted September 11, 2012 Were talking less that a second, as soon as ive taken my hand of the key, once the initial burst of fuel is burnt it plummets, well it did.That's what i mean, if theres no heating element working, there's no Lambda working. Link to comment Share on other sites More sharing options...
JC Posted September 11, 2012 Share Posted September 11, 2012 Question, have you got a diagnostic tool? I have one and very useful! Link to comment Share on other sites More sharing options...
Naylor2006 Posted September 11, 2012 Author Share Posted September 11, 2012 The HEGO sensor isn't used that quickly on cold start. If your ECT sensor was mis-reading, perhaps the engine thought it was in warm running mode when it wasn't? Who knows. Exactly why I didnt even check it, it's an instant drop. Could be a side effect of 2.0l conversion, my mate had the exact same thing with his when his wires broke of, same conversion as us. Maybe something different happens with the cold start sequence, who knows. Question, have you got a diagnostic tool? I have one and very useful! No but I think I'm gonna get one, guess it makes electrical things much easier to diagnose. Link to comment Share on other sites More sharing options...
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