Alan Bowler Posted May 27, 2007 Share Posted May 27, 2007 Might be a bit premature, but after a wet weekend swapping parts around (thanks Charles Elliot) I seem to have made progress. First problem was ECU connector that had worked slightly loose (made worse by enthusiatic driving at Dunsfold I guess). Kangarooing while the engine warms up resolved (fingers crossed) by disconnecting lambda sensor 🤔 ❗ I'm not running with a catalyst. Looking at the sensor, it seems very white (dull white). Is this normal, or maybe silicon contamination? Anyway, question is, do I need the lambda sensor? Whats the effect of running without it? [Thanks again for offers of help on previous thread] AB Edited by - alan bowler on 29 May 2007 10:57:21 Link to comment Share on other sites More sharing options...
Alan Bowler Posted May 29, 2007 Author Share Posted May 29, 2007 BTTT AB Link to comment Share on other sites More sharing options...
Peter T Posted May 29, 2007 Share Posted May 29, 2007 It depends if you have an ECU that you can switch it of in, if so then nothing. But if your ecu is trying to read a sensor/lambda and it is disconnected then it will default to a program that is fairly safe. This is not something to rely on though if you intend to leave it disconnected for good , as engine damage could occur for reasons of poor timing or mixture. R500 260 BHP Mango Madness Link to comment Share on other sites More sharing options...
Mark Durrant Posted May 29, 2007 Share Posted May 29, 2007 Alan I think I have a spare Lambda sensor that came with the last car (need to check when I get home). If I still have it your welcome to try it to see if it solves your problem Mark D Comp Sec Link to comment Share on other sites More sharing options...
Alan Bowler Posted May 29, 2007 Author Share Posted May 29, 2007 ECU is standard EU3 Supersport, so I guess I need it. Seems to run pretty well without it though. Mark - yes please - YHM. AB Link to comment Share on other sites More sharing options...
MartinWoodham Posted May 29, 2007 Share Posted May 29, 2007 IIRC the ecu runs off the map if it can't get a lambda reading, and it runs off the map at wide open throttle anyway. Lambda control is there to manage emissions and is only effective at steady state throttle positions - under acceleration the ecu will add fuel anyway. So my guess is it'll only make a difference at idle/ constant throttle. Given that we're talking about a 7 here, you should clearly be wringing its neck at all times, in which case the lambda sensor isn't doing anything, apart from bunging up the hole in the exhaust manifold. 😬 Martin Aero'd supersported ex-Roadsports B...anyone got a cheap LSD? Link to comment Share on other sites More sharing options...
old captain slow Posted May 29, 2007 Share Posted May 29, 2007 Alan - what symptoms were you getting? C7 CDW Link to comment Share on other sites More sharing options...
Alan Bowler Posted May 29, 2007 Author Share Posted May 29, 2007 David, I had bad misfire, revs dropping to nothing when pulling away as the engine warmed up. Cleared with a heavy throttle blip. Was OK when up to temperature/ at high revs. Then I started getting misfires all the time. This was fixed (I think) by disconnecting/reconnecting the main ECU connector several times. I borrowed another ECU over the weekend, which always made a good connection. Mine is a bit stiff (ahem). I was able to reproduce the cold start/warm up misfire at will, and then fix it by disconnecting the lambda. It needs a few more runs to be sure (too wet yesterday), but I'm feeling positive. Seems to be using alot of fuel though. AB Link to comment Share on other sites More sharing options...
Mark Durrant Posted May 29, 2007 Share Posted May 29, 2007 If it is using a lot of fuel it would suggest it is running rich so I wonder if the temperature sender for the ECU is playing up Mark D Comp Sec Link to comment Share on other sites More sharing options...
old captain slow Posted May 29, 2007 Share Posted May 29, 2007 Reason I asked is I've had bad (I mean really bad) misfire and running on 2 cylinders. I cleared it by disconnecting and reconnecting the air temp sender and the water temp sender. I wondered if it was just one of these with a bad contact or if I was just kidding myself. I had previously changed the Lambda sensor and the throttle position sensor. Your opening sentence in your reply to me describes pretty much what was happening to my car, but mine was also doing it when revd under load. Edited to say mine was also smelling as rich as rats when idling. I've got my fingers crossed cos I'm taking it to Cornwall for a week so the next time it's tried will be down there. C7 CDW Edited by - David W on 29 May 2007 18:01:38 Link to comment Share on other sites More sharing options...
Alan Bowler Posted May 29, 2007 Author Share Posted May 29, 2007 Pretty sure my problems were down to lambda sensor - still disconnected and another problem free start/warm up cycle. I just checked the water sender - resistance was changing steadily as it cooled, so I think its OK (could be a broken wire to the ecu though, or incorrect resistance). It did feel like I was on 2 cylinders - espcecially on light acceleration pulling out of junctions as it warmed. Fuel use might just be my paranoia. Will measure it. David - when you replaced your sensor, did you check it wasn't the connector rather than the sensor itself that had failed, or a bad wire to the ECU? The wires all seemed a bit taught on mine. AB Link to comment Share on other sites More sharing options...
Mark Durrant Posted May 30, 2007 Share Posted May 30, 2007 Alan I still have the Lamda and it is already packed for the trip to Pembrey. I will also bring some electrical contact cleaner with me just in case it starts playing up again Mark D Comp Sec Link to comment Share on other sites More sharing options...
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