Stu_I Posted June 13, 2012 Share Posted June 13, 2012 Just investigating my exhaust system and it seems i (correct me if i am wrong) that i have 1 lambda sensor connected, and another one has been disconnected (cut off more like!). I have uploaded pictures here Hopefully you can see from images that by my catalyst and the lambda sensor has been cut, and inside the engine bay, another lambda sensor is connected. Any reason for this? Apologies if this is a basic question but quite new to 7 ownership so still learning my way around! Cheers, Stu Edited by - Stu_I on 13 Jun 2012 07:45:05 Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 Am i right in thinking that i should have 2 probes connected, the one near the exhaust manifold, and the one before the catalsyst. However, in my 7, the catalyst probe has been cut (or disconnected), so i only have 1 probe connected. What are the disadvantages of this? Do i need both connected? Is it a simple job to re-connect? Cheers, Stu Link to comment Share on other sites More sharing options...
charlie_pank Posted June 13, 2012 Share Posted June 13, 2012 stu, I can't see the pictures. It's not normal to have 2 lambda probes connected. Perhaps someone fitted a wideband and didn't tidy up the old one properly. what engine do you have, and in what state of tune? Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 Morning Charlie. Is this any better? Hopefully sorted last link! Engine is a 1.8VVC K-series engine 160bhp. Cheers, Stu Link to comment Share on other sites More sharing options...
charlie_pank Posted June 13, 2012 Share Posted June 13, 2012 I can't see why you'd put the lambda on a single primary like that instead of at the collector like the one that has been removed. You'll only know the mixture of one cylinder with your current setup. Maybe the perpetrator didn't like soldering and didn't want to extend the wires/ Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 All seems a bit wierd.... hence the question! So the lambda that is on the single primary should really be removed, as you said, currently it would only be reading the mixture from one cylinder and not all. I should re-route and use the one from collector should instead, which in theory would mean all cylinders are monitored. Ive been asked whether mine has one or two lambda sensors. Do you you see a need for two? In my mind, i would imagine they would be doing the same job so no need? So how do i know if mine is a wideband or narrow band lambda sensor? Reading about both, it doesnt seem likely that someone would have both on as from what i have read the wideband is abit more advance lambda than the narrow band, as well as telling the engine if its running lean or rich, but also by an amount. Stu Link to comment Share on other sites More sharing options...
Jerry Auton Posted June 13, 2012 Share Posted June 13, 2012 In case it's helpful; mine has two options for the sensor (as yours) and is currently in the primary. (K 1.8, powerspeed exhaust) Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 Hey Jerry. So same situation as mine? Now i am wondering why i have two options, one by primary and one by collector. Stu Link to comment Share on other sites More sharing options...
Mankee Posted June 13, 2012 Share Posted June 13, 2012 I also have a lambda sensor in just the one primary. The second one you have near the CAT was probably fitted to aid the fitment of a wideband lambda for mapping duties as it's easier to get to. The previous owner may not have bothered to get a proper bung and just used an old lambda sensor. I've done the same thing before on a previous car, but the exhaust stayed in the shed for 364 days of the year, so it didn't matter! Link to comment Share on other sites More sharing options...
Jerry Auton Posted June 13, 2012 Share Posted June 13, 2012 Ah! Yes, I recall now Powerspeed telling me that (mapping) was the reason for the one by the collector . Edited by - Jerry on 13 Jun 2012 11:35:16 Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 For my limited knowledge .... you wouldnt run a wideband and narrow together would you? It would be one or the other? Actually dont even know what my exhaust is! I am assuming it is a 4-1 but no idea if it is powerspeed or another brand. Edited by - Stu_I on 13 Jun 2012 11:57:52 Link to comment Share on other sites More sharing options...
Mankee Posted June 13, 2012 Share Posted June 13, 2012 You can do, but they do different things and you don't really even need a lambda sensor if your management is set up that way. Looks like you have standard management though, so your standard narrow band sensor only affects fuelling at light/medium throttle and below certain revs. At wide open throttle and high revs, the management doesn't use the lambda sensor for fuel trimming. A wideband is useful for a gauge on the dash or for finer readings when you want to make precise mapping adjustments. Or if your management is set up for it, you can use a wideband to set up self-mapping. Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 Ok making a bit of sense 😬. I am busy trawling through archives trying to understand lambda sensors with the 7 and other owners experiences. I am in process of importing the car to germany so emissions are now top of my list, hence trying to understand the exhaust system and emissions. Especially if i didnt understand why the collector option had been bunged, and getting questions on whether i have one or two lambda sensors. I presume my exhaust is a standard 4-1 exhaust, with narrow band lambda sensor. Would be nice to understand any key features on both to see for sure what i have. Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 Sooooo now trying to understand how it works. From reading about narrow band lambda sensors, they only know that the engine is running rich or lean, not by the amount, so based on the air/fuel ration then know it is above or below. When the engine is idling, or in low load conditions, it is operating in a closed loop condition. In this condition, the ECU and Lambda sensor talk to each other and the ECU adjusts the amount of fuel based on the "chat" about air/fuel ratio. When the engine is revving, or high load, it is operating in open-loop mode, whereby the sensor is ignored, and the ECU enriches the mixture to protect the engine. if i was using a wideband, i would know the exact air / fuel ratio, and either able to see it (via gauge or equipment) or make adjustments. Does that mean you are manually "talking" to the ECU and controlling the air / fuel ratio? So for instance, if you were over the 1.03 range, you could control it more accurately? If was not using a wideband, and my range was lets say over 1.03, how would the process differ with a narrow band, as i wouldnt know the amount, i would just know it is either "too rich" or "too lean". Apologies if these are numpty questions.... just need to understand how mine is working! Link to comment Share on other sites More sharing options...
Mr Locust Posted June 13, 2012 Share Posted June 13, 2012 The exhaust looks like a Caterham SLR road system (long 4-1 cat). Lambda bosses are fitted in no 4 and the inlet cone of the cat. With a std ecu setup, the working sensor is most likely to be a narrow band unit. The one with the cable cropped is probably just filling the hole up! Link to comment Share on other sites More sharing options...
charlie_pank Posted June 13, 2012 Share Posted June 13, 2012 I agree that the spare probe is just plugging the hole. With a wideband unit, things happen too quickly to be able to tweak manually as you're driving. You either log the AFR along with throttle position, fueling and RPM and then make adjustments to the map later, or you run something like the Emerald setup which has a map for target AFR and makes its own adjustments based on what the wideband tells it to achieve the required AFR all the time. Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 Cheers for replies . So depending on the ECU (emerald in your example), depends on whether the wideband would plug directly into the ECU (and talk to it) or you would use your std ECU and manually adjust based on the wideband results. Link to comment Share on other sites More sharing options...
charlie_pank Posted June 13, 2012 Share Posted June 13, 2012 If you're going to manually adjust based on the results, you'd need some kind of unit to datalog to give you the info you needed to make the adjustments. Link to comment Share on other sites More sharing options...
Stu_I Posted June 13, 2012 Author Share Posted June 13, 2012 Things are a lot clearer. Would be interesting to see other owners setups and pictures. Its definitely been "you learn something everyday" days 😬 Edited by - Stu_I on 13 Jun 2012 14:47:43 Link to comment Share on other sites More sharing options...
Grim Reaper Posted June 13, 2012 Share Posted June 13, 2012 It's not recommended to fit a wideband Lambda sensor close to the exhaust port, 40"/100cm is recommended position (to avoid overheating) here Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 13, 2012 Share Posted June 13, 2012 My 1.8 VVC has the sensor in No. 4 primary. I have a 4-2-1 collector with a socket at the entry to the silencer/cat - with a bung in it. I would like to relocate the sensor there (by extending the cable), but not sure there is room between the socket and the sideskin ? Link to comment Share on other sites More sharing options...
charlie_pank Posted June 13, 2012 Share Posted June 13, 2012 Try it and see? Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 14, 2012 Share Posted June 14, 2012 It is on the list - when I get some time at home ! Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted June 15, 2012 Share Posted June 15, 2012 Did it this afternoon - it works. Link to comment Share on other sites More sharing options...
Mr Locust Posted June 15, 2012 Share Posted June 15, 2012 Like it was designed to go there? Link to comment Share on other sites More sharing options...
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