HedgehogSandwich adi Posted March 25, 2002 Share Posted March 25, 2002 What do you lot do with your lambda sensors after a cat removal? Mine is just hanging above the (now decatted) pipe and apparently causing fuelling problems. Cheers adi Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 25, 2002 Share Posted March 25, 2002 Your decat pipe is no damned good without a place to put the thing so get a nicely made fitting done and screw it into place, just as on my Decat pipe, you shuld also try to place in about the same place longitudinally. Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 25, 2002 Share Posted March 25, 2002 Ahem. You'll find that the decat sensor is the one installed into the pre-downpipe exhaust section. You can see it easily from the engine bay - looking at the turbos with the front of the car on your right, it's level with turbo #2 (the one nearest the windscreen). Following the exhaust pipe downstream, after the lambda sensor you get the flange that the downpipe connects to. Then it's the downpipe, sans CAT. The sensor that is left over post-decat is the CAT temperature probe. It's required to be left attached to the car electrical system, but it doesn't need to be in the exhaust pipe. All it does is report to the ECU that the CAT is going into meltdown - which ain't going to happen as it's sat in the garage Wire the thing up to the chassis and forget about it. Obviously Soarers must have their CAT temp probe and the Lambda sensor in the same bit of pipe, hence the confusion. Now - fuelling problems? Hmmm. Describe the problem! Underfuelling? Overfuelling? Running rough? Where in the rev range? what behaviour, etc. etc.? -Ian Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 25, 2002 Share Posted March 25, 2002 Ahem, what's a Decat Sensor? (Edited by Mycroft at 9:28 pm on Mar. 25, 2002) Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 25, 2002 Share Posted March 25, 2002 Senses de cat, mon.... I slipped into some Jamacian patios (pah-twa before you get pedantic on that) for a minute. This is interesting, as it's occured to me that the 7M-GTE engine (mkIII Supra) also had the lambda sensor prior to the downpipe. And all the replacement downpipe's I've seen advertised for other cars haven't even mentioned that they are pre-fitted for the lambda sensor. Now, I would have thought that the lambda sensor should be as close to the turbo's as possible to get the best reading. As there is no real mechanical or design reason why it should be in either the turbo pipe or the downpipe, the designers would surely put it in the turbo pipe to satisfy the need to get it in the exhaust stream as early as possible? The 7M-GTE precludes the 1JZ-GTE, and the 2JZ-GTE comes after, and they both have the sensor in the turbo pipe, not the downpipe. So why did Toyota move it to the catted-up downpipe on the 1JZ, and then back again for the 2JZ? Intriguing. I've had a shufty around the net, but haven't found anything interesting on Soarers yet... But I'll keep looking. -Ian Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 25, 2002 Share Posted March 25, 2002 There are a few good reasons for keeping the probe out of the engine bay and closer to the first harmonic in the exhaust, your sequential system precludes this as the first harmonic moves as the second turbo finally gives some punch, so to keep the casing clean and to provide a correct EP across the membrane it is mounted quite close to the headers, can be the cause of the over rich tendency that is present in Supra's but entirely absent in Soarers. You can solve this problem, as I expect you know already. Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted March 25, 2002 Author Share Posted March 25, 2002 Right...so is it a cat temp sensor or is it a lambda? There is a light on the dash which illuminates when the cat overheats, and seeing as this is the only sensor in the cat then i suppose it stands to reason it would be the heat sensor for the cat. Although i've no doubt mycroft is also right in his diagnosis as the cat on the soarer defintely has the lambda sensor in it. But the big question is....does my exhaust design follow supra rules or soarer rules.... The 1JZGTE supra seems to be a cross breed between a soarer and some sort of prototype test jobbie for the 2JZ. It shares techologies designs from both, yet also uses its own individual ideas. Madness.. Right, so is there any way of telling what it is...i take it if i find a lambda further up the frontpipes then the cat sensor has to be a for temp, if there isnt one i'll take it its a lambda sensor. or maybe not.. Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 25, 2002 Share Posted March 25, 2002 Just have a look, Hedge. There should be two probes - one for lambda, one for the CAT temperature. One of these should still be installed, otherwise the car would be sending unhappy signals to you. Can you bag a photo of the exhaust side of the engine? (I'm assuming that you have a 1JZ?) If not, let me know where the lambda sensor currently is. It's fatter than the CAT temperature probe, and has four wires under the cable sleeve, not two. The best piccy I have is off my MkIII - it's the big fat sensor in the right-hand red circle, sticking down into the turbo exhaust elbow. http://www.ian.chisholm.clara.net/gfx/supra/manifoldstud.jpg We discussed the usage of the 1jz as a test-bed for the 2jz technology in a previous thread, I think. The parallel twin setup does seem a prelude to the funky sequential system. What's the fuelling probs you have, then? -Ian Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2002 Share Posted March 26, 2002 Quote: from Mycroft on 10:06 pm on Mar. 25, 2002[br]There are a few good reasons for keeping the probe out of the engine bay and closer to the first harmonic in the exhaust, your sequential system precludes this as the first harmonic moves as the second turbo finally gives some punch, so to keep the casing clean and to provide a correct EP across the membrane it is mounted quite close to the headers, can be the cause of the over rich tendency that is present in Supra's but entirely absent in Soarers. You can solve this problem, as I expect you know already. Aha - so there is a technical reason for it. Thought there might be. I didn't know that the Toyota techs introduced a problem with the Supra fuelling by moving to the 2JZ design though. What a daft move. I also didn't know that Toyota moved the probe out of the engine bay itself on the Soarer. The engine design sounds radically different in this respect (as the first cat on the Supra is still in the actual engine bay, never mind the lambda sensor!), and I really would like some piccies - I am interested in learning this stuff, especially when it's engines I will come across more often than not. You must have some shots of this bit to display, surely? Regarding the Supra running rich - I haven't heard of this problem before, so I definitely don't know about it already, let alone how to solve it! I don't claim to know everything, just stuff I've had practical experience of Anything else and I would be dangerously close to talking shite! So, in closed loop mode, the engine runs rich because the lambda sensor is too close to the turbos, yes? How does that happen? I thought closed loop was just that - it balances itself out eventually? And if the sensor is closer to the headers than on the soarer to keep it clean, does that mean the soarer's one gets dirtier? Wouldn't that eventually affect the fuelling more than simply having the sensor a bit closer to the headers? And how does the sensor being closer to the headers actually keep it cleaner?! Or is this all a facet of the soarer's more basic parallel twin setup in some fashion? -Ian, learning new stuff every day... Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 26, 2002 Share Posted March 26, 2002 Quote: from Mycroft on 10:06 pm on Mar. 25, 2002[br]There are a few good reasons for keeping the probe out of the engine bay and closer to the first harmonic in the exhaust, your sequential system precludes this as the first harmonic moves as the second turbo finally gives some punch, so to keep the casing clean and to provide a correct EP across the membrane it is mounted quite close to the headers, can be the cause of the over rich tendency that is present in Supra's but entirely absent in Soarers. You can solve this problem, as I expect you know already. Ehh? I don't follow much / any of this at all? Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 26, 2002 Share Posted March 26, 2002 Do you know how the Lamda probe works? How it compares 'natural air' againt exhaust gases? That it is in fact 'hollowed out' for just this purpose? I ask because I don't wish to patronise by starting at the basics or make you feel like a moron by starting to far up the evolutionary tree. (Edited by Mycroft at 5:45 pm on Mar. 26, 2002) Quote Link to comment Share on other sites More sharing options...
Syed Shah Posted March 26, 2002 Share Posted March 26, 2002 Be aware that Chris is probably the most knowledgeable member of the BBS. I 'think' therefore he just wants you to put your question more clearly Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 26, 2002 Share Posted March 26, 2002 My reply was ained at Ian C, CW's post was made in the interim. I try to avoid explaining things so that only the smartest 'kid' in school understands, finding an acceptable norm is quite hard, too simple and the 'smart' members decry it as too simple and 'wrong' because 'you didn't mention 'this'', too techy' and the members with no 'history' of car involvement feel excluded and talked down to. Both 'versions' just create too many additional postings which leads to frustration in the poster. You have seen this before apparently, people come start to do/say things, mis-judge the 'level' at which to 'pitch' the info and upset a few who just become sarcastic, slagging off/X-questioning all and everything they say. As Ian C said yesterday, 'seen it all before' it is boring. All the forums lose their 'tech' guy(s) quite quickly, or they just get fed up and stop trying to help. Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted March 26, 2002 Author Share Posted March 26, 2002 Well' im happy enough you technical bods have been here to help on this one (and the other two forums i've been posting it on )!! Right, i've now decided its a heat sensor, and as such will leave it alone. Yes Ian it is a 1JZ, on my old 3.0t i seem to remember the lambda sesnor stuck in the manifold, and it was much bigger than this little thing (the one i just removed is about and inch and a half long, thickness of a biro). And it also only has two wires under the sleeve. Its very diffiuclt to make a diagnosis with this engine as although its the same as a soarer, many parts, such as the exhaust .(along with turbo operation, ecu etc)..are different. I may not have a fuelling problem, its just that it was suspicious after some plug fouling and dodgy running...i need to get it checked to be on the safe side. Thanks for everyones help. (Edited by HedgehogSandwich adi at 9:33 am on Mar. 26, 2002) Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted March 26, 2002 Share Posted March 26, 2002 Quote: from Mycroft on 8:02 am on Mar. 26, 2002[br] You have seen this before apparently, people come start to do/say things, mis-judge the 'level' at which to 'pitch' the info and upset a few who just become sarcastic, slagging off/X-questioning all and everything they say. Unfortunately talk is one thing, but when individuals produce the goods (e.g. Chris Wilson) then they gain the respect that they so desperately seek. Still this is a technical thread and not the place for sentiments. Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2002 Share Posted March 26, 2002 Quote: from Mycroft on 12:43 am on Mar. 26, 2002[br]Do you know how the Lambda probe works? How it compares 'natural air' againt exhaust gases? That it is in fact 'hollowed out' for just this purpose? I ask because I don't wish to patronise by starting at the basics or make you feel like a moron by starting to far up the evolutionary tree. Haven't got a clue how it works, which is why I'm asking loads of questions! I'm trying to apply common sense, educated guesses and what little I do know to ask the right questions in order to learn. Regarding not knowing what level of knowledge to aim at, I find that the best way to handle such situations is to say what you would normally say without going into too much detail. The response from the questioner should then allow you to judge the level you need to aim at. I won't feel like a moron, I assure you - I don't know much at all about cars/chemistry/gas flow thermodynamics, but I'm willing to admit this and I'm ready to learn. But I also question things so that I get it straight in my head - I hassled Pete Betts a lot when I was trying to diagnose the electrical fault, as I don't know much about electronics either (but now I know enough to fix problems like that on my own - hurrah!) -Ian Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2002 Share Posted March 26, 2002 Quote: from HedgehogSandwich adi on 9:26 am on Mar. 26, 2002[br]Well' im happy enough you technical bods have been here to help on this one (and the other two forums i've been posting it on )!! Right, i've now decided its a heat sensor, and as such will leave it alone. Yes Ian it is a 1JZ, on my old 3.0t i seem to remember the lambda sesnor stuck in the manifold, and it was much bigger than this little thing (the one i just removed is about and inch and a half long, thickness of a biro). And it also only has two wires under the sleeve. That's the CAT temperature sensor, all right. Did you spot the lambda probe? I'm concerned about this as it seems it should be in the downpipe on a 1JZ, and I can't find any images anywhere to see where you should be looking. If it's just hanging outside the engine bay, your fuelling may well be iffy, and potentially the ECU isn't reporting any problems as it's still attached to the wiring loom... It must think you are running all kinds of lean if it's detecting ambient air :biggrin: -Ian Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2002 Share Posted March 26, 2002 Quote: from Martin F on 10:23 am on Mar. 26, 2002 Unfortunately talk is one thing, but when individuals produce the goods (e.g. Chris Wilson) then they gain the respect that they so desperately seek. Still this is a technical thread and not the place for sentiments. Heh - you'll find Chris Wilson desperately seeks faster lap times, not respect -Ian Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted March 26, 2002 Share Posted March 26, 2002 Yeah i noticed that my post could possibly be mis-interpreted, but i'm sure Chris knows what i'm getting at. Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 26, 2002 Share Posted March 26, 2002 Technical Thread, yeah right. Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 26, 2002 Share Posted March 26, 2002 Ian C are you sure the Lambda probe IS in the down pipe on the JZA70 1JZ motor, I know adi said so earlier but I think he may have given the wrong name to the piece he meant! Quote Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2002 Share Posted March 26, 2002 Hell no - I've never looked at a soarer or a 1jz-equipped Supra in that much detail, I have no idea where it is - I was going on your initial reply!! I know Adi said that the lambda sensor was loose post-decat and it turns out it's the cat heat sensor - my first post tried to clear that confusion up. From then I was going on your post indicating that the lambda sensor should be in the cat/decat pipe, i.e. the decat pipe is no good damned good without it in place. you sounded quite emphatic What with Adi's comment about the fuelling, I figured this needed investigation... As your decat pipe has the lambda probe in it, and it's the same engine (if not the same car wrapped round it), I think it's important that Adi checks to see just where the thing is on his car, so we can see if it's plumbed in or not! C'mon Adi, tell us, tell us! -Ian Quote Link to comment Share on other sites More sharing options...
Guest Mycroft Posted March 26, 2002 Share Posted March 26, 2002 I'm CERTAIN that if the lambda probe is dangling under the car and there are fuelling problems the 2 would be connected! Quote Link to comment Share on other sites More sharing options...
Guest Martin F Posted March 26, 2002 Share Posted March 26, 2002 Quote: from Mycroft on 6:09 pm on Mar. 26, 2002[br]Technical Thread, yeah right. It was until your emotional outburst. :biggrin: Quote Link to comment Share on other sites More sharing options...
HedgehogSandwich adi Posted March 26, 2002 Author Share Posted March 26, 2002 A lambda what? what were we talking about again? Ah yes..i remember No im certain this is a cat heat sensor, like i said earlier my fuelling issues were guesses and nothing else. I've had dodgy running before but that was caused by filling with opti, but spomeone also mentioned that this may have been because of lean running, or igntion. Also someone else looked at my car the other day and said i had a slight miss at high revs. putting it all together i came up with the notion i may have fuel/ignition problems, and all this was totally unrelated to the lambda sensor, it was just coincidence it came about at the same time. Right....next point. I distinctly remember the lambda on my old mk3, size shape etc. I've had a look at my JZA and it appears there is one under the turbo's somewhere, possibly near the downpipe...but like i say very near the turbo's. There may be another but i haven't spotted it yet. I think Ian is right that the lambda is in the downpipe. The 1JZ soarer and 1JZ supra are seem to share block and head, but thats about it. As far as inlet, ECU's, exhaust, and various other bits they are different. So, you can seem my dilemma. At the moment Mycroft and the lexusclub are my best source for info, yet after that its guesswork. Unfortunately there are so few of these in the UK and america its impossible to find decent info written in english. In japan theres loads of them, but even with a translation site its impossible !! adi Quote Link to comment Share on other sites More sharing options...
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