| Author | Message | ||
     Brent Bevil (Brbevil) New Member Username: Brbevil Post Number: 15 Registered: 02-2003 |
Could I wire the connects from the other three O2 sensors into one? Thus fooling the computer the readings are the same or would that royally screw things up? | ||
| Parrish R. Blackmon (Discoveryfl) Member Username: Discoveryfl Post Number: 81 Registered: 10-2002 |
I have done quite a bit of research on this topic. My understanding is that the front O2 sensors control the left and right banks and that connecting them together will screw things up. Better to leave them alone. The rear sensors (behind the cats) are only for cat sensing, which essentially tell the ECU that your cats are going bad and serve no engine tuning purpose. I am going to attempt connecting these two wiring bundles together so that I can remove the two cats and replace them with one super high flow. | ||
| Brent Bevil (Brbevil) New Member Username: Brbevil Post Number: 16 Registered: 02-2003 |
Parrish - Let me know how that goes. Thanks for the info on the O2. I didnt think about the L & R banks. | ||
| Shaun Power (Shaunp) Member Username: Shaunp Post Number: 84 Registered: 05-2003 |
Most Australian cars don't have cats or O2 sensers the ECUs are the same the only differance is the tune restistor non cat is 180 ohm and cat is 3.9 k ohm. As a result Oz car don't show as many error codes. This is for 14 CUX injection. If any one is interesrted I still have my factory LR injection testset book ( the one that comes with the factory tester). Happy to pass on details. | ||
| Paul T. Schram (Paulschram) Senior Member Username: Paulschram Post Number: 1803 Registered: 02-2002 |
Shaun: The 14 CUX doesn't use four oxygen sensors. The four sensors did not come into use until the GEMS system was implemented. | ||
| Love Jones (The_tool_man) Member Username: The_tool_man Post Number: 47 Registered: 06-2003 |
soooo.... shaun, how can we fool the ECU? | ||
| Paul T. Schram (Paulschram) Senior Member Username: Paulschram Post Number: 1807 Registered: 02-2002 |
It is going to be very difficult to fool the ECU into thinking there is an oxygen sensor connected when there isn't one. The output from the oxygen sensors varies constantly and the ECU makes changes based upon this input. If you were to make a circuit that would provide a continuously changing output voltage that the ECU would see as an oxygen sensor output, the ECU will make a change based upon that input. When the oxygen sensor returns a non-sensical response to a change made by the ECU, you are going to see multiple fault codes, none of which will be true, save for oxygen sensor non-response, or out of range. | ||
| Kyle Van Tassel (Kyle) Moderator Username: Kyle Post Number: 365 Registered: 11-2002 |
You can have the chip burned and delete the O2s or there is a jumper that sets it middle of the road. This is true for other makes and I am sure can be done on the rover. Why would you want to jump around them ? Others do it on go fast cars ... Or are you trying to save a buck by not replacing the o2s? "Blow me" | ||
| Shaun Power (Shaunp) Member Username: Shaunp Post Number: 88 Registered: 05-2003 |
Paul Australian cars only run 3.9 engines with 14 cux injection. Range Rover ser 2 run 4.0 and 4.6 with mems. Ser2 discos run the 4.0l as per Rangies. It would seem our less stringent smog laws mean we make do with the left over parts. I do have some spare MEMS ecu's and bitts and pieces though. | ||
| Paul T. Schram (Paulschram) Senior Member Username: Paulschram Post Number: 1817 Registered: 02-2002 |
Shaun: NAS rigs are similar, with NBS Rangies having the OBD-II distribuotr-less system (engines without distributors are the work of the Devil!), something I just learned! The 1996 and later Discos all use the four sensor system as well. As for removal of oxygen sensors, one can remove them and manipulate things to make it work, however, one will not likely be particularly efficient, nor clean. While I'm not concerned about either of these situations, I see little to no reason for removing the sensors for a nebulous cost savings that will likely be consumed in increased fuel consumption. | ||
| Shaun Power (Shaunp) Member Username: Shaunp Post Number: 89 Registered: 05-2003 |
Paul according to my LR test book instruction manual it reckons all 14cux ecu's are the same and that the fuel map for the particular market is selected by the "tune State resistor", this is taped into the loom near the ecu connector. Cat cars use a 3900 ohm resistor, Oz cars use 180ohm,Saudi 870. These resistors are just 1/4 watt units that cost about 10c. So if anyone wants to try a different fuel map I reckon you could just disconnect the O2 sensors and try the Australian or Saudi map. I don't know if you guys have have emission checks on your cars, if you ran the Oz map it won't meet your emission levels but it might go a bit harder. On another matter are you permitted by law to replace you ECU with an aftermarket unit. I have recently fitted an Australian unit called a Wolf 3d to a Jag and it works a treat. The car has heaps more power. This unit comes with it's own testbook/programmer or you can do it with a lap top. It stores 2 maps that you can switch on the move. You can get rid of the air flow meter as it uses a vacuum map sensor. It will map your ignition timing with or without a distributor and will run closed loop with O2 sensors if you want. All this for $1200 Oz ($780 US). | ||
| Love Jones (The_tool_man) Member Username: The_tool_man Post Number: 49 Registered: 06-2003 |
Shaun said: "I don't know if you guys have have emission checks on your cars, if you ran the Oz map it won't meet your emission levels but it might go a bit harder." what do you mean by go a bit harder? also, we do not have emissions requirements in our city. PLUS we live mostly in mexico, so there are no emissions tests there. i wrote you an email. i would like to know about the ecu fuel mapping. | ||
| Love Jones (The_tool_man) Member Username: The_tool_man Post Number: 50 Registered: 06-2003 |
also, will this modification eliminate the codes 44-45 from appearing? also, my d1 is a 3.9, does it use a 14cux? paul, i am not trying to take any short cuts, i am just trying to rid my disco of things that will DEFINATELY fail in the mexican jungle. | ||
| Paul T. Schram (Paulschram) Senior Member Username: Paulschram Post Number: 1840 Registered: 02-2002 |
I replaced my oxygen sensors at 173K miles and they probably were working acceptably at the time. They are far more likely things to break than one's oxygen sensors-I'd almost go so far as to say that oxygen sensors would be the last thing to go on my list of emergency breakdown parts. If nothing else, the truck would go into limp-mode and you'd get home. Yes, your truck is managed by a Lucas 14-CUX engine management system. | ||
| Parrish R. Blackmon (Discoveryfl) Member Username: Discoveryfl Post Number: 83 Registered: 10-2002 |
Here's the deal. The exhaust system on the Discovery is incredibly inefficient. What I want to do is make it more efficient. By removing the two catalytic converters and replacing them with one high efficient converter (and one high efficient muffler) will diffenently improve the vehicle's performance and fuel mileage. The only issue are the rear O2 sensors behind the two cats. I have no desire to mess with the two sensors in front of the cats that control engine tuning. Thoughts? | ||
| Paul T. Schram (Paulschram) Senior Member Username: Paulschram Post Number: 1846 Registered: 02-2002 |
Just remove them and expect the MIL light to be on constantly. As Kyle said, you can probably burn the EPROM to delete the rear-most sensors. I was mistaken in that I thought you were trying to save some money and achieve a performance gain, neither of which would be easy to attain with no oxygen sensors. Peace, Paul | ||
| Shaun Power (Shaunp) Member Username: Shaunp Post Number: 92 Registered: 05-2003 |
I don't know what US cars go like but from reading this forum it doesn't sound like they go any better then the OZ cars infact it sounds like they use more fuel even with closed loop injection. I guess this is the cost of emmision laws, more complex more fuel less power. Raf I will reply to your mail on how OZ cars are set up if you really want to have ago at the Oz fuel map as soon as I can. | ||
| Peter Matusov (Pmatusov) Senior Member Username: Pmatusov Post Number: 886 Registered: 09-2002 |
wonder how many of you guys ever tried to build an audio power amp with no negative feedback... maybe not too many. it is unbelievably hard. More so is to make fuel delivery consistent with engine and driver's demand. If anyone's taken apart a Quadrajet and sorted out all vacuum hoses in a mid-80s car, he/she'd know it all. The lambda sensor was a blessing for automotive industry, 'cause the required emissions levels could be met in a pinch. Things simplified ever since, and OBD-II is a simpler and more efficient system than all before it. So, why fuck with a nearly perfectly working thing? Parrish, where does the information about LR exhaust being "incredibly inefficient" come from? Do you have numbers? Know exhaust backpressure at full throttle? The only thing that doesn't look pretty in a Disco's exhaust is the manifolds - and that's where your options are limited to nearly none. Now, you're sure aware of the fact that with a free-flowing exhaust you'll lose low-end torque? By the way, there's a whole industry about fooling the ECU with bogus sensor signals, and its only purpose is to shove more gasoline into the engine. I think I could design a circuit that would take an O2 sensor signal, and modify it in a way that ECU would think there's extra oxygen in the exhaust. Will you get more power? Yes. At an expense of quickly destroyed cats and (if that bothers you) running a vehicle with illegal emissions equipment. | ||
| Ken Dunnington (Ihwillys) New Member Username: Ihwillys Post Number: 44 Registered: 09-2002 |
Why not install both of the rear sensors in the now single exhaust after the cat? This keeps the sensors you already have. All you have to do is a little more welding. If you were really pinching pennies(which I doubt considering the mod), you could cut out the bungs and weld them into the single exhaust. Ken | ||
| Parrish R. Blackmon (Discoveryfl) Member Username: Discoveryfl Post Number: 84 Registered: 10-2002 |
Ken, I'm working on that angle as well. As a matter of fact, I'm leaning that way. Sensor welds only cost about $3 a piece. It's hard to believe that anyone would disagree that the Discovery system is not inefficient. Small displacement V8, relatively no horsepower, and 10 miles per gallon. Crap, and some of that has to do with the exhaust system. Perfect closed OBD-II system? That's quite funny. | ||
| Peter Matusov (Pmatusov) Senior Member Username: Pmatusov Post Number: 889 Registered: 09-2002 |
Parrish, if you make 10mpg, something's indeed crappy with your V8. My 96 only showed less than 12mpg once, with average speed over almost 3 hours of 87.5mph. FWIW, much lighter JGC with a lower profile and better aerodynamics showed 14mph at the exact same stretch of the road. At that time, the Disco had a roof rack; after I took it off, normal highway gas mileage was between 15 and 17 mpg. Similar between two moderately heavy-footed drivers. I take it you have no numbers to back the statement about inefficiency of a rover v8's exhaust. BTW, you can make a closed EFI system as perfect as you want, has nothing to do with exhaust. As an example, I bought a rangie with cats melted, one plugged nearly completely, another empty with pieces flown downstream and lodged in the muffler. It could not rev over 3k rpm, and manifold vacuum under medium load went down to 2inHg. Nevertheless, the gas mileage was 12-14mpg. No vacuum to draw air in, no gas to burn. | ||
| Shaun Power (Shaunp) Member Username: Shaunp Post Number: 94 Registered: 05-2003 |
True closed loop injection (lambda sensors)is the best way to get the most out of an engine as long as the fuel/ignition maps are good. The problem is that with any map it has to be a compromise between power/fuel consumption/emissions, "and they have to meet the emmission laws" of the market, different countries have different laws and as a result cars are different. While I have said that cars with 14cux injection could be made to run using one of the maps that don't need lambda sensors I wouldn't bother myself. My own Australian car has not got cats or o2 sensors by virtue of 4x4s falling through a loop hole in the local laws during the 90's. If it goes better then US cars I don't know, it certainly seems to use less fuel compared with comments posted on this site. This is not a result of a better injection system just less stringent smog laws. If was looking to improve perfomance of a Disco though playing with the injection I'd just ditch the whole system and use something else,like a Wolf 3d or Motec ecu. Again if you guys have to meet smog tests your stuffed. |
