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MG MGB GT V8 Factory Originals Technical - ROVER O2 SENSORS
|I'm installing a 3.9 from a range rover with EFI. I need O2 sensors but here in the US rovers are considered an exotic and the price is nuts. Is there any other type of sensors that I can use? I have two Ford sensors with three wires but I am not sure of the correct voltage. Any help with part numbers and cross referencing would be great. |
|Jim, 99% of all 02 sensors on the market are not only compatible but moreover identical. They just have different connectors on the end of the wire(s). I'm quite serious ... assuming your 3.9's wired for 3-wire sensors, which I think may be the case, the Ford units should be fine. Ask anyone who nerds around with fuel-injected cars. You'll find that, e.g., BMW sensors are almost thrice the price of Ford sensors but they are _exactly_ the same thing, again but for the connector. The most common brand is Bosch ... their 3-wire sensors have two white wires and a black wire ... the whites are for the heater (doesn't matter which is + and which is -) and the black is for the sensor output itself. If your 3.9's harness is only wired for 1-wire sensors, it's no great emergency; the system will just take a couple of minutes to go into "closed-loop" mode. Or you can just hook up power and ground wires so as to use the 3-wire units.|
(That being said, some of the later model high-end German cars do use slightly different sensors and they may have different slit patterns in the business end of the sensor. But you'd not want 'em anyway due to the cost.)
My V8 just has a carb, which is kind of Bronze Age, and I envy you with an EFI setup. I should really convert it over to save gas and pollute less.
|Jim - following on from Harry's advice - if you are staying with the original GTV8 blockhugger exhaust system you may find it simpler to omit the O2 sensors - in which case just change the tune sensor in the injection loom - one less thing to go wrong |
|I agree with Harry on this, most all O2 or Lamda sensors are the same. Variations are 2,3 or 4 wire. So two wire has heater current and sensor output on same leads, 3 wire has heater on two and sensor output on 1, 4 wire has two for heater and two for sensor. I think the output from the sensor is in the range of 0-2v dc, where 0.8~0.9~1.0v dc is ideal O2 content.|
Harry, if you want to convert to a cleaner fuel, suggest you try Propane/LPG. In UK (and British Columbia/Alberta, Canada) auto-LPG is half the price of street gas/petrol (although of course, regular gas/petrol is half the price in Canada compared to UK anyway, but thats another story......) Apart from the deaded CO2 the major by-product of Propane combustion is ...... Water !!!! The Canucks are running all sorts of V8's on propane/LPG e.g. Chev 1500, Dodge Ram 1500 etc so must be able to get the kit your side of the water. Have seen an LPG converstion of MGBV8 in UK where owner converted to a 4-barrel Holley, but also have seen an SU carb'd Volvo coverted to LPG in UK Classic car magazine. This used a pair of machined aluminum adapters between air filter elements and mouth of carbs.
Consumption of Chev 1500 "duelly" was 26~27 on Gas/Petrol, 25 on LPG with little or no performance penalty.
|Roger,when you said to change the "tune resister"to eliminate the O2 requirement,what color/resistance wire is needed.It was my understanding that the "tune resister"was used to change things such as ignition advance,fuel curves/maps,etc to suit the conditions of where-what the engine will be used for.Is a new chip needed also?I am curently building a B with a fuelie 3.9,and am always on the lookout to improve the set-up that is currently beung used.Thanks for any input.|
|THANKS for your help guys. I'll try the ford O2 sensors in my RV8 headers. I don't want to screw up the ecm. By the way, my harness does not have a tune resistor although there is a plug in the harness. the ecm # is prc 9060 which is a north americian market only peice I beleive.Once I get this thing to work I intend to get a chip from an outfit like RPI. Wish me luck!|
|Slightly off topic, but I wonder if any of you can tell me if a Rover knock sensor will work with the Ford EEC-IV system? I just ordered a pair of them ($$pensive-Ouch!) about a week ago.|
I installed a 1994 system similar to Jim's in place of a clapped out OE Carburretor 3.5l - as you might guess from my ealier note - i decided to keep the OE exhaust system instead of cutting holes in the inner wings ( a la RV8) which means the car has to run without oxygen sensors. Specialist advice was needed because neither I nor the local landrover agent could get the engine to run with the right mixture.
The advice that I received is set out in the note above- about £5 and 10seconds later I was able to screw down the fuel air mixture to give a CO reading of 1%.
The tune resistor does not effect ignition timing on my setup and if it does more than compensate for the lack of O2 sensors - I don't know about it.
However in the process, I did also pick up some advice about the gearbox input and the speed sensor both of which are worth considering when the time comes.
I am away from my car and my books at the moment but if you e-mail me over the weekend - I will look out the colour of the tune resistor eventually fitted.
Finally on the subject of the exhaust system (for those who have not yet cut holes in their inner wings) I remain to be convinced that all the pros and cons of fitting the RV8 sytem have been adequately addressed in the archives here and would only say that after much thought, I find the case for modifying the car finely balanced.
Not a scientific answer - just experience of a very successful conversion.
All Efi "Hot wire" systems should have a tune resistor to tell the ECU whether to run the cat or non-cat fuel map. If there is no tune resistor then the ECU will default to a "Limp Home" map, this is a cat map and will make a non-cat car run rich. PRC9060 is a normal ECU with the regular set of maps in it and the plug is possibly where Land/Range Rover connect their diagnostic kit when things go wrong. What colour wires go to the plug?
A Green (470 Ohms) resistor will give a non-cat tune, and White (3900 Ohms) a cat tune.
I have left the gearbox and speed sensor (and the air conditioning input for that matter) all open circuit. Connecting the speed sensor will activate the speed limiter (at about 112 mph) will it not? Without it the ECU will think the car is stationary but what else will it do apart from probably illuminating the fault lamp? I might connect the radiator fans to the air conditioning input as I guess it increases the idle and I suppose the idle is also increased when an auto box is shifted out of park or neutral but what does the gearbox input do with a manual box?
Incidentally, I have a MGOC supersports shell, SD1 3.5 engine with a 3.9 cam, the heads are ported with vitesse valves, RV8 style exhausts without O2 sensors and a mix of hot wire Efi parts with a green tune resistor from a 3.5 ’94 and ’92 Range Rover (Discovery?)
I was wondering why you were'nt able to use O2 sensors with the original exhaust system? Does it have to do with the restrictiveness, or lack of physical space, or some other reason? This is relevant to my conversion cause I plan a custom exhaust, not thru the fenders, and also want to use a throttle body fuel injection, and had hoped to use the O2 sensors to aid fuel management.
|I have a pair of late Range Rover 4.0 sensors and plan to fit one to each side, and use a switch so I can swap over the sensors. This should act as a diagnostic when comparing readings from both half’s of the V8.|
The sensors take a 18mm x 1.5mm boss, but how much of the sensor head should protrude in to the gas flow?
|As has almost always been the case with this car, it appears I'm on my own. Good thing I'm used to it. The knock sensors came in today and weren't exactly what I was expecting. The one I had looked at on the lift appeared to have a stud through it which threaded into the block. These look very much like I would expect an oil pressure sender to look, with a 12mm threaded end and a hole in the middle of it. So can anyone confirm that Rover used two different designs for the knock sensor?|
|I TOOK A CLOSER LOOK AT MY WIRING HARNESS AND NOTED THAT THE BLUE PLUG FOR THE TUNE RESISTOR HAS TWO WIRES CONNECTED TO IT. THE COLORS ARE BLACK SLATE AND SLATE BLACK. IS THERE A TUNE RESISTOR THAT GOES WITH THE PRC9060 ECU? AND IF SO,WHY DON'T I HAVE ONE. |
IT WAS MENTIONTIONED THAT THE ECU HAS A NORMAL MAPS IN IT. NORMAL TO WHAT? AND WHAT CAN BE DONE TO CHANGE THE FUEL MAPING BESIDES A CHIP UPGRADE.
WHERE MIGHT I FIND A SHOP MANUAL ON LUCAS FUEL INJECTION, THERE IS NO SUCH THING THAT I CAN FIND!
Apparently there were some Efi looms made after 1990 (14CUX systems) with the tune resistor taped inside. It should be connected to the plug or wiring you have found. Mine is green for non-cat 470 Ohms, part number PRC 8172, the cat tune resistor is 3900 Ohms, sorry I don't have a p/n.
You need to change the chip to change the fuel map.
PRC9060 is one of a sequence of part numbers.
The nearest I can find to a shop manual for the Efi is in the Haynes manual for a Range Rover.
The auto gearbox sensor wire should be earthed through a 510 ohm resistor to tell the ECU that the gearbox is manual. A speed sensor is useful as it allows the ECU to opene the idle air valve when the car is stationary. Without it you may find a tendency to stall on idle. Apparently the RV8 uses a cable diven speed sensor ..I obtained one from an MG Maestro EFI(which also uses a variant of the Lucas hotwire system).
This thread was discussed between 04/10/2001 and 10/10/2001
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