how to reset ecu???

hi all can anyone tell me how to reset the ecu on my 4.0 se 1998 p38 as have replaed o2 sensor and maf and been advised to reset the ecu can i do this or does it have to go to garage i have a snap on solus ive recently purchased can it be dne with this ???

can someone pls let me know how this is done thanks

its done using Testbook

Or Faultmate

Rasheed is right,but after only swapping one oxy sensor the engine ecu will soon see its output and start trimming the injector pulse width and the long term trims will come back right.Unless it was running for a long time like a complete dog,I wouldnt worry about it.

I may be applying this idea in a totally incorrect place but I know that disconnecting the BeCM from the battery for 30 minutes depletes its internal battery and is the equivalent of the reset switch on a PC. Is there this kind of option for the engine ECU? You do have to reset the windows and sun roof, but works a treat.

ive changed both o2 sensor and maf has been running bad since ive owned it and trying to cure the problem after ive changed the 02 sensor came up with 02 sensor high voltage if this has any significance to the problem am out of ideas now just runs badly with low idle and chucks out black smoke if you rev it hard and just stinks of fuel it ticks over normal for a few mins till warm then idles low as if cold start (choke) is not working ?????

Check the fuel pressure.

how do i do that and what should it be ? may tell me if i data log it or is there a more simple way

It sounds like the oxy sensors are failing to step down to 0v giving a rich signal,where did the sensors come from ?

i brought them from ebay but were brand new and boxed and the correct part so would not have thought so but i guess its possible what should they change to from as think when i data logged it they were just reading 5 is this 5v? and also had a fault code 02 sensor high voltage ?

Pressure che k is done from the fuel rail. There is a shraeder valve that you screw the gauge on and then start the engine. Rave will give you the pressure. Most good garages will have a gauge. Going from what Eight said, did you you buy a cheap MAF from eBay?

no was a used genuine maf and the o2 sensor were brand new ?

So are the oxy sensors genuine NTK ones,with the correct plugs etc ? if they are giving out 5v all the time, the engine will run very rich as the ecu is seeing the 5v as a lean reading and will drive the injector pulse width as wide as possible.If the sensors dont switch down to 0v showing a rich signal to the ecu it will just stay rich and stink etc.

yeah they are i think defo had correct plugs was no need to alter any wiring could there be any other reason for not switching other than a faulty 02 sensor for example maybe the wiring pre plug to the sensor etc as would be suprised if both sensor were faulty to be honest but then this is a rangerover lol

You need to check the heater circuits for them,if the sensors are not being heated they simply wont switch unless the engine is in a high load /speed situation.

how do i check them is this a case of putting a mm on one of te wires and checking for a voltage or something or am i way of sorry if a stupid question but am tryin to learn and getting abit over my head now lol

Don,t think your snap on will do it, like stated you need testbook ,faultmate etc.I have both but sadly am in north Lincolnshire..

i have pmd wills who is in northampton who i believe has the bit of kit will you all know how i get on if he gets back to me thanks for the help so far

I have a T4 system which i am still getting operational and just down the road in Olney so if you dont have any joy and i get it all working, your more than welcome to use it.