Desperatly seeking Land Rover help

[Parke_A_Saurus]

I am in need of help, before I BURN this truck to the ground, with repairs/diagnosing issues with my Land Rover Disco II. I have a knock sensor code and different O2 sensor codes that I just can NOT seem to get rid of, I have already replaced all the sensors and cleaned all connections, as well as a bunch of other work.:banghead:
I also have recently developed some electrical issues, radio with no sound, 12 volt plug not working, compass not working, windshield wipers not working, washer fluid sprayer not working. Fuses relating to all components are fine. I have all the schematics but no understanding on how to interpret them in comparison to the vehicle itself. Thanks in advance!

 

[jafir]

It might help if you post the codes. Are the o2 sensor codes heater codes, or mixture codes, or what?

 

[Parke_A_Saurus]

It might help if you post the codes. Are the o2 sensor codes heater codes, or mixture codes, or what?

My apologies I am getting codes:
P0327:Knock sensor 1 circuit low input (bank 1 or single sensor) LH bank signal less than threshold determined from ECM model above 2200 rev/min
P1130:Oxygen Sensor Fuel Trim at Limit *Codes* A U
P1150:Oxygen Sensor Fuel Trim at Limit *Codes* B U

After resetting the codes I did receive the codes:

P0327:Knock sensor 1 circuit low input (bank 1 or single sensor) LH bank signal less than threshold determined from ECM model above 2200 rev/min
P1171:Oxygen Sensor System Too Lean Fault Banks A & B

Reset again and back to original codes. Using an UltraGauge for the scan tool.

 

[capri_auto]

Just something to think about. I've had bad sensors right out of the box several times.

 

[Ed Z]

I have cured a few gremlins buy locating and cleaning rusty ground connections...

 

[cymax]

when was the last time u changed spark plugs...?

 

[discostew]

Are you able to get a scanner hooked up to it so you can watch O2 sensor voltages ?

 

[DiscoveryAuto]

These codes don't appear to be oxygen sensor codes, they are fuel trim codes. Although an oxygen senor can be the cause of a fuel trim code, they are usually not the cause. The oxygen sensor is reporting to the ECM what it is seeing. So it looks like you need to find out why the fuel trims are off. I'm not sure if these are rich or lean codes. Lean codes are usually caused by vacuum leaks, low fuel pressure, or a bad mass airflow sensor. Rich codes are usually cause by a severely plugged air filter, excessive fuel pressure, or a bad mass airflow sensor. Do you have access to a scanner that can read fuel trim and oxygen sensor values? If you don't it might be better to leave the diagnosis up to a competent repair shop.

 

[Parke_A_Saurus]

when was the last time u changed spark plugs...?

I changed the plugs and upgraded to Magnacor wires less than a month ago.

Are you able to get a scanner hooked up to it so you can watch O2 sensor voltages ?

These codes don't appear to be oxygen sensor codes, they are fuel trim codes. Although an oxygen senor can be the cause of a fuel trim code, they are usually not the cause. The oxygen sensor is reporting to the ECM what it is seeing. So it looks like you need to find out why the fuel trims are off. I'm not sure if these are rich or lean codes. Lean codes are usually caused by vacuum leaks, low fuel pressure, or a bad mass airflow sensor. Rich codes are usually cause by a severely plugged air filter, excessive fuel pressure, or a bad mass airflow sensor. Do you have access to a scanner that can read fuel trim and oxygen sensor values? If you don't it might be better to leave the diagnosis up to a competent repair shop.

As stated I am using an Ultragauge. My upstream O2 sensors are only showing voltage upon immediate start-up, and quickly go away as the truck warms up to operating temperature. On the Ultragauge I am also usually not showing any short fuel trim to either bank. If and when it does show short fuel trim it is around 2-3%, my long fuel trim is consistently showing a 25%. The other morning, for some unknown reason, the check engine light turned off, the upstream sensors showed normal voltage readings and fluctuations and everything started operating normally and then at the end of the day reverted back to the usual symptoms with the check engine light returning.

 

[rovercanus]

It may have been brought up before in this thread but have you changed your MAF? These can cause symptoms similar to what you are stating. Cleaning it won't always work and is at times just a temporary fix.

 

[Parke_A_Saurus]

It may have been brought up before in this thread but have you changed your MAF? These can cause symptoms similar to what you are stating. Cleaning it won't always work and is at times just a temporary fix.

I have contemplated it. Just trying to save $200+. Anyone know of another MAF that will work other than Land Rover?

 

[discostew]

You might be loosing the ground for your o2 sensors . All 4 o2 sensors get grounded thru the ECM on a red / black wire . When it acts up again ground that red/blk wire in one of the o2 sensors and see if it starts showing activity again .

 

[seventyfive]

at start up the oxygen sensor heater circuit is active, once the predetermined time expires the heater circuit is shut off. That is why you're seeing half a volt.

If you are seeing 0 volts at both front oxygen sensors that explains you're long term. A positive long term means the ecu is trying to fatten the mixture as much as possible (by pulsing the ground to the fuel injectors as long as possible). Your ecu is trying to fatten the mixture because it's seeing a lean regulating (pre cat) oxygen sensor reading.

So the ecu is doing its job.

You need to find out why the regulating oxygen sensors are not reading at all after the heater circuit shuts off...in other words verify the wiring is in proper order. Usually you want to use a meter with a scope function and back probe the connectors. You can use the volt function if you don't have a scope function. You may have some shorted wires or bad sensors. But if BOTH regulating sensors are reading zero voltage you may have other issues going on.

Here is a quick way to remember oxygen sensor readings.
When your low on money (lean) you fell low (0 to .5 volt)
When your high on money (rich) you feel high (.5 to 1 volt)

Regarding air mass meter, at idle you should be seeing 5-7 grams per second at operating temperature. Usually a bad air mass meter, in a D2, will give you a lean fault accompanied with a trans fault (I think it's 4th gear monitoring).

The other electrical issues you're having sounds like a BCU issue. Have you removed the access cover at the passenger footwell a pillar and glove box to physically see if water is leaking into your wiring harness or control modules?

An issue with D2's is water getting into all those wire junctions in the wiring harness that runs under the blower motor against the firewall. The junctions are almost all wrapped in the bottom of that harness.

 

[riceybean]

http://www.amazon.com/RANGE-ROVER-S...8515&sr=8-3&keywords=maf+land+rover+discovery

If it doesn't fit just remove the sensor portion and install it in your old MAF.

But it sounds like a BCU problem to me as well.

 

[terrormachine]

On your knock sensor issue: make sure someone didn't pinch the wire that runs behind the power steering pump bracket.

 

[Parke_A_Saurus]

On your knock sensor issue: make sure someone didn't pinch the wire that runs behind the power steering pump bracket.

I did have the Power steering bracket off recently to replace it. I will definitely check that out. Thanks!

 

[Parke_A_Saurus]

You might be loosing the ground for your o2 sensors . All 4 o2 sensors get grounded thru the ECM on a red / black wire . When it acts up again ground that red/blk wire in one of the o2 sensors and see if it starts showing activity again .

I have thought of a lost ground, and am still thinking that may be the culprit of my other electrical issues as well. I have RAVE just no idea how to interpret the wiring schematics when comparing it the the vehicle itself. I am assuming it would be the same ground that the amplifier is hooked to, just not sure which ground that is.

 

[discostew]

I have thought of a lost ground, and am still thinking that may be the culprit of my other electrical issues as well. I have RAVE just no idea how to interpret the wiring schematics when comparing it the the vehicle itself. I am assuming it would be the same ground that the amplifier is hooked to, just not sure which ground that is.

I wouldn't get to excited about all your issues being fixed with one ground connection . Push a t pin into the o2 sensor connector to make contact with the red/blk wire and see if you get the proper o2 sensor activity when you ground the t pin with a jumper wire. If it takes care of your problem I will tell you how to fix it without buying an ecm , or a mass air sensor , or any of the other darts mentioned .

 

[Parke_A_Saurus]

I wouldn't get to excited about all your issues being fixed with one ground connection . Push a t pin into the o2 sensor connector to make contact with the red/blk wire and see if you get the proper o2 sensor activity when you ground the t pin with a jumper wire. If it takes care of your problem I will tell you how to fix it without buying an ecm , or a mass air sensor , or any of the other darts mentioned .

So I am just going to use a jumper wire with a t-pin connector and ground it to the frame or nearest grounding point. Is that correct?

 

[discostew]

So I am just going to use a jumper wire with a t-pin connector and ground it to the frame or nearest grounding point. Is that correct?

Yes that's right . It's hard to tell what you have going on without standing next to the truck but I'm guessing that you have fixed o2 sensor voltages of about 430mv . Or about the same reading if it were disconnected . Before you mentioned a voltage of about 1 volt that went away when it was warm , that was probably the heater circuit you were watching . You want to watch the signal circuit .