this is how a narrow band o2 sensor works.. the ecu constantly adjusts the mixture from rich to lean in closed loop mode trying to maintain an 14:9 ratio on average.. if you were to connect an a/f gauge to your good pre cat sensor you would see it constantly sweep from lean to rich in closed loop. the post cat sensor monitors how well a job the cat is doing of burning up the left over hydrocarbons.

 

Well I ordered two new O2 sensors, an IACV, and plugs. Hopefully that takes care of it. I'll post an update when I get them installed. Thanks guys.

From RockAuto:
NTK 25044 Oxygen Sensor $53.79 2x $107.58
STANDARD MOTOR PRODUCTS AC151 Idle Air Control (IAC) Valve $43.79 1x $43.79
CHAMPION 318 Spark Plug $1.86 8x $14.88

 

ET, I know you have a running total somewhere, what do you figure you have invested in the truck so far, excluding what you paid the stealer for it?

 

$3,841

 

Wait was that supposed to include tools for the hungry Rover? If so, $4,258.

 

I was under the impression you already had new 02s, I'd bet all that crap that floods out the exhaust when you start a fresh engine may have toasted your 02s.

A new engine deserves new sensors, especially in your case given what you started with. Even with that info I wouldn't count out the iacv, good thing you ordered all 3.

 

ET -

From another LR publication -


stabilized

Perhaps your heater for the "bad" O2 is disabled? Wire connection? On the attached drawing that would be the wire marked "R" at the sensor connector. Should be able to read for volts at that point. And you should have had a code for it, but who knows?

 

Let me know if I did something right, I'd like to tell my wife. Lol

 

If it will get you relieved from trash removal duty for two days, OK.


You pointed out what the instruments tell you. If they are changing, good. Not changing - why? Of course, there are precise values that the ECU monitors to make control function. But if your sensors don't make sense,,, that could be a problem. Having any sort of basic scanner is a big step up over the idiot lights on the dash.

But no scanner, regardless of price, can tell you the oil PSI in the stock D1 or D2, because we only have an idiot light. And the coolant temp gauge in a D2 is a computer controlled idiot light with a pointer (as are many complex vehilces - thye want to lull you into reliance on that steady as a rock gauge).

I'm not sure what ET's TPS reading is doing, mine is 9.4 at idle or when switched off. About 22% at 50 mph. Might be something in the linkage, etc. But the TPS single value is not so important, it tells the ECU when it is at minimum position, maximum position (fuel being consumed at maximum rate), and if it is changing up/down. The ECU uses the MAF signal to adjust the injector time (pulse width) to keep everything balanced. The idle speed can vary, controlled by IACV, with TPS staying at bottom location. Main thing for TPS is smooth, not noisy or dirty.

 

Look at it this way...

1. It is way cheaper than buying a new car
2. There is less technology to worry about
3. You can fix it yourself
4. There is a wealth of information/help to reference
5. You have a nice collection tools
6. You can possibly work on older LR's as a fall back job...