If you can get an independent gas analyser to look at the gases when the trims have shifted, see if the CO has increased greater than 0.2% (and lambda less than 0.97) - rich and see what the primary sensors and secondary sensors are telling you. On the voltage, it does depend on the type of...

Theoretically they are just a check, but with some cars, eventhough manufacturers will say all they do is check the catalytic converter efficiency, they still act on the fuel trims. You may be completely correct on this system, as there are differences between the systems. On the live data...

Having a look at the rear sensors, they should have a time between sensor transitions. Have you replaced the rear sensors? - sorry just checked previous post and you have. If the rear sensors are telling the ECU it's lean, the rear sensors might shift the long term fuel trims, which you say...

Have you got an SAI switching valve? Don't plumb it in for the air, try just connecting one up so it is there electrically, but doing nothing. It might make the computer happy, instead of having a problem. The next problem that could occur is if the fault sensing side of the ECU actually...

And if you have had poor cooling, head gasket failure is much more likely to happen.

If you get a failing water pump, if there is a cylinder overheating then pre-ignition/knock might happen and if the knock sensor is working, then the ignition timing will be retarded and power/performance is reduced. If you don't change the coolant often enough, like every 3 or 4 years, then...

Water pumps can get noisy. On other cars I get them done every cambelt change, or every 60,000 miles or so. For their cost, leaving them any longer isn't worth the risk and damage if they fail. Impellers break up and could be the chirping/tinkling sound. Leaving a failing water pump can...

I have had similar noises on another car, but they were related to the alternator. Chirping is a loose alternator / auxillary belt. Tinkling (metallic ringing) could be the alternator mount / metal tensioning bar that has sheared/partially broken, that is acting like a tuning fork. Yes...

Final point, does the ECU use lambda sensor during cruise as the primary sensor, but during acceleration, the MAF and TPS become the primary sensors?

Have you pulled a plug or two? If it's rich or lean, you'll soon tell. The pinking (MAF failure or TPS) is due to the lean mixture. Lean mixtures are more likely to pre-ignite than rich mixtures, hence the need to keep mixture stoichiometric or rich. Temperature sensor failure -...

What do you say about the 0.35 fuelling? If this is the lambda value, it's rich not lean. I had MAFs go and you notice at all engine speeds, and you get pinking. If he has tried a different MAF, then two shouldn't have the same problem, unless it's the wiring. With the hot surface/hot...

Can you check on the 0.35 concerning the fueling. If this is a lambda value, then your fuelling is way too rich, and did you say it's not going closed loop? If the temperature sensor isn't working - might be infinite resistance, then the ECU will throw in as much fuel as it can, and closed...

What LPG system are you using? I have heard of some systems causing problems, where the LPG system hasn't been calibrated properly or the lambda sensor wires have been cut through, and the difference in the fuel injection duration on gas is so different that the ECU recalibrates itself, such...

I only suggested the TPS because it is there to enrich the mixture during fast/snap throttle openings, and to give a zero throttle position. The airflow meters and lambda sensors will make sure that everything runs correctly, but might go lean during snap throttle openings without the TPS, or...

Throttle position sensor is another that can give a jerky acceleration. The TPS is important for mixture enrichment during acceleration. When they wear, it is usually around part-throttle position where it gets most use. The track gets broken up and the ECU doesn't know what's happening. You...

MAF sensors can give problems from 40,000 miles up. I've had 3 replaced on different cars at 45,000, 71,000 and 75,000 (already gone). Age - anything over about 6 years.

As a general point, crank sensors can start to have problems. If the signal gets weaker and if the sensor or even the timing gear that provides the impulses get dirty, or the sensor starts to pick up EM interference, by the shielding breaking down, then this can mean that the ECU is seeing...

If they are diagnosing and fixing ECUs, then it doesn't matter how it got damaged, they should be telling you what needs to be fixed and how they are going to fix it. Talking down to customers is never a good policy, especially if they show they haven't got a clue. On the adaptability of...

Just ask for the ECU back and see what happens, and quote back to them that you have found out that they don't know what they are talking about, with your detailed technical knowledge, quoting part numbers and tuning information. If the second ECU works and you got it cheap, see if they are...

If you want secondhand spares, do a search "land rover breaking for spares" Don't forget to select UK sites and must have "breaking" You get a load of special sites up, and ebay, where you can identify landrover breakers and contact them directly - don't use the ebay buying method, talk...