Would like some info on the correct pre-cat Bosch lamdas to buy for my P38 - 4L - 2001 (Thor) and if you know of any non rip off stockists ( not LR main dealers though)
Heater circuit duff one one and the other has given up the ghost.
Not too keen on OEM or items made in soup shops in Taiwan !
Grateful to Simon for sussing out the defects.

OEM should be OK as they are, or at least should be or they aren't OEM, made by the Original Equipment Manufacturer who supplied LR in the first place. It is those that are listed as aftermarket that you need to avoid. In fact, Bosch would be your best bet https://www.lrdirect.com/MHK100940-Sensor-Lambda/

Thanks, have opened up the link and noted the info.
Round about the price I was expecting.
Cheers for the quick reply

Bosch were the OEM to land rover... and aftermarket ones never seem to read quite properly. It's definitely a false economy buying aftermarket ones, as they won't last!

Any rough calcs as to what mpg loss could be attributed to a duff pre cat lambda or two ? (Thor engine)
I assume the duff lambda(s) would also affect LPG mileage, is that correct ?

It'll go into a default open loop mixture when it detects problems with a lambda sensor which will be richer than it should be. No idea how much richer though although I would expect something in the region of 10-20%. As the LPG system slaves off the petrol system, a rich mixture on petrol will give a correspondingly rich mixture on LPG.

It was me that advised Hugh he needed new lambdas, I recently converted his P38 to LPG. OBD reports both pre cat probe heater circuits are broken, one lambda still gives signal the other doesn't. Also the MAF seems to read consistently low (all loads and rpms), either that / or petrol pressure is down / or all 8 petrol injectors are flowing less than they should... so it seems MAF is the most likely of those situations. LTFT's consistently (again all loads and rpms) at around +20% on the bank that is running closed loop and it's new enough to be almost fully OBD2 compatible as opposed to showing 99% LTFT's like the older models do.

Hugh has said he isn't getting the mpg he expected on LPG, I calibrated the LPG so trims (on the good bank) are the same as trims on petrol so hopefully things will improve when the lambda's and possible MAF are sorted.

Since Hugh's I converted RutlandRover's P38 to LPG as well. Also 'effected repair' of a water leak from the throttle body on RutlandRover's... Bypassed the throttle body heater for now because it seemed the TB heater itself was leaking but left enough slack in the replacement water hose so that he can re-connect the TB heater when he's fixed the leak on it. The plastic water pipes to the TB heater snapped in many places when I only went to disconnect them from the TB lol... But it was leaking from the TB well before then and RutlandRover supplied water hose for me to prevent the red stain from below the TB from recurring. I reckon I see more problems with fragile plastic water hose on P38s with red acidic coolant than I do on P38s with blue glycol coolant...

Cheers Simon, all this tech talk is way over my small cranium, but interesting nevertheless.
MPG on gas (currently 13 mpg @ 55p per litre ) the engine runs as sweet as a nut even with the niggly 7 - 900 idle.
So, getting 26mpg real terms with petrol @ £1.23 p / l plus a profit of 13p per litre
On the plus side I've had a really good conversion and picked up valuable info that would have cost me a good few quid from an Indie with his testers and gizmos.
Horrible thought, the Indie may not be as clued up as this forums members and then where would I be ?
With a bit of luck and a fair wind the new lambdas and MAF will improve matters considerably - new plugs as reccd for LPG have been fitted
Decided not to flog my Freelander TD4 just yet, so have had it sorned - ya' never know what's round the corner

hugh wrote:

Decided not to flog my Freelander TD4 just yet, so have had it sorned - ya' never know what's round the corner

With a P38 you certainly don't. I kept my Classic for nearly 3 years after I got the P38. For the first 6 months or so I didn't trust it as far as I could throw it. It never actually left me stranded but I chickened out of using it for two European trips taking the Classic instead. But, the more you use it, the more confidence you'll get in it.

I see simon mentioning blue antifreeze, against red, I use oats ( orange ) which is what this engine should have, the plastic pipe problem is normally a 15-20 yr old pipe that’s gone brittle.
Mine must have been changed as it’s quite flexible, engine in and out twice has confirmed that.
I know it’s been discussed about replacing with a silicon hose, certainly with the Thor it’s about the only thing that might fit going the original route,
Maybe this is another to add to the first things to do when purchasing a p38.

Sorry, not trying to hijack the thread

Blue was recommended for GEMS but OAT for Thor. I don't think anything changed just that OAT wasn't available when the GEMS came out. I don't think the type of anti freeze in use has any real affect, the plastic pipe just goes brittle with age and multiple hot/cold cycles. Replacing the whole run with silicon hose is the best solution. Don't do as many have done and use fuel hose. It may be readily available in the right size but goes almost solid very quickly as it isn't intended to have hot water flowing through it.