As an afterthought, I'll take an ECM reading tomorrow morning with everything at ambient...
Well, unless someone's dropped a GEMS motor into your Thor, then you've got a non-Thor airbox instead! Definitely no sensors on the Thor airbox.
Can't tell you whether that's a GEMS airbox though, 'cos my GEMS doesn't have one so I've nothing to compare it with. The plug on yours does look the same as my GEMS inlet air temp sender though.
Confirm you have the bunch of bananas plenum cover and not a big rectangular box with 4.0 cast into it. As long as you have the bananas, you can forget about the missing sensor.
So, after a day's faffing around testing senders, cables and earths I settled on fitting the new new one. The old new one was definitely giving bad data on both the BECM and ECU sides. The engine temp gauge now reads correctly- middle of the gauge and all parts on the hot side zapped with the IR thermometer are at or around 90C. Cold side 30-35C.
The ECM is still reading high (around 110C with above data) though although the thermistor resistance for ECM side was ballpark similar to the original one. Makes me swallow deeply and think "what if it is actually 110C?" even though measuring everything with IR thermometer confirms it's not.
So, what next? I'll probably drop in another ECM (handy having spares lying around) and see what happens then. Nice to have the old girl back on the road though, even if it was only to drive home from workshop.
Depending on where you live, trim colour etc. (Stick your car details and location in your sig), there are usually a few on the Bay. These for example
http://www.ebay.co.uk/itm/RANGE-ROVER-P38-ROOF-LINING-/142385684019?
http://www.ebay.co.uk/itm/Range-Rover-P38-Roof-Headlining-Headliner-with-Sunroof-AWR1572LUM-/332188292094?
No air pocket there:
Tightbutts.com didn't supply a sealing washer with the new genuine part. The old/ new OEM had a sealing washer swaged onto it. Good thing I've got a box of Dowty seals sitting around.
Went wild and bought an in-line bleed fitting to put in the highest of the 19mm hoses. I know you don't need one, but I'm putting it in there to make life easier in future.
Sloth wrote:
Hmmm I can't find that one? Sounds interesting though.
I'd considered that the sensor might be sitting in an air pocket and thus reacting to surface temp rather than immersed probe temp BrianH. As you say, when I fit the new one (after testing it, connected and active on the car in a little pot of boiling water and tracking the readings on the thermometer, voltmeter, Nano and engine temperature gauge as it cools!) I can be as sure as I can that there's coolant coming out around the threads before I tighten it.
How about the 66727? 95-90/ 100-95 and the shiny shiny?
That's a Ford sensor so should be easy to get a connector from a scrapper or it looks like you can even buy them new
http://www.ebay.co.uk/itm/Genuine-Ford-Escort-MK-IV-Orion-MK-II-Water-Temperature-Sensor-Connector-6167770-/272380082780?
Thanks for the bleeding stuff Tony and Chris. Never had a problem before using my vacuum filler (and I've used it lots of times on the GEMS and the Thor). I will refill and bleed using the traditional method (as above ish, only using the reducer temp sensor-highest point- to bleed heater/ lpg lines) after I've replaced the coolant temperature sender, which will hopefully arrive with Mr Postie this morning. I'd better hand his fan thread back to Sloth now :)
Did you see the X-Eng data sheets for the Intermotor sensors Sloth?
I used the one they supply with the shiny shiny for the Hybrid (had a tuned Vitesse efi 3.5 in it with twin electric fans) which had the cooler 88-83/ 92-87 switch. Worked fine for me with no conflict between fans and thermostat and never had to resort to the manual over-ride. I did run a lower temp thermostat (82C IIRC) in the Hybrid though.
When you say "airbox sensor" which one do you mean?
What year is your P38? There were two types of motor (or 3 if you include the diesel, but if yours is a 4.0 it's not one of those) fitted to the P38. GEMS and Motronic/ Thor. Changeover year was around '99.
Two types of motor- two types of inlet system. GEMS had a separate air intake temp sensor in airbox, Thor incorporated it in the MAF.
So, both have a MAF, directly downstream of airbox, GEMS has two plugs, one for MAF, one for IAT, Thor has one.
LPG P38s don't need additional lubricant
Head linings- either buy used good (but they all sag eventually as the adhesive/ foam interface breaks down), pay a trimmer to re-trim it, or re-trim yourself.
AS Trim off eBay or Martrim will sell you a kit to do that.
I'm scratching my head trying to make sense of this, so, thinking out loud, just talking engine ECM for now...
As measured temperature goes up, resistance and voltage drop. As voltage "seen" by ECm is lower then ECM will give a diagnostics temperature as higher than actual. Schoolboy maths on the ratios between "is" volts and "should be" volts comes back with the sort of diagnostics temps that I've been getting.
Time to take the bloody sensor out I think. I'll check resistance of cables, but as there are errors on both sides (BECM and ECM) and the two sides of the sensor have their own separate earths it has to be the sensor. Doesn't explain why the temp gauge is under-reading, but if one thermistor is the wrong value, then it's possible the other is too.
Have to let the thing cool down before I can pull the alternator. Boy this car's hard work...
Interesting results at ECM connector. Much lower voltages than should be, but pretty linear:
Temp (top hose)_ Actual _ Should be
39_1.73 __ 2.75
44_1.58 __ 2.4
48_1.27 __ 2.2
50_1.13 __ 2.1
53_0.975 _ 2.0
59_ 0.76 _ 1.7
62_ 0.7 __ 1.6
65 __ 0.68 _ 1.5
Did another idling run from cold to 100c indicated on Nano, when its panic alarm went off. Temp gauge got to nearly top of blue. IR temperature of top hose (and LPG reducer, heater feed, and rad top got to 60c. rad bottom 30c.
As an aside, still getting air burps back through expansion tank, which is strange. Have pressure tested system and its held steady 15 psi for 30 mins so I haven't royally f**cked up installing the heads!
Time to drain the top of the cooling system, pull the alternator and get stuck into the sensor i suppose, but will do some voltage checks at ECM first, so I can see what it's seeing compared to what it should be seeing...
Worked for me- if I'd wanted to add another roll cab to my collection. Was almost tempted as my tools have over-run my 2 stacks and I have a 30 year old Snap On top box that would quite benefit from sitting on something better than an old metal printer cabinet :)
Could collect within 1 hour from my closest Halfords or they'd deliver for.... £40.00 gulp
If it wasn't for the toolbox requirement, you could drop a factory sub where its supposed to fit. Seem to be some on the Bay starting around £40.00. I do have a spare speaker and amp somewhere for the single speaker version.
I'm playing hunt the air lock as well, as it did a favourable impression of a geyser from the expansion tank when the stat opened! It hasn't moved outside the workshop yet.
Just needed thermistor data to remove some variables (ie test it). Last thing I want is to cook the rebuilt engine.
FWIW on the old sensor gauge side reads 0.7k, Motronic side reads 1.5k. so, if that sensor's not faulty, the thermistor values are different. I'll check the new one. Who knows, it could have been built backwards! The plug only fits one way.
Actual temps- idling during warm-up:
IR thermometer on manifold where sensor sits- 64C
Temperature gauge- just into blue sector (that's as far as it rises)
Nano on ECU 108C
Coolant at expansion tank- 88C
Getting some strange coolant temp anomalies on the VSE. New ECT sensor (Delphi) fitted as part of the head replacement job.
Diagnostics temp high, gauge temp low. Both wrong compared to actual measured.
The ECT sensor on the Thor is a dual thermistor type- one feeding gauge, other engine management. Plug can only go on one way.
Does anyone know whether both thermistors are same value? I have temp/ volts/ kOhm values from the Bosch SID for the ECU side of the sensor, but can't find anything for the gauge side.
Ta!
My vacuum filler failed me big time today (first time ever!). Got the mother of all air locks in the VSE.
Not sure if it's because I drained both sides of the block, despite the dire warnings in RAVE, as had to get all the crap out of the waterways after the heads swap.
Are you going to put a timer in the ignition off fan circuit?