Very good, well done!
I've been away on holiday a few days so I'm late to see this thread but I've done plenty fuel system related work on Supercharged Rangerovers (I've converted plenty of them to LPG).
They have a returnless fuel system but fuel pressure is adjusted by electronics controlling the fuel pump... It could be termed 'on demand' fuel pressure. The engine management on them is very sensitive to vacuum leaks (including false air from a disconnected or failing cam cover breather, evap purge valve flowing when it should be closed, etc).
One unusual aspect of them - Say you've had an error code, then you reset the error code (which after some error codes will reset fuel trims)... If you then just start (after resetting fuel trims) and leave it idling the chances are you'll get fuel trim error codes. The way around that would be to clear error codes then not leave the car idling, instead start it up and immediately go for a drive.
With a basic scan tool you probably won't be able to manually reset fuel trims. But causing one of the more 'severe' error codes such as open circuit petrol injector then resetting error codes will reset fuel trims. I.e. If you want to reset fuel trims but don't have a scan tool with that function you can still reset fuel trims by disconnecting a fuel injector, let the system log the error code, then clearing the error code will reset fuel trims. But then don't forget to go for a drive immediately after starting the engine or you'll probably get a fuel trim error code anyway ;-)
A scan tool will show you fuel pressure... There's an electronic fuel pressure sensor built onto the fuel rail, there has to be one for the on-demand fuel pressure system to be able to read fuel pressure and control the fuel pump properly. Edit - Noticed you're getting 40>60psi, that seems about right to me, as memory serves my scan tools read between around 400 and 600kpa on most Supercharged Rangerovers depending on engine load.
The lambda sensors are wide band, any voltage reading from them is meaningless (a voltage reading from a wide band probe is meaningless without knowing how the 'pump' in the wide band probe is being controlled) but an OBD scan tool should be ale to tell you directly what mixture is, probably in terms of lambda (lambda of 1 means correct mixture, 0.995 slightly rich, 1.005 slightly lean). Mixture should stay close to lambda of 1 (which is 14.7:1) but go rich under boost conditions maybe down to around 0.8 at full engine output. The scan tool can tell you mixture because the engine ECU knows mixture, it contains a dedicated wide band lambda sensor control chip that 'homes in' on mixture by reading lambda voltage and knowing how much current (uA) it is applying to the 'pump' in the wide band probe.
Pleased to read that Gordon :-)
If I were to start reading again at the first post I might guess that it started fine from cold due to running open loop fuelling and as soon as it warmed up and switched to closed loop fuelling it ran poorly due to a duff lambda sensor.
Sometimes error codes can be misleading.. If the code doesn't point to an electrical issue such as open circuit SAI system maybe the ECU error detection assumes an SAI fault (because SAI is active) when there is a mixture issue?
Bolt wrote:
Well, Pulsed, but at what frequency? and at what point is a switched supply considered to be PWM?
In other words, if one was looking at the signal relative to B+, what would you normally see for pulse duration?
If it was not bucketing down right now, I would go check to see what I get.
I used the term PWM very loosely, I'd guess the usual pulse frequency of evap purge valves to be around 5 pulses per second (5 pulses of full battery voltage) and pulse durations of around 0.1 seconds. So not PWM in the usual sense.
Gilbertd wrote:
@LPGC, no it isn't a PWM signal, it is a permanent live directly from the fuse (via a splice) with the ground,either permanent or pulsed supplied from the ECU. So provided he is testing the voltage with respect to ground and not across the pins, it should show full battery voltage.
Yes of course, pulsed on the negative not the positive.
Could the 7v be a digital multimeter reading of a 12v PWM signal (so in reality the parts get expected voltage... but because the power isn't constantly on the multimeter reads pseudo average voltage)? For sure purge valves are quickly pulsed as opposed to being held constantly open.
Gilbertd wrote:
As Pete says, we drive on the left so the right hand is free to use the sword on someone coming the other way.
I've heard that somewhere, also heard it's because if your whip (right) hand is nearest the middle of a road you're less likely to whip someone at the side of the road. Makes sense if driving a manual car too as you keep your right hand on the steering wheel when changing gear.
On the main topic....Not sure about P38's but on most evap equipped vehicles evap purge valves are usually pulsed (rather than being just held open for long periods) and the PWM of the valve wouldn't be enough to upset fuelling (false air to lean / petrol vapour to rich) enough to cause a problem even if there were a problem with it, except for really picky systems like Jag engine'd L322's and certain Volvo's. But if the evap system is in doubt you should be able to confirm/disprove an issue by blocking the pipe to the manifold.
As an aside (still on topic but off on a bit of a tangent)...
For some vehicles (don't know if this would be compatible with the RangeRover's none standard OBD) it's possible to fit an AEB OBDuFix (universal fix) to allow the engine to run without a lambda sensor when the fuel injection system expects a lambda sensor to be fitted.
These units connect to the lambda sensor signal wire and to OBD, they read the fuel trims via OBD and if the fuel trim goes positive they emulate a rich lambda reading which then steers the fuel trim back toward zero (or emulate a lean mixture lambda reading if the fuel trims go negative). In this way they constantly steer fuel trims toward zero whilst not upsetting the petrol ECU because it sees the constantly flicking lambda voltage it expects and fuel trims always stay close to zero.
https://www.aeb.it/en/products/emulators/obd-emulators/
They were designed for the purpose of preventing petrol fuel trims reaching extreme negative or positive when converting a closed loop petrol system to run on LPG using an open loop or standalone closed loop LPG system (such as a mixer system or an early standalone LPG injection system). Not necessary if fitting a 'slave' type LPG system which bases it's fuelling on would-be petrol fuelling. I haven't fitted one for many years but there was a time when we offered customers 2 ways of converting certain vehicles (e.g. 4L Jeeps), either a mixer system (standalone closed loop system so when running on LPG for a long time petrol fuel trims would eventually drift to one extreme) or a more expensive sequential slave type system (which avoided the problem if calibrated properly)... These units could prevent poor starting and harsh running on petrol (due to very wrong fuel trims messing the mixture up after a long period of running on LPG) and they were a must on post 2000 4L Jeeps because they'd put the MIL on which would disable the cruise control when fuel trims reached an extreme.
Usually fitted on vehicles that do have a lambda probe fitted (no need to address fuel trim issues if the vehicle doesn't have fuel trims because it doesn't have a closed loop fuel system / lambda probe), so they don't emulate the lambda probe heater circuit but that could be emulated with a simple dummy load (bulb etc?).
How is this collection for a good cause going Gilbert?
I wouldn't want to take your thread off subject, this isn't Range Rover related but may be of interest because it is ULEZ related...
I convert a lot of imported Nissan E51 Elgrands to LPG, a people carrier with a 2.5V6 or (much more often) 3.5V6 engine, they're mostly 2002-2004 (series 1), 2004 - 2006 (series 2) and 2006 - 2009 (series 3) model years. If the owner of a 2006> model applies for ULEZ exception they're usually granted it straight away but if the owner of an earlier model applies they may be granted it straight away or they may have to appeal many times before (hopefully) being granted the exception.
Because they're imports the V5 doesn't usually have the emissions data but all model years have the same engine and emissions.
Nissan won't help provide the emissions data that ULEZ usually ask for. so the only thing that owners of pre 2006 models can do is point out that they're all the same mechanically and point out that there's a precedent for these vehicles to be ULEZ compliant because ULEZ recognises straight away that post 2006 models are compliant.
Owners of pre 2006 models are using a carefully formulated initial application and (where necessary) carefully formulated appeals letters which they continue to refine, yet still some are granted exception straight away while others have tried many times and are still told the vehicle isn't ULEZ compliant... I reckon it sometimes comes down to whom at ULEZ processes the application / appeal. Most contact with ULEZ gives the impression of computer generated auto-replies.
You may (or might not) be right about 20mph being worse for emissions than 30mph.
Difficult to say whether or not for a given trip a higher number of total engine rotations is better or worse for total emissions for a given trip because emissions per rotation (firing cycle) will be different at different engine loads (and load isn't just about rpm, it's also about throttle position etc).
I know a bloke who years ago closed one direction of the M6 for a while after flipping his large caravan and Ford Explorer (not Gilbert lol). I asked him how he managed that, he said he was doing 90mph when all of a sudden it started snaking... But I've been in cars with him on test drives, wouldn't want to be in the car with him driving at the best of times and especially not while towing.
I was going on the cost per KWh figures, 29p for electric and 7.3p for gas.
Most of an engine's inefficiency is due to wasted heat (pumped out of the exhaust and sinked to atmosphere via the cooling system) but that heat need not be considered an inefficiency if the objective is to produce heat for heating and it can be captured.
Assuming the generator would be only around 33% efficient (gas KWh in to electric KWh out) it would be possible to generate electric at 21.9p per KWh, which in itself would be cheaper than buying electricity from the grid before even before thinking about making use of the heat that the generator's engine produced that would normally be wasted. Use the electricity generated to power a heat pump and make use of the engine/exhaust heat to heat radiators / hot water tanks directly.
I.e. Due to the difference in cost per KWh (gas vs electricity), for same cost we can use nearly 4 x as much gas as electricity. So even if a generator is only 33% efficient it still works out cheaper to make our own electricity at home using the genny than to buy it from the grid. But then the 67% usually considered the genny's inefficiency can be put to the same useful application as gas boiler.
The 'generator' wouldn't necessarily even need to generate electricity, it could run the heat pump directly from the engine. Unless you want to produce a lot of cheap (compared to grid price) electricity, maybe to charge an EV or large household battery powered invertor system from.
Burning gas is the most common method the UK grid uses to generate electricity anyway and they make a profit burning gas to make electricity to sell to you despite grid transmission losses (all those power lines and transformers waste heat to atmosphere).
I know it wouldn't be in the environmental spirit but could it work out cheaper (than using electricity) to drive the heat pump using an efficient engine fuelled by mains gas? It would also be possible to make use of the coolant heat (instead of having an engine radiator) and the exhaust heat.. Could maybe even run an alternator from the same engine to get cheaper electricity too.
Heh, thought once occurred that maybe it would be possible to claim to have had solar panels fitted (while not actually spending any money on them because none were bought), set up a genny running from mains gas, sell the leccy it made back to the grid (feed in tariff) claiming it was produced by solar panels.
Both of the above taking advantage of the kwh price difference between mains gas and electric.
Probably best to fit a replacement torque convertor at the same time if the fluid is full of bits?
Years ago I bought 2 x Rover V8's (old 3.5 motors), at that time I was fit and could carry one by myself, wouldn't be able to do it now lol.
Thanks Gilbert
How are the systems reversed (heat / cool a room) ?