4.6 conversion problems

Split the wires and now have P0340 Camshaft Position Sensor Circuit Malfunction which according to the wiring diagram shouldn't be affected by that wire!

Unless of course you get so desperate you miss something, ignore the joined wires:doh:

Ok bill check the loom over the gearbox/bell housing not uncommon to find the loom trapped!
How was the gas system connected
Disconnect the gas ecu does the sensors work right then?

Will investigate that, Stu. The gas system wiring hasn't been altered since before the engine was replaced as far as I am aware but will try it.

Since playing around with the wiring and replacing the fuse, I seem to be getting a bit more action from the 02 sensors, not right and gives up after a while but have a look

Land Rover Discovery II 4

Cheers

Bill

Question the O2 sensors are heated. And I assume the wire from the fuse 2 supplies the voltage to the heaters? Therefore if this compromised then the O2 sensors won't heat and therefore won't work properly?

I think the heater is to get themto operating temp then the exhaust gas temp takes over, you should see the heater switch on then off as the temp rises

No,the heaters must work as the temp of the gases at low speeds/loads is not high enough to make them work.You can see them being fed power as live data on Testbook.

But if the gas are hot enough then the heaters will be off yes and no then

Heaters on at low engine speeds and low loads, giving an envelope of operation, and switch off as everyone says at higher engine speeds and load. Depends what they chose the parameters to be at the factory.

If you buy one new sensor, and replace one of the current ones, you would be able to see if:
A) fuel has had silicon in it - a few years ago, some supermarket petrols had high silicon content and knackered many O2 sensors - lots of garage repairs had to be paid for by the oil companies.

But you won't get positive data to say that the ECU is supplying voltage, which you need to test for directly. The ECU might say that the heaters are on, but is the voltage getting to the sensor?

You would need to check the current flow as well.

You might be able to unplug the engine ECU and probe the lambda sensor wires from that point to check the heater circuit resistance is ths same as the lambda heater resistance, any higher resistance would mean that the heater would not be seeing the full voltage it needs.

A lower resistance would mean a short before the heater itself, infinite resistance - broken wire of course.

You could apply the voltage that is specified to the heater circuit, with the lambda sensor removed from the exhaust manifold, and check the temperature of the sensor itself. Be careful how you do this because it is going to get hot if it is working properly.

Once the lambda sensors have been tested to death or to confirm life, you might then be able to get onto the further question of fuel injection parameters.

If you have checked all components for normal operation, checked for air leaks, checked global parameters such as fuel pressure - fuel pump and fuel pressure regulator, and all those are fine and normal, then the fuel injection parameters finally might need to be looked at.

If the fuel trims are getting richer, it means that the ECU understands the data from the lambda sensor as being lean - obvious bit, but tells you that the ECU is doing the calculations, and is increasing the injector duration to compensate.

Injector duration, because this is Pulse With Modulation (PWM) is the way the ECU adds more fuel. If you see what the normal duration starts at, then increases to, you can tie this in with the % change of fuel trim.

With fueling, and controlling the injectors, you need to check the voltage at the ECU pins - i.e. before all the wiring, then at the injectors themselves to ensure that the voltage is actually not being reduced.

The voltage could be reduced by a bad bit of wiring - high resistance, or an LPG ECU, where there may be a relay or a thyristor/transistor, or even the voltage supply that are not normal. High resistance due to a failing component would reduce the voltage at the injector. The opening speed of the injector would be slower, due to the lower force applied, because of the lower voltage applied to the coil of the injector.

This would all need to be compensated by a longer duration signal from the ECU.

This is getting specialised, and you would need an oscilloscope to look at this.

If the fault appears over time with the engine running, it could indicate a component heating up as its failure mode.

I think Vougese39 made the point of disconnecting the LPG ECU, but with many LPG conversions this isn't possible, unless you actually replace the loom with a new one.

With LPG conversions, you have the LPG ECU switching the voltage supply from the engine ECU between the petrol and gas injectors, and this may not even be directly, where it might be directly with the petrol injectors, possibly through a relay, but it will never be directly with the LPG injectors.

With the wiring loom having been cut, to enable the switching ON/OFF (between) each injector type, a new area of electrical failure (unreliability) has been introduced.

If you can get a spare LPG ECU this might be the easiest approach.

With 10 ohm injectors, an equal resistance in series will reduce the voltage at the injectors by half. Relays can have an increase in the resistance of their contacts.
Electrical components can heat up.

But, you may need to look at the supply voltage to the LPG ECU, i.e. how good is the positive wire fixed to the battery terminal, or where does it go from. It might be a ground that is poor and so some voltage is being lost in that poor ground.

To look at this, you would need to probe all the wires for voltage and ensure that there is no voltage lost, or on the ground at the LPG ECU isn't a positive +1V or something higher than zero, which indicates a poor ground.

On replacing the loom, you might be able to unplug certain LPG parts of the system and jury rig a short loom to rewire the petrol injectors, effectively to remove the LPG wiring aspect of the system temporarily, thereby removing any effect that any hypothesised LPG system failure could have. This could confirm/deny the LPG system as the problem.

Looking at that fuse, it looks like someone has put it somewhere hot, i.e. it isn't a failure of the fuse itself.

Fuses are designed to blow way before the plastic would melt.

Is there a source of heat aimed at that fuse box?

If the fuses get hotter, then their resistances would increase. If plastic is melting from another heat source, that heat might be enough to affect the resistances and therefore voltages related to the components linked to those fuses.

Difficult to say by how much though.

Might be a red herring, where someone has got lazy and used a dodgy fuse.

URGENT!!!

It could be the FUSE HOLDER or FUSE BOX itself - not the fuse.

If there is a bad wiring joint on the fuse holder / box that would give a resistance, give a voltage drop and heat up that fuse!!!!

You need to strip that fuse holder / box down and look at the wiring joints - that one might have corroded.

This might be it.....you need to examine it very carefully.

If there is a resistance, it will increase as it gets more current through over time - and give the symptoms you are getting!!!!!

As resistance increases with temperature, then the voltage drop gets bigger with the increase in temperature, as the resistance increases, the voltage drop increases, until either the wire breaks - just like a fuse blowing, or you reach an equilibrium of a certain resistance, temperature and voltage drop and a rate of component cooling, maintaining the equilibrium temperature (hot).

You might need to check if an extra load from the LPG electronics has been wired through there, just incase the wiring has been overloaded in terms of current. Some wiring will age quicker if extra loads are put on a flaky wiring system, which only just copes with standard loads.

I believe that LRs are well known for wiring faults.

Or you could just carry on down the diagnostic route you have taken

One point on the same page to save from eye ache when it went off song did you change petrol company shell has a serious issue at the moment with it's new petrol had a customer is Scotland which it would not start found it was a contaminated petrol from them ran fine on tessco!

Try doing an intellectual property review of 2000 patents over a period of a month, which works out at 100 patents a day in an 8 hour shift. That gives me eye ache.

10 pages in 2 weeks?

Doesn't it warm your heart that there is a group of helpers/supporters who really want to get this problem fixed, and who are willing to spend their free-time, "working the problem" as NASA would say to continue the earlier vein.

On the topic of petrol, one rolling road/tuning company near me did some tests on Shell and Tesco Super UL, and found the Tescos stuff was more stable with storage.

Had a day off from it today, had family up from deepest darkest Essex.

Checked the Fuse box already tis fine, fuses can melt from continuous operation at there limits.

That was my plan Stu, not petrol as far as I am aware I mostly use Texaco if filling up with gas or Esso if petrol only. Had an email from the Simon who fitted the engine and he said as far as he is aware B&H use all original parts for their rebuilds (except the liners) but will check on Tuesday.

Yes RM, the fact that there are people out there who are willing to spend so much effort to help is very much appreciated. If you were all a bit nearer I have a very well stocked "cellar" of home brew ranging from supping ales to head crackers of 10-12% abv, lagers and ciders too, which you would be welcome to share a bottle or two.

Cheers

Bill

Thanks for the offer, looks like you are getting through the different possibilities gradually. I was not surprised when one bloke told me he spent £2k getting one electrical problem fixed, with everything that has to be worked through.

I'll keep an eye on progress and cut back to chipping in occasional thoughts as you progress, or if you ask specific questions or ask for ideas.

More random thoughts, the 02 sensors are showing mostly lean running, ie low voltage = too much Oxygen in the exhaust fumes, now if it was too little fuel one would assume the car would lack power? Which it doesn't, so could I still be looking for an air leak that effects both banks, if so what could I have missed?