Sorry about that, here's the whole webpage with the pics:

Kuvagalleria 2

 

Well as I said - if you don't have problems with car give it to a mechanic and soon you'll have. The damn LPG system is bringing the Jag to a "Restricted Performance" somehow. So far it seems to be absolutely random and since I still don't have my OBDII reader I can't check what's causing the safe mode.

The car is working normally and occasionally the "Restricted Performance" appears on the dashboard, but without the check engine light. The strangest thing about this is that this happens while idling, while driving with high RPM, while stopping the car, even immediately after starting the engine when it's still working on petrol.

I'm planing to give a new nickname to my beloved car - "Mysterious" because this is maybe the fifth case when I have problem, no one knows why and I'm sure that this one will disappear as sudden as the previous problems I had with tranny, with suspension etc.

One quick question - what's the easiest way to clean Restricted performance?! Don't mention the hard reset with disconnecting the battery because the LPG tank is restricting my access to the battery and it takes about half an hour to get to it Another good idea would be to clean it with OBD reader, but this doesn't help me as well I was hoping that if I leave the car for a night the error will disappear by itself, but unfortunately it didn't. Any suggestions? Maybe a fuse that is easy to be removed... that will serve the same way as disconnecting the battery.

 

This is an interesting thread.

Not noticed Methane for sale here, LPG yes.

Regards your Restricted issue, I have no real idea. I'd check all the connections in the engine bay because evidently quite a bit of work has been done there. Something could have been knocked loose.

I'd also go back to your installer, they must have the means to test their installation. From what you have said, there is an electronic aspect to this because of the way the system kicks in with temperature.

And lastly, you don't say how far you have driven the car since the install, could this be one of those simple issues that needs to be worked through with a drive cycle?

I've only ever driven one LPG car (RR) and I can't remember whether it was 100% LPG all the time unless the driver switched over to petrol.

 

Will there be an error shown (e.g. restricted performance) if the engine runs too lean (at WOT)? And what's the capacity of the injectors in the 4.0 S/C engine?

Just thinking about the E85 compatibility...

 

Maybe you are right... while working they could have broken or disconnected something as for example the coolant fluid level sensor - when I took the car from the workshop it was displaying Coolant level low and after I checked the problem was that they have unplugged the sensor from the bottom of the expansion tank I really hope that this is the issue with the restricted performance. Otherwise we will need to check each and any part they have installed to see when the problem will disappear.

They do have computer for diagnostics but I think it can check errors only on the LPG system ECU. I hope they will have an OBDII reader as well.
As for the temperature and RPM sensor - I'm still curious how they are getting those values... I've asked them and they told me that the system is not reading data from the car's ECU. I wonder how they managed to do it?!

Up to today I have driven the car for about 300km mostly urban. I don't believe that the issue with the safe mode is related to some drive cycles... they (the drive cycles) may affect only the calibration of the LPG system and optimize the work of the engine.

Yes it's possible to make such adjustment and the car will run on both LPG and petrol... for example 80/20 percent but I'm not sure what are the benefits of this. The only thing I wanted for my Jaguar is a special addon which is automatically switching to petrol when you step on kick-down. This is because the car is always more stable and powerful on its original fuel - the petrol. After you stop accelerating or the RPM drops under 4000 the car again runs on LPG.

 

Ok - today was a good day for revealing the mystery problems I hope that this post will be useful for all of you that decides to install LPG on XJ8.

The Restricted Performance case.
I'll try to shortly describe the issue. After I took the car from the workshop with the newly installed LPG system it started entering in safe mode showing "Restricted Performance" on the dashboard (it's good to know that the check engine never lit up). This was happening in different conditions - while accelerating, idling, on switching between petrol and LPG, etc. Basically on every ride for more than half an hour the "Restricted Performance" appears sooner or later, but always in totally random condition.

The problem with this safe mode is that the car's computer is restricting the performance and you can't run the car with more than 2500-3000 RPM, can't use kick-down etc. Once the car is in Restricted performance, the only way to clean it up is either to disconnect the battery and touch the positive and negative (while disconnected of course) for 20 seconds to do a hard reset or to use OBDII reader to clean the errors.

What's actually happening?
Well in my condition and I strongly believe that in 90% of similar problem with LPG the errors were coming because of the injectors. To confirm this - check the error log on the car's ECU. If the fault codes are "P0201 – Injector Circuit Malfunction – Cylinder 1" up to "P0208 – Injector Circuit Malfunction – Cylinder 8" that this is the scenario I'm talking about.

When the car runs on LPG (or on petrol but after a long run on LPG shortly before this), LPG system computer does switch a 100ohm resistor in series with the petrol injectors to stop them firing - the way to shut down the petrol system when the LPG is runing. In 99% of cases the 100ohm is the panacea for almost any car without problems. However for Jaguar XJ8 this value is too high and the stock car's computer thinks there is an open circuit, meaning that the injectors should work but they are not so the ECU is flagging "restricted performance" and it's recording error for all the 8 cylinders. Because all this is a very sensitive electronics - the fault may appear in different conditions based on temperature, the injectors overload in the exact moment of switching between petrol and LPG etc.

How to cure the problem
Actually it's more than easy I was surprised that for 1 hour and 2 euro extra costs the problem was fixed. The solution is to either change the internal resistors of the LPG computer with a lower value (as much as I found in Internet - 33 ohm should do it) or alternativly solder a further set of resistors in parallel with the injector emulator wires. I believe the second option is a better one so we did it. The exact resistance for each injector should be 47 ohm and the place to install them is where the factory injector wiring has been cut into when installing the LPG system.
The internal LPG ecu 100 ohm plus the total sum of 47 ohm resistors running in parallel on each injector will give a very similar overall value (approx 32 ohm). This value worked well for me, low enough to stop the petrol ecu thiking there's open circuits and still high enough to stop the petrol injectors firing, and most importantly no more "restricted performance".

Thanks to javers from the jaguarforum.co.uk for helping me collect all this information I'm sharing now.

I hope that this will serve you, because I've lost about two days and a lot stupid arguments with mechanics before finding a solution. I'll try to keep updated the thread with more ideas and solutions related to the LPG installations

 

Wow, that could have been hard to find for someone! Congrats!

 

First, how in the heck did you save up enough to buy a Jag on that salary?!

Second, what do you do in IT? A number of my associates are hiring (I also work in IT.)

 

I never load my jag, my jag loads me (just kidding but thank you for the very informaive thread)

 

Very interesting post.

Being from Alberta where our main economic driver is oil and gas, we are under seige from a lot of people due to our growing oil sands production. The refining process carries a heavier load, thus more CO2 emission, although they are making considerable strides on improving that. (still pales by comparison to coal). We have an abundance of clean burning natural gas in Canada and the US. I know that a lot of environmentalists want us to drive 'Volts" but the majority of the electricity generated to charge them will come from coal fired plants for the foreseeable future.

I heard just last week that the Circle J truck stops were planning to install LNG ( liquid natural gas) at 300 of its locations across the US. The idea is that diesel trucks could convert to LNG. Natural Gas is currently at very depressed prices, about $2.45 per mcf (thousand cubic feet). For long haul truckers, compressed natural gas is not a great option, as it takes up too much room, but liquified gas is much more compact. I have only just heard this, and don't know if there are many LNG conversion options for cars yet, but for sure it is cheaper and way lower on CO2 emissions than gasoline/diesel. It does not eliminate fossil fuel usage, but certainly improves on the situation. Just with the tucking industry on board, it would make quite a difference. They put the miles on to justify the conversion from a cost perspective.

Some see LNG as potential end to reliance on Mid Eastern oil. The auto builders would have to get on board, but it sounds like the infrastructure is starting. For sure there are huge natural gas reserves in North America. It will be interesting to see if this option gains any traction.
Maybe Estillian is leading the way.

 

As I previously mentioned - the LNG is also a popular conversion for cars here in Eastern Europe. The ecological benefits of using gas instead of oil are tremendous, but there are a lot thing that should be improved in that kind of installation. I'm not sure if this is the future of the cars, but for sure the gas is already a part of the automobile history

As you said "Some see LNG as potential end to reliance on Mid Eastern oil" but believe me - some also see LNG and LPG as as potential beginning of a new reliance on Russian resources which is maybe even worst

And talking about improvement - Renault and Citroen are already offering stock LPG engines! A very good idea which increased their sales for the past 2 years!