L320 4.2sc issue

[Themoog]

Hi all. I have a 2005 range rover sport supercharged that has a brc lpg system installed and a valve lube system too.
I'm no expert on lpg but I'm having a really strange problem..
On a cold start only after the motor has been running for circa 5 - 10 min the engine temp guage reads normal. When the lpg kicks in the temp gauge drops instantly by 1/4. This coincides with the engine hunting and the interior blower fan going on an off. If I switch off the lpg the temp shows normal but the rpms are too high. The engine cooling fan come on too even though the engine is obviously not hot enough.
If I switch the motor off and then back on, everything returns to normal almost like its been reset somehow.
Anyone got any ideas? It baffling me..
I have replaced the engine coolant temperature sensor twice to no avail..
If you type 'range rover sport temperature guage anomaly' into YouTube you can view the fault happening. Sorry If tried to attach it here but it wouldn't have it for some reason.

[LPGC]

When was it installed and which BRC ECU is fitted?

Would think the unusual temp gauge and heater fan activity will be due to an LPG reducer plumbing issue, reducer mounted too high in the engine bay or not plumbed in a way that sees the reducer always get a flow of hot water regardless of cabin heater settings/activity (should be plumbed in parallel with the matrixes not series). It shouldn't take as long as 10 mins for the engine to switch to LPG, this could also point to a reducer water flow problem. If coolant level is (or has been) low enough to cause an airlock to form in the reducer this could effect water flow through the matrixes too.

Normally when set to 'auto' and a warm(ish) cabin temp is selected (any temp selection besides full cold will be warm relative to outside conditions this weather) the climate control will start with a very slow fan speed when the engine/heater matrix's are cool (engine warming up) and increase fan speed as the engine/heater matrix's warm... but if the hevac detects a cold engine/matrix's the fans may well slow down again. So the heater fan speed is likely just related to the engine temperature reading that the engine/hevac system sees and which you also see on the dash gauge.

If the engine management system on these engines sees a problem (incorrect fuelling etc) they often set a higher idle speed. If the LPG system reducer is too cold when running on LPG it will likely cause incorrect fuelling. I've lost count of the number of supercharged rangerovers I've converted (maybe 30 or more) and they idle/run properly with no MIL light problems when I've converted them... But I've sorted problems on a great many that have been converted elsewhere even when basics such as plumbing have been done properly and have seen more than a few where plumbing hasn't been done properly!

Very likely all these problems are connected and the route cause just a reducer / heater water flow issue. There are other possibles such as the installer could have wired the system to the engine's coolant temp sensor instead of to a temp sensor on the LPG reducer (and could be a problem with that), could be a problem with canbus interference if the installer has connected the LPG ECU to the vehicle's OBD system.. All far less likely than the simple explanation of a water flow problem though.

When the engine is cold check coolant level. While the expansion cap is off give the engine a rev and see if coolant level drops. Usually these engines warm up quite quickly... If the reducer is plumbed in properly, is low enough in the engine bay and isn't airlocked the reducer should start to feel warm very soon after starting the engine. Also is the concentration of antifreeze in the coolant OK?

[Themoog]

Gosh.. That was a it technical. Thanks for the reply.
The lpg system was already on the car when we got it and I have no idea who installed it although I am quite mechanically minded and it looks like a proper install.
The car didn't have this problem when we got it nearly two years ago and oddly it does not do it during summer months.
There is an lpg specialist a few miles from us (Bourne near Cambridge) so I may give it to them to take a look.
Yes the antifreeze is correct as I had to replace the supercharger rad so I sorted that.
I shall endeavour to locate the reducer and check like you said.
On a side note- do these engines suffer from exhaust valve wear on lpg?
The reason I ask is that the car was in at my local garage last week as the eml kept coming on and a scan showed lean mixture on both banks.
Could that have something to do with the lpg system?
Interesting..

[Gilbertd]

Last question first, yes, the Ford/Jaguar engine in the L320 SC does have soft valves seats so does need to have a valve lube system fitted, worn valves shouldn't give a lean mixture error though. You're in the right area though, Tinley Tech aren't far from you and they are BRC importers these days so should be able to give it the once over.

[Themoog]

Well I bumped into a friend of mine this morning and he has a discovery with lpg. I mentioned the symptoms I am having and the first thing he said was have you got an air lock in the coolant. Then he showed me the reducer so now I know what to look for.
His is mounted high up on the right side of the engine bay. I'll check ours later.

[Themoog]

Well no joy with Tinsley Tech and the lpg place near me disappeared 7 years ago even though the website still says they are there..
Ive looked and seem to have two lpg reducers side by side. They are located on the opposite side to the battery in the engine bay. One of them is clean but the other has a slight oily residue around the join where the two halves of it are bolted together. Further investigation is required..

[Brian_H]

Start with the simple things first - does the reducer get hot once the engine is running and upto temperature. It should be hot enough that you don't want to hold your hand on it if the flow through it is good. If not it may be airlocked. Oily marks on the outside could be an indication the reducer itself wants attention, or could be from something else possibly.

Worth checking if it gets hot on petrol, then compare what happens when you put it on gas.

You can attach photos here directly if you click the full editor & preview button to make a post as well, which might help spot problems?

[LPGC]

Also check for a broken diaphragm, I've changed loads of reducers on supercharged Rangerovers where the installer fitted 2 of the smaller BRC units.

[Themoog]

Well I started the car up this morning and the reducers started to get warm pretty quickly - within 2-3 min I reckon.
There seems to be what looks like a temp sensor on one of the reducers which could well be the culprit given that when the fault occurs I can turn off and back on and everything is normal.
Ive found a place near Stevenage that say they can fix it but I'm just waiting to hear if they have a courtesy car..

[Brian_H]

There should be a temp sensor there somewhere, so sounds like you've found that. But is that on petrol or gas? If its on petrol, is it any different after trying to run on gas or does it stay warm?

[Themoog]

There is no gas in it at the moment so that was just running on petrol. I'll put some lpg in it today or tomorrow and try again.

[LPGC]

In addition to my points in post #2 the erratic temperature gauge and heater operation could be caused if the LPG ECU is connected to canbus/OBD (which would be to allow the LPG system to read and act on fuel trim readings).

[Themoog]

Interesting.. Today it ran out of gas but instead of switching to petrol automatically the car just stopped. It beeped a few times but that was it. I had to manually switch to petrol. Its never done that before.

[Themoog]

How do I upload a photo? Every time I try it stops and I get a msg saying ‘http error’

[Gilbertd]

Upload your photo to Imgur or similar, get a direct link to it. Rather than using the quick reply box, click on full editor & preview and you then have an option to insert a picture. That will put the image command (img inside square brackets, then paste the url to your picture, then /img in square brackets) in your post.

[Themoog]

[Themoog]

That’s the set up on the L320

[mgrover]

LPGC isn't that location of the reducers incorrect because its not lower than the coolant tank?

[LPGC]

LPGC isn't that location of the reducers incorrect because its not lower than the coolant tank?

Yes, it's above the expansion tank level. But I believe has already been mentioned to Themoog on a different thread and it's not unusual to see reducer(s) mounted in this position on Discoveries / RRSports without causing a problem. I would have avoided fitting reducer(s) in that position but we can assume it ran OK with reducers in that position for a long time before any problems with components developed and it would be a fair bit of work (and maybe involve fitting different types of reducers) to relocate them.