1998 P38 Range Rover guidance?

[v8vroom]

Hi all,

I have seen a 1998 Range Rover that has 107k on the clock and has been converted to LPG (not sure when). It has an IMPCO 110ltr system installed. No service history for it apart from clean outs.

I am conducting research elsewhere on common problems for the car, but I'd like to know if anyone here has any experience with this car being LPG converted. Any advice would be appreciated, thanks.

[Brian_H]

Gillbertd would be the obvious person for that here, They are a fairly common vehicle to be converted

It may be worth you looking around on https://rangerovers.pub/ as most of the forum members here who have one will also be there.

Not sure if a 98 would be Gems or Thor setup, the Thor is better suited to a multipoint system, Gems could be either single point or multipoint.

Any specific you want to know about?

[Gilbertd]

98 is GEMS the same as mine. It was already converted with a singlepoint system when I bought it 12 years ago with 205k miles showing on the clock. It's now at 469k (will be 470k by the weekend), still running the same singlepoint. I've replaced the vaporiser once in that time but other than that the system just works. As for everything else, a P38 was an extremely complex car using lots of new ideas when it first came out. The BeCM (Body electrical Control Module) was a new idea (even thought something similar is used on virtually every car these days), the air suspension was a total mystery to everyone, including main dealer mechanics, so a lot of cars were ruined by having it replaced with coil springs and numerous other niggly things can give problems. If you are handy with a spanner and have an understanding of electrics, go for it. If you intend taking it to a mechanic it will bankrupt you.

Personally I'd budget for a lot of work on a low mileage car. There's many things that deteriorate with age rather than mileage (and others that suffer through lack of use). The most important thing to keep in perfect condition is the cooling system, one overheat can kill the engine (although that goes for anything with an alloy engine). The nicest thing about a P38 is if the engine is still running and it has a wheel at each corner, it will still get you home. I regularly drive mine all over Europe without a second thought, although the fact my in-laws live 1,520 miles away means a family visit is a fairly long run.....

[LPGC]

Just to emphasise the points...

P38's must be one of the most popular LPG conversion vehicles in the UK ever, I remember in the mid 2000's converting around a dozen on the trot (one after the other without converting a different model vehicle in-between), I've probably converted the best part of 100.

Gilbert is the P38 expert here and he's one of the forming members of rangerovers.pub where all things P38 related are discussed (not just LPG conversions). You should join rangerovers.pub forum.

[v8vroom]

Hi all,
A small new finding on another P38.
The owner says if he harshly accelerates from idle, the car will switch from LPG to petrol. Is this a big concern?

[Brian_H]

That would suggest its either underspec components, badly fitted components (tank) or poorly setup.

Some systems will allow switching to petrol at high loads, you generally won't want that to be the case, its there to provide some valve protection on vunerable vehicles (which the p38 isn't one) and to cover when the components fitted can't flow enough fuel (can be worked around with careful selection of components).

Your more likely to see that on a sequential system than the Impco type or other single point setups.

One other thing that can cause it is an incorrectly fitted tank or one fitted with the wrong valve, they come in different sizes, different shapes and orientations. if the pickup isn't on the bottom of the tank, then you can draw up vapour instead of liquid fuel when the lpg sloshes around in the tank, this is more likely if the tank is getting towards empty.

I've got a Disco 2 4.0 which doesn't switch back (thats a Thor model). Thats using a Romano vapouriser and KME Nevo ECU with OMVL SL injectors. Kit was all specc'ed by Simon (LPGC) on here except for the tank which is a 160 litre cylinder in the boot (which if I was converting it again, would not be the tank option I'd go for now as it makes the boot near useless, but the spare wheel well option isn't an option for the Disco 2 unlike the p38)

[Gilbertd]

As Brian says, it's being starved of fuel so pressure drops and it thinks it has run out so switches back. Most likely underspecced components somewhere but it could just as easily be a liquid phase filter that is clogged solid so restricting the amount of gas that it can flow.

[v8vroom]

Thanks.

I’ll take the car to a specialist most likely next year as this isn’t my daily.

I did, however, fill up for the first time since owning the car. As the tank is situated directly in the boot, as opposed to the spare wheel well, once the pump was removed from the car, there was a LOUD vibration coming from the back of the car (presumably the tank.)

Is this considered normal? I’ve never heard such vibrations in my XJ8.

[Brian_H]

Not normal no, would sound like a valve thats not fully closing. I've known a combination of car and pump to make machine gunning sounds when it reaches the full point whilst filling, but not after disconnection.

If the tank is really empty you can get some odd sounds when it first starts filling due to the gas boiling in the tank due to it being near empty and hence no pressure there (you'd notice the same as the last few bits are getting used up as well). I've only ever really noticed that on the large cylinder tank in the Disco, Torroidals its not so noticable as far as I've seen (usually they are better insulated against the cabin though)

[v8vroom]

So, I went to a specialist to diagnose the problem but the issue was as that he couldn’t locate the diagnostic port.

I’ve asked the previous owner and he responses “I think you can access the diagnostic through the interior OBD port as it’s part of the fuel ECU.”

I don’t want to go back to the specialist with that response and sound like an idiot. Is his response even a thing?

[Brian_H]

For anyone on here to give you much assistance we need some idea of what you actually have? You've mentioned some Impco bits, and mentioned a problem with the tank making noises?

I can't see personally what diagnostics would tell you about noises from the tank, are you trying to fix something else?

Impco bits mentioned may mean there isn't much or anything in the way of electronics to get diagnostics from as far as I understand, any idea if its connected to an exhaust sensor? (there may be an additional sensor welded into the exhaust for this)

Photos would really help get an idea of what you have and some sort of idea of what your trying to solve would be helpful? You can upload photos by clicking the full editor and preview button below to reply.

[Gilbertd]

I think the Impco kit was on a different car he was thinking about buying but didn't in the end. So we have no idea what is on the one he did buy.....

Find the ECU, which isn't part of the petrol ECU, it is a separate box that is slaved off the petrol ECU and read what it is from the label. From your posts on the RR.net forum (and not the sensible one without all the Yanks on it), you have a 99 so will be a Thor. Chances are the LPG ECU has been put in the plastic box behind the battery that is used for the petrol ECU on an earlier GEMS but is just an empty storage space on a Thor. Any half decent LPG specialist would know about that, considering the number of P38s that have been converted, and should be able to find the diagnostic port on it's flying lead.

[Brian_H]

That helps fill in some of the blanks, if its a normal sequential type system, then likely the diagnostic connector will be somewhere on the loom within 12"/30cm of the ecu. Typically its on a superseal or molex connector, superseal might have a cap on the connector.

Some ecus use other ways of connecting, at least 1 you disconnect the dash switch and connect to that.

As Gillbertd says, find the ecu and identify it is going to be your next step now.

If your specialist couldn't find the diagnostic connector that would be setting off alarm bells for me unless its something really odd thats been fitted to it.

[v8vroom]

That helps fill in some of the blanks, if its a normal sequential type system, then likely the diagnostic connector will be somewhere on the loom within 12"/30cm of the ecu. Typically its on a superseal or molex connector, superseal might have a cap on the connector.

Some ecus use other ways of connecting, at least 1 you disconnect the dash switch and connect to that.

As Gillbertd says, find the ecu and identify it is going to be your next step now.

If your specialist couldn't find the diagnostic connector that would be setting off alarm bells for me unless its something really odd thats been fitted to it.

Hello,

I lost access to my account in March, but I am back. I've been living with this issue since I bought the car, but as I plan to do a road trip abroad, I am ticking off all the issues.

Regarding the tank noises, when filling up, there's a loud shaking noise. Gunshots, almost. I am not too fussed with this as I plan to remove the cylinder tank and install one in the wheel well. I can't remember the maximum size that my P38 can fit.

Regarding my ECU port, the specialist who installed my LPG system was able to locate it. It was indeed hidden behind the box behind the battery.

My local specialist connected the car up and concluded my reducer needed replacing, so I will be replacing that when my car is out of the garage for another issue lol.

I am always sceptical, which I truly hate. Does anyone else think it could still be something else?

[Gilbertd]

From your posts on RR.net, the LPG system is the least of your worries.....

[LPGC]

'Machine gunning' towards the end of filling a tank to the top was a common issue with certain types of multivalve, also common on multiple tank setups. But still 'gunshots' would normally be an exaggeration, really the machine gunning sound was just the (much quieter than actual gunshots) tank fill valve opening and closing repeatedly. Different model (and later same model) tank valves didn't have the same issue, at least not on single tank setups.

No surprise that your LPG ECU's diagnostic port is near the battery, most of us would have suggested you look for it there on a P38.

Could what be something else? You've mentioned 'gunshots' during filling, I've addressed that above, mentioned running harshly and/or switching back to petrol during acceleration... That could be due to one/more of many things. Impco is the brand name of a 'gas carb' type LPG system, it doesn't switch back to petrol automatically when you're run out of LPG, a system that switches back to petrol automatically when you've run out of LPG would be a sequential system (so it seems you have a sequential system fitted?). It would be possible to fit/use an Impco pressure reducer, normally used as part or an Impco gas carb setup, as the pressure reducer for a sequential type LPG system but it probably wouldn't be well suited to a sequential type LPG system.

As BrianH said above, we really need more info. Both about your setup and about the problems.

Gilbert's said you've mentioned other issues on RR.net... I'm not sure if I've read those posts (or if I have read them I don't know it's you that wrote them) - If the car won't drive properly on petrol then with a sequential type system it probably won't drive on LPG properly either.

[v8vroom]

From your posts on RR.net, the LPG system is the least of your worries.....

Slowly ticking everything off now.

[v8vroom]

'Machine gunning' towards the end of filling a tank to the top was a common issue with certain types of multivalve, also common on multiple tank setups. But still 'gunshots' would normally be an exaggeration, really the machine gunning sound was just the (much quieter than actual gunshots) tank fill valve opening and closing repeatedly. Different model (and later same model) tank valves didn't have the same issue, at least not on single tank setups.

No surprise that your LPG ECU's diagnostic port is near the battery, most of us would have suggested you look for it there on a P38.

Could what be something else? You've mentioned 'gunshots' during filling, I've addressed that above, mentioned running harshly and/or switching back to petrol during acceleration... That could be due to one/more of many things. Impco is the brand name of a 'gas carb' type LPG system, it doesn't switch back to petrol automatically when you're run out of LPG, a system that switches back to petrol automatically when you've run out of LPG would be a sequential system (so it seems you have a sequential system fitted?). It would be possible to fit/use an Impco pressure reducer, normally used as part or an Impco gas carb setup, as the pressure reducer for a sequential type LPG system but it probably wouldn't be well suited to a sequential type LPG system.

As BrianH said above, we really need more info. Both about your setup and about the problems.

Gilbert's said you've mentioned other issues on RR.net... I'm not sure if I've read those posts (or if I have read them I don't know it's you that wrote them) - If the car won't drive properly on petrol then with a sequential type system it probably won't drive on LPG properly either.

When filling up, I've noticed three different things, at different times.
1. 'Gunshots' when finishing filling up.
2. Vibrations throughout the process of filling up.
3. Normal operation. No weird sounds.

"Could what be something else? " - my reducer needs replacing as the car thinks the tank is empty under harsh acceleration.

In terms of switching over when the car thinks it no longer has LPG left, there will be beeping and flashing, but I have to press the button to switch to Petrol mode. (not sure if the beeping means it has already switched, and I have to press the button just to stop the noise?)

The other issues are P38-specific. At most, perhaps a change in sparkplugs. Thankfully, it runs well on petrol.
I will take pictures once I have the car back.

[LPGC]

Noises during filling up are not related to any other problems, certainly not related to any reducer problem, beeping or the car cutting back to petrol. Vibrations will occur if 'machine gunning' occurs, there may be some vibration during filling up anyway. I advise you not to concern yourself with tank noises or vibrations during filling up, they're not really a problem and are not affecting anything else such as how well the engine runs on LPG.

When it beeps it has already switched back to petrol. It seems that with your LPG ECU you need to press the switch to stop the beeping, the same is true of many LPG sequential ECU's / switches including all of the AEB based stuff.

We are a long way from knowing if your reducer is OK, or needs adjusting, or needs repairing, or needs replacing, or needs replacing with a different make/model. For starters, what make/model reducer is fitted?

[v8vroom]

Noises during filling up are not related to any other problems, certainly not related to any reducer problem, beeping or the car cutting back to petrol. Vibrations will occur if 'machine gunning' occurs, there may be some vibration during filling up anyway. I advise you not to concern yourself with tank noises or vibrations during filling up, they're not really a problem and are not affecting anything else such as how well the engine runs on LPG.

When it beeps it has already switched back to petrol. It seems that with your LPG ECU you need to press the switch to stop the beeping, the same is true of many LPG sequential ECU's / switches including all of the AEB based stuff.

We are a long way from knowing if your reducer is OK, or needs adjusting, or needs repairing, or needs replacing, or needs replacing with a different make/model. For starters, what make/model reducer is fitted?

Once I get the car back from the garage, I’ll investigate and provide a response.

For now, I do plan on replacing the tank in the car. What’s the largest dimension that the wheel well will take?