Cold Starts?

[rbss]

All unecessary electricals off. Agree about the cruise control, it seems to be working great in manual transmission cars, auto-boxes have tendency to drop the gear at smallest incline (definitely the RX300 is! :D).

I am also taking away the miles covered after startups on petrol, to get the "true" mpg on Autogas. It's been just 2 weeks, so I will get much better idea over time.

[NEV72]

Actually I meant using the cruise control so as to keep a check on a heavy right foot, for when you're on a long motorway drive, as I don't know about you but often find myself looking at the speedometer and seeing you're doing 80 plus, because it certainly doesn't feel like it.

[rbss]

^{it is easily done, true. due to the amount of speed cameras on A90 I developed a habit of constant checking of my speed ;) Hated to see a ticked for doing ... 81mph :D First in 21 years :/}

^{I still use cruise control, but whenever I see some incline, I tend to switch it off and take the hill gently. It amazes me how the car reacts to even small hills - it waits until you're in 1/4th of the way up, revs remain unchanged, and suddenly it decides "we need power!", so it drops the gear, or sometimes even two and ... stays at the same speed, it's not like it has to correct anything ;) It would go without any problems without changing the gear, but it just trying to show you that technology is smarter ;) Maybe it's me being spoiled by the cruise control on manual Skoda Superb (obviously it wouldn't change the gear, but it never really struggled to keep the speed using the same gear and just tiny bit higher revs), but I find the cruise control in Lexus rather ... annoying ;)}

[NEV72]

Tell ya what, you think the cruise control is clever in the 300, I had the 450 premier as a courtesy car last week and that has adaptive cruise control + pre crash system, well impressed with that.

[Boxbrownie]

I tend to use a new TomTom nav set to 76mph warning speed.......stops me getting carried away on the Mways.........do the newer 350/450's not have a overspeed alarm on the cruise system?

My ML has a speed limiter built into the CC which is very handy, so you can drive normally but when you get to your set speed....the throttle stay put, easily overidden if need be but its a great safety aid.

[rbss]

Another trip to Glasgow, cruise control off (to stop changing gear at each incline), grandpa mode on ;) , managed to get a very respectable 24.5mpg. I have noticed, that the car seems to be using less fuel doing 75mph, than doing 65mph (counter-intuitive, but checked the computer and it was showing the same thing).

On the way back, cruise control on at 75mph, had to overtake few cars (kickdown), and ... checked how the S-mode works on the gearbox :D. Pedal to the floor, LPG gets disconnected and switched back to petrol automatically (not sure if it should be like that) and the car goes like a rocket :D Well, not really, but how it sounds ... makes me want to drive in S-mode only :D

With all these silly things, mpg down to 18.5 :D

Still. taking LPG price into consideration, it's just silly for such a big car.

Biggest gripe so far - I should really go for the bigger tank - I think I got used with my skoda to visit the petrol station once a month and not ... once a week :D

Will book the car this week for oil/filter change, spark plugs change and checking of the wheel geometry - noticed the outside side of the tyres are worn more than inside/centre. Pressures at 34PSI all round just now .

[Boxbrownie]

24.5mpg??? I whizzed along to Bath and Bristol this weeked to see the kids and used M25-M4 sticking to about 70-75(true) mph and averaged 27.8mpg including crawling around Bath and Bristol city centres in the middle, are you sure the LPG is working correctly?

[rbss]

I have taken into account: total miles minus the miles on petrol (approx first mile after startup), and litres of LPG that went in. I think my computer was showing a bit higher reading, but I know it's very optimistic, and it still shows the mpg for petrol (it doesn't know that I'm using LPG). 216 miles and 41 litres of LPG. that's actually 24mpg. When I included the miles on petrol I had 24.5mpg (221 miles on 41 litres). That covers Aberdeen > Glasgow, some miles around Glasgow (including getting into 11th level of car park :D), trip to Balloch and Stirling, where I had to put LPG in.

Prins manual says the MPG on the LPG will be 5-20% higher than on petrol. The max petrol mpg I had was 30 (computer showed nearly 31).

If I take 30MPG (which was really driving across the country, flat motorways) as a best MPG achievable (which most likely is, I never seen anyone claiming getting much more, majority of people reports 24-25mpg on petrol?) the 5% margin would give 28.5MPG and the 20% margin would be 24MPG.

So far, I am much closer to the 20% margin (or maybe even more :/) - but I will be taking the car in the next 2-3 weeks to the installer to get final tuning and few other tweaks. I am hoping the MPG will going to increase as a result of that visit ;)

[rbss]

On a side note, I also have another observation... Most people regard RX300 as one of the very quiet cruisers – I find it ok, but definitely not very quiet. My previous Volvo XC90, and Skoda Superb were both a good bit quieter at cruising speeds (on the same motorways).

There is a fair bit of road noise coming to the cabin, car has Bridgestone tyres currently, maybe that’s part of the reason? But as I am aware, they are one of the recommended types for this car...

[Boxbrownie]

There is a fair bit of road noise coming to the cabin, car has Bridgestone tyres currently, maybe that’s part of the reason? But as I am aware, they are one of the recommended types for this car...

And thats why I fitted Michelin Primacy 3 tyres to mine, far quieter than most, excellent economy and wet grip is class leading......whats not to like?

Who said price?

[rbss]

Haven't seen them in 235/55 R18 size ;) My tyres are still 6-7mm so I will need to live with them a bit. Need to check that outside wear though.

Any comment on your LPG MPG Boxbrownie? ;) I am very curious to hear what other LPG users are getting, if majority gets better results, it definitelly calls for LPG re-map!

[stevet]

Mines by far the quietest car I've ever owned. Maybe that outside wear is also creating the extra noise?

[Boxbrownie]

My LPG consumption is the best fuel economy figures I have ever had...........my car never uses a drop (or should that be Kilo?) :P

[carld]

Rbss, in your earlier post you mentioned that when you put your foot hard down, then the lpg disengages and turns back over to petrol. There has to be an issue with the pressure system, the only time it should change over is when you run out of gas thats all. My friend has a porsche cayenne on lpg, he tried the cheapest system available and that was what would happen on his, he ended up having to get a new system that could handle the pressure. Not saying your system is not adequate, it may need tweaking or , i had to change the nozzles in my injectors on my bmw ( only little plastic things ), as when i accelerated hardish the lpg couldnt keep up with the demand from the accelerator, it took 20 mins for the lpg installer to refit wider inserts so allowing more gas through, since then its fantastic. Might be worth checking out.

[rbss]

I am making all the notes regarding the LPG and will talk to the installer during the visit. Thanks all for your input.

@ stevet: Regarding the noise, maybe yours 400h is quiet (especially on electric power) but my RX300 isn't. It can be very quiet on nice flat and new surface, with no wind and without accelerating. I don't mind the noise on acceleration, because the V6 sounds quite sweet ;) The road noise and wind noise are the biggest factors, as I have said the XC90 and Skoda superb were definitely quieter (XC90 on Hankooks, SKoda on Marangonis initially, then on Yokohamas, and even now on winter Vredesteins).

[ColinBarber]

I'm not really sure you can compare against a Skoda Superb, one is a saloon car and the other an SUV. A Superb is noisy compared to a GS450h.

Maybe you have some door and window seal damage if you are getting a lot of road and wind noise. Road noise can be high on certain surfaces, which is also tyre dependant, but obviously I cannot tell if your vehicle is abnormally high.

[carld]

RBSS, the lpg system that you have had fitted, does it have the flash lube also.

[rbss]

Yes, prins valvecare is installed as well (also sequential injection).

[carld]

That's fine then, I didn't need one on my bmw but the BRC on my lexus doesn't have one, I only found out today when I took it in for a LPG service. So I'm getting one installed next Tuesday at a cost of £85 pounds, which is cheap. I expected a lot more. If it saves burning the valves out its a no brainier. I still haven't run the gas out yet, but I managed to put 52 Ltrs in on Monday and there was still gas in the tank, so that blows the theory of me having a 51 ltr tank.

[NEV72]

Look out for Flashlube oil on eBay, much cheaper than shops, as you'll find you go through a fair bit.

Well worth it in the long run mind.

[carld]

Cheers Nev, i cant understand why it wasnt fitted when the system was done.

[rbss]

I remember seeing Prins report showing Lexus 1MZFE engine as .... NOT recommended for LPG conversion due to issues with VSR. Two important pieces of information were saying that the problems can start very early (if I remember correctly, just after 20k km on lpg) and that VSR might still occur, even on systems with Valvecare.

Did it put me off from converting to LPG? Well.... a bit.but then I've done some research on european websites, and apart from one guy saying that he had the problems (no valvecare installed, rx300 mk1), the rest was claiming there's no problems whatsoever, with people clocking well over 100 or 150k km on LPG (I think the highest report was something like 206k miles equivalent).

I also seem vaguely remember (you can tell already my memory isn't the best!) that my LPG installed was saying that other lubrication liquids could be used, and I think Flashlube was mentioned there - I didn't pay too much attention, as I was getting two bottles of Prins lube, which in theory should last for 10k miles. But I'll raise that when I'll be going for a checkup/tune next Saturday.

Meantime... car is booked for oil/filter/spark plug replacement and wheel alignment check - tomorrow. Hopefully the issue with cold starts will go way :/

[rbss]

Small update. The oil/filters have been changed, and wheels aligned (from I was told they weren't far off though). Not sure if it's me, or what, but the car does seem to be running a bit quieter now.

Unfortunately, the plugs have not been changed. Guys noticed the LPG pipes and panicked. Need to find another garage.... or learn how to do it myself! (judging from the YT, it's hell of a job though! :D).

[Boxbrownie]

When I was investigationg LPG for my RX I was told by EVERY installer the "flashlube" was essential on the V6 Toyota/Lexus engines because of common VSR on these engines.

As your mechs saying no to the plug change.......hmmm another advantage of LPG

I'd try another independant if possible, changing the rear set is not so much difficult as long winded.

[rbss]

yes. I take all installers were making comments based on "experience" ? ;)

As far I am aware, there is Prins report that shows the info about Lexus cars with V6, and ... some anegdotical evidence of VSR on the net. One of the guys who was claiming his engine was damaged said that he had the lubrication system installed, but after 40 or 50k miles on the LPG.

I hope not to be proved wrong, but so far I have seen only 2-3 reports on the net detailing the VSR on Lexus engines with LPG. None of them is clear and factual. I have also found some reports of the VSR on Lexus engines (and not only Lexus engines) ... without LPG, so it's not only the LPG issue, but LPG conversion can make things worse (from what I understand). On the flipside, I've seen tens if not hundreds reports of cars running without any problems.

When I talked to few people in Poland and Germany about the issue, I was told that 1) lubrication system is required 2) Valve clearance check should be performed every 30k miles or so. (now, knowing that even spark plugs are difficult on this engine, I am somewhat scared to think what clearance check involves! :D).

After all this... I managed to go through the first 1k miles, with no problems ;) I hope another 49k, and I will be singing the same song! ;)