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PostPosted: Wed May 30, 2012 1:35 pm 
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Hi all,
Well I finally took the plunge. Thanks to everyone who gave advice and thoughts to my questions thread in the 'find an installer' subforum.

In the end I went with MintLPG to do the install. While I had heard some negativity about them, I had also heard some good things too and they had major plus points for having actually converted ML500's in the past and being just down the road from me. To help others in future im going to document my experiences (and tips) here so that maybe this can help someone else one day.

Firstly, when I booked the conversion I paid a £100 deposit over the phone with my visa credit card (not debit card). This is actually a really handy thing to do as it makes the credit card company liable in the event that you have a problem and the retailer is out of business/wont help/cant help etc. This applies even if you pay the balance of the conversion off with cash, groats, turnips, whatever. As long as you pay the initial deposit via your visa or mastercard, you are protected for the full amount of the conversion by your credit card company by law. Fantastic. This is a good read for more info on that: http://www.moneysavingexpert.com/shopping/section75-protect-your-purchases.

Anyways, I digress. Mint is a bit off the beaten track in a rural setting on a farm, but I didnt let that put me off. The chaps there were fantastic in my view - great at explaining things, super friendly and were quite understanding even though I was delayed in getting there. Dropped the car off around lunchtime and got a call 2pm next day to come collect it.

Under the bonnet: Tidy. Cabling well secured, wrapped and insulated. Everything securely fastened down, well routed and a good job done on the electricals. Ive seen a picture floating around of an ml500 that mint supposedly did and that looks a mess - id like to clarify the install they did on my ML looks absolutely nothing like that. Unless I was specifically looking for under bonnet work, I would hardly notice anything is different.

Filler cap: Not colour coded to bodywork, but meh its hardly noticeable really. To be fair, i never requested that (but was not offered either!). The filler is mounted in the bumper in the exact position I requested. I checked that the correct metal mounts are used underneath the plastic and theres one there of about the right size and thickness so properly done there.

Tank: 70L Torpedo slung underneath in the spare wheel well (there is plenty of room for it, no clearance issues or protrusions). One issue ive noticed so far is the tank seems to only hold 50L in usable capacity (or more to the point, the gas runs 'empty' and switvches over to petrol after exactly 50L of gas has been used). I would have expected it to be 56ish. Perhaps an air lock? Ill be asking the chaps to check it out when im back for the 1k service.

MPG: Round town my car is a pig on petrol. About 16 mpg. I get about 12 on the gas round town, so about right? Motorway, I get about 25-27 mpg on a 'economy granny style' drive and about 20-21 on a constant 80-85mph drive. With gas im getting 16 to 17 MPG (using the brim and check miles method) when doing the 80-85mph runs and im going to nurse it home like a granny tonight (~200 mileS) so will report back the MPG then. I expect to get about 20mpg.

In car: switch placed in right position as agreed. no mess, no protruding wires. its the automatic cutover job so does the biz for me while I basicly ignore it for everyting except checking the LPG levels. One thing ive noticed, which is a bit weird considering how quiet mercs are - I can hear the vaporiser hissing when i accelerate. I did think I was going to get some settings (based on their website) of 'economy/normal/sport' but im guessing this is a setting in the ECU itself, as opposed to a switch i can toggle.

Engine: Havent noticed a loss of any power at all. This is probably due to the compression ratio of the v8. No new noises or problems so far after 450 miles, doesnt even seem to get any hotter than when it runs on petrol. It does seem to run quieter on LPG.

Warranty and After care: Not really needed this. I had the walk around, the installer told me all about each component, what they did etc. Showed me how to fill up. Usual stuff, but he was very friendly and enthusiastic about it. The warranty is a lifetime warranty for as long as I own the car, though I do notice that on some of the paperwork there are some fun exclusions (for example 'poor quality fuel' can invalidate a warranty - how am I supposed to know what 'quality' of fuel a particular autogas station is providing?).

Register and insurance: No physical LPG certificate, but it is on the UKLPG register online. Insurance company notified, £0 difference in premium (direct line)

All in all, a positive experience so far. I will keep this thread updated with any thoughts I have or problems I encounter with the install. I shall also add that im nothing to do with mint LPG, dont know anyone there personally and have not been paid or incentivised to write this thread. Im doing this because I think its difficult to find information on LPG conversions that have worked out well and the forums seem to be more filled with people who have problems with installers.


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PostPosted: Wed May 30, 2012 9:40 pm 
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Another 180 odd miles at a granny 65 mph motorway all the way, and im back home. Filled the LPG up on my return and calculated from the miles - strangley i got the exact same MPG (16) driving economically as I got on monday when i hurtled up (the same route) to london at 85 the whole way. I literally made it home on fumes. Im a little worried about that as there should be a significant difference between the MPG while driving with a lead foot and not (bear in mind, it does get much higher economy when i drive it like a gran on petrol vs driving like a nutter on petrol).

I removed the engine cover and had a good sniff around, right before the fan kicked in i thought I had a whiff of LPG on the right hand side 4 cylinders but with the fan going it was moving air through so quick i gave up. Will try to sniff around tomorrow and get some bubbles to see, but that may explain the rather static MPG on gas, irrespective of driving conditions.

Im also going to wire up the OBD connector and do some logging at some point around injector pulse etc. Does anyone know if the main engine ECU (not the piggyback) will increase injector pulse width when on gas? or should that remain the same as petrol and the piggyback ECU ensures the correct gas level goes in?


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PostPosted: Thu May 31, 2012 2:10 am 
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simonp wrote:
or should that remain the same as petrol and the piggyback ECU ensures the correct gas level goes in?

Yup, that's exactly it.

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PostPosted: Thu May 31, 2012 8:54 am 
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Did you fill up at the same place? Some pumps appear to be able to get more in than others, and it seems to vary with ambient temperature too making it difficult to get an accurate short term mpg figure. If the displayed mpg figure (taken from the petrol injector times) is the same on either fuel, that means it's set up correctly and the petrol ECU isn't having to make large adjustments.

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PostPosted: Sun Jun 10, 2012 4:37 pm 
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thanks Rossko!
Quote:
Did you fill up at the same place?


Same two places, one at this end of the country, the other up in london. Always use the same two.

Quote:
If the displayed mpg figure (taken from the petrol injector times) is the same on either fuel, that means it's set up correctly and the petrol ECU isn't having to make large adjustments.


Huge difference when running on LPG. I drive along a flat bit of motorway at 55mph, note the petrol MPG, hit the button to go over to gas and the MPG on the display shows about a 7 to 8 mpg drop instantly.

On top of that, today cutting over to gas there was a huge 'pause' as if the engine had no fuel, then it kicked in. I drove 2 mins down the road, the engine hesitates really badly, the check engine light comes on, the whole thing starts shuddering really badly. I immediately flipped back over to petrol and it kept on wit the hsuddering, felt like it was running on only 4 cylinders as it would tick over, jsut really rough. I turned the ignition off, had alook round and then restarted it. The CEL light is still on but its running just fine.

Its just coming up to the 1,000 mile mark since the conversion so ill be not using the gas any more and taking it to them to see what is the matter for its 1k service.


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PostPosted: Sun Jun 10, 2012 4:43 pm 
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simonp wrote:
[MPG display] Huge difference when running on LPG.

Not good.

simonp wrote:
the check engine light comes on, the whole thing starts shuddering really badly. I immediately flipped back over to petrol and it kept on wit the hsuddering, felt like it was running on only 4 cylinders as it would tick over, jsut really rough. I turned the ignition off, had alook round and then restarted it.

Mercs have a habit of shutting cylinders down when misfire detected. It then won't recover, even if the cause is removed, until a stop-start.
Given the MPG clue, it may be running lean on gas (which can cause misfires)

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PostPosted: Sun Jun 10, 2012 5:06 pm 
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rossko wrote:
Mercs have a habit of shutting cylinders down when misfire detected. It then won't recover, even if the cause is removed, until a stop-start.
Given the MPG clue, it may be running lean on gas (which can cause misfires)


Good info, thanks. That explains a lot.. though if the MPg im getting is it running lean, i shudder to think what it could be if it were running richer. Could it run lean due to a leak somewhere in the engine bay?


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PostPosted: Sun Jun 10, 2012 5:15 pm 
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Don't forget that you will use more gas if it is not running efficiently, which it won't do if it is lean or rich. However, you are not alone http://forum.landrovernet.com/showthrea ... -NOT-to-go!

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PostPosted: Sun Jun 10, 2012 6:05 pm 
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Oh dear !


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PostPosted: Sun Jun 10, 2012 8:46 pm 
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That doesn't sound to good does it !!!!.but then again its not that different to the comments you find on here if you look for them. the problems listed can happen to any installer (approved or not ) as someone said the merc will switch of cyls if a problem is detected and won't put them back on until switch off and back on however the light will stay on until it has been reset. Tuning issues are something we all have problems with from time to time ,but bad workmanship is something that is not acceptible ,after reading that post on LR and various other posts on here it realy is apparent that you only get what you pay for. And looking at what some (top end installers) are turning out I might have to increase my prices ,they certainly aren't getting what the paid for.......

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PostPosted: Fri Jun 22, 2012 1:32 pm 
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Thanks for the feedback everyone. I just wanted to update you on progress.

Took the car back for the 1000 mile service yesterday, its nearly 2000 miles since it was installed, but I havent driven on the gas due to the issues for the last 1k. The guys at mint listneed to the niggles, problems and immediately got to work. There is also a new staff member there who has moved from a LPG converter in cardiff that has closed - he listened and fell over himself to help me and make sure everything was running right. He seemed highly knowledgable on gas conversions and got straight to it himself, while talking me through everything as he went.

First there was a small leak from, i think he said, a screw on the temperature sensor. That was repaired. He then checked out the piggyback ECU tune and said it was definately too lean and (in my view, sincerely) apologised for the issue. He cleared the fault codes and re-tuned the gas ratio then we both went out for a drive. He did full datalogging with me during the test drive to show me the trims and pulses etc. Cutover to gas now gets the same values as petrol from the injectors. It does definately now feel like there is less power from the engine, but that is to be expected with richening the mixture and frankly its hardly noticeable on the size of lump I have. The instant 'MPG' meter (working of injector pulses) dips momentarily when cutting over to gas (im assuming this is becasue the mix goes lean before the fuel starts to flow properly), but then returns to the same MPG i was getting on petrol so im happy that things are looking better there.

All in all, as I said to the guys yesterday, things invariably go wrong and the forums are the places people will hear about problems first. What I look for is how a provider handles a problem, and in this case I think they did things the right way. Ive read horror stories of people going back to some converters with problems, only to be given the brush off and other pats of the car being blamed - happily there was none of that for me from Mint. Hopefully nothing further goes wrong that requires another visit, ill keep you posted if thats the case.

Having said that, if i had been driving from the other end of the country for the work, then had to drive back one or more times to fix problems, id definately be unhappy with that - but I would then have to question why I didnt use an installer more local to me. This was one of the reasons I chose mint - they are relatively close by so going back to resolve a problem wasnt going to be a massive pain for me, and part of my research showed that some people do have problems on the one day installs

Ill keep an eye on things and report back if anything goes wrong and also how my MPG looks ont he trip to london and back next week.

Cheers


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PostPosted: Tue Jun 26, 2012 8:56 pm 
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"There is also a new staff member there who has moved from a LPG converter in cardiff that has closed - he listened and fell over himself to help me and make sure everything was running right. He seemed highly knowledgable on gas conversions and got straight to it himself, while talking me through everything as he went".

This guy is Pawel. He is Polish and here they call him Paul.
They closed LPG Wales on the 8th of June and he moved to Mint LPG on the 11th of June. At LPG wales he was a partner with Greg. Greg all of a sudden left by leaving him a piece of paper saying he no longer want to work. Very sad. Pawel said to me that he could not work on his own as if there is a problem they always get together to fing a solution.
This guy was trained with Profess a gas near Aberdare. He had 15 years experience in Poland in LPG.
Very polite and knowledgeable.

I knew all this as when my car came to 1000 miles service with LPG Wales he rang to update me with what is going on. As I did not know where Mint LPG is, he offered to meet me then I drove behind him.

The car used to smell gas when stopping in traffic. He replaced a faulty valve. took him an hour but sorted.
My warranty was transferred to Mint LPG with no hassle at all. He left his mobile number with me to ring him at any time. I hope I do not need to wake him up at the middle of the night.

Yes Mint LPG is in a farm and when my car went on the 12 June I did see a dark ML500. no so sure if it is yours but certainly the filler was at the rear and not far from the towing bar. Can not remember if it is a personalized number plate. May be its another car. :wink:

Best wishes


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PostPosted: Tue Jul 17, 2012 4:23 pm 
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Back from a lovely few weeks holiday to sunny britain (fnar fnar) and took the car out for the first time on monday (200 mile motorway).

Well, drove it slow and steady until about bristol, got a call that i needed to be somewhere quicker so put my foot down.. the thing hit 5000 RPM and *misfire* its doing it again. Ive had a look under the bonnet and the LPG smell is back. Fairy liquid says its a (quite large this time) leak from the same palce that was fixed on my last visit. Injector pulse width is up a bit again, guessing because its losing pressure. Back on the petrol for now. Cant take it into mint until late next week at the earliest, so any resolution will have to wait until then.


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PostPosted: Tue Jul 17, 2012 9:28 pm 
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The blip on change over to sounds like the injector nozzles are mounted to far away from the petrol injectors. It would be worth looking to see where they go in.

As already said the Mercs do need spot on fueling and ignition. What spark plugs do you have fitted?

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PostPosted: Thu Jul 19, 2012 6:02 pm 
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not sure on the sparks, it was last serviced by the previous owner, though im going to have it done in the next 1k or so - any recommends for good ones to use? Do i need to go crazy and use something like platinum+4? The nozzles in the manifold do seem in quite a differnet place to the petrol injectors, but i wouldnt say they are toooo far away (its not like they are in the top of the manifold or anything).

oh yeah, why on earth would my tank start reducing its capacity? its a 70l tank and I could only ever get 50 litres in there from bone dry. Then that went down to 45liters from bone dry and now im lucky if i get 40 litres in there from bone dry (and by bone dry, i mean the system cuts back over to petrol with the alarm noise even at rpms down in the 1500-3000 range)

In other news, the UKLPG association called me up out of the blue. My car has been randomly selected to be screened by their inspectors to verify and grade the work carried out by mint. Will keep you all posted of the outcome of that one!


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PostPosted: Thu Jul 19, 2012 6:25 pm 
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simonp wrote:
In other news, the UKLPG association called me up out of the blue. My car has been randomly selected to be screened by their inspectors to verify and grade the work carried out by mint. Will keep you all posted of the outcome of that one!
That could be interesting...... Maybe they've had a few complaints and are actually doing something about it.

The injectors should be no further than 300mm from the inlet valves and all should be the same length. Ideally the nozzles should be as close as possible to the petrol injectors though.

As for sparks, LPG and Platinum 4 prong sparks do not make a good mix. It is better to have a slightly smaller gap for LPG than for petrol and the 4 prong ones aren't adjustable. Standard plugs but with the gaps closed up slightly well be fine but they don't last that long on gas, Iridium equivalents work just as well, if not better, and last much longer. According to http://www.sparkplugs.co.uk/pages/prici ... rs-ccp.asp the standard plug is an NGK PFR5G-11 with the Iridium equivalent being an NGK BKR5EIX-11. The 11 on the end signifies a 1.1mm gap but I'd close them up to 0.9mm or buy the straight BKR5EIX which has a 0.9mm gap in the first place. The Iridium ones are cheaper than the standard ones too!

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PostPosted: Thu Jul 19, 2012 7:00 pm 
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Gilbertd wrote:
That could be interesting...... Maybe they've had a few complaints and are actually doing something about it.

Or just maybe they're just doing business as usual, genuinely random follow-up checks. There's no special reason to get all cynical about someone doing just what they've always said they do.
As it 'appens we have recently had just such a call ... "picked one of your installs from a few months back, please can we have contact details" No, not this car either, nor the first time :)

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PostPosted: Wed Jul 25, 2012 9:48 am 
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The inspector has just been and gone. What a really nice gentleman, very honest and spoke highly of some of the forum members here wont name names, but you probably know who you are!)

He was not a happy man with the install, and said he would be calling Mint immediately. I am under instruction to not use the LPG at all and to await a call from mint. He picked up on more issues than I picked up on myself. Things he said need fixing promptly;

- Piping from gas tank to engine bay is routed underneath all of the chassis, very exposed. Anything could kick up off the road and slice it (or if a garage uses the chassis as a jack point it could also sever the pipe)
- There is a large leak from the temp sensor on the (and i dont know what the proper name is) 4 way feed pipe that the injectors on the right side of the engine bay screw into
- The same 4 way pipe is mounted on the coil pack (!!!) posing a serious risk
- The same 4 way pipe is fouling on metalwork and is already showing 'wear' damage
- The pipes between injectors and manifold are just pushed on (no clips holding either end in place)
- Gas piping improperly secured and fouling in various places in the engine bay

There were some other things that I asked for opinion on, for example the Vaporisor. the opinion given was that it was not large enough for a v8 engine (which could explain my misfires at high RPM). That was qualified with the statement that was opinion only and the part could have the capacity for the size of engine. However, with the high RPM misfires, this seems a likely possibility.

I also asked about my 'shrinking' tank, which now seems to take only 43 litres from empty. He confirmed it should take 56 litres from empty and that it could be any number of issues that have caused this problem, though I should take this up with Mint when they call me.

This gentleman was fantastic, very honest and seemed geniunely disappointed with my experiences so far. Very nice bloke!


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PostPosted: Wed Jul 25, 2012 11:38 am 
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Mint sometimes use MagicIII reducers, which do look remarkably dinky for their bhp rating.

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PostPosted: Wed Jul 25, 2012 2:10 pm 
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spot on, thats the one ;)

Rated to 450bhp apparently http://www.autogasgroup.co.uk/ProductDesc.aspx?uid=14


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