Advice wanted on V70 engine mapping, LPG, and tweaking.

[Fiend]

Please bear with me on this as I am total noob about cars.

I've got a '98 V70 XC 2.5 Turbo Petrol Automatic, and due to the ridiculous gallons-to-the-mile type fuel economy, got it converted to LPG (although due to LPG being ****e, totally inefficient and very sluggish, I now tend to alternate depending on the situation).

I found the LPG very bad at first on the poor efficiency / poor performance double whammy so I took it back for some tweaks. The LPG guy showed me the engine map set-up, a two axis graph with RPMs along the top and gas pedal / throttle usage (or something like that) down the side. He'd set it up badly in the first place with all of the numbers being around 170, the effect being it was using too much gas at low revs and cruising speed and too little gas at high revs and during acceleration. He tweaked it so most numbers were at 140, except high gas pedal / throttle - mid revs at 180-ish, and high gas pedal / throttle - high revs at 210. Thus meaning I now have better performance when I put my foot down.

I'm due to take it back for another tweak and want to know more about getting it set-up for the optimum efficiency / performance balance.

Basically I now have a car with 4 performance options:

LPG + Economy Mode = fairly slow, reasonably efficient (due to LPG prices outweighing lower MPG)
LPG + Sport Mode = mildly powerful, mildly efficient (useful for overtaking runs)
Petrol + Economy Mode = mildly powerful, not so efficient (generally smoother)
Petrol + Sport Mode = fairly powerful, not at all efficient (but good fun)

My current line of thinking is to tweak the mapping for the LPG so it is less powerful and more efficient and rely on the sport mode or petrol for when I need more power. Since I have those options available it seems wasteful to have LPG running more powerful as around town or on motorways it's fine if it's sluggish.

BUT. I need to know more about how this works....

1. How does the turbo work?? The LPG guy said it was kicking in at 3000 RPM (although with LPG it took longer to get there and wasn't as powerful overall). Will it always kick in at 3000 RPM? Or does it correlate more to gas pedal usage?

2. How does the sport mode work?? It seems to kick the revs up pretty quickly towards the 5500 mark at most speeds - is this just overrevving it (by dropping a gear??) or getting the turbo to kick in sooner??

3. Does the mapping set-up sound sensible?? Any advice for it??

Thanks in advance.

[5seaterT5x2]

i've got a 95 t5 auto on lpg and it's superb in all ways. Trouble with lpg is the muppets who fit/setup the system i've been running lpg on different vehicles for over 7 years no regrets what so ever once i found a decent firm to set em up. Dunno where you are but these guys are in east london if you want contact info let me know

[entwisi]

ditto, sounds like your fitter doesn't know what he's doing. Mine was(Till the water pump went and warped teh head, now on a 2.3 T5 lump) a 2.5 LPT fitted with Prins system and is pretty much inditinguishable from petrol to gas.

Cheap kits are exactly that, cheap, hard to tune, don't stay in tune etc. If you have a good kit (bigas, prins, OMVL) then you need to find a fitter that has a clue.

I've been on gas for nearly 9 years now and its teh best thing I ever did. my current car has done over 80K on LPG and in total I have covered >250K miles on teh stuff.

[abdul]

the lpg fitter has done a bad job u should be able to tell a slight difference but not sluggish

[Fiend]

Okay.... The installer I used was highly recommended by a friend who had had 5 cars converted to LPG by this installer (from a VW van to a 3 litre Jag to a V6 Astra), and is a member of the Authorised LPG Installers thingy. I made the best choice I could based on that recommendation, and I've spent £1700 getting it done. What other people have had done - great for them, but I can't take back the conversion nor the money spent on it, so anyone implying I should have had something else done in the first place, don't bother.

However if you're suggesting that I take it elsewhere to get the set-up tweaked, then yes I appreciate that and will try that.

The system I've got is a Landi Sequential Injection system.

So, can anyone help with the questions I asked??

[abdul]

try changing plugs dristributor rotorarm leads

[timbo_1975]

STOP STOP STOP!!!!!!!!!!!!!!! (and apol's, as i am going to shout)

I cannot explain this more importantly nor more quickly- a properly set up LPG system especially on a Turbo engine WILL (not should, or might) give AS good a performance on gas as it will on petrol. OFTEN BETTER.

The original mapping which by his own admission was set up with '140' right through is simply shocking. Has this chap actually installed ANY LPG systems before, and does he actually know how an internal combustion engine works? I would love to know what system he has actually fitted, and how he has fiddled the MIL lamp to stay off with it running so rubbish!

I appreciate you are not overly technically minded, but continuing to run the car set up along way from optimum is going to end up with a melted or permanantly damaged engine from running lean, especially under boost.

Afew things from your post:

a) £1700 is not an expensive lpg conversion. I would have expected it to be in the £2300 region having fitted a good quality liquid gas injection system. What system does he claim to have fitted?

b) the engine should be properly checked that it is running totally spot on on petrol and returning sensible mpg to substantiate that it is healthy. I would expect 21-24 around town, 30+ on a run. You dont mention.

c) pre conversion tuning done with especial regard to plugs, leads, cap and rotor- replace them if in ANY doubt whatsoever. No sign of this.

d) the installer is responsible for fitting and setting up a system to work properly, if after acouple of honest go's he cant then take it to A REPUTABLE firm for correction (which may require starting again from scratch) and getting the cost back from 1st installer.

I would severely recommend you have a word with the following firm ( i am not linked with them) and at the photo's to compare what you have fitted to your engine (notably 5 new tubes to each inlet runner from the injectors) etc. - follow the link to conversion gallery

http://www.go-lpg.co.uk/

hope this helps. Tim.

[Fiend]

The original mapping which by his own admission was set up with '140' right through is simply shocking. Has this chap actually installed ANY LPG systems before, and does he actually know how an internal combustion engine works? I would love to know what system he has actually fitted, and how he has fiddled the MIL lamp to stay off with it running so rubbish!

Okay.... The installer I used was highly recommended by a friend who had had 5 cars converted to LPG by this installer (from a VW van to a 3 litre Jag to a V6 Astra), and is a member of the Authorised LPG Installers thingy.

And the mapping was initially set up about 170 across the board.

If by MIL lamp you mean the Lambda symbol emissions warning lamp, that comes on when I use LPG.

a) £1700 is not an expensive lpg conversion. I would have expected it to be in the £2300 region having fitted a good quality liquid gas injection system.

It might not be expensive per se but it's f---ing expensive enough to me. Enough that I don't need to hear about how I should have got something else instead - unless anyone can persuade the installer to de-install the system and give me a refund to spend on a "better" system. £1500-2000 was quoted as a typical conversion price on at least one of the LPG sites I visited.

What system does he claim to have fitted?

The system I've got is a Landi Sequential Injection system.

I have the documentation for it.

b) the engine should be properly checked that it is running totally spot on on petrol and returning sensible mpg to substantiate that it is healthy. I would expect 21-24 around town, 30+ on a run. You dont mention.

The car was serviced by a Volvo garage earlier in the year, a few months before the LPG conversion. I don't know what it was doing around town, 20 mpg sounds about right. On longer journeys I tested on a trip to Scotland and back (with a passenger), doing 80 on M-ways, 70 on A-roads and a bit of single track road mixed in. Averaged out at exactly 30 MPG. I don't have high expectations for MPG, it's a bloody 4WD tank with a petrol engine.

With the LPG system in the original set-up I tested it on a long motorway journey at 80, and it was 21 MPG, a loss of 30% efficiency. I've only done one comparable test with the new set up and it came back at 22 MPG for the same journey.

c) pre conversion tuning done with especial regard to plugs, leads, cap and rotor- replace them if in ANY doubt whatsoever. No sign of this.

I don't know what was done to it in that vein.

d) the installer is responsible for fitting and setting up a system to work properly, if after acouple of honest go's he cant then take it to A REPUTABLE firm for correction.

I took it back and very clearly explained that I was not happy with the situation. This was when he changed the mapping as I described in my initial post. He said quite clearly that LPG will give me a small drop in performance AND a noticable drop in MPG, and he could tweak the mapping to give me more power OR more efficiency BUT it was a balancing act. I'm not really sure how I'm supposed to argue with that to be honest....apart from trying to get some more knowledge about it on here!!

(which may require starting again from scratch) and getting the cost back from 1st installer

What do you mean by that??

I would severely recommend you have a word with the following firm ( i am not linked with them) and at the photo's to compare what you have fitted to your engine (notably 5 new tubes to each inlet runner from the injectors) etc. - follow the link to conversion gallery

http://www.go-lpg.co.uk/

Looking at this page: http://www.go-lpg.co.uk/V70.html, what I have is similar except the injectors are further forward and go into the engine via a small length of piping. It's worth noting that from that page they say: "this gave an equivalent fuel economy figure of 42mpg in terms of what it would have cost on petrol.", which is pretty much exactly what I'm getting on motorways and although this is a slightly older T5, mine is slightly bigger engine and AWD.

[timbo_1975]

I apoligise for some points in my post being unclear as your second post had not appeared and i was responding to your original one.

Depending on which prins system is fitted, it can be largely self mapping- this works by the gas ecu reading the petrol injector opening times at any given moment, adding a correction figure (not always the same across the board as you man may have set) and then opening the gas injectors to match- hey presto and not rocket science.

The main problem is the gas ecu is always lagging behind by several engine cycles as it needs time to do the calculations, compounded by the fact that the gas injectors are not physicially IN the manifold, so further time is needed for gas to actually reach the engine, so the gas ecu is always 'living in the past.'

To solve these short comings, and that of the MIL coming on (the green lambda lamp) which is caused because the petrol ecu no longer sees the exhaust readings sweeping back and forth as it swings the fuelling back and forth.

I cannot stress enough that the quality of the fitting and the knowledge of the installer is paramount in making yours and any system work properly (they all can,mostly, but often can't due to poor install or set up) ESPECIALLY on a forced induction engine.

Your mpg is inline with the petrol figure, which is good, as does the condition of the engine by all accounts. But you say performace is rubbish unless you use full throttle. It wouldnt surprise me if the installer has set the gas ECU to revert back to petrol for full power- is your tank level going down?! This is definately not acceptable.

Tim..

[LesRED850R]

I apoligise for some points in my post being unclear as your second post had not appeared and i was responding to your original one.

Depending on which prins system is fitted, it can be largely self mapping- this works by the gas ecu reading the petrol injector opening times at any given moment, adding a correction figure (not always the same across the board as you man may have set) and then opening the gas injectors to match- hey presto and not rocket science.

The main problem is the gas ecu is always lagging behind by several engine cycles as it needs time to do the calculations, compounded by the fact that the gas injectors are not physicially IN the manifold, so further time is needed for gas to actually reach the engine, so the gas ecu is always 'living in the past.'

To solve these short comings, and that of the MIL coming on (the green lambda lamp) which is caused because the petrol ecu no longer sees the exhaust readings sweeping back and forth as it swings the fuelling back and forth.

I cannot stress enough that the quality of the fitting and the knowledge of the installer is paramount in making yours and any system work properly (they all can,mostly, but often can't due to poor install or set up) ESPECIALLY on a forced induction engine.

Your mpg is inline with the petrol figure, which is good, as does the condition of the engine by all accounts. But you say performace is rubbish unless you use full throttle. It wouldnt surprise me if the installer has set the gas ECU to revert back to petrol for full power- is your tank level going down?! This is definately not acceptable.

Tim..

good advice timbo ! For the best power and ecu ability what would be the best system ? And if in future mods are done to the engine is it a matter of bigger injectors ? Would a new total engine ecu from a third party be the best way to get total control? Too many Qs ...I know LOL Cheers Les M.

[timbo_1975]

Thanks. I will add, i am not an LPG installer nor connected to one, and thus bow to their superior knowledge. I am motor technician and electronics engineer and work with ecus and software.

It just really irritates me when people have an LPG kit fitted, pay very good money for it, and then accept that it doesnt work very well!

As far as what is a good system to fit, well it depends enitrely on the car- some suit different engines better. I do like the romano N and DT autogas systems though.

I would not even contemplate replacing the petrol ecu with a one-box-does all , as the wiring would be way toooo complicated and you need to retain the factory ecu as it integrates with the dash, ecc, transmission (if auto), immobilizer etc.

I do see a competition Mitsi Lancer grp N rally car now and then which is LPG only- there is no petrol system fitted at all. The ecu is a autronics which is totally customisable however. I can assure you there is no performance loss in this case, infact it has quite alot more torques than several of its competition through being able to run more boost in the mid range without detonation than a petrol counterpart.

[LesRED850R]

Thanks,now about upgrades,do you need bigger gas injectors then ? AND do you redo volvo ecu programs by chance ??? Cheers Les M.

[timbo_1975]

You dont actually change the injectors, only the jets which are rated in HP increments, depending on regulator used (i.e. the gas pressure behind them!)

I dont specifically do Volvo ecu's no- i work on non manurfacturer specific ones eg the autronics, that are designed to be customised..

Tim..

[Terminator]

I agree with everything that has been said about the quality of the fitting, being absolutely vital to a successful installation.

A correctly set up fully sequential system will not cause problems on a normally aspirated engine. With a forced induction engine however, it is vital that the LPG system, even if fitted correctly has the ability to cope with the extra power and therefore the extra fueling requirements over a normally aspirated engine. I have a BRC system fitted to my V70R which is good for 70bhp per cylinder so no problems. This is a more expensive kit than the Landi.

I am sorry Fiend, but my concern would be that you have been recommended the wrong system for your car and should take this up with your supplier/fitter.

[Fiend]

Depending on which prins system is fitted, it can be largely self mapping- this works by the gas ecu reading the petrol injector opening times at any given moment, adding a correction figure (not always the same across the board as you man may have set) and then opening the gas injectors to match- hey presto and not rocket science.

Yes, I've heard someone explain that elsewhere, it makes sense to me.

The main problem is the gas ecu is always lagging behind by several engine cycles as it needs time to do the calculations, compounded by the fact that the gas injectors are not physicially IN the manifold, so further time is needed for gas to actually reach the engine, so the gas ecu is always 'living in the past.'

To solve these short comings, and that of the MIL coming on (the green lambda lamp) which is caused because the petrol ecu no longer sees the exhaust readings sweeping back and forth as it swings the fuelling back and forth.

Errrr, what exactly solves these shortcomings??

Your mpg is inline with the petrol figure, which is good, as does the condition of the engine by all accounts. But you say performace is rubbish unless you use full throttle. It wouldnt surprise me if the installer has set the gas ECU to revert back to petrol for full power- is your tank level going down?! This is definately not acceptable.

I am as certain as I can be that that is not happening: The ECU graph he was using showed no such thing, at full power it was just increasing the number (as you say probably the correction figure), when I put my foot down with gas it still feels like it has a certain "roughness" that the gas has and the petrol doesn't, putting my foot down with gas doesn't give as much power as petrol, and the tank isn't going down much (only from the usage at start up)

...

I am sorry Fiend, but my concern would be that you have been recommended the wrong system for your car and should take this up with your supplier/fitter.

Okay. I'm going to visit the installer tomorrow for a general check-up. What exactly should I say to him that's going to get a satisfactory result?? Particularly bearing in mind I know nothing about LPG, I don't have any facts and figures to take issue with, and all I've got is you guys words vs. his word...

E.g.

Fiend: I'm not sure this is the right set-up...

Installer: STFU you know nothing about LPG.

or...

Fiend: Are you sure you should have installed a Landi system for this??

Installer: STFU I've installed it right and the job's been done.

or...

Fiend: I've asked on internet forums and been told you probably haven't installed this right...

Installer: the people on the internet forums can STFU up too, I'm an authorised LPG installer, been doing this for decades, installed 3000 systems etc etc, I know my work.

or...

Fiend: I'm sure I should be getting better performance / mileage out of this...

Installer: STFU, I've told you before, LPG runs a bit weaker, you can have one or the other...