Auto-LPG Conversion Thread

[ghosthunter]

i had almost emptied my gas tank the other day pero above empty pa ... and in my experience me reserve pa yun ..... unfortunately i was parked at an incline ..... shet ayaw na umistart ng oto ko !!!! kelangan pala talga me gasolina ka kahit madami ka pa LPG just to start the engine .... after many tries naririnig ko lang is taktaktaktak seemed to come from inside the engine (from spark plugs ??) .... fortunately malapit lang ako sa gasolinahan .... bought some gasoline .... tried again .... but the battery seemed to be weak na .... ayun tawag ng rescue hehehehe friend came with battery jumper cables .... ayun nag start na hehehehehe.

The next day okay naman sya .... from manila pumunta ako qc then greenhills then qc then back to manila .... all was well naman. But this morning shet ayaw na naman mag start !!! buti na lang me good samaritan at nag pa jumper na naman ako .... ayun umistart naman ng maayos .... nag idle lang ako 1hr sa parking lot hehehhe para ma charge ang battery .... after that patay makina ... start uli ... umandar naman ng maayos ..... haaayyy sana umistart bukas ng umaga hehehehe.

Sounds you have a weak and dying battery more than a fuel problem. (or an alternator not charging your battery correctly).

[paolorenzo]

it may have been the incline, and fuel tank tilted and fuel went away from the the hoses leading the the engine? It's definitely not an LPG problem. Tama si GH, your battery may be starting to show signs of old age. Have your alternator diagnosed na rin (free naman diagnosis sa battery shops eh).

[chinacrisis]

Hi tsikoteers, some more questions:

1. is it correct to say that a well-tuned venturi/emulator conversion will be able to maintain the FC and power of the car at low rpms (up to 4k)?

2. is it correct to say that the FC and power loss inevitable with a venturi/emulator conversion will be found only at higher rpms (5k and above?) ?

3. is it correct to say that the advantage of a closed loop system versus the open loop system is that the settings for tuning it will be provided by the ECU, but on-the-fly performance will be the same as a well-tuned open loop system?

Thanks in advance for the replies.

[ghosthunter]

1. is it correct to say that a well-tuned venturi/emulator conversion will be able to maintain the FC and power of the car at low rpms (up to 4k)?

No. Venturi systems can get close but not equal the FC of gasoline. Expect a loss of fuel mileage of 5% to 10% depending on tuning. Running lean, it is possible to match or exceed the gasoline FC figures but performance suffers as possibility of engine damage in the long term.

2. is it correct to say that the FC and power loss inevitable with a venturi/emulator conversion will be found only at higher rpms (5k and above?) ?

Yes. Also air filter condition can affect FC figures as well.

3. is it correct to say that the advantage of a closed loop system versus the open loop system is that the settings for tuning it will be provided by the ECU, but on-the-fly performance will be the same as a well-tuned open loop system?

SGI systems still have an advantage of potentially better air-fuel mixtures at ALL rpm range. Even a well tuned venturi system has one major drawback, the venturi itself. This constricts the air-flow which increases the intake manifold vacuum pressure at higher RPMs. SGI systems don't restrict the air flow, hence better high RPM performance.

[glennjv]

Thanks Xoom and GH.
Sana nga may 60L toroidal sila but I'm guessing walang available.
So if its a 40L tank, the useable amount would roughly be just 30L.
My FC on gasoline is 10.5km/L (last fill up ko).
So on LPG on my Mazda 3 lets say 8km/L lang siya.
My range would be 240km per fill up. Hmm that'll last maybe 3 to 4 days tops.
Called them up and I told lorna kung pwede sa kin nalang yung 55L toroidal na dadating=) pumayag naman. (increases my range to 330km)

I hope the conversion of my car goes well.

Here's an experience I had driving the Camry my dad converted to LPG yesterday. (Coding kasi car ko) On my way to the office at around 930am all was fine and it could even reach 100kph like gasoline.
Upon entering the parking ramp and getting the ticket from stop. The car had a hard time rev'ing up but I was able to park. So I thought... that was weird.
Ok on my way home at around 730pm it was raining really hard. So I thought hey this is good, LPG supposedly runs better in colder conditions.
So from Pioneer upto Buendia, all was fine then there was heavy traffic approaching the underpass of edsa cor ayala. It was crawling. So ok lang. Then after a few mins from STOP the car was losing power again, having a hard time rev'ing up. A few meters forward STOP ulit then Go ulit, the car was having a hard time rev'ing up when its on Drive and Stopped for a while. On my 4th attempt, it was really having a hard time to Rev up..... the car stalled. Turned off everything after less than 5 secs I started the car on Gas.. Vroom... No problem...

Approaching the incline of Magallanes the car automatically switched to LPG...toink! I was able to climb Magallanes but I definitely do not have the power, so parang Diesel siya umakyat...hehe bagal.
Traffic was moving fast again and the LPG was fine again from Nichols all the way to Alabang. WEIRD.

I told my dad the camry still needs to be fined tuned it looks like it has problems when STOPPED and on Drive for a long time.


Here's my question regarding SGI kits...
For example on my Mazda 3 it has a O2 sensor. Does the A/F mixture "Adapt" / Change in real time based on how my engine is doing?
Does the ECU do this thing?
I'm thinking sana my Mazda 3 conversion has less problems kasi its a newer model that's more compatible with the SGI kit.

In the case of my dad's camry the A/F mixture is like Pre Defined so it doesn't know to change the A/F mixture when needed?
Does it act like a SGI kit? or like a Open Loop lang? (na Fuel Injected)

[niky]

On stock tuning, the LPG injectors will mirror exactly what the gasoline injectors are supposed to do, with a slight correction factor put in so that your stock O2 sensors will be happy... but it's your stock ECU that controls closed-loop tuning and the preset ECU maps that control fuel... the SGI computer just translates those instructions for the LPG injectors.

Thus, it's really important that your LPG AFRs (air-fuel ratio) closely mirror your gasoline AFRs in closed-loop (typically 0-3000 rpm on a modern engine) so as not to cause weird running due to your stock ECU trying to adapt to the LPG.

But the cold running issues can be due to tuning and/or vaporizer/coil mismatch issues. We're still discussion ways to figure out how to regulate fuel pressure when it's cold... apparently, changing the fuel pressure setting on the LPG vaporizer helps for some people... we're looking at the problem.

[ghosthunter]

I told my dad the camry still needs to be fined tuned it looks like it has problems when STOPPED and on Drive for a long time.

Sounds like the Camry needs more time to be tuned well.

Here's my question regarding SGI kits...
For example on my Mazda 3 it has a O2 sensor. Does the A/F mixture "Adapt" / Change in real time based on how my engine is doing?
Does the ECU do this thing?
I'm thinking sana my Mazda 3 conversion has less problems kasi its a newer model that's more compatible with the SGI kit.

Well, the factory ECU is still doing it's "thing". The SGI kit reads the signals and adjusts the lpg flow based on the factory ECU signals. The LPG ECU simply corrects the amount of fuel flow per cycle.

As for the Mazda3... the M3's ECU is uber sensitive. Even our Mazda3 1.6L still experiences occasional CEL (check engine light) at around once every month to once every two months. Other than that, the car runs pretty well although it experience initial problems like power loss and stalling until the LPG kit was tuned by SPEEDLAB.

In the case of my dad's camry the A/F mixture is like Pre Defined so it doesn't know to change the A/F mixture when needed?
Does it act like a SGI kit? or like a Open Loop lang? (na Fuel Injected)

I am assuming it's using the SGI kit so the LPG system is simply following the stock ECU's signals (which is what it is supposed to do). Just bring it back to the LPG installer for another round of tuning or bring it to SPEEDLAB if they have the software tuning kit for your SGI system.

[chinacrisis]

No. Venturi systems can get close but not equal the FC of gasoline. Expect a loss of fuel mileage of 5% to 10% depending on tuning. Running lean, it is possible to match or exceed the gasoline FC figures but performance suffers as possibility of engine damage in the long term.

Yes. Also air filter condition can affect FC figures as well.

Thank you for the quick reply sir GH, but medyo confused pa rin ako. I guess to clarify lang, is FC and power loss in a venturi system to be felt in all spectrums of RPM, whether high or low?

[ghosthunter]

Thank you for the quick reply sir GH, but medyo confused pa rin ako. I guess to clarify lang, is FC and power loss in a venturi system to be felt in all spectrums of RPM, whether high or low?

Power loss starting mid range RPM (or around 3500 and 4500). This is because you are trying to suck in more air through a small openning. At low RPM, the openning is adequate but at higher RPM, it becomes a constriction.

FC in well maintained system, keeping the engine running at lower RPMs can help maximize fuel mileage (as with any fuel).

Just imagine the difference in a carb and fuel injected engine. The analogy between venturi and SGI systems are pretty much alike. The efi systems are more efficient. Carb are easier to tune in DIY situations but are sensitive to any changes like airfilter condition and atmospheric pressure changes.

[tebs]

yep, i always use my petron bpi credit card whenever i fill up with petron's xtend. and i get rebates on the proceeding month