Technical Calibration of factory fitted LPG injection

[FirstTimeFiatDriver]

From my experience with LPG conversion kits that have a parallel ECU module with a separate proprietary diagnostic port, the LPG injection needs adjustment periodically, because the performance of the injectors drops as they get older.

What I would like to know is if the same procedure should be done to the factory fitted LPG system that's controlled by the one and only ECU of the car and that can be accessed by the car's OBD-II port. Does Fiat's official scan tool offer the ability of adjustment of the LPG injection map?

 

[the green vanper]

Hello,

I've checked in my 5.1 registered version of MES and it seems it is not possible

Those are the adjustments that can be done after connecting to the ECU:

In the actuators tab there are functions for the gas injectors available though:

But they are only used to activate the function to test.

I used this model:

 

[FirstTimeFiatDriver]

@the green vanper

Thank you very much for your input! Is it possible to monitor how they function though, I mean for testing purposes, in order to find out if they work within normal limits.

 

[the green vanper]

Reading of those LPG related parameters is possible on the parameters tab:

and then live on the graph:

 

[FirstTimeFiatDriver]

Once again thank you very much!

I guess the Gas injection time graph is adequate for diagnosing the system.

 

[FirstTimeFiatDriver]

@the green vanper

Does your car have a factory fitted LPG system? What's the pressure of the LPG? I am trying to troubleshoot increased fuel consumption. Using Fiat's scan tool I saw that the pressure was 1.50 bar.

Meanwhile with my own generic scan tool I saw that LTFT has reached -31 %, which of course is way of of the expected values. Air–fuel commanded equivalence ratio was 1 though.

 

[the green vanper]

No, I do not have a Tipo, nor LPG installation.

I was just checking on MES what options are available.

As far as I remember, the factory LPG installation was possible on the x244 model only. Mine has CNG, but the pressures are completely different (200 bar in the tanks, 8 bars in the injection system).

 

[FirstTimeFiatDriver]

No, I do not have a Tipo, nor LPG installation.

I was just checking on MES what options are available.

As far as I remember, the factory LPG installation was possible on the x244 model only. Mine has CNG, but the pressures are completely different (200 bar in the tanks, 8 bars in the injection system).

I'm not sure which the x244 model would be. The car I'm talking about is a 2018 Tipo with the 1.4 T-Jet 120 hp engine and comes with a factory fitted LPG system.

What I would like to know is the pressure at the injection rail. If anyone is able to share the specs please do.

 

[the green vanper]

The x244 is the second generation Ducato:

After the 2002 facelifting until the end of the production (2006) it had a PSA XU10J2U 2 liter engine that could run on petrol, LPG or CNG, depending on the variant.

I hope that someone having a Tipo will be able to give more accurate information on the LPG pressure.

 

[FirstTimeFiatDriver]

I was just reading the workshop manual. In page 47 there is a pressure mentioned 0,95 bar. Is that the pressure of the injection?

 

[chris3234]

The x244 is the second generation Ducato:

View attachment 454815

After the 2002 facelifting until the end of the production (2006) it had a PSA XU10J2U 2 liter engine that could run on petrol, LPG or CNG, depending on the variant.

I hope that someone having a Tipo will be able to give more accurate information on the LPG pressure.

The forum is largely UK based and the Tipo isn't. A popular moddel here
Ontop of the fiat haven't sold any factory's lpg cars here so any information may be hard to come by

 

[the green vanper]

@FirstTimeFiatDriver LPG models are very popular in Italy, I'll try to look on their forum, that could be easier.

 

[FirstTimeFiatDriver]

@chris3234

Nevertheless the workshop manual is uploaded here and it reads: "II gas liquido che si trova nel serbatoio ad una pressione dipendente dalla sua composizione e dalla temperatura ambiente viene vaporizzato nel riduttore e regolato ad una pressione di uscita superiore di 0,95 bar rispetto alla pressione presente nei collettori d' aspi razione" or with automatic translation "The liquid gas in the tank at a pressure that is dependent on its composition and the ambient temperature is vaporized in the reducer and regulated to an outlet pressure that is 0.95 bar higher than the pressure in the intake manifolds".

So can anyone figure out what pressure should I target when reading the data with an OBD scanner?


@the green vanper

Is there any well know Italian forum? If you know any please share, if not it's OK. I will figure that out by searching the internet.

 

[FirstTimeFiatDriver]

Here is what Landi Renzo says (page 110):

The regulator is a single stage compensated unit with a membrane with water/gas heat exchanger.
The regulator is set to release gas at a pressure of 0.95 bar (95 kPa) more than the pressure in the intake manifolds of normally aspirated vehicles.

And in the technical table:

Operating flow rate (relative): Asp. 0,95 bar - Turbo 1,2 bar

So I guess the value the OBD scanner should read is 0,95 (or maybe 1,2) + MAP pressure, right?

 

[the green vanper]

So I guess the value the OBD scanner should read is 0,95 (or maybe 1,2) + MAP pressure, right?

I understand it in the same way.

 

[FirstTimeFiatDriver]

@the green vanper

One last question. The official wiTECH scan tool reports 2 different pressures for the LPG. The one which is called "Gas rail pressure" which I see that it is available using the MES tool too and another one which I think was simply called "Gas pressure" or something like that. These two pressures were not identical, but there was a difference of around 0,2 bar, as far as I can remember.

Does the MES tool report a second gas pressure? If not, is it possible it does not mention it because it's not reported by the ECU of the car you tested it or can you also see all the available parameters the MES supports, including those not supported by a specific car model?

 

[the green vanper]

For the wiTECH tool, you should ask them from which sensor the readings come from.

I'd then ask on the multiecuscan.net forum for the second reading, why it isn't available on their tool.

I've heard / read that AlfaOBD offers more data in some cases. I don't know if in any way it supports LPG installations.

And to be frank, I don't know nothing about LPG, so I can't say if and how many pressures should be present in the installation.

 

[FirstTimeFiatDriver]

There are 2 reasons the reading may not be available:

1. The reading isn't supported by the scan tool / software, so it will never be presented by the software.
2. The ECU of a specific vehicle does not support that data, so the scan tool does not present it, as it is unavailable for that car.

In general I know that aftermarket LPG kits have one pressure sensor. I don't think that they have a second one. Anyway, I visited that certain garage, because it specializes in Italian cars and they had the official scan tool available, they are not maintaining LPG systems in general.

I plan to visit a mechanic who specializes in LPG systems, but I'm not sure if generic scan tools will have full access to Fiat's data.

 

[the green vanper]

Aftermarket installations are not diagnosed by the car OBD2 port.
Having a factory installation your car has one injection module for both fuels or two separate modules connected to CAN, which both should be managed and diagnosed by the OBD2 port.

In case of my factory installed CNG there is one module which operates 8 injectors (4 for methane + 4 for petrol).

And that's more or less you've wrote in the initial post

I will also repeat what I've read earlier: LPG being not so popular in the UK I'll try other forums (italian, dutch), as their members can have more LPG specific knowledge and experience.

Let us know what the LPG workshop will tell. Good luck with them

 

[FirstTimeFiatDriver]

Aftermarket installations are not diagnosed by the car OBD2 port.
Having a factory installation your car has one injection module for both fuels or two separate modules connected to CAN, which both should be managed and diagnosed by the OBD2 port.

Yeah, but beside the fact that factory installations have one ECU module for both fuel systems that is accessed via the OBD-II port, the rest of the system has the same architecture, it has the same components.
Aftermarket systems have 1 pressure sensor for the LPG, so I'm not sure what was the 2nd pressure reported by the wiTECH.

Anyway, when I'll have an update I will share it here.