NefMoto

I'm collecting ideas how to tune for LPG properly.

It is a gaseous injection system for the LPG (mainly propane/butane) gas. The LPG ECU takes care of controlling the gas injectors, based on petrol injection time, MAP, rpm (transformation maps involved). Plus all of it depends on gas temperature and pressure.

Usually the system cold-starts on petrol, and switches to LPG at a certain coolant temperature.

The system is working OK,- but not perfectly- for years on many cars, now I'm talking about a 1.8T 180HP, wideband

pros:
- high octane (100-110?)
- cheap
- no wall wetting

cons:
- phase change happens in evaporator ->no cooling effect in combustion
- evaporator gets heat from coolant -> slower warmup
- big gaseous fuel volume occupies oxygen's place (lower VE)


ME7 specific setting I've found so far:
- tune KFZW, KFZW for higher octane, lower flame speed, especially at low RPMs
- disable wall wetting above switchover temp. ZBAKM , ZBALM, ZVAKM, ZVALM
- disable warmup enrichment in KFFWL_0, KFFWL_1

I'm not sure these will cover things I seek.

High load enrichment is another story..

These settings seem to work OK -for the brief test I did today.

What lambda do you run at WOT? There are pretty big differences between vapor and liquid fuels.

Stockish now. -Still haven't found much info on that. 

Some people say, go leaner on load to prevent detonation for gas (CNG) engines.
But I assume they're already starting from a very lean (lambda >1.1) base in those industrial engines, so leaning is a proper way to make burn slower and colder. (see attached pic)

I will give you a tip.

The reason you ever run anything richer than lambda 0.9 (lean best torque) on a liquid fuel is so that the fuel can evaporate and cool the cylinder.
On a gaseous fuel, if you run richer than lambda 0.9 all you will do is increase EGT, because more fuel is wasted, and there is no cooling effect from adding gaseous fuel.

So stuff like BTS and ATR on a gaseous fuel must be disabled completely, as they will do completely the opposite of what they are designed to do.

Yeap prj, I also discover this few years ago. Adding more lpg was making turbo much more hot, and red light :) making leaner cause that engine push harder , and turbo wasn't shining:) maybe little  in complete darkness.

Thank you guys. Very valuable info!
I'm trying to tune this way.

Unfortunately there's no real EGT in this car but I thought maybe I'll need to cut max power down without the cooling capability of the extra gasoline?

If you don't do stupid stuff, then EGT's on LPG will be even a bit lower.
But if you leave BTS and ATR in tact then it's a different story...

You need real EGT.

OK, I've set 0.9 lambda for high load all over the place in KFLBTS, running 1.09...1.00...0.94 in between.
0.9 values in KFLAMKRL also, and TABGSS -> 1200C, effectively disabling ATR I guess.

Looks good in the logs so far.

I won't push max power limits until I see real EGTs.

Thanks!

*

tried to adjust  following those tips:

KFFDLBTS all off,
KFLBTS 0.9063 bottom right,
TABGBTS - 810C,
TABGSS - 1200C,
DSLOFS off,
Rear O2/Kat off
KFZW and KFZWOP 1.5% - 9% up,

So far runs good, what i have noticed is ecu rendering much lower mileage on LPG +- 6.5l/100km.
Here is my log, maybe you could check that quickly and tell me what is going wrong direction:
(b.t.w. why you would want to adjust KFLAMKRL?)

Hi papasound,

I am actually also converting an Audi A3 1.8t ARZ to LPG and trying to tune it a little bit.

I found your post and it is very helpful to me. I have a few question regarding my basic understanding and what you have done one your ME7.
You are saying that your are completly disabling BTS, but in Fakt aren't you using LAMBTS-Funktion almost the hole time for lambda-regulation? LAMFA seems to be disabled by default. (set to 1)
So it looks to me, that you are using LAMBTS for setting the AFR dependig on load and RPM. Please correct me, if I am wrong. I am trying to understand, what is going on. ;-)

KFFDLBTS all off
By doing this, you will not allow an AFR-Adaptation by ignition angle or cylinder filling rate. Are there any disadvantages by doing this?

KFLBTS 0.9063 bottom right,
This seems to be the wishmap for AFN, is it right?

TABGBTS - 810C
I don't really understand, why you set this to 810 (Mine isby default 400)
It seems, that this is the minimum temperatur (calculated from EGT-model) when function LAMBTS gets active. Who s controlling your AFN under 810*C ?

TABGSS - 1200C
This disables real EGT-monitoring with hardware-sensor?

DSLOFS off
What is the purpos of this? It seems to affect boost pressure?

This is a very interesting project and without your post I had no idea, where to start with LPG-tuning.

Yogi

I'm going for LPG to, does the LPG injection follow the ME7.5 strategy? Or it uses one one external ECU that overrides the OEM ECU??

Hi there, i'm just gathering all sorts of information about LPG from all around the web.

To be honest this BTS/ATR, LAMBTS/LAMFA concept became total mystery to me since i have started to mess with it.
-
KFFDLBTS all off because LAMBTS = KFLBTS + (KFDLBTS x KFFDLBTS)
*Note from S4 Wiki*
"Therefore, setting KFLBTS to 1 where you don't need it won't disable bts, you also have to set KFFDLBTS = 0 to disable bts completely.[16] Note that Mbox has DLBTS (2D), not KFDLBTS (3D)"
-
*Note from S4 Wiki*
"The lowest value of the three (lamfaw, lamfawkr, lambts) become your requested AFR."
this is where the mystery for me is still trying to figure out.
-
TABGBTS - 810C because my default 820C, other cars have different defaults 400-970C. you need to see ur logs.
-
TABGSS - 1200C, in this case ATR will never kick in unless you melt your exhaust
*Note from S4 Wiki*
ATR (closed loop) - when measured EGT (block 112) reaches TABGSS (980°C), ATR will add fuel via dlatr, which is generated by the ATR PID.
-
DSLOFS off - i was experimenting, should be stock.
----

So regarding LPG from what i gather - is that LPG burns slower until 3000-3500 RPM and burns little bit faster afterwards.
So if you try to adjust KFZW* for LPG raise timing from 1k rpm by 3-8, all in until 3k rpm, and litlte bit lower after 4k rpm (-1.5-3).
That way you stay safe for petrol when you need it and it works great with LPG.  Otherwise if you are using only LPG ive seen safe timings delta + 12-15 < 3k > - 5-7. The other thing is to get AFR right everywhere.

Some usefull links:
http://www.megamanual.com/ms2/tune.htm#emissions (http://www.megamanual.com/ms2/tune.htm#emissions)
http://www.acl.com.au/web/acl00056.nsf/0/359683e8a538a3e64a2566c0007bb33e?OpenDocument (http://www.acl.com.au/web/acl00056.nsf/0/359683e8a538a3e64a2566c0007bb33e?OpenDocument)
http://forums.evolutionm.net/evo-x-engine-management-tuning-forums/557403-lpg-tuning-guide.html (http://forums.evolutionm.net/evo-x-engine-management-tuning-forums/557403-lpg-tuning-guide.html)

It is pointless to use LAMBTS at all, just disable it by FFing TKATBTS and TABGBTS or set FBSTABGM to 0 or whatever other method you desire.
Pointless to edit the maps.
ATR - CATR to 0.
Just drive fueling with LAMFA and advance the timing.

The problem is, if you drive on gasoline with these settings you are going to probably do some damage to the engine - so to do this right, you need to do map switching, for example using the signal for the evaporator relay...

Hi guys,

this really nice information.

In the end I am interested i a setup whre I can use the same mappig for LPG and petrol.

I have a theoretical question: Under the same circumstances and same AFR : Is the EGT with petrol higher than with LPG?

Because in a standard-LPG-conversion nobody touches the ECU-mapping. So at high loads AFR/lambda on LPG will be adjusted like in petrol mode. lets say somethink like lambda<=0.8. This is in petrol mode done because of the cooling effect of liquid fuels. But if on a standard-LPG-conversion, the LPG will run at same AFR  without killing the enigne.

Lets do another gedankenexperiment:
If I switch of BTS and move to LAMFA-only-mode and adjust lambda to 0.9 on high loads. Will it really kill my exhaust-system in petrol-mode and not in LPG-mode?!? Sure, cooling effect of petrol is missing, but it is always missing in LPG mode. So what will happen?

Won't it be better to adjust lambda to 0.9 in a mixed setup of petrol and LPG?

Map switching will be the best option, sure, but it is a little bit overkill at the moment for my setup.

My actual questions are:
1. For a driving setup of 10% petrol and 90% on LPG will it be better to leave ECU-mas in stock-mode with low AFR and liquid cooling or adjust the mapping to LPG.
2. Which is worst case scenario?
a) driving with petrol-mapping on LPG in full load (low lambda/AFR)
b) driving with LPG-mappig (lamda=0.9) on petrol in full load
c) is it comparable?

Yogi

Then you need map switching.
Lower than 0.9 lambda and EGT goes very quickly very high on LPG. That is why on most turbo cars with LPG conversion where nothing is done to the ECU the head and valves are scrap metal after 100 000km.

On LPG the EGT is lower in general, also the timing advance is better and that helps even more. But this changes if you put too much fuel in, as there is no cooling effect and the LPG will keep burning when being exhausted and basically the exhaust ports on the head and the valves will be screwed.

Map switching is the only right way. Or keep it like it is, and make it switch from LPG to petrol any time you go anywhere near the throttle or higher RPM.

Thanks for your info, PRJ


I am actually considering of taking the risk because it seems to be my best option... LPG-conversion is almost done and it seems to produce lower EGTs than with stock mapping. I don't really like the LPG/petrol-switchover-version.  ::)

But what about petrol-EGT@lambda=0.9? no cooling effect, okay, but HOW dangerous is it for my EGT in comparison to LPG-mode? Has anybody some figures?

Yogi

While we are here -  could  Someone please point me to some reasonable and affordable map switching solution for me7.5, i like this idea more and more. Thx

I wonder why you don't like it because that is the only way to do it correctly.
Yeah, you will melt your engine very quickly if you run high boost and lambda 0.9, especially in higher gears on gasoline and 1.8T.

Hi,

thanks for the info. Have you got a source for the thesis, that EGT goes upon LPG, when lambda goes lower than 0.9?

This would be very interesting to me. I have also seen some LPG-damaged engines, but on all of them reason for the failure was a bad LPG-conversion. The AFR-mixture went very lean on high rpms in high gears and caused the engines to melt.

So any source of information about LPG-EGT-temperatures is interesting to me.

Yogi

Source of thesis? lol.
Very basic thing of tuning gaseous fuels, but hey, if you don't believe me, then get an EGT gauge and look for yourself.

Hey Prj,

relax ;-) I believe you, but I understand me too, please. Believing is religion. This is technology, it is about facts. I am trying to learn and understand this things. If it is a very basic thing about tuning gaseous fuels, it should be easy to show me a link or a reference, where I can find this information and more. Maybe a book or an internetlink?

An the most important thing: I am very happy, that you take your time to help us with this LPG-thing. I know very well, that this is not a matter of course, that somebody invests his time to explain some foreign noobs some complicated things on the web.

Yogi

I told you exactly what to do, if you are not happy with that, do your own research.
I am not going to spoon feed you google links and PDF's. Your attitude sucks - give a finger and you try to take an arm!

I happen to like his attitude about religion, though.

Hi prj,


I am very sorry, if you feel like this. This was not my ambition.

Yogi

FWIW I did not sense any attitude in your post.

Come on guys, let's get on-topic!

I'm publishing my current LPG tune based on ideas written here, and some other valuable info from this great site :)

This is for a stockish AUQ engine, DBW, wideband, VVT

Things included -theoretically :)

1. Power/boost level: stock, ~180HP
2. Ignition advance: low-load & low-rpm : increased ~ 3-7 degrees.
   High-rpm : stock
   High-load : stock (experienced knock with high-load@low-rpm using higher values)
3. General fueling: lean-burn lambda=1.09 all over the place, excepting idle which is 0.99, and high load which is 0.9-0.94
4. Warm-up enrichment: above 27deg C (switch-over to LPG) it is almost cut to zero. 
It stays on for very low inj. PWs because many LPG injectors have a tendency to "stuck" and needs enrichment until getting to working temps.
5. Acceleration enrichment/ Wall wetting : disabled above 27 deg C.
6. EGT component protection disabled/limited to lambda=0.9
7. Ignition dwells corrected to new 2.0TFSI values -which coils seem to be the very same as the new original 1.8T replacements
8. Extra economy: CAT heating and wobbling around idle mixture disabled,
 catalyst conf. disabled, SAI disabled, idle torque reserve disabled
9. Error code handling: SAI outputs diag. disabled, Leak diag restricted to higher RPM (DTC 17705 resolve)


I consider this setting to be "safe" and smooth for high octane petrol use also, -not for pushing hard on petrol.

Experience: I've a few months of normal commuting use and a few LPG-tank refills on this setup; seems fine so far.

- starting and cruising is smooth, even in cold weather. powerful when pushed hard
- error codes of cat. efficiency, vac. leaks, fuel trim "rich", SAI problems, etc. disappeared : no DTCs at all.
- City fuel consumption reduced from ~13l/100km to ~11l/100km (LPG) on same routes and pace

Any comments welcome! :)

Why would you go lambda 1.09? This hurts fuel economy, as it's too lean. 1.05 is enough.
Not to mention, I am curious how you achieved it? Hacking the O2 sensor voltage? ME7 won't request leaner than 1.0 without ASM hacks.
This is a bad idea, as won't make any difference for fuel economy, and will hurt drivability.

There's a debate on what lean lambda is best for economy. I've seen values from 1.05 to 1.15, not sure which one works best on this engine so I picked a middle-value.  It is not dyno proven yet AFAIK.

It is set by a target lambda constant in the binary (just like other config values). It is called LAMBDIAG "LAMKO" constant here at nefmoto. You're right that it's not defined as a free-to-change value in FR or anywhere.   It is @67944 in this HN binary BTW.

I've seen no disadvantage of disabling KFMRES torque, to be honest there's no difference in engine idle at all. Besides from running at normal 10-20deg ignition advance instead of ridiculous 0 degs and so.  KFMRESK is stock, so when the clutch is depressed, voila there's the torque reserve again. -And yes, idle consumption is better this way.

My attachment disappeared from the previous post, strange.

Yeah, try turning your power steering or turning your aircon on.

Tried both, plus switching lights and rear defog.  Tried to switch more of them at the same time. 
Don't see much difference to original.  :D

Let me put it this way. If what you say was true, and there was "no difference" then no OEM would run torque reserve on idle, as idle is a significant contributor to the EPA fuel mileage estimation cycle.

You tune your car like you want, but calling OEM's stupid is not very intelligent.

If you had any experience with idle tuning, then you would know that by removing torque reserve you kill fast path idle intervention.

Nice try lezsi, when there's so little info on a topic it's really helpful to have working examples such as latter. 
I will try to incorporate this incrementally on tt225 lpg and lets see what logs are saying.

I'm not sure but a friend told me that his engine sometimes runs backwards because of complete wrong ignition.
I'm not sure in which direction he failed the ignition...
How ever - when it runs stable at stock ignition - fine. :)

*

Well. There are a lot of timing settings which run in the first moment without issues but during daily driving you could get a problem.
At the idle some tuning of the ignition is not needed because fuel economy or power is no aim.

I respect OEM's efforts and results, that's why I kept ME7 instead of installing a stand-alone (sitting on my shelf a long time).

OEMs have their priorities and constraints.  I don't have the same fortunately. 
I don't need to pass such strict emissions standard, don't have to calculate for worn engines with clogged injectors and weak spark, etc.

The interesting part is that it seems even with KFMRES zeroed out, ME7 still have the ability to advance idle to catch-up when necessary.

I have some difficulties with ME7logger to make a high sample-rate demonstration, but I'll make a video shot or something if you're interested.

generally peak & hold injector are used for LPG.
hence, the other external unit is used to provide peak current

Hi prj:
bit off topic, but
i am curious to know that how can you you use your narrowbands for lambda>1. Any hints!

Hi!
I am new here, I have installed LPG on a 1.8T 300ps minimum (off the WG), I do have switching maps installed and 2 softwarez.
I will ask a tuner to tune for LPG as soon as I figure out what are the best parameters for burning the LPG fuel.
I have liquid injected LPG that follows the PW of the petrol injectors and has the advantage of cooling the charge when changing phase.
I would like to learn what would be the most suitable target AFR and Ignition Timing curve if turbo spools till 3500rpm and has 1.1bar constant till redline.
Any hints, what should I read first?
TIA!
Alex

This is my tuned KFZW (KFZW2) map for working on LPG fuel (ignition angle difference). What do you think?
Prj your opinion Please ?

PS. For 018A box

My opinion is that you should drive the car.

Low down is OK, top end is NOT ok. Why would you retard the ignition? At top end you can probably run close to KFZWOP because LPG has very high octane.

Thanks Prj!
I retard the ignition at low rpm because LPG burn slowly. What do you suggest to do in top end of this map(s) ?

Increase it significantly.

The angle values in the red zone should increase ,do I understand correctly ?
Increase in "-" or "+" degrees ?

PS: Below is my stock and modifed KFZW.

If it burns more slowly you have to advance NOT retard.

Engine basics!!!

Sorry,
I expressed myself wrong in post #44  :-\

In my tuned KFZW(2) map(s) from:
- 1000 to 2520rpm ( top end) i advance the angle with +1.5 ÷ +5.25 degrees (slowly burning lpg) of stock map;
- 3000rpm - 0 degree;
- 3520 ÷ 6720 rpm (low down) i retard  the angle from -0.75 to -3.00 degrees (fast burning lpg) of stock map.

Is this correct?

No, because it also has higher octane level.
You are doing this WRONG.

You need to DRIVE the car and not make theoretical maps on forum!
Log -> feedback -> adjust, repeat.

I will made and post here .csv log, but first I have to start somewhere.
So I ask what is the idea in LPG tunig ignition curves.

The idea with ignition timing is you put the car on a dyno and add timing untill you start to lose torque. Or better, take out a little timing before you begin just in case it was already at mbt. I will do a full ignition recalibration for lpg on the dyno later this year, I will put my global results here when it is done.

I would not just add or subtrqct timing everywhere, you have no way of measuring if you are making or losing power... my engine is currently only calibrated for wot because the knock sensors give feedback for that range..

It's been some time since this topic was created. Despite this fact I want to clarify some some things.

LPG on lambda lower than 0.9 still has cooling effect. Also, richer lambda helps reducing the knock and EGT. Same as the gasoline.

I have done some test runs varying lambda on the LPG and double checking it with wideband o2 sensor because I wanted to test prj's LPG tuning theory. 2.7t here, FMIC, dp, stock k03s, RS6 WB EGT sensors, same tune, same road, same day, same conditions, only lambda changes:

Here I attach some charts:

0.9 vs 0.81 - here is comparison of 0.9 lambda vs 0.81 lambda tune I daily drive. It can be clearly seen that even if 0.9 lambda run was started on the lower EGT, it is higher on the redline.
0.87 vs 0.81 - same history, higher egt on the redline than 0.81, even though the 0.87 run started on lower EGT than the 0.81. Also, the 0.87 run egt is lower than 0.9.

I have also checked it ATR works properly on the LPG, lowered tabgss to 850, and the car was richen to almost 0.76 but the EGT was steady. On the 0.81 tune  There was slighty lower knock retard, but it wasn't that obviuos to show it on the chart like EGT.

There is no cooling effect unless you inject liquid LPG. If you do then it works exactly the same like gasoline.
If you have evaporators and you are injecting gas, then there's no cooling effect, unless your evaporators freeze and you start injecting liquid lpg. The entire evaporation and cooling happens in the evaporators which are being heated by the coolant.
Then gas enters the combustion chamber, it does not cool anything.

Your observation with EGT is related to burn rate correlation.
There is never any point to go richer than lean best torque on gaseous LPG. The graphs actually show that, the difference is irrelevant, you have 25C in there.
Advance the ignition to knock limit on both and they will be equal.

It makes sense to at least study the subject a little and get some education instead of running random lambdas and drawing wrong conclusions based on 3% variance in EGT.

Can’t advance more timing if there is actually more knocking on 0.9 lambda than on 0.81…
0.81 tune is at its knock limit, when i get to pc ill upload charts
The difference is 50c between 0.9 and 0.81 bcs its only gear 3 run. Already done 3-4-5 run and egt reaches 960 on 0.9 compared to 890 on 0.81. This is not a small difference.

I had read some research publications and havent spotted any information of not richening mixture on gas LPG. As far as I know petrol when evaporates from intake valves is gas too. It does not evaporates on exhaust valves. So whats the difference besides IAT cooling? :)

Do you have any evidence that what youre saying is true? If so, please share. I am open to change my view. But currently reality shows opposite.

The only cooling that you get is charge cooling from evaporation with gasoline. If you inject gas, there is no charge cooling. This does not have too much to do with EGT.
Also, gasoline evaporation temperature is iirc about 200C. It mostly does not evaporate until it enters the combustion chamber, you do not have 200C in your intake manifold.
Otherwise atomizing injectors would not be needed.

EGT is dependent on how far the combustion happens from lambda 1 and on the ignition angle efficiency.
The problem with LPG is that the flame speed is already lower than on gasoline at rich lambda, and with a much richer mix at high rpm the flame speed is so slow, that the burning continues during the exhaust stroke. With stoichiometric mixture the flame speed on lpg is actually a little faster than on gasoline, but the dropoff is much more severe.
This results in cracked exhaust manifolds, damaged exhaust valves and so on. Your EGT at the turbo might show lower, but the temperature of the exhaust valves and their seats is going to be much higher. Obviously the tradeoff point is different for every engine, but running 0.7 lambda on lpg is not it and ATR is a very bad idea on LPG.

If you are richening the mixture more, you need to advance the ignition just to get back to roughly the same point, but at some point it is no longer possible or reasonable. See attachment.
Put a car with LPG on the dyno, just to get the same power as on gasoline with 15 degrees or so ignition at higher rpm's you will need 20+ on LPG.

Anyway, it is not my job here to educate you on this topic. Pick up a book, because right now you are making the wrong conclusions and you do not understand what is happening in the combustion chamber.
And the worst thing is, you are stating so many things as fact. Maybe it's a language barrier, but if you are not sure about something, then better not be too loud about it.

Thanks for your answer prj, that makes sense what you wrote about. However:

I've been searching for some research results to compare laminar flame speeds LPG vs gas. And yeah, you are write that flame on lambda 1 during lpg burn is litter higher and its right. However, If we compare (see attachments) flame speeds for similiar initial temp, speed for lambda 0.8 for lpg is actually higher than gasoline. I skipped the fact that lpg is little warmer when it leaves evaporators than gas, which makes flame speed even higher.

https://www.sae.org/publications/technical-papers/content/2010-01-0614/ Here is citation that seems to confirm that. Unfortunately I do not have acess to full publication.

https://www.researchgate.net/figure/a-Comparison-of-maximum-burned-gas-temperature-for-gasoline-and-propane-combustion-at_fig14_263874565 - chapter 5.1 "LPG is used in SI engines, the burning rate of the propane is faster than
the burning rate of gasoline. On other words, propane burns more rapidly and thus the
burning process in the engine occurs in shorter times than gasoline engine. Thus, the
combustion duration of propane is decreased"

https://www.sciencedirect.com/science/article/pii/S1876610216314242 Chapter 3.1 "This is because LPG having higher flame propagation
speed and higher adiabatic flame temperature when compared to petrol, hence combustion duration will be less"

That's the point that I dont understand. If LPG on rich lambda burns slower and continues during exhaust stroke then egt should be higher too.
I do not have thermocouple on the exhaust valvetrain part, but If the measurement enviroment does not change and the burn rate is lower, EGT should be higher.

I can walk faster than 60cm/s.  Those laminar graphs are useless for IC engines.

Precisely. All they show is that burn slows down, but it does not show how it works under huge pressure.
As I said before. Put the car on dyno. Make the lambda and charge the same and see how much more advance you need on LPG just to make the same power.
There is a reason so many people complain about burned exhaust valves on LPG, and there is a good reason the engine makes less power on LPG at the same advance and charge.

Or really, just do what you want.

The fact that you have LPG on a RS6 already means you should be shot.

Even if they are, prj used it as a confirmation of what he said.

Well, I didnt want to say that but thr car was previosly on dyno, without advanced ignition for lpg. It made 7hp and 15nm less than on gasoline. I think thats a good result for gasoline ignition, considering the fact, that for the same lambda lpg is 6% less to burn than gasoline.

Thats my 4th car with lpg, previous ones were 1.8t and none of them got valvetrain damaged, even if i made each of them 100-150kkm…

Btw Its 2.7t with rs6 egts not the rs6 ;)

Not my experience, I have had multiple LPG cars on dyno and the difference was much more than 7 hp for me.
I did the first cars with LPG and mapswitching over 10 years ago I think on old 2.2T ecu.

I did not. I used it as an illustration that LPG burn rate is more susceptible to lambda change than gasoline, nothing else.

But hey, as I said. Do whatever you want. I stopped calibration 2 years ago, it's not relevant for me anymore.
All I can do here is give advice based on my previous experience, which most likely has a sample size that is a magnitude larger than yours, since I did this professionally for a long time.

You probably didn't drive them with stock ecu map WOT or the LPG switched to gasoline at WOT.
If you drive 1.8T with stock mapping and especially those that have ATR active at WOT on LPG you will damage the engine.

If you set up KFDZWKG correctly, then that's already 90% of the problem solved, the other thing is limiting ATR target leaner.

Hi prj. I've read all of your posts related to LPG tuning on NefMoto. I have a question to you related to a (future) LPG installation.

The car in question is a 2002 Fiat Stilo 1.6 16v 103ps (1596cc, 182b6000, last gen of Fiat SOHC engine block, with a DOHC 16v valvetrain). When new, these cars could hit 113hp at flywheel. I don't know how mine holds but, it can hit easily 205kmh (GPS tested, straight line) with 2 people and 100kg of stuff in the boot. So I suppose pretty close to that.

I bought it used at 300.600km from the countryside of Greece. Right now it sees tons of city stop-go traffic in Athens and with fuel prices heading to almost 2eur/Liter I would get an ROI in less than 8000km (LPG 0.86eur-0.92eur per liter). I also do long highway trips of 300+km every 3 months or so.

In Greece the auto LPG mixture is 80-20 (Butane+Propane) with slight variations towards 70-30 in some cases.

I know many people have used LPG in this engine and it has last over 360.000km of city driving with proper maintenance. The ECU is a Marelli IAW 5NF.T9 that uses a MAP sensor.

Now the question is: should I invest +200eur to get a kit with a EuropeGas ECU that can also dual inject petrol (up to 50%) in high load scenarios? Bear in mind that the better LPG kit also has Hana injectors which are very fast won't create issues with idle etc. I don't know if cheap LPG ECUs can handle the ignition advance separately but I think that something that is needed to achieve good fuel consumption using LPG AFAIK.

Or should I get just a basic quality LPG kit and tune it all the way to the redline (7100 rpm rev limit) using ONLY LPG? Should I always target the lean best torque AFR? And maximum lambda 0.92? Stoichiometric should be close to 15.5:1 for our LPG mixture.

I want to say that I plan to keep the car for at least 4 more years. In any case, these Fiat engine did not have issues with head gaskets as they mostly had oil consumption issues. Mine burns around 180ml/1000km (a quart per 3200 miles) with low quality 5w40 oil and I plan for a good 5w50 next change to see how it helps. In any case, the LPG conversion will pay itself, even if the engine eventually breaks down (which can also happen using petrol btw).

Thanks!

After 4 years and 140k km on lpg with k04 engine still generates the same power (just dynoed). Valvatrain seems to be ok too. Just sayin :)

What is your WOT lambda and ignition advance?
If it is close to 0.77 lambda, then probably you never made just a few WOT runs during those 140K kilometers.

There is a simple thing that make the things goes wrong - if ME7 (or any petrol ECU), decide to keep EGTs low it inject more fuel, for a simple reason that this unburnt fuel will evaporate taking thermal energy from combustion chamber or/and exhaust manifold.
So more fuel = less EGT.

However lpg is already evaporated when injected, so instead of cooling down - it getting hotter.

ECU thinks it is hot - let's cool it down => put more fuel... ufff it is still hot => then put MOOOORE fuel... Aghhhh it is really hot here!

I mean technically the further you get away from Stoich the lower the EGT is.
But injecting tons of LPG really does a number on the flame front speed, so without a ton of extra advance you get LPG burning at the exhaust valves, which causes premature failure.

Simply put, the normal strategy for temperature control on gasoline does not work well for LPG.

So I installed a EuropeGas LPG kit with fast 1.9 ohm Hana injectors. I did 13.000km with it before opening the engine (for an issue unrelated to LPG).

Due to a head gasket leak on cylinder no1 (which did exist before installing the LPG, as apparently I was losing coolant) I did a cylinder head job: skimmed head, milled exhaust valve head seats, 8 new exhaust valves (stronger stellite ones specifically designed for LPG use, IVAM or Freccia, don't remember which ones the builder chose in the end) and of course new valve stem seals and head gasket.

The kit was tuned to use 100% LPG (even though it supports gasoline enrichment or full switch) due to a lazy tuner. In fact, after 5000 RPM I had noticed reduced power compared to gasoline mode.
I now want to tune it but because this is not a typical Bosch ECU but a Marelli the support is limited (I've yet to find a Damos file for this IAW 5NF ECU for WinOLS).

If I manage to adjust the ignition advance, what should be the target vs gasoline to achieve better power (if possible more than gasoline) at high RPM without ruining the valves? I have to say that in the 1800-3000 RPM range, LPG was giving me far more torque, so I suspect that the ECU was adjusting the ignition advance on its own given the higher octane content of the fuel.

The factory ECU is rather dumb though: no EGT probe, no wideband lambda and only one mixture correction metric (and I've yet to understand if this is equivalent to STFT or LTFT).

Could the loss of power at high RPM be due to wrong ignition advance and slow burn time of LPG? Or just too rich of a mixture? Do you think it's pointless to try to achieve the same power at high RPM and I should just switch to gasoline above 5000 RPM? I have found a good LPG installer (and tuner) that will take care of it, but I need to learn more so I can help him to achieve my goals with this setup.