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

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

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.

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.

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!

Hi prj,


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

Yogi

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!

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.