Running warmup enrichements backwards

[mitsuko]

I wonder if this is possible .

Normally , the warmup enrichement would look sometjing like this .

0°C 130%
50°C 110%
70°C 100%
etc .

If I would enter

0°C 70%
50°C 85%
70°C 100%

Would dat result in a lean mixture when cold , going less lean as the clt temp rises , to end
at 100% at normal operting temperature

Is this possible or am I just dreaming

Pat
.

[kjones6039]

Just curious here.... what are you wanting to accomplish by this?

Ken J.

[mitsuko]

lpg vapour injection .

The vaporisor / pressure reducer regulates lpg pressure to 0.85Bar over map.
The injectors inject a pw defined volume ,
Both these factors are regardless of temperature .
Vaporised lpg temperature is roughly thesame as coolant temperature .


With a cold engine , the lpg is injected cold . .
But the tuning was done with a hot engine .

Cold lpg vapour has a much highter density then hot so with a cold engine I'm running pig rich ,
on freezing days to the point of a no longer ignitable mixture .

Running the wue reverse would most likely cure that problem .
MS1 V2.2 , extra 029y4a

[Marek]

Yes that is correct.

Most, if not all people who run lpg have a reversely biased warmup table for presicely this reason. Exactly how much depends on your fuel pressure and temperature correction curves for the lpg. With MS1 that option to correct (or even measure) may be somewhat lacking, so MS3 is a much better platform for lpg.

If MS1 doesn't allow you to have numbers lower than 100 then you'd have to think laterally and have a correction that goes something like 100->130 rather than 70->100.

kind regards
MArek

[kjones6039]

lpg vapour injection .

Yikes!!! WAY above my paygrade!

Thank you.

Ken

[jamies]

When i setup one of my vehicles with LPG vap inj and MS3 i didnt need to reverse bias the warmup,
the LPG temperature curve seemed to handle it well, and it used to start cold no problems at all.
have you got your lpg temperature curve dialed in?

[mitsuko]

This is an MS1 , so there's no temperature curve or anything else for lpg .
It was the very first megasquirt ever to run a bi fuelled car back in 2004 .
http://www.msruns.com/viewtopic.php?f=87&t=1376
Car ran great for many many years 200.000+ miles , then it was sold , but I
kept the ms and all the injection parts .

Back then it was not possible to reverse the wue so in winter I had to warm up the car on petrol
before switching to lpg .
But now that the extra code has evolved , it would seem possible to do that , that's why I started this topic


@Ken : Not that different from petrol inj you know .
A vaporisor / reducer instead of a fuel pump , and lpg injectors instead of petrol injectors .
Apart from that it's basicly thesame animal .

@Jamies : Any details on your setup ?
Vaporisor , injectors ...
Never knew ms3 could do that .

@Marek : Now that is a good idea .
Why didn't I think of that 10 years ago .


Pat

[jamies]

my vehicle had a 351 cleveland with 36-1 crank trigger and distributor modified for cam sync
KME gold reducer / converter and magic JET injectors with fittings drilled and tapped into a single plane intake
ECU is MS3 with Jeans peak and hold drivers modified for 6 / 1.5 amp peak and hold
I had rail temperature and rail pressure setup and it would start cold any day of the year on lpg.

I had the car for about 7 years then since sold it to a mate, who still has it and still going fine.

MSQ attached for reference but it is running an older firmware version... still...

[mitsuko]

Hey Guy's , you know what ...
This works , actually it works great

I did the math , calculated theoretical values for the lpg density at lower temperatures .
Converted them to percentages
Entered them in the warmup table .
Fully warmed up 100%
Freeezing temp 75%
and a lineair interpollation for all the others .


The engine now runs a tiny little bit lean for the first half minute or so , then
quicly goes to stoich and stays there .
Compared to the pig rich condition I had before ....
Now it's just a matter of adjusting the parameters a bit to get them right on .

It will also produce a very stable iddle almost right away , without any auxiiary air
and it's driveable right away . No more bucking or stalling .
That's an advantage of lpg ,
At atmosferic pressure it's in it's gaseous state .
No fuel condensing again after being atomised and/ or sticking to the intake walls .

Pat

[Marek]

I always start and run on lpg.

It starts literally without cranking. From the datalogs, I compute that it is usually by the 3rd cylinder to fire that makes it take off - that is only 1/2 revolution, i.e., near instantaneous start. It is driveable straight away and smooths out completely at ~50'C.

By contrast, the petrol side is never as well tuned as this.

kind regards
Marek