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Technical Panda with LPG sometimes won't start

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Technical Panda with LPG sometimes won't start

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downybear

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Nov 29, 2010
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Hi Friends,
I have posted this post previously on Panda (Classic) forum.
My mistake..

I have a sequential LPG injection in my Panda 1.1 2005. It works very good, car goes without problems many weeks, months, but sometimes car won't start on petrol (octane).
I have to turn engine 5, 6 minutes and after that engine starts and works PERFECTLY. If engine starts, works about 30 seconds, stops again. Next start is easier but not immediatelly as well.

Next day engine starts after few turns, and works very good from start.
This was the same in August - about 15 C deg morning, and now - about -5 C deg morning.

Many servicemans said that this is because of LPG installed in car.
Is it true?

And WHY next day engine starts without any problems and works good many weeks?
Is it possible that my ECU (Magneti Marreli 4AF/4EF/59F/5AF EOBD INJ) "seens" LPG and changes start parameters?

I have checked many times petrol pressure befor firing car. After pressing a valve on the bar, petrol goes very high. Fiat ECUscan software (free version) shows good pressure as well and no errors. Only exception - sometimes missfire only error - this is clear - engine won't start.

Please help me - if ECU parameters may changes while using LPG, I will buy full version of ECUScan and I will do autoadaptation myself each month. But I would like to know that this is true ( I don't belive in it - many of my friends using LPG in Toyota's, Audi's, Opel's and everything is ok.

I have checked two different LPG injection software in the same hardware - the same effect.

While engine works on idle, petrol injection times on petrol are very similar to petrol injection times on LPG. Differences are not bigger than 5 percent.

Any suggestions and/or knowledge about this ECU?
Thank you in advance for help :).
Regards
Mariusz
 
the lack of a response may be due to the fact that a LPG Panda is probably very rare in the U.K. and no one else has had your problem

good luck
 
I also have a Panda running on LPG - I don't understand the technical side of it at all, but it has now been installed for 15 months and I have had no problems in starting at all, so I suspect it is nothing to do with the ECU...

Sorry I can't be of much more help except to say good luck in solving the problem!
Trevor
 
trevorwat said:
I also have a Panda running on LPG - so I suspect it is nothing to do with the ECU...

Trevor
Click to expand...


I would check your battery connections, alternator connections, starter motor connections and all earth connections
 
panda4x4x4x4 said:
I would check your battery connections, alternator connections, starter motor connections and all earth connections
Click to expand...

Yes,
battery - checked, alternator - new (September), starter motor - works without problems 5-10 minutes, lights don't go lower while turning engine.

Earth connections - this is last thing, but not done yet (I think). I have suggested this action in workshops but they don't understand and says - THIS IS BECAUSE OF LPG...

How to find earth diagrams for this car, especially chassis connection points?
I know that ground (earth) has a connection points between wires inside the "wiring busses" - how to find info where the points are, before complete wiring dissassembly?

Finally, I think I will do it myself, to be sure. But not now - currently -11 C deg :) in Warsaw.

Regards
Mariusz
 
Is it possible that heat soak is causing something like a vapour lock in the injection system? Have you tried always reverting to petrol feed before you stop the engine - that would prove pretty conclusively whether or not it's an LPG issue.
 
babbo_umbro said:
Is it possible that heat soak is causing something like a vapour lock in the injection system? Have you tried always reverting to petrol feed before you stop the engine - that would prove pretty conclusively whether or not it's an LPG issue.
Click to expand...

Hi,
Sorry I don't understand exactly "heat soak" (english isn't my native language). But I understand "vapour lock" in the petrol injection system. I have checked it many times - while engine wouldn't start I have pressed valve on the bar (left side from front) - there was only petrol, not "vapour's pssss" :).

Currently I am already almost sure that this is (was) problem of the wiring.
Few days after my last post I have ordered grounding and wiring checking in trusted service station.
They did it and from this day - NO PROBLEM. Engine starts like never before :)
I would like to believe that there was problem in grounding/wiring - like somebody has mentioned above - but I will sure after next 2 months.

So, currently is very good in temperature range observed in last weeks from -20 up to +9 C deg today.
I will inform community in the next weeks if problem has been solved.

Regards
Mariusz
 
Last edited:
babbo_umbro said:
Is it possible that heat soak is causing something like a vapour lock in the injection system? Have you tried always reverting to petrol feed before you stop the engine - that would prove pretty conclusively whether or not it's an LPG issue.
Click to expand...

Ah your semi there.

OP have you checked the regulator has got a decent coolant supply and isn't freezing?
 
Most Easterly Pandas said:
Ah your semi there.

OP have you checked the regulator has got a decent coolant supply and isn't freezing?
Click to expand...

In my opinion it has no connection.
I have had problems to start using petrol while regulator (LPG reductor) doesn't need heat yet.
Problems was only after several hours of park.

Or I don't understand you? In this case - sorry :).
Explain it for foreigner in simples way :)
Thanks
Mariusz
 
Hi, all
Info for everybody who will meet stupid diagnosis about LPG :)

I have mentioned above that trusted service did earth connections checking in my car. And today, after several months, it looks that it was a reason of the problem.
Until now I have had only few situations when engine start was a little problematic. In the same time aku has gone as well.
After replacing aku problems has gone again. So it looks that something wrong is there in wiring yet, but in general problems has nothing to LPG.

Regards
Mariusz
 
Hi,
sorry for "aku" :)
This is polish abbreviation of battery which is named "akumulator" - and sounds like english "accumulator" not used in cars industry but used in microcomputers - I am a microcomputers developer :).

Regards
Mariusz
 
Hi Andy,
Thank you for hint.
If my problem will go back I will start from checking map sensor wires/connectors.
Currently everything is ok, except one or two accdents when my wife observed similar problems starting car to go home from office.

Regards
Mariusz
 
As MEP says check the cable connections.

I've been looking at fitting gas to my Punto. I believe they are supposed to start on petrol then switch to gas after a few seconds. In very cold weather some will not switch over until the engine is warm.

If you always refill the gas and hardly ever use petrol for normal driving, the petrol in the tank will hardly get used. Petrol doesn't age very well and poor starting might be sign. Try starting the mower with petrol left in over winter.

By the way "Acc" is the old RAF name for the mobile batteries used to start the aircraft as in TrolleyAcc(umulator) :) Spitfires were
 
WhiteSei said:
As MEP says check the cable connections.

I've been looking at fitting gas to my Punto. I believe they are supposed to start on petrol then switch to gas after a few seconds. In very cold weather some will not switch over until the engine is warm.

If you always refill the gas and hardly ever use petrol for normal driving, the petrol in the tank will hardly get used. Petrol doesn't age very well and poor starting might be sign. Try starting the mower with petrol left in over winter.

By the way "Acc" is the old RAF name for the mobile batteries used to start the aircraft as in TrolleyAcc(umulator) :) Spitfires were
Click to expand...

Switch over happens when coolant reaches about 45C from memory. In the summer (15-20c ambient temp) this will happen within 2 minutes, during winter though (below 5c) can take anything upto 4-5min.

With 20k a year driven I used 185L of petrol last year. In the winter (nov-march) I'll use about 130L of petrol. I'll then use about 50L in the summer (April-October). The quantity you use will obviously be dependent upon your driving, ie lots of short journeys or few long journeys as petrol will only be used from cold in the main.

In the winter I drive and not cycle to work 3.5 miles away, and easily do 2-3 miles of the journey on petrol, it's only on the longer journeys the LPG really pays for itself.
 
@WhiteSei:
Wires - yes, currently is very good, last thing is to check connections to MAP sensor - I haven't time yet.
Old petrol - yes, I know about this "feature". This car is mostly used on a short distances in a town, for longer trips I have SEAT Toledo. So I am refueling petrol not to full tank, but 8-10 liters only. It comes for 2-3 LPG refueling, in 2-3 weeks, not longer.

@Most Easterly Pandas:
I have possibility to force LPG in my system when I want to do it. So I have checked this winter very fast switching to LPG at about minus15 to minus18 C deg.
It wasn't easy, but possible - on high engine revolutions, about 4000 rpm, after about 1 minute with petrol, than about 30 secs on LPG at 4000 rpm, and I could go using throttle as soft as possible.
Of course LPG at this temperatures goes out partially as a liquid and smells a lot. I did it few times for test purposes only - it isn't good for engine and feelings aren't good as well - you are feeling in a car like in a "gas chamber" :)

Regards
Mariusz
 
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