LPG idle misfire issues - Page 2

mcfe · Dec 1st, 2023, 17:27

Spark energy is affected by battery voltage and rpm. On my s60 p2, there is a dwell time table in the ecu code. It affects how long the coil is charged and how strong the spark is based on Voltage and RPM.

Jason t5 · Dec 5th, 2023, 08:00

I did wonder if it was a battery issue so I replaced it with a brand new one.. still having the same problem 😔

mcfe · Dec 6th, 2023, 09:11

I am guessing it drives fine on gasoline? To me it sounds like the car is adapting to the running of LPG and is detecting either too lean or too rich and is changing injection times WHICH ARE INTERCEPTED by the LPG computer, which affect your lpg system. That or the LPG system is doing some adapting of its own.

I would look at STFT LTFT values just to verify between LPG and Petrol in real time of course. You need to figure out why the car is misfiring e.g too much fuel and is causing it to choke or too little and is trying to burn just air. Perhaps the pressure of the LPG system is at fault.

This is just my theory of course so don't take it as fact I could be way way wrong here.

ijmorrison · Dec 13th, 2023, 20:42

Had a similar one last year on my S80 2.5t with LPG.

Long term fuel trims and short term maxed out.

Reset and would be ok ish for couple days then back to warning light and maxed trims.

Fault finally traced by my mechanic too ..... Petrol injector seals ..were allowing just enough air in to throw everything out but oddly was smooth enough on petrol.

Parts were about £30 from frf.

Maybe get your ear in or try to smoke test ?

Iain

Dec 6th, 2023, 09:11	#13
mcfe Junior Member Last Online: Today 06:11 Join Date: Apr 2019 Location: NoTown	I am guessing it drives fine on gasoline? To me it sounds like the car is adapting to the running of LPG and is detecting either too lean or too rich and is changing injection times WHICH ARE INTERCEPTED by the LPG computer, which affect your lpg system. That or the LPG system is doing some adapting of its own. I would look at STFT LTFT values just to verify between LPG and Petrol in real time of course. You need to figure out why the car is misfiring e.g too much fuel and is causing it to choke or too little and is trying to burn just air. Perhaps the pressure of the LPG system is at fault. This is just my theory of course so don't take it as fact I could be way way wrong here. Last edited by mcfe; Dec 6th, 2023 at 09:20.

Dec 13th, 2023, 20:42	#14
ijmorrison Senior Member Last Online: Mar 8th, 2024 23:58 Join Date: May 2013 Location: Great Yarmouth	Had a similar one last year on my S80 2.5t with LPG. Long term fuel trims and short term maxed out. Reset and would be ok ish for couple days then back to warning light and maxed trims. Fault finally traced by my mechanic too ..... Petrol injector seals ..were allowing just enough air in to throw everything out but oddly was smooth enough on petrol. Parts were about £30 from frf. Maybe get your ear in or try to smoke test ? Iain __________________ S70 T5 1999 (now written off grrr) S80 2.5T LPG 2004 XC90 D5 2005 (2006)

Dec 1st, 2023, 17:27	#11
mcfe Junior Member Last Online: Today 06:11 Join Date: Apr 2019 Location: NoTown	Spark energy is affected by battery voltage and rpm. On my s60 p2, there is a dwell time table in the ecu code. It affects how long the coil is charged and how strong the spark is based on Voltage and RPM.

Dec 5th, 2023, 08:00	#12
Jason t5 New Member Last Online: Apr 22nd, 2024 19:42 Join Date: Feb 2023 Location: White British	I did wonder if it was a battery issue so I replaced it with a brand new one.. still having the same problem 😔

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