2013 VE Factory LPG Only. LWR Engine. PO304 and PO300 Codes. Stability Control turns off and rough idle.

[NB66]

Hi Guys, I've got a factory lpg VE and it has the following symptoms. .....Factory LPG Only. LWR Engine.
PO304 (Cyl 4 misfire) and PO300 (random cyl misfire.) Stability Control turns off and very rough idle. Rev the engine a bit higher and the fault clears but check engine light remains on.

I've been told to check battery and electrical connections earths etc and done that. Also checked the ABS sensors and they seem OK. Also changed plugs and coils. Fault still remains.

One mechanic reckons it could be a burnt valve on Cylinder 4.

Others reckon its a bad earth or some sensor playing up or even the ECU. Any ideas ?

And finally...... YES it is a burnt valve on Cyl 4 !!! Confirmed by a leak-down test.... ;o)

 

[lmoengnr]

Start with a compression and cylinder leak down test, that will tell you what each cylinders 'health' is.

 

[eddy6241]

i had a burnt out exhaust valve on 06 VZ alloytec on factory dual fuel, similar symptoms at about 235000kms cylinder misfire code, poor idle but would drive ok, rested codes then would recurr a day or 3 later... until the valve got bad and major loss of compression on 1 cylinder... i replaced the one exhaust valve, about 30 dollars for the valve and 350 in gaskets etc.. wasnt more than about 400 in parts, 900 as i did camchain kit as well .. ran good then had it again on another ex valve about 50000km later so learn from my mistake, if it is an ex valve replace all the ex valves first time.... but may not be an ex valve at all but just FYI

 

[NB66]

i had a burnt out exhaust valve on 06 VZ alloytec on factory dual fuel, similar symptoms at about 235000kms cylinder misfire code, poor idle but would drive ok, rested codes then would recurr a day or 3 later... until the valve got bad and major loss of compression on 1 cylinder... i replaced the one exhaust valve, about 30 dollars for the valve and 350 in gaskets etc.. wasnt more than about 400 in parts, 900 as i did camchain kit as well .. ran good then had it again on another ex valve about 50000km later so learn from my mistake, if it is an ex valve replace all the ex valves first time.... but may not be an ex valve at all but just FYI

So you did the job yourself ? I'd have to get a mechanic to do it. Any idea on the cost with labour ?

 

[Skylarking]

I've been told to check battery and electrical connections earths etc and done that. Also checked the ABS sensors and they seem OK. Also changed plugs and coils. Fault still remains.

How were these things checked?

The battery for example should be load tested to determine it’s ok as just checking it has 12.something volts with a multimterer isn’t enough of a test…

To test the ABS sensors you need to see the wave form on a screen for a given rotational speed to ensure it’s providing the correct voltage and waveform.

A compression test and leak down test will give you a good idea of the mechanical condition of the engine (but requires correct cam timing so it if the chain is loose and jumped a tooth compression can be compromised, who knows)…

 

[lmoengnr]

you need to see the wave for on a screen for a given rotational speed to ensure it’s providing the correct voltage and waveform.

A compression test and leak down test will give you a good idea of the mechanical condition of the engine (but requires correct cam timing so it the chai is loose and jumped a tooth, who knows)…

That will show up as low compression, which will at least require partial disassembly of the engine to check valve timing, bent/burnt valves etc.

 

[eddy6241]

So you did the job yourself ? I'd have to get a mechanic to do it. Any idea on the cost with labour ?

Yes did myself... Its heads off job, id guess 5 to 10 hrs for a knowledgeable mechanic ,or about 3 weeks of spanner throwing in the garage for this amateur ...

 

[NB66]

and lotsa swearing no doubt..... ;o)

 

[NB66]

and lotsa swearing no doubt..... ;o)

Update on this.... the mechanic has replaced the MAF sensor, and now the rough idle/stability control off symptom isn't there any more BUT the check engine light still comes up and his scanner says 'park assist' is OFF. 30kms of driving and no engine misfire though!

 

[NB66]

A question.... Where is the EGR valve on the factory lpg LWR engine and where does it feed back into the intake side ? Near Cylinder 4 ?