Peugeot 307 nfu misfire cold

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Peugeot 307 nfu misfire cold

Postby boskl » Wed Sep 20, 2017 3:30 pm

Hello,

We got a problem with a Peugeot 307 2006 nfu engine. runs on petrol and lpg.
With cold engine it runs rough and sets a misfire code for cylinder 1 and 4, not always both.
New coilpack and plugs have been fitted because oil leak in spark plug holes.
With engine cold it seems to run good at first and then you can feel it begins to mis, if you let the engine warm up until 70 degrees after this it runs good and doesn't misfire.
Tried a engine flush but it did not solve the problem.
Most people say hydraulik lifters or valves are to deep because of lpg.
Made a running compression test with wps in cil 1 2 and 4.
Also a secondary ignition.
Maybe someone can help me with it.
Attachments
Peugeot_307_2006 sec alle 4 2.psdata
(12.27 MiB) Downloaded 25 times
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Re: Peugeot 307 nfu misfire cold

Postby Technician » Wed Sep 20, 2017 10:33 pm

Looking at your scope traces two or three cylinders spark lines are seriously sloping in the downwards direction, normally these slope lines are reasonable horizontal with a slight gradient. I'd be removing the spark plugs for a thorough visual inspection, check the centre electrode for detachment, I've seen this a couple of times recently. The air fuel ratio may also be rich. If worth noting that the firing lines are out of tolerance with each other, normally the firing lines should be within 3 KV of each other, if I remember correctly from your traces using the ruler I have observed around 5 KV differences.
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Re: Peugeot 307 nfu misfire cold

Postby PicoKev » Wed Sep 20, 2017 10:43 pm

Hi Boskl

No mention of mileage and previous service history but as others have apparently already told you LPG is the king and Queen of valve recession.

Most manufacturers mandate valve clearance checks every 10,000 mile on LPG.. :shock:

Everything is irrelevant on an LPG engine until the valve clearances are confirmed to be correct! Not at work so no info on that engine.

On a quick look at your waveform (on a very small screen) it looks like it is running weak. Notwithstanding no info to say under what conditions the capture was made and not much of the details section filled in.

Remember no one else can see the car the more data provided the better.

Check those valve clearances and see what happens. 8)

Kev.
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Re: Peugeot 307 nfu misfire cold

Postby boskl » Thu Sep 21, 2017 8:18 am

Hello,

Thanks for the replies.
Car has 300000 km. Normal service history.
Capture was made stationary with engine running rough.
Car has hydraulik lifters.
Also made some in cylinder captures but the attatchement gone wrong.
In cylinder captures made stationary with cold engine.
Attachments
Peugeot_307_2006 cilinder 4 running comp.psdata
(5.76 MiB) Downloaded 12 times
Peugeot_307_2006 cilinder 2 running comp.psdata
(8.34 MiB) Downloaded 11 times
Peugeot_307_2006 cilinder 1 running comp.psdata
(5.69 MiB) Downloaded 12 times
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Re: Peugeot 307 nfu misfire cold

Postby ben.martins » Thu Sep 21, 2017 10:55 am

Hello Boskl,

Many thanks for uploading your captures. Just to confirm that is 300,000km? As PicoKev has mentioned LPG can cause any number of problems especially with valve seat recession. I've yet to check your compression captures but from looking at the secondary ignition waveforms I can see Cylinder 4 has a high Sparkline KV compared to the others. Cyl 1,2 & 3 all come in between 1 and 2 kV yet cyl 4 is at 5.5kV meaning a lot of energy is being used up in order to keep the spark going. Maybe a snap test still looking at secondary ignition would be useful? Also when you made the initial capture was the vehicle misfiring?

Will take a look at the your compression captures and I'm sure between us here we can get an idea of what's going on.

Kind regards

Ben
Attachments
Peugeot Secondary Ignition Bad.jpg
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