2007 RX400h MisFire Cylinder 2

[seanie248]

Hi All

Just wanted to share this in case it helps anyone else. 

2007 RX400h, running perfectly, then parked up for a few months.

New Battery installed and then it kept mis-firing under heavy load. Never brought on engine light, but using a reader, showed errors

• P0300 (multiple misfire)
• and a code for a misfire on cylinder 2.

Changed plugs, Coil packs, but still the same, always misfire on Cyl 2. Car would drive perfectly if you didn't accelerate very hard, but, for example if you went over 110kph, engine misfire.

Then one day, I noticed that when I filled up with petrol, there was no "hiss" when I opened the filler cap. 

1 New filler cap later, €45, and all sorted. Driving perfectly again. ( even seems to a bit more pep ) 
I presume the rubber seal perished when it was sitting idle for a few months. Probably on the way out anyway.

Hope this helps someone else some day.

Seanie

 

[Sundance]

Interesting tale Sean, appreciate it. 👍

But I'm no petrol head so am slightly bemused by the connection between a specific cylinder misfire and a worn petrol cap seal.

I get the reduced fuel tank pressure tripping an error code, presumably thanks to a fuel tank pressure sensor, but why the misfire?  And specifically on No.2?

Might it incidentally indicate excess (but not critical) wear related to cylinder 2? ... or am I overthinking this? 🤔

[Greisingel]

The fuel cap seems to be devilish source of so many problems. It may be that the reduced tank pressure for whatever unfathomable reason concentrated a flow issue particularly at that point off the fuel rail. Very strange. Glad it seems to be fixed. How many miles on the clock?

[seanie248]

Hi guys, thanks for the feedback

Mileage 210K Kms.

Interesting point Rowley, I might do a bit more digging about wear on C2, or the injector rail.

As there is no engine light coming on, I was thinking that it's just related to not coming up to proper pressure, and as nothing else was giving the car a reason for an error like faulty sensor etc, then it might just be a generic error, kinda like what Andy is saying. Not getting the fuel it expected, and C2 was what was reported.

I'll report back if I find anything extra

[ColinBarber]

Random cylinder misfire error or multiple cylinder misfire errors are a result of something common such as fuel or air because multiple plugs or coil packs don't fail at the same time.

Cylinder 2 injector is fed by the end of the second fuel rail - it makes sense that a fuel starvation problem would manifest itself there first.