Hello all,


First let me say thank you to Disco Mike and the rest of you for all of your help on the Discovery 2 we bought. You don't know it, but you have saved me constant anxiety and countless hours working on this vehicle. Your 25,000+ posts on the landroverforums. are amazing, we should all be paying you for the saved labor hours.



But to my current issue:

P0305 - Cyl 5 misfire, flashing SEL 2-3 seconds while driving around (but not in park?) goes steady for a few minutes then flashing again, okay so raw gas in the cat conv. from Cyl 5. Not too rough running but does make puffing/chugging noise, not sure if that is the misfire or valve tappets. Live data shows both O2 sensors go Open Loop when the SEL blinks.


Did a smoke test since we recently had a vacuum or exhaust leak that drove me crazy replacing 4 O2 sensors on Bank 2, the recent smoke test showed massive vacuum leak from behind the alt and AC.

Tore her down and replaced the lower inlet manifold gasket. Back together with same code. Changed all plug wires while apart, changed just #5 plug with no difference.


Dry compression test this afternoon, Cyl 5 = 60psi, next cylinder over was 90 psi, stopped there as 5 was so low.


I'm now stuck as to whether this is a coil pack going bad or as the compression test might suggest a valve issue (not a head I hope). Even thought MAF after some searching but couldn't figure how that would cause a single cylinder to misfire. Thinking about doing an engine flush and induction cleaning for stuck valves but equally ready to give up.


I've got the tools and education to do more here but after an exhausting weekend I'm overthinking and need some direction. (Some basic tools: Code reader, compression tester, spark plug 'light', Mechanic Steth., etc.)


I'm in Colorado Springs currently in a rent car while trying to figure this out and throwing money at nothing (well the leak needed fixing but not for the code).

Let me know what you guys think,
Thanks!

 

If it sounds like a steam locomotive, it's probably head gaskets.

 

When you removed the wire for the #5, did you check the leads? Was it corroded on the coil pack end? I had misfires before but I changed the packs too and found out the inside connection was greenish and corroded.

 

Thanks,

Twix:
Yeah a steam locomotive is a perfect description of what I'm hearing.
So I'll search for how to confirm head gasket is blown vs other issues. Any tips on confirming?

Should I start looking for a new car? Worth it to replace the gasket then keep it / sell it?



LR03NJ:
No, I'm sure I glanced over the wire and the coil pack while it was out during the inlet gasket replacement but I didn't thoroughly look them over (should've checked the coil packs for cracks and corrosion), nothing stands out in my memory but I had already changed the wires about 2 years ago so the original wire may have been worse and I was distracted by the gasket job. At this point I'd change it out just to rule it out or mask the issue if possible.



Ran a can of BG 44K for only about a half hour around the neighborhood and a couple exits down the highway.

Am I going to hurt anything running it around to run BG in it? Just from the short drive today I threw more codes:

Still P0305 - Am I going to melt my Catalytic converter when the SES starts flashing?

Now also

P0300 - Random/ Multiple Cylinder Misfire - Does this mean I have other cylinders misfiring, it only shows Cyl. 5?

P1230 - Fuel System Issue? I thought I heard the fuel pump running way too long while looking at the exhaust, may have been something else whirling while I was under there

P0332 Knock Sensor Circuit Low Bank 2 (wait isn't my misfire on Cyl 5 on Bank 1?)

 

If the misfire cause the SES light to blink, that means a catalytic damaging misfire and should not drive your truck for a long time. It will feel like it really need a tune up, but you just did. About the #5, did you check the condition of the plugs. Is it seated all the way in? Are the threads good? When I remove plugs, I ususally count the turns when replacing them. Once, I remember, the plug seems tight and it was halfway. Be careful not to strip them then youll have compression problem as well. Please recheck all your recent install, switch the HT wires that cause the misfire as well. HT wires, many said last a long time of even the lifetime of the car but in some cases they break within inside for some reasons. Our neighbor bought a new cadilac and few weeks after had misfire, dealer changed a lot of things and still caused misfires and at the end he mentioned to me that it was just a HT wire that caused the misfire.

 

I think if it was a failing coil pack you would have a misfire on the other cylinder number 5 is paired with (wasted spark system).

Try double checking that the number 5 wire is fully seated on the coil pack in on the plug. It was somebody on here in just the last week or so who was pulling his hair out about a single cylinder misfire and ended up discovering it was exactly what I just said - the wire was simply not plugged fully into the coil pack.

I know it is a pain to do but I would try swapping the number 5 wire with another of similar length and see if the misfire follows. Or, since you said you changed the wires, try putting one of the old wires on number 5 and see what happens.