Engine: 3.2: XC90 Misfire

[seandodwell]

Hi All,

I'm trying to get to the bottom of a misfire on Cylinder no. 6.

I have swapped plug, coil pack, and cleaned all injectors, and added a new one to no. 6.

Does anyone know if new injectors are plug and play or do they need coding in VIDA? I used FOMOCO ones matching the ext.

Any other ideas, fuel rail pressure is good, fuel pressure switch is good, new fuel filter fitted. My local garage drew a blank say I need to go to Volvo Main Dealer, earliest appointment is late April...HELP!!

Or anyone know mobile Volvo mechanic in west London??

2007 SE Sport 3.2 petrol

[Carlosos]

Are you getting a spark at the spark plug? Harness?

[seandodwell]

Yes all electrics check out, they did say they checked compression on 1-5 but could'nt check 6 as the spark plug was slightly threaded, so I've ordered a re-threader and compression tester will report back on that. Still want to know if injectors are plug and play or need coding?? Help>..!

[seandodwell]

Anyone do these injectors need coding once replaced? Thanks.

[ommony]

Did you ever manage to figure this out?
Mine has just developed a misfire on cylinder 6 as well. Haven't had a chance to dig into it properly or plug the laptop in to see what's going on, but in my case I know it's not injector-related as I have the same misfire on petrol or LPG. I've swapped coils/plugs quickly and didn't make any difference. Hoping and praying it's just something simple like damaged wiring and not a dead cylinder with low/no compression. I'm on 260k miles, so anything is possible.

[seandodwell]

Originally Posted by ommony

Did you ever manage to figure this out?
Mine has just developed a misfire on cylinder 6 as well. Haven't had a chance to dig into it properly or plug the laptop in to see what's going on, but in my case I know it's not injector-related as I have the same misfire on petrol or LPG. I've swapped coils/plugs quickly and didn't make any difference. Hoping and praying it's just something simple like damaged wiring and not a dead cylinder with low/no compression. I'm on 260k miles, so anything is possible.

ommony - sadly yes finally got a confirmed diagnosis. - Burnt valve, who knows the cause, but its head off and rebuild. Options were second hand engine (unknown beast) or scrap the car, it's 2007 SE Sport, but I love it and have done quite a bit to it, this is the first engine issue. I figure I can strip out the head myself, (a special Cam tool set required but readily available -£100), plus about £800 for a complete back to new head rebuild by a very helpful chap in Par Cornwall, I'm in London, but my brother lives near by. the gasket set is about another £150 plus consumables, the garage wanted £2.5k +, defo not in my budget. Since these 3.2's are getting rarer I think I'm going to do this and keep it.

I have two general questions for anyone who has an opinion.

1. Should I replace the timing chain & tensioners whilst I'm in there, &..

2. If I'm replacing the chain is it wise to replace the sprockets(Both cams inc. VVT and lower smaller drive unit sprocket (very expensive option!! about £800 extra for a full chain and sprocket set!!!).

3. Does anyone have any good recommendations for gasket sets for this little job!! & or Timing chains, Although I'd probably go original fro that if I change it.

Any comments welcome thank you.

[ommony]

Sorry to hear that -- nightmare!
Fingers crossed my problem is something else, but I'm getting a sinking feeling I may be in the same boat as you. Going to be investigating further over the weekend and will report back.
If it turns out that I also have a burnt valve or valve seat recession (not exactly unheard of with LPG) and I also need a head rebuild, maybe we could find a way to mitigate some of the costs; for example, I'd be happy to split the cost of the cam tool, and maybe your guy in Cornwall could do us a bit of a discount if he gets two identical heads in at the same time? Maybe not, but could be worth asking.

[seandodwell]

Hey ommony,

You were up early!!!

Yes happy to do some sort of tool share. Not too sure of my timetable right now just off to pick up the car from the garage. I've seen this on ebay (see link below)so will probably start here. I can't imagine the Cornish chap will do a two fro one type thing, but I also haven't done a check see what's a)closer, b) cheaper, speaking to him he seemed very genuine, and the transport is not such an issue for me. Where are you located? I'm just trying to decide if i replace chain, or chain and pulleys, or not! It's about another £450 to do that I think.

https://www.ebay.co.uk/itm/394873794...3ABFBM_tG189pj

[seandodwell]

This is the full chain kit, I'm sure there are others, if any one knows of any, or have any experience with any, can they let me know. Thx.

https://www.rendcarparts.com/parts-f...82/RD30759065S

[ommony]

Right, so after confirming that I had spark and fuel, I carried out a cranking compression test on all 6 cylinders. 1 through 5 were all healthy and happy. Cylinder 6 had ZERO compression. So, unless I have a giant hole in the piston, I'm in the same boat as you with some sort of valve-related problem (could also be head-gasket, but no other indication of that). I need to do a cylinder leak-down test to narrow down the cause, but I don't have the equipment for that so will have to take it to a garage to do the test. Regardless, it sounds like it will definitely be a head off job. Lots to think about!