4.4 misfire help ITS DRIVING ME MAD

[Phil.c]

Hi guys

My motor is driving me mental hopefully someone can help
The x5 is a 4.4 v8 on a 2002 plate with 97000 on the clock I've been having trouble with it as late first the lambda sensors which I've cured
Now yesterday I get the engine management light up again so I plugged in the laptop its saying

3E (062) misfiring at several cylinders
35 (053) misfire detection cyl 8
36 (054) misfire detection cyl 6
Its well down on power and when I give it heavy gas the light flashes

So I changed the coil packs this morning on 8 and 6 with new ones checked the plugs they look ok and took the car round the block gave it some wellie guess what the light started flashing again so back home plugged Laptop back in now I've got
3E (062) misfire at several cylinders
35 (053) misfire detection cyl 8



Has anyone got any ideas I love the car but they do have there faults
Cheers phil

[Horizon]

When I had my 840 ci, same M62 4.4 ltr V8 as in your X5. I used to get the light on and it would go into limp mode when I booted it, say in kick down. Got the codes read, misfire on all cylinders on the same bank.
Lucky I spoke to an old timer at the indie I used. He said do you hear a rattle when its cold, coming from underneath ! I said funnily enough I did, he said get it on the ramp and bang the cat underneath, I did and you could hear debris rattling inside.
The cat had broken up and was restricting the exhaust flow at high revs so causing a misfire, priced up a cat at the dealers £750 !!
ECP £250 fitted that one and problem solved

[Phil.c]

Hi mate
Thanks for the reply the misfire I'm having is the same bank so it could be that

Cheers phil

[Horizon]

If the lamba sensors were playing up, maybe it's been over fuelling, as the lamba sensors read the 02 levels after the engine has burnt the fuel , so regulates the mixture. If it's been running rich it can damage the cat.
Mine only had lamba sensors before the cat, later ones have pre and after cat sensors, which I suspect would flag up a faulty cat.
Is the problem occurring after you have been giving it the beans, or during normal/ sedate driving?

[Phil.c]

If I drive it easy it seems ok but if I give it a boot full It bogs down and I get the flashing eml come up then if I go back to driving it normal the light goes off

[aldmc]

I had same problem at almost identical mileage, changed plugs fine since

[Ubatoid]

If shes on gas  - de-cat. If not almost certainly sounds like a clogged cat.

[Phil.c]

Hi guys
Quick update for you all had the cats replaced on the x5 today and guess wot its FIXED!
No lights on dash and its pulling like a train again

Thanks for all your help guys  )

Phil

[X5Sport]

Clogged or what?  Did they say?

Glad it's sorted though....

Richard

[Phil.c]

Yeah clogged big time

[Horizon]

[quote="Phil.c"]
Hi guys
Quick update for you all had the cats replaced on the x5 today and guess wot its FIXED!
No lights on dash and its pulling like a train again

Thanks for all your help guys  )

Phil
[/quote]

Glad you got it sorted, when I had the problem, most said start with the plugs then the coil packs etc. surprising how some garages just guess when they are spending your money.
Won't ask how much for two cats to be replaced

[Phil.c]

I know what you mean about the garages just putting parts on and guessing I've got a real good Indy in Hatfield he has been working on my cars for years
As for the cost of the cats I gave £160 for the whole front section from a salvage place up north I didn't fancy paying for new ones just incase it wasn't them

[X5Sport]

The next question is what caused the clogging?  Any sign of oil getting in there?  Is your oil consumption still OK?  Do you do short journeys so the cats don't warm up properly?

Good call getting used ones.

Richard

[Phil.c]

Oil is fine I've only topped it up once in about 3500 miles its due for a change now so ill keep an eye on it
The only thing we could think made the cat get clogged was the bad lambda sensor I had a while back I only use the car at the weekends so most of my journeys are a bit stop start

[VegyBS]

I am having this exact same problem, even down to the same cylinders. I've been putting it off as I don't want to buy new cats right now. Fortunately mines on LGP (which is probably half the reason for the cats going anyway) so I could just knock them out for now.

Mines been like this since I've had it too, didn't show on my test drive as I was only able to do it around London on busy streets.

Hopefully I'll get to experience it's full (well 12 year old full) potential once it's sorted!