1998 Z3 M44 engine misfire shenanigans...

[TFW]

Car developed a misfire on the way to work, limped it home and ordered a generic Bluetooth code reader and the 20-pin to OBD cable.

Fired up Torque-Pro Lite to see how it got on and Voila, stored codes a plenty.

P0130
P0135
P0300
P0301
P0303
P0302
P0304

As I have no idea which are current and which are old I cleared them started up, no codes after a start up.
Drove round the block and two codes returned

P0130
O2 Sensor Circuit Malfunction

P0302
Cylinder 2 Misfire Detected

Trouble is I can unplug each cylinder in turn and see no change in running.

Will have another look in daylight

 

[mwpe]

I recently had a misfire on my 325 compact and the code reader said misfire cylinder 5 so I switched the coil packs between 5 and 2 and the fault changed to misfire cylinder 2. New coil pack, 5 minutes to fit and all is well.

 

[TFW]

This has a single coil pack with drivers for each output so I cannot move any around between cylinders.

 

[Paul Rice]

The misfire on my M44 turned out to be a blown head gasket. Mine showed Cylinder 3 misfire. Worth trying a compression test

 

[TFW]

Will give that a go but a gasket will take more time than I have to spare at present.
It will get some time on the naughty spot to think about what its done and watch me change a clutch on the MG ZS V6 instead if the gasket needs changing, if the head comes off I will be swapping the head entirely for one that isnt running with a thread repair spark plug.

 

[TFW]

I went to do a compression this evening and found a problem but not one I was expecting, plugs have about 3,000 miles on them.

Can you guess which one is from cylinder 2 ?

 

[Johnwindwood]

Always check the simple things first. Having said that, what the heck has happened to that plug????

 

[TFW]

My first guess is the repair insert was rubbish at carrying the heat away from the plug, this happened at "Some Speed" on a wide open throttle.

I will poke a bore cam in there when I can find it, hopefully the shrapnel off the plug went out the exhaust valves....

 

[t-tony]

Just hope it didn't damage the valve. Did you do a comp. test yet?

Tony.

 

[Grumps]

Just hope it didn't damage the valve. Did you do a comp. test yet?

Tony.

Was about to tag you mate on this.

 

[Paul Rice]

Hopefully a quick fix, if not i know where there's a good M44 head

 

[TFW]

Just hope it didn't damage the valve. Did you do a comp. test yet?

Tony.

Yes, a little me time with a Gunsons guage

Scores on the doors

1 - 190
2 - 0
3 - 205
4 - 200

Think I will pull the head before ordering anything, I wanted to take the camshaft cover off but ran out of time today.
What are the odds of a broken valve sping/chipped valve/ disintegrated valve seat ?

 

[t-tony]

Best guess is a bent valve. Could you get an endoscope through the plug hole?

Tony.

 

[colb]

At least you will have it fixed for the summer weather, keep the camera handy and post us on your progress, bet you won't be putting NGK's back in even though your diagnostic as to the cause being that thread insert not transferring the heat from the plug. Must say that plug looks well burnt.

 

[TFW]

At least you will have it fixed for the summer weather, keep the camera handy and post us on your progress, bet you won't be putting NGK's back in even though your diagnostic as to the cause being that thread insert not transferring the heat from the plug. Must say that plug looks well burnt.

Think I will shy away from NGK in general for a while http://www.ngk-sparkplugs.jp/english/techinfo/fake/index.html
They seem to have an issue with fake plugs being branded as NGK.

Regarding the bore-cam, I wanted to get an additional set of mirror lenses that would allow a decent view of the valves, these looked ok ish on price until I saw the postage cost

https://www.ebay.com/itm/Depstech-H...434577&hash=item23c5da1b3e:g:hP4AAOSwzbxaYxlF

 

[t-tony]

If you have an android phone I have one you can borrow. You just need to download an App.

Tony.

 

[TFW]

I have two of the Depstech endoscopes whilst the 45 degree mirror gives a view of the cylinder bores, what I need is the 30 and 60 degree camera attachement will allow visibility of the valves.

 

[the Nefyn cat]

Doesn't matter how many cameras you poke down it, with compression numbers like that you've pretty much got no choice but to get the head off. And that way lies a fair bit of expense.

 

[colb]

Agree with the cat, it's got to come off to see how bad it is

 

[TFW]

My problem is, once it is in bits I have a blue ornament that cannot be moved while I wait for parts.
At present it's movable, if I can decide it needs a valve I can order one or more and a gasket set and set aside a Saturday to get stuck in.

If the valves are intact and operational the culprit is likely to be piston ring's.