Bosch Y6DC Spark plug life expectancy

davidoli · 22nd August 2007, 10:38

Whilst attempting to power out of one of my favourite right handers yesterday , my Mauritius 3.6 misfired / overfueled heavily at full throttle in 3rd and then 4th gear before letting out a wonderous backfire .

Luckily , I had a set of new Bosch Y6DCs in the boot and these cured the misfire .

Bearing mind I have recently come off a 50 day speeding ban and the previous plugs were fitted in mid April 07 prior to my last Ring trip , during which the 3.6 only covered 6 laps , I was suprised that the plugs only appear to have lasted 2500 miles approx .

Obviously , it may be the case that only 1 or 2 of the previous plugs failed . Even so , this is still not great .

What are other members experiences of plug life ?

gwm635 · 22nd August 2007, 14:00

Hi David,
I have heard of M88/3 in M635's fouling plugs after little or no use

raymondw · 22nd August 2007, 14:10

Hey David,

I can confirm this for the M88/3 where I have experienced this myself with new OEM plugs. After replacing the X5DC with newly supplied OEM the problem was solved.

But I have not experienced this with the S38B36. I replace them once every four years (~30k km) and never had a problem with them. That doesn't say that I haven't experienced ignition problems, but these where caused by a broken igniter and distributer cap (twice, 2001 and 2004) and an aging HV-wiring loom of which at least one wire had a damaged insulation (2004). As corrective action I replaced all parts in these occasions.

My educated guess is that by replacing the spark plugs, you had to reinstall and install the HV wiring-loom and you may have changed the fitting position. It may very well be possible that by doing so, you have increased the creepage distance from one or two weak points in the wiring. If your HV wiring has never been replaced before and thus is over 15years old, this may have solved the problem temporarily, but not indefinatelly.

davidoli · 22nd August 2007, 14:11

Hi Garry ,

I can understand if the fueling / mixture is well out of sorts i.e. overly rich .

All of the plugs were a lovely lightish brown colour but the centre electrode had begun to round off on a couple ......

Interesting ........

Good points Raymond ........although when changing the plugs in April , I also changed the distributor cap , rotor arm and had new HT leads fitted in a bid to have everything spot on for losing my ring virginity .

I'll keep an eye on how she runs over the coming weeks and order up another 6 plugs to stick in the boot .

raymondw · 22nd August 2007, 14:29

Hey Gary and David,

I may have to clarify my X5DC problems. Shortly after I have bought my E28 I dicovered that the wrong spark plags were installed. I corrected this with the correct X5DC but these didn't work. I had the E28 booked into the dealership for a lot of corrective actions in spring 2002 and they solved the problem by replacing the spark plugs again, but didn't find the cause of it.

I did that myself much later when I discovered that teh PO fauled around with the CO screw and set the mixture to between 3% and 5%. Furthermore, the TB setting was incorrect causing the idle switch not to function properly.

So all in all, I cannot say that the X5DC fail due too a manufacturer defect, but more by an incorrect CO and idle setting.

As for the B36, both cannot be adjusted manually, but if thye O2 sensor doesn't work, the DME will enrichen the mixture as a safety measure in order to protect the engine against operaing in lean mode.

gurman · 22nd August 2007, 17:48

Can the O2 sensor fail to work and NOT register a 'BONG', guys?

davidoli · 22nd August 2007, 17:50

Quote:

Originally Posted by gurman

Can the O2 sensor fail to work and NOT register a 'BONG', guys?

yes..... get a diagnostic check to confirm faulty o2 sensor .

gurman · 22nd August 2007, 17:54

Sorry for stealing the thread and going a weeee bit OT.

I have two DME's and one registers a faulty O2 sensor and one doesn't so I was just curious. I think it's ok though davidoli

davidoli · 22nd August 2007, 17:57

No worries , get the fault cleared on the DME that registers the faulty o2 sensor , drive the car for a bit and see if the fault reappears .....

Nilocnut · 22nd August 2007, 21:40

Davidoli,
How exactly did you lose your Ring virginity?