sorting out a inconsistent misfire - changing coils?
sorting out a inconsistent misfire - changing coils?
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Discussion

stuthemong

Original Poster:

2,532 posts

247 months

Friday 19th February 2010
quotequote all
Hi guys,

Nearly getting there now, but have a misfire that peeks his head up now and then. Esp prevelent at moderate acceleration in the 3K RPM area. If it does it (warbles) and I back off and reaccelerate, it pulls absolutely fine.

So.

I've bought new leads & have some new coils to fit - thought I'd just change the lot - is chanign coils easy? Do you just reach in, unplug, unscrew & remove - or does the damn fuel rail have to come off? I've done a quick search but can't find anything obvious.

TIA.

Stu

IF this doesnt solve it I'll have to look at the spark plugs / injectors I guess, cross that bridge as-and when. As I have no idea how old the coils/leads are on my car, I think it just makes best sense to replace them first as a matter of course & there are Magnacors on there which I've read can cause these types of issues smile

Edited by stuthemong on Friday 19th February 12:27

al 350i

974 posts

225 months

Friday 19th February 2010
quotequote all
change the plugs as well, not expensive and should be done every 6k

stuthemong

Original Poster:

2,532 posts

247 months

Friday 19th February 2010
quotequote all
I did think of that, but they were changed only 2-3K Ago...... They are such a hassle to get out I think I'll leave them for now - hopefully they aren't to blame for the misfire issues.

al 350i

974 posts

225 months

Friday 19th February 2010
quotequote all
did the misfire appear 2-3k ago by any chance! and i know what you mean about changing the plugs, my plug socket is now alot thinner now thanks to the help of an angle grinder!!

jas xjr

11,309 posts

269 months

Friday 19th February 2010
quotequote all
maybe a bit random but try a can of throttle body cleaner. i had a problem on my jaguar similar to this.will not do any harm to try it

Olly

2,174 posts

314 months

Saturday 20th February 2010
quotequote all
The coil/s will come out without removing the fuel rail (it will take some wriggling, but it does come out). I've done both of mine with everything still in situe & it's do-able (I can change one in about 25mins)!

Make sure your write down carefully which leads go to which coil/position though ! type

Oh - and watch for cut off zip ties on the bulk head - they can make it look like you've gone 10 rounds with a large cat if your not careful !

(Run the engine for a couple of mins before you get start, and it means you'll still be able to feel your fingers by the time your done !)

stuthemong

Original Poster:

2,532 posts

247 months

Saturday 20th February 2010
quotequote all
Leads & coils replaced, and the second TPot (replaced one two weeks ago).

'*NEARLY*' getting there.

olly's tips were spot on. Little bit of heat to ease the pain, and it looks like I've been mauled by Terry the tiger.

The car is obviously much happier, it's not doing the horrible missing like it did before and I've managed to do a couple of wide open pulls in third to 6KRPM or so. Awesome biggrin In fact, I went for a mini-celibratory hoon out towards Kimbolton. LOTS of disapproving looks from dog walkers - ahhhh, the cerb is back!

Taking it into Cambridge now & hoping my luck will hold. biggrin

Just need to work out why my drivers door internal release no longer works (button works, tested tonight - must be somewhere else...) and try to work out what a weird metallic 'dangling' noise is when I change direction rapidly. Removed one spanner from boot which I suspect to be culprit so more testing on this tonight!

Assuming all this is treated for minimal outlay, it will finally be time to treat myself to some carbon lorraine pads!






Edited by stuthemong on Saturday 20th February 17:38

Olly

2,174 posts

314 months

Saturday 20th February 2010
quotequote all
Good news ! thumbup

Hope you had a good drive ! driving