Matt_taylor

my car is missing really badly,

im thinkin a lead? or maybe the coil pack?

driving along, put my foot down and it misses ??

Matt_taylor

anyone??

done 100 miles with it like it and its not gettin worse?? think it could be a dodgy lead??

Claaarkio

iTrader: (1)

Get it down a garage and get some tests done, better than replacing part after part until you find the right one!!!

Matt_taylor

yeh my mate hasa garage and is a scooby owner so might take his apart,

anyone got a pic of the coil pack??

Claaarkio

iTrader: (1)

They sit directly on top of the spark plugs, one on each.

Dave

Matt_taylor

i was on ebay and had a peek and they showed 2 different types thats why i was confused

Yamarashi

Depends what year your car is?.... as to whether it has a coil per plug or a single coil pack and HT leads. Its very easy to see if you look under the bonet. If you have the single coil pack it will probably sit on top of the inlet manifold and your problem will more than likely be one of the leads as these coil packs appear to be more reliable.

Matt_taylor

its a MY97UK turbo

it has a block on top of the manifold like u say with the leads going to it

Yamarashi

Probably one of the leads then ... you can carefully pull the leads out of the coil one at a time (wear rubber gloves if you are concerned with getting a jolt!!) while the engine is idling to see if the engine note changes. If you pull one out that doesn't make the idle note change then thats the dodgy lead. If the lead is quite far gone you might also be able to see it flash/glow inside (when its pitch black outside!), this is due to the voltage jumping across the damaged conductor in the lead. If its a lead these can be bought individually from a subaru dealer for about £15 each.

Matt_taylor

excellent mate thankyou very much!! i owe u one!

when i get home from work im taking a look,

will it sound like its firing on 3 cyclinders etc??

Claaarkio

iTrader: (1)

This will only work if the lead is constantly failing though, and they often only start to fail under load. you could just buy one (if they are the same length) and swap it bewteen all four till you find the one thats failing

Yamarashi

It will sound like its firing on 3 cylinders ... as it will be firing on 3 when you remove the leads one at a time ..... but the key here is that the faulty lead (assuming it is a lead) will be struggling anyway (and not only when loaded as you drive) ....so ... you want to listen for the lead that makes the LEAST engine difference when idling as the others (good leads) should make it run EVEN lumpier when they are removed (ie running on 2 and a haly cylinders). Hope this makes sense! Its worth doing the dark night test as mentioned before as you can also see any tracking (spark jumping to earth) that might be happening and if you can see or here any this will show up the problem lead or area.

ps if it turns out to be the coilpack (try swapping with a friends one if possible) I have a spare one I may sell if you get desperate.

Claaarkio

iTrader: (1)

manually check rubber ends too, any splits can causing arcing to the head.

Yamarashi

Claaarkio .. you are right and even measuring the resistance of the lead might not show up the problem unless you move the lead around and force the conductor to make and break. I had a similar problem which was even random under load sometimes but you can see the lead glow slightly in the troubled area(s) when in pitch black.

Its also worth looking for tracking on the coilpack (as it should exist from when the car misses under load). This is fine lines (looks like pencil marks)from where the voltage has been trying to find an easier route to earth via the coil pack bracket and to the inlet manifold.

All the leads are a different length unfortunately but that doesn't stop you getting the longest one and then trying the substition method.