wiltshire_boy

I've read as many threads as possible on this problem and just wanted some confirmation before i splashed out on some coilpacks please.

I get a misfire in 3rd and 4th (not found the room to try it in 5th yet) when flooring it WOT. It seems to occur at about 5000rpm and clears itself if you back off a little. I also get a random "lumpy" idle when warm as well. It will also hiccup slightly when pulling away.

I have cleaned the MAF and crank position sensor, couldn't get the cam position sensor out. Also cleaned the boost solenoid and throttle position sensor. Regapped the plugs to 0.6mm which improved things slightly. Reset the ECU.

The above problems started after i had changed the plugs and i have read that just disturbing them is enough to make them play up. I can understand why they might break down under load but why has this affected the idle and low revs as well?

The car has done 93,000. Is it worth changing all of them or just buy one used and swap it about?

Sorry for the essay and thanks in advance.

Roy.

scoobyslut

I would suggest you have a look at the tips of the coil pack,to see if the actuall insulator material has cracked or split apart. There may be a small rubber sleeve on the tip, carefully remove it and have a look. that way, you will know how many coil pack you will have to replace.
Be careful on removing and refitting these items as they do damage quite easily.

wiltshire_boy

Thanks Scoobyslut, i've already tried that, everything looks to be in good condition and i cleaned the spring loaded brass (?) contact as well.

I think i am just delaying the inevitable really but just wondered if i had missed anything else that might be causing these symptoms.

wiltshire_boy

Anyone?

teknopete

Here u go m8 as u don`t seem 2 be gettin anywhere.

1/ remove plugs and visually inspect them with a magnifyong glass
at the tips (for splits) then at the ceramic ends for hairline cracks. As a crack in the ceramic will open up during load causing the unit to arc on the inside of the block instead of at the tip.

If no joy

2/ Inspect coil packs at ceramic end again with magnifying glass / eyeloop. The smalest of cracks there will again open up duning load.

Q. Did u drop any of the plugs when changing them ?
If so check that one first or just replace it.
Q. Were any of the packs dropped / knocked during removal / refitting ? If so check that 1 first.

I jest you not the magnifying glass is necessary, I had a bad coil a few months back which when inspected looked ok, then looking with an eyeglass i could see what looked like a hairline flaw in the ceramic. It turned out to be a crack

Hope this helps

Pete

dhorwich

wiltshire_boy

where you careful when refitting the coil packs, because if you just tighten them without holding them is position they can move away slightly from the contacts on the head...

I had the exact same problem and discovered it was one of my coil that had cracked..

Dan

wiltshire_boy

Cheers guys,

I'll check 'em over carefully.

I'm getting a lot faster at removing that airbox now!

Roy.

wiltshire_boy

Right!

Removed my coilpacks today to give them a thorough inspection and test them on me multimeter. They were all reading 0.8 - 0.9 Ohms except one which was reading 1.6 - 1.7 Ohms. Seemed obvious enough i thought, i just need to replace the one coilpack and i should be sorted.

But... while i had the coilpacks off i thought i'd change the plugs back to what was in there a month or so ago just as an after thought (i knew i hung onto things for a reason! ).

Slapped it all back together and went for a test drive.

Couldn't believe it, all hesitation under WOT and lumpy idling had gone! Made sure that i got everything good and hot just to confirm it but the problem is fixed.

Now, it can only be either:

a) One, some or all of the plugs i'd put in were faulty. Quite unlikely but possible i suppose as they had been sent through the post and had been lying around for quite a while (I bought them in a group buy on Scoobynet in September last year).

b) My engine really doesn't like NGK PF7RB plugs instead of the NGK PF6RBs i had taken out. Even more unlikely as they were gapped the same and should if anything run a little better when things get really hot.

Or c} I disturbed the coilpack connections and maybe dislodged some crap or accidentally cleaned a connection?

Whatever, it is now back to how it should be and even runs a little better because of all the other solutions i had tried.

Hope this helps somebody

Roy.

wiltshire_boy

Just to add a thanks to everyone, especially teknopete. I wouldn't have thought to try different plugs otherwise.

Aren't they great when they're running well.
(Scoobys not Teknopetes )

Roy.



[Edited by wiltshire_boy - 10/22/2003 10:11:27 AM]

teknopete

Roy,

Good 2 hear u sorted it out m8.
We all know how frustrating these daft little problems can be
and we also know it`s worth the hassle when it all comes together again

Enjoy

Pete

Imprezive

Hi, I had this problem with a zetec, yip- not boxter i know,
however, it used to miss like hell when i changed to new plugs, went back to old plugs and miss gone. had it checked on computer thingy and it was a lead problem??
Guy in garage said the new plugs were trying to pull to much current through leads??? changed leads and fitted the new plugs again- braw, miss gone. Hope it helps.

cheers
Billy