[Mk2] [Turbo] Stutter under boost

[mikey2]

On low boost, which is stock pressure its fine, doesnt pull hard, but doesnt stutter, if i raise the pressure to 11 psi, it stutters like mad, like missfiring.
I changed the plugs this morning, put nice shiney new iridium grade 7's.
The old plugs looked ok, and it was doing the same thing with those in.
There are no error codes at all.
Am a little concerned that the cars problems extend further than just a seized turbo! Does anyone have any ideas? I am guessing the next stage is change the leads, then the dizzy, but i cant help feeling its more than that!

[sparki]

You are running a high Octane fuel aren't you ?

[3S Service Centre]

check your coil bud for any small cracks or nasty rusty bits

[mikey2]

I am running either tesco super or sainsburys super.
I put bp ultimate in it once as i was running on fumes and lost, but made no difference.
I will have a look at the coil, where abouts is it??
Thanks

[djpkins]

underneath the fuse box in the engine bay...coil, leads. Is it over fuelling?

[mikey2]

yep i found it, yes it is over fuelling, the plugs i took out were black, but no overly sooty, i will take the coil out tomorro when i get a few mins.
Do they crack on the outside or do i need to strip it to find any cracks?
Can i take the dizzy cap off without causing any dramas? i dont want to make things more difficult than they need to be, when i get a few pennies together its going to 3S for a damn good going over!!

[djpkins]

Cracks will be easily seen if they're there I reckon...I have both a rev 3 coil and a turbo dizzy cap for sale if you need to replace matey...the dizzy cap has been tabbed with copper plates so it will last for ever...well, years anyway also got a virtually brand new set of leads as well..

taking the dizzy cap off won't do any harm at all...these cars eat dizzy caps...be carefull not to lose the screws taking of and putting back on...also taking care not to overtighten on the way back on...could crack the dizzy cap.

[mikey2]

can i fit a rev 3 coil in its place without any other mods?
Can you keep them by for me until tomorro afternoon?
I will assess mine in the morning.
Also, do you have a price in mind??

Ta

[mikey2]

Right, i have the coil and ignitor off, pics are coming, i could not find any cracks on the coil at all, infact it looks quite tidy, the ignitor though, it looks like there are 3 screws missing on the ignitor though, there is one there, but the other 3 there are just holes,

[djpkins]

Doesn't look weather fkd , although the broken screws would suggest that it's been off...what colour is the sticker? If it's not the coil...next is the king lead then the dizzy cap/rotor arm.
Is it stuttery when it's warm...is the problem randomly intermittent...if you have normal spark plugs and NOT iridiums, you can try closing the gap...

[mikey2]

It stutters all the time on high boost only, low boost is set to minimum, so just actuator pressure, it seems that the problem is when i try and go over 10 psi.
I do have a set of normal plugs, i can close the gaps up no problem.
Do you think i should just put these back on?
are the missing screw not going to leave the casing partially open???

I undid the single screw, i found underneath that it had obviously got wet, seeing the corrosion on the lid.




Sorry for the crap pic, had to use the phone and it insisted on using the flash!
Is there any way i can check these? resistances and the such across the pins? I know its going to be a pig to put back in, i dont want to do it more than need be!!!!

[mikey2]

These are the plugs that came out, they are all pretty much the same.



Should i regap these and put them back in. if so what should i gap them to?
They are 0.75mm at the moment.

[mikey2]

Any Ideas?

[mikey2]

check your coil bud for any small cracks or nasty rusty bits

Is this what you mean by rusty bits? its the only metal bit there!!!




Also, what size should the leads be? i cant help feeling they are a little small.


Ok, have had the dizzy off too, no signs of cracking or water damage, the contacts look good, if a bit arced, but i cleaned them up. I think this is pointing at the leads now, they are certainly not 8mm leads on there, i will have to dig out the vernier and measure them.

[mikey2]

Nope, still stutters, kinda feels like a very quick on off of power, it judders more than stutters, sometimes it pulls through it, others it doesnt.
Just now, i pulled away in first and it went like stink, like it should, then died at the lights and was a bu88er to start again, then it was fine, but still wont pull right.
Hopefully will have some cash flowing in early next week, its going for a check up then!

[Lewis Jay]

Check you AFM plug and wiring.

[mikey2]

i havent checked the AFM specifically, i did have the plug off when i changed the turbo, and also had the whole inlet side of the turbo out of the car, i was specifically exceptionally careful with it, as i know they are sensitive, the plug is on ok, as i checked that when i put it back on.
Also, its not throwing any codes.

[Lewis Jay]

No it wont throw any codes mate, just bog down randomly.

Wiggling the plug while revving it up can show the fault if its plug related.

Check the resistance values against the BGB values and check the each individual connector for corrosion and wear on the plug.

Often the best way is just to swap out a good know AFM and see how the car drives as they can be temperamental at best.

[mikey2]

Thats the thing, its not random at all, its constant, whenever i go over 10 psi it stutters, anything under and its fine, just doesnt go as i think it should!
Doesnt bog down though.

[Lewis Jay]

Thats the thing, its not random at all, its constant, whenever i go over 10 psi it stutters, anything under and its fine, just doesnt go as i think it should!
Doesnt bog down though.

Bog down, stutter, hesitation all the same really depending on the severity.

Check it over it maybe the issue if not its one thing rules out