misfire issues on boost and solutions.

[GazzaG60]

Hi

recently i have started having issues with missfire as i ramp in boost to over 1.2 bar. previously its been fine and this started intermitently a couple of weeks ago. now its almost every run.

i have found if i ease it in its not as bad but that doesn't help.

yesterday i fitted some new plugs. denso IK24. i like to test items these have not solved the issue. im going to order some bosch ones to see if they help as im sure that will be one of the reply posts to use the proper plugs.

i have replaced the boots on the packs with new ones so they are good.

Whats next and how would you test to find the solution. or do i go 034 and hope for the best.

id appreciate experiences and solutions to try to build up a knowledge base on this area.

many thanks. if i can get it sorted today/tomorrow i may make the rollers.

[GazzaG60]

i have 5 factory plugs to collect after work. ill try them if not then its uphill from here.

[newsh]

Isn't there a spare channel on one of the POS you can swap round to see if its a POS problem? I'm a 3B bloke so not too familiar with the coilpacks. Then its down to swapping coilpacks with someone to check them I guess.

[GazzaG60]

yes there is.

i wil try something along those lines. theres a doc somewhere on it.

not sure what the usual traits are with POS. whether they are boost affected or not.

[haaran]

A knackered POS will cause a nasty misfire and a very lumpy ride as you're potentially only running on 4 cylinders.

[EspenW]

What is the AFR when you start to boost?
(remember that misfires can cause lean spikes, making the wideband read wrong)

[GazzaG60]

afr's look ok. i need to datalog. i see 0.85 dropping to 0.75 or so at peak. i then lift off. this is all around the 4krpm mark.it build up nice and smooth then the misfire sounds kind of tumble dryer.

will a pos be always lump though or are they boost affected.

coils are original by the way 123k on them. the look ok.

[A80Avant]

what is your dwell time?

my most recent misfire was cured once i tightened the plugs properly and then replaced the coil pipes to new units.

my next move would be marc's coil packs.

[A80Avant]

mine only came up above 250-260kpa

[lind4hl]

since you talking dwell times and afr i guess all of you running vems,

Then WHY use these nasty old coils?

1,8T Vag coils (with 115R last in the partnumber) i would go for..

[GazzaG60]

ill have to check the dwell. in in the car today but not with the laptop.

what dwell you using VAS. the coils dont overheat so maybe a bit more in them.

[GazzaG60]

looked at ther msq you sent me. i could try adding a little. you have 0.5ms over me.

[A80Avant]

i use 3.14ms and then +2ms on the 2 banks

1.8T coils may be cheap but brake down sooner than a fuel fill up.It has been discussed over the US forums quite a bit. This is the reason 034 and Marc + others have come up with the high output coils.

so far at 304-305kpa my coils work fine. Why change them? i bought a 5set from VAGPARTS when i did the rebuild and have only done about 40K kms. Once they have had their time i will go for the high output ones

[GazzaG60]

the reason im using the coils is they haven't gone bad til now.

i expect to go 034 ho setup

[martinjs]

[QUOTE=lind4hl;448771]
Then WHY use these nasty old coils?
QUOTE]

Something that lasts 100k+ or even upto 200k miles i would hardly call nasty.