renewing spark plugs on v2 96 wrx

[neal]

hi there, I recently decided it was probably about time I changed the spark plugs on the car, when I did I started it up and it idled fine, drove fine but when I put my foot down and revs got up to about 4500-5000 on boost I noticed it started to miss.

a guy at work suggested I may have hair-line cracked one of the plugs whilst fondling it into place so with that in mind I took them all out again and found nothing wrong but thought to myself that I may as well put the old ones back (seeming there was no issue when these were in the car in the 1st place) so I gave them a brush up and put them back in but the car is doing exactly the same thing... idles fine, drives fine but when I put my foot down between 4500-5000 its missing again.

does anyone have any suggestions??

my thoughts are maybe I was being too gentle on both accounts of tightening the plugs into place and that they are not wound in tight enough perhaps??

any help would be really appreciated.

[Andy_Mac]

Are the gaps set correctly. Even buying the correct plug for the car doesn't necessarily means the gaps are set to the right value for your car.

And its a long shot but have you possibly knocked the tips on the old ones and stuffed the gaps on them too?

[evljat]

What did you gap the new spark plugs too?

And are the coils on securely?

[Guest]

0.6-0.7 blshhoasjkbnsc

[B4_685]

 evljat said:

What did you gap the new spark plugs too?

And are the coils on securely?

Had same issue with my B4 - check coil packs are tightened down securely - also ensure they have clean contact with block as they ground through the bolt that holds em down. Did you have an auxiliary grounding strap attached to any of the coil bolts?

(assuming coil on plug - sorry not sure of setup on that model)

[neal]

0.8 on both new and old mate. cheers for reply

[neal]

coils bolt into position. gap is set to 0.8

[neal]

0.8 on both sets of plugs

[neal]

didn't notice any grounding strap on the coils. im pretty sure the bolt for the coils is wound in tight.

[Marky]

Worth a shot whipping the coils off and giving them a clean up - bit of degreaser or silicon spray - might be just a poos connection between coil and plug on one of them

Fixed a lot of skyrine misfires from that, just getting all gunkyd up

Yes its a word

[Joker]

what fuel/boost you running? otherwise I vote cracks on the coils : are they coil on plug? or is it a coil pack thing

[neal]

cheers for that I will give em' a clean out. they did look quite clean inside when I took them off but I will clean them anyhow. car has done 148000 so engine isn't too gunky

[slystiguy]

Looking at your other posts it appears you have a gf8 version 2. If that's true and it's got the original engine setup it will run a coil on plug setup. The coils themselves tend to crack or have hairline cracks. Very very common and usually gives symptoms when you put some boost through it. 99% chance this is your problem.

The easiest way to fix this would be to replace the coils BUT unfortunately they're pretty hard to come by in good condition an stupidly expensive some charging 100+ for a set.

Another option is to silicone up the cracks then wrap in electrical tape (might get you through another couple months but only a temp fix).

Another* option is to go to pickapart and get one the the coilpacks from a later model wrx/legacy you then splice 8-10 wires into the new coil pack and throw away your old ****ty coil setup and have the ability to run 20PSI without issues. It's a pretty easy mod and I can point you in the right direction if you wanna go that way. I did this mod myself with little electrical experience and the whole setup cost me $45 from pickapart (coil pack and 4x leads). It's also plug an play if you wanna convert it back.

Edited May 30, 2014 by slystiguy

[ADIKT]

Thought the cop>coil pack?

[neal]

okay cheers for your reply slysti I will pull the plugs off and have a real good look and let you know if decide to go down the route of later model coil packs. I thought the ecu controlled boost, fuel & ignition maps? I worry that 20psi would melt my puny cast pistons. my aim is to swap out the ecu for a v1 sti (they ran cast internals from what I researched), swap out the little td04 for td05 replacement & replace the puel pump to safely run 14psi instead of factory 10psi the early gf8 wrx's run.

the spark plug renewal was supposed to be just a little treat for the car before I installed all the upgraded ecu, turbo and fuel pump. but a simple spark plug change is turning out to be a pain in the arse

do you not think it could be something as simple as being too gentle with tightening the plugs?

Edited May 30, 2014 by neal

[neal]

turns out it might well be the coil pack adikt. im' going to pull them off for a proper look over the weekend mate.

[neal]

im running standard ecu and running 10.5psi. I was running 12psi for a while (with no issues) but decided its probably a bit lean for the factory setup so I decided to wind in the mbc to 10.5 until I upgrade the turbo, ecu & fuel pump. oh yeah... coil on plug apparently.

[Koom]

 ADIKT said:

Thought the cop>coil pack?

Same, thought that was the general consensus. I'd recommend swapping the early coils for some of the 3 wire, internal igniter coils that were first found on the bg5b gtb's. Takes a bit of wiring though as you need to bypass the original external igniter, then run a third wire to each (from memory, they need an earth added, which joins together and is connected the back the manifold with the other sensor earth's).

They're a much stronger and more reliable coil.

If looking for issues on the original ones, look for any micro cracks on the ceramic insulation. Doesn't take much for them to start dying.

[slystiguy]

I looked at both options on my rs. I haven't tried the later model coil on plug and everything I read was positive... But I think the coil pack is the better option if you're not going to be pushing really high boost or chasing serious power. They're just easy to find and cheap and reliable upto decent psi, so suitable for most people. The wire in is pretty simple as well.

[neal]

okay thanks koom & slyguy I will check the coil plugs in detail and see what condition they are actually in and if they are perishing I will go down that route you guys suggest although im not too confident on wiring it all up, I will need to pay someone to do it I think. I have a guy I have used for mechanical stuff I met on this site but I think he is sick of working on early wrx's (shame cos he did a good job at a good price) so may need to find someone else in Auckland.

[neal]

hey guys heres the finishing post and awnser to the problem, i figure its only fair to post up a solution to this problem for those who are experiencing the same symptoms and searching the net for answers but also to concur with what these guys have been saying all along..

the problem is a cracked coil on plug which is found on the v2 wrx but to my amazement it wasnt just one or two but all 4 coil plugs were hair line cracked.

when i was told to check the rubber tip insulation for cracks i didnt find anything (to be honest the rubber sleeve tips seem in really good condition, like new infact) but when i cleaned up all the coil plugs i noticed what seemed to be a hair line crack on the actual plastic thats on the plug just above the rubber insulation (now i know what slystiguy meant ) so i wriggled the sleeve off but as soon as i did the end of the coil plug disintegrated so i thought i would check another and yet again i noticed a crack just above the rubber insulation sleeve and when i attempted to remove the sleeve exactly the same happened again so i checked #3 plug but yet again i noticed a hair line crack and when i attempted to remove the sleeve... yep you guessed it, it fell apart so by the time i reached #4 coil plug i figured 'whats to loose' and sure enough it fell apart.

whats interesting is that all 4 coil plugs have fell apart in the same place on the under side of where it slots into the engine which is interesting i thought that they all give out at the same point.

my theory is that i only got away with running full throttle and boost for so long is because the coil plugs were undisturbed for so long and that as soon as i unsettled them by removing/reinstalling them it caused them to weaken and maybe the damage was done the 1st time i put my foot flat to the floor on test for the new spark plugs that caused them all to hair line fracture? just a thought.

the picture i am posting is how all 4 look, exactly in the same place and even taper-in the same.

cheers for reading and i hope this has been a help to someone with a classic WRX having the same problem and thanks to you guys on here for helping me out

Edited June 7, 2014 by neal
need photo

[slystiguy]

Glad to see you got it sorted!