krusty

Hi guy's,
I'm a new member and this is my first thread.
I own a mint 96 GF8 imported wrx wagon, I changed my plugs today for the first time since i've owned my rex. I removed the NGK PFR6G's which came with the car and replaced them with Denso IK20's. The car was fine before i changed the plugs but i changed them as i've owned the car for 18 months without changing them!!!!! I got the denso's in and on idle it seammed smoother, But when i took it down the road it started to miss fire at 3,000rpm and won't let the turbo boost! I took it down to track art in Ashford were i got the plugs from and the owner took it for a spin, at this point it was'nt missfiring but it was'nt boosting properly either. He said it seamed fine?? On my way home i put my foot down in 2nd and 3rd and she was missfiring from around 3,000rpm again! What the hell is going on? I've been told from track art to take my apexi induction kit off as it could be the maf sensor, but it was fine before, then they said to lower the boost on my turbo, but she running a standerd 11psi so i would'nt want to lower that! I have been told by a mate of a mate that the Denso's run to hot so my ecu is detecting detonation so in turn my ecu won't let me boost properly, He also told me that the same denso ik20's cost him a £3,000 engine rebuild as they melted a piston!!! Scooby clinic have told me the denso's are poo and the spark isnt big enough and in turn the sparks are being blown out under boost?
Can anyone help please! All i done was change my dam plugs lol!!
Also, just a quicky, My central locking does not work atall! I have to unlock each door individually at a time, Any ideas there? Other then that my scooby is fine lol!!!

dan83590

Get some NGK's back in. Will cost you about £35-£40. The Scoob turbo is dead sensitive where plugs are concerned.. Make sure you gap them correctly too.

mac12

put some ngk's back in £25 ebay and while there check coil packs....

dazdavies

iTrader: (22)

Although NGK's are the prefered plug the Denso's should be fine.

Just make sure they are gapped correctly to 0.7mm and you shouldn't have any problems.

If the problems occur during boosting then its a good indication that they arent gapped properly. I'd certainly try re-gapping before shelling out on another set of plugs.

Daz

krusty

Cheers guys, I was crapping myself thinking i had an engine rebuild on it's way!!!! I will try to gap the Denso's tomorrow, If that does'nt work it's back to the trusty NGK's! Is ther anyway i can test my coil packs or is it a subby dealer thing?

360ste

iTrader: (1)

Make sure you have got the plug leads or coils on properly first as it can be all to easy to have a loose plug connection. Which at normal running still gives enough spark to fire but once on boost there is not enough oomph. Before paying out for new plugs put the old ones back in to see if that solves the problem. I lost a coil pack on my bugeye at idle it was a bit rough and would drive off boost but once on boost it was crap.

krusty

Cheers guy's,
Just gapped the dam denso's to 0.7mm and it still does the same, all though i did notice the rear passenger plug was bent???????? Waiting for her to cool down and am trying the NGK's again! I must admit i've never had any problems with NGK's and i would only run NGK in my speedway bikes so the same should go for my rex!!! Is it possible that after changing the plugs 1 or more of my coil packs could have gone due to bigger spark or something, Or would that be just looking for an easy fix?

Slowboy Racing

Bent? If the tip is bent "don’t" use it

Put the original plugs back and try again, if its still the same mabie a lead is not sitting correct etc. Your coils won’t have failed from changing the plugs.

krusty

Nah its not the tip its the top of the plug???? I thought changing my plugs would make my scooby love me lol, Now she hates me lol!!!! So NGK PFR6G's or PFR7G's? I am planning to have ecu re mapped and boost raised in a short while once this poxy problems sorted!!!!!!!

Bob Rawle

Don't use std Denso plugs on these cars they simply are not good, if buying more NGK's get PFR 7B's and gap them at 0.65mm.

I do use the IK01 race plugs but they are nearly £50 per plug so not a consumable.

bob

jasonius

iTrader: (1)

if it's bent the insulator could be cracked, therefore causing a misfire of sorts.

with regards which NGK's, depends on the level of mods you have. if the car is std/light mods the stick with the #6's. if it's higher modded then you're better off with #7's..

krusty

Cheers everyone for all your help and advice! Can't say thanks enough, The problem won't be anything serious aye? It's just after taken out the plugs out and gapping them i can't help but think it's going to be something expensive!!! Im going to call milsport tues for some coil packs unless anyone knows of a good reasonable priced supplier? Im really panicing now! Can new plugs really give you this many problems on a wrx?

vulnax999

iTrader: (7)

If the coils packs ar estill the originals ones, and the car is an older classic, then removing the coil packs to change plugs may well have causedthem to "fail" - become weaker ... I had this and found my high boost did blow out the spark as the coil packs were wearing out. Try gapping the plugs narrower - to say 0.6mm, minimum o.5mm as this will help keep the spark going.

For info, I have used the Iridium equivalent of PFR7Bs ( from NGK ) and was pleased, just trying the Denso 0.4mm wide centre electrode Iridium equivalent now and seem very good!

krusty

Yea as far as i know the coil packs could be the originals? Thats the only 1 problem with buying an import, you don't get much history!! Mine is a 96 wrx gf8 wagon. Did your coil packs pack up when you changed your plugs then?? I really can't help but think it's going to be something serious!!

Scott.T@PolarPerformance

If the coil packs were cracked or damaged and you changed the plugs. The process of removing the coil pack and refitting may of made them worse.
pull out one of the coil packs, remove the rubber cap and check the tip. if it;'s cracked throw it and buy a set of 4.

vulnax999

iTrader: (7)

As Scott.T said above, after changing plugs I had intermittant misfire at higher boost, and found 1 coil pack was iffy. Changed for 2nd hand one, was ok but then happened again soon after, another coil pack. In the end got a set for about £60 each from Alyn at ASPerformance, next day delivery!

Problem Sorted!!!

krusty

Has anyone got any pics of a coil pack on its way out? Where do they crack most common etc and do i inspect the rubber part for cracks or tears that go over the plugs etc? Did that make sense? lol

Scott.T@PolarPerformance

Damaged Coilpack

£200 per set delivered from JPS Motorsport, Milton Keynes

krusty

Cheers for the pic, I did'nt know the rubber boot was in 2 pieces, It looked like it was a 1 piece mould. I did'nt notice any cracks in the coil packs when i was changing the plugs, but to be honest i was only looking for cracks at the top of the packs on the clear white bit where the wires go in. So i was thinking mine were fine!

Bob Rawle

If you have a damaged plug then thts going to cause problems, refit your originals ... dig them out of the bin, gap at 0.65 and see, if you have to buy new then get heat grade 7's, whatever your mod state ...

Or just spend the £200 on the off chance thats the problem of course.

bob

krusty

Is there anyway i can test my coil packs?

krusty

Would coil packs be the worst thing that can be wrong then? I keep thinking if i done something wrong like cross threaded a plug or over tightend a plug or something, But even that would'nt give me these symptoms would it??? And i was so careful while changing them!

st3v3

Krusty,no offence mate,but listern to what people are saying, re-fit your old plugs first to see if its the plugs or coil packs.

If the problem is still there with your original plugs then you might have to buy coilpacks.
On the other hand if its ok and runs fine just replace the plugs and get some new coilpacks in good time.

Incidently, Bob Rawle and scot T are experts in the tuning of Subaru and Know what they are talking about.

krusty

Cool guy's, Waiting for it to stop raining then putting ngk's back in! Thanks everyone for your help!!

Scott.T@PolarPerformance

Before you put the NGK's back in check the coil pack tips.
If they only have hairline cracks then wrap a few layers of insulation tape on the ends then refit the rubber cap.
This may fix the problem if it's only a mild miss-fire, but is only temporary.

krusty

Just put some new NGK PFR7B's in my rex and all is back to normal! Thanks heaps to everyone for your help and advice, My coil packs looked fine although i am looking at getting a new set in the next few weeks, Thanks again to everyone!!

vulnax999

iTrader: (7)

Glad you are sorted now!

I am running iridium Denso's ( 0.3mm centre electrode ) at 25 PSI boost and they are fine. Guess it depends on the plug spec?

krusty

LOL!! Yea and the NGK almost half the price! Wish i was running 25 PSI!!!!!