w13dle

iTrader: (5)

hi all ive got a boost issue on my 1994 wrx & im trying to eliminate it bit by bit im going to change the plugs first off as they where last done by the previous owner who had them changed at a garage so maybe crap plugs & not gapped correctly, which plugs shall i go for the cars slightly modded the NGK PFR7B or NGK IRIDIUM IX heat range 7 or others? & what should they be gapped to? thanks

myblackwrx

iTrader: (1)

i use NGK PFR6B (93wrx with decat,full stainless exhaust) gapped to 0.7mm.

I would suppose it depends on what 'slightly modded' means

MarkC

iTrader: (12)

ngk pfrb 7 for modified cars and no need to adjust gap heat range 7

w13dle

iTrader: (5)

mods currently are decat middle section, back box, panel filter, polar performance ecu cheers

mickywrx

iTrader: (29)

Another vote for 7B's.

w13dle

iTrader: (5)

any reason for these over the IRIDIUM plugs? thanks

dazdavies

iTrader: (22)

yes the irdium tips have been know to fail and come off the plug and thus bounce around in the bore.

With your mods the 6B's will be fine.
I was running these at 360bhp for a good long while

7B's are for the next level IMO.
I was running these at 450bhp no probs whatsoever

mit

iTrader: (10)

Not always true. I had a missfire at high revs/boost with 6b's,and was advised to fit 7b's,and re gap to between 0.5-0.6mm,standard is 0.7mm. Set the gaps at 0.55mm,and made a world of difference!
If your running higher boost,it can blow the spark out.The lesser gap illiminates this.

Just out of interest,what problem are you having?

Mit

Skooby53

iTrader: (1)

I'm also using the 7B's and gaped them, on advice from Bob Rawle, at 0.65 and that's spot on. I'm running a UK spec car with 281 bhp, I had the 6B's in for a while but had problems with an intermittent misfire. Once I changed them all was well.

w13dle

iTrader: (5)

im getting hesitation under boost at first i thought it was bad turbo lag but after going in a friends 93 wrx his was so responsive with similar mods, mine turbo comes in around 4k as it should but then as the boost gets higher it hesitates then goes very noticeable in first gear if pulling off quick, ive been advised to change the plugs which im going to try first cheapest option, then check the coil packs, & ive already cleaned the boost solenoid but didnt clean through the hoses attached so thats also one to try

mit

iTrader: (10)

Thats exactly how mine felt,only when properly warmed up,was fine cold.
I changed the plugs,as sugested by Zen after they fitted the ESL live. Im running 1.35bar boost. Im glad the packs were good,as their £50 each! Got a set of 7b's for £29. Only problem with the packs is they can look fine with no cracks etc,but could still be breaking down.
The car's sooo smooth now,hits max boost with ease.

w13dle

iTrader: (5)

ive just ordered the 7b's will get them fitted at the weekend see if it cure's it, the problem does feel more noticable since ive changed the ecu & runing more boost

Ozzy_555

I have some NGK PFR6B's to fit to my car should i opt and change for the NGK PFR7B's instead?


Cheers.

mit

iTrader: (10)

You can re gap 6b's as well,be best to put a post up.Theres loads of people running 6b's with higher power.How much power/boost are you running?

Ozzy_555

Standard boost 215bhp is about right for a UK Turbo 2000 i think

mit

iTrader: (10)

You don't need 7b's then,6b's with the standard gap will be fine,it's whst their ment to have!

PeeVee

iTrader: (1)

Not quite true actually!

Only UK turbo 2000's were fitted with 6 B's, A STD JDM WRX was fitted from the factory with 6 G's. (which have cntr electrode made of a different material)

If you do a search, you will find that there are cases of modified wrx's that have had B's fitted and then suffered from a misfire on load. This has then been cured by fitting G's.

IMHO If you have a STD WRX then you should be fitting 6 G's gapped to 0.7mm, if your car is mildly/moderately modified, you should fit a set of PFR7G-11's and then re gap to 0.6mm. (As recommended by Prodrive)

I'm sure that there will be many people that will say that they have run WRX's on B's without a problem, but this does not mean that it is the correct plug, it just means that their ign system & the coils are in very good condition and are capable of handling an inferior plug, or that they have had problems & after fitting a set of plugs have then had to go out and by a set of coils.

Phil

Ozzy_555

Just thought maybe changing to 7B's might cure the missfire that i'm having i've more or less tried everything else running out of ideas!

MarkC

iTrader: (12)

i use ngk laser platinium heat range 7 bought them from flat4online for 40 sterling inc delivery

Ows

whats the diffrence between NGK PFR6B and NGK PFR6Q and are the q's ok for 1995 uk 2000 turbo?

w13dle

iTrader: (5)

ive already ordered the 7bs now just still bit unsure what gapping to go for when fitting them, ive also had alook round for these other plugs mentioned PFR7G-11's but none of the top subaru online shops seem to stock these cheers for the advice chaps

Skooby53

iTrader: (1)

When you get the 7's gap them to 0.65 and give it a blast. The 6's would of been alright IMHO as your car is slightly modified. As the plugs are on there way just pop them in and hopefully you will cure your problem.

mit

iTrader: (10)

But he does have a standard UK turbo 2000,so im right!!!

PeeVee

iTrader: (1)

yea, sorry Mit.

I was referring to the original OP's car and had missed the fact you were answering a question raised by someone else


Phil

w13dle

iTrader: (5)

well i fitted the new 7bs today gapped them as recommended to 0.65 also checked the coil packs which looked in good condition & sprayed through all 3 pipes attached to the boost solenoid with brake cleaner & took it out for a hard drive does seem slighly more responsive pulls quite nicely upto 5k then im getting a judder & a pop noise it wasnt like this before i replaced my ecu with the polar perfomance was just hesitant mid range then pulled fine 5k upwards any ideas chaps please??

joz8968

iTrader: (13)

That is a classic explanation of a misfire...

I don't suppose you know how old your coil packs are? I'm thinking that it is some, or all of them that are to blame.

Even though they may look okay, that's not necessarily the case, especially if they're the originals i.e. c 14 years old.

Problem is, brand new they're about £68 each <ouch!>, but that said, I feel it's false economy to get 2nd hand ones as you have no idea if they're any good. At least with new ones, they're gonna be working fine... and probably continue to do so way after the car eventually meets it's maker, lol.

w13dle

iTrader: (5)

im not sure how old they are the previous owner was the first owner in this country that was just over 2 years ago & kept every reciept for anything he brought spent on it & i cant see anything coil pack wise, how come it didnt seem as bad or pop before replacing the ecu is that down to the more power higher boost making it more noticeable? i havent got a boost gauge at the moment i know its a essential just thought with it not being a dawes device a generic ecu change it would be ok till i can get one thanks

joz8968

iTrader: (13)

Your PP ECU runs 1.1bar with a fuel cut at 1.3 bar and if your coilpacks are knackered, then 1.1bar is pretty much the max amount of boost they'll tolerate, so you're on the edge of them misfiring, which is probably what you're experiencing.

[ASIDE: Funnily enough I'm going through the same thing at the mo. I have an PFC running 1.1bar and my coilpacks were knacked (I've replaced 2 - got to replace the other 2 at end of month). Very occasionally, I'll get a misfire if I hoon round a 90-deg bend.]

As a test that I think will tell if you have dodgey coilpacks, is to refit a standard ECU (e.g. a W6, U8) as it runs about 0.8bar and 1.0bar fuel cut. If it doesn't misfire, then I'd be inclined to believe coilpacks are to blame (especially as now you've got brand new 7B's gapped to 0.65mm)...

w13dle

iTrader: (5)

thanks for the advice think thats next on my list then new coil packs camskill are doing them for £58each new, ill change couple at a time i think like yourself when ive got the money see how i go on & pick up a boost gauge along the way keep a eye on it it, it deffinately pulls alot better & eariler quite impressed to say didnt cost all that much

bandit1216red

where are u located ive got 4 brand new coilpack spare