Ok, ive a 199s wrx import, which was running 250bhp. I got some 440injectors and ano apexi power fc fitted and mapped and it ran 317bhp @ 1.4bar...

Now when i floor it and boost gets to around 1.0bar it splutters, missfires etc.

I got told off the lad who mapped it to fit new plugs and gap them to 0.6mm which ive done, and its a little better but still missfires when over 1.0bar of boost.

Has anyone got any ideas as to what it could be, whats causing this problem.

Any help is appreciated

Ross

 

What year is the car? could be cracked coil packs if pre 96.

 

Was meant to say 1994 not 199s damn blackberrys!!!

Coil pack? They are on each individual plug on the 94 model yea? Expensive? Hard to come by?

 

Yes individual coils they tend to crack with age resulting in a weak spark that can be blown out at high boost. You can try and remove each one, remove the rubber from the top and check for cracks....a little insulation tape over the cracks can prolong the life a little....worth a shot, if not they do tend to come up secondhand, new i think they are a couple of hundred quid for 4.

 

don't replace them with the same type of coil packs, there ****e! Fit newage ones instead there much better
http://forums.nasioc.com/forums/show....php?t=1192028

 

I have a my94 running 1.3 bar of boost on an apexi. FMIC, injectors, fuel pump, turbo etc.
I have pfr6b plugs gapped to 0.7mm and runs perfect.
Have you been messing around near the boost solenoid at all? I ask this because behind the boost solenoid bracket on the shock turret there is an ignitor pack for the coil packs.
Might be worth checking the plugs are pushed in properly.

 

Well the lad who mapped it fitted a manual boost controller, so the boost solonoids are not in use IIRC?

NGK laser platinum plugs ive used gapped to 0.63mm (smallest i had available)

 

Electrical, spark gap is important at that boost level, maybe worth increasing the gap as a start point. I would expect that the electrical system is to blame. Earth kit and new or modded coil packs is the way to go.

 

Well i put the plugs in untouched to start with, took the car for a spin and it was coughin and spluttering at 1.0bar, so i then gapped them to 0.63mm and its will boost up to 1.3-1.4 and splutter sometimes, miss-fire etc. So im with you on that one by saying its ano electrical problem, i'll try the plugs on the stut first, then i'll try a seperate set of coils. If all fails i might just get the boost turned down to 1.2 or something

 

was it an experienced mapper that did your car apexi?

 

Ive heard good thing yea, Jamie at Evotune in Durham mapped it on the rollers, then took him out and he listened for any DET

 

Unless you have the AVCR/equivalent to go with the PFC or a later map sensor, your car will never make more boost without cutting

 

Map sensor out of what, 98 sti? So if i fit a later one then my problems will be no more?

Because it isnt cuttin out, its just missing sometimes

 

Early WRX's only run to 1.2 bar before hitting fuel cut. You need a boost controller/AVCR wired in or a spliced map sensor from a 99 STi to run higher boost on a stock WRX boost setup Basically your target boost has been set beyond the cars current capability. You may very well get up there but the car is politely saying **** off. Unless you have it running sweet the mapping over 1bar (.2 margin) is a little unchartered in terms of fueling I would say and not safe to keep pinging off the cut All IMHO.

The other thing is the true capacity of your 440's ? were they cleaned or flowtested before fitting ? you may think you have duty cycle headroom thats not there

 

Well when he was mapping it there was no problems with it boostin up to 1.4bar, obv theres more load when your on the road though. If it is the boost then it would of done it on the rollers despite there being less load, if you know what i mean. Plus its not cuttin out, boost isnt dropping when its miss-firing. Its happens between 4krpm and about 6krpm, from 6-7 its fine, no missfiring

 

THREAD REVIVAL

Still waiting on some coilpacks being delivered, in the mean time ive heard i need an STI maf sensor to run on my wrx ? would the maf sensor cause this ?

 

I cant see how you can map the car in the first place without a sensor that will go to the higher boost you were at. I noticed you have 6 range plugs, I was under th impression that range 7 for over 1 bar was needed on a subaru. Some of the tuners on here will prob put me right but i think you have the wrong plugs too. I always run copper plugs and change more often. I have a similar prob on my 93 WRX it cought a cold when it was wet, def got a coil problem. I am now in the process or the upgrade, mine just coughs at anything over 10 or 12 PSI.

 

well it ran on the rolling road no problem, must be when its under `more` load on the streets.

Its worse than ever now, not quite full throttle and u could get away with no missfiring up to 1.5bar. Full throttle it will cough and splutter above 1.0bar

 

Plugs/coils .

will sort it :-)

 

So what plugs would you recomend? Part number?

 

NGK PFR 7B , think thats as hot as you need, there will be other answers, but remember I am not 100% subaru Savey!!

 

those are the ones i have put in, Laser platinum. NGK R writtin on the plug