Hi all,

I have just been out in my 93 WRX 74000klms, Green Mushroom HKS induction kit under open bonnet vent, HKS exhaust,
its having the occasional misfire at any rev below 3500, its not happening
all the time, never when cold, but its a real pain, it can happen in any
gear as well, even holding a constant 2500 in 4th this evening the revs just
started to drop, the car got jerky then big misfire & back to normal, or
when pulling off from lights its fine at 1 set the next not able to rev or
pull off then pop pop bang & your flying which can prove entertaining when
your not able to move then find your doing a drag start.

I'm guessing at plugs & leads, plugs at about 15000klms old, so now the
questions.

Is this just the plugs & leads.
Could it be the coil packs ?
Could it be the injectors clogging up ?
Has anyone else suffered anything like this before ?
Is there anything else I should look at ?
What is the cost of replacing the plugs, leads & Coil packs ?
What is the cost of replacing the injectors ?
Am I going to do any damage if I keep driving it ?

As usual thanks of any hints or advice.

Stuart.

 

Drove the car this morning.

Fine again when cold but as soon as it heated up the same happened again.

Anyone any ideas ?

 

Funny you should say this mate as my 93WRX has the same problem can be running fine then all of a sudden it's like it's only running on 3 cylinders, missing etc then it will clear itself if you find out any info let me know !!

 

93 doesnt have leads.. just coil packs.. about £80 each...

David

 

£320 eeeeek just what I need on top of Christmas

 

or use bosch mec723's from ingram in aus... do a search...

They work out at about £100...

David

 

Just cured my MY94 UK Turbo with new coil packs & High flow fuel pump runs like a dream now. I was getting very low fuel pressue & a couple of the coil packs were cracked upon inspection.

Dean

 

DeanF

Where did you get them from & how much were they, also what fuel pump did you get ?

 

Coil packs were from (http://www.subaru-manchester.co.uk 0161 224 1431)@ £49.00 each & the fuel pump was a FACET High flow from TSL @ £145.00. Might be worth a trip to your local garage to get them to check the fuel pressure or ask a mate if they have a gauge Etc.
Much better now More torquey, NO hesitation & no wear near as ropey @ high revs. ( must say this worked for me but no gaurentees its the same prob on yours, Coil packs & plugs definately worth inspecting though)

Dean

 

Merry Xmas...........
Mine is doing that. uk95 wagon full decat, boost lifted to 16psi and full cut lifter.
I have had a lot of problems and in the end with new plugs, coil packs ( failed only when hot ) knock sensor, cam sensor, crank sensor,cleaned out pipes and a lot of exspence it went like a dream.
Then today went out and its missing now and again as if its the fuel pump stopping for a split second?????????
Hope this helps but i'll keep looking at thread.

 

mmm heading with the coil packs at the moment, as it does only happen when hot & not every time.

waiting for christmas to finish / clear the bills before I progress on

 

It is safe to say that it is ignition related and not fuelling. If a plug (or plugs) fail to spark, the injected fuel will pass through those cylinders unburnt. Upon contact with the exhaust manifold this fuel will ignite - hence the popping and banging. This is known as an afterfire (not a backfire as most people think - that would be fuel igniting in the intake). Be careful, this could destroy your cat if you have one. Coil packs are a safe bet, but if money is tight try a decent sent of plugs first.

 

barge

My car is doing the same thing, (95 STi) When it does this my cat light comes on? also does it when hot and cold. I changed a coil pack about 2 months ago but this one just packed up and the engine ran horrible with check engine light on. Easy to find faulty one by disconnecting lead by lead, but this fault is driving me mad.
I got my lead from Graham Goode £70 inpp I was told £200 for a set of four but, Ive just changed one and another was changed on service just before I bought it (3 months ago) If I could find out which was no 1 cylinder I could narrow it down to 2 leads or maybe the plug would be in a different condition? who knows?

Keep us informed how you get on

PETE

 

Cured mine after lots of time and expense. I now have a good stock of perfectly good plugs/leads etc!
Turned out to be a dirty Air Mass Sensor just downstream of the air inlet filter.
You need 'security' allen bits and a bottle of meths. Total cost about £8.50. Time - half an hour.
It's a UK spec turbo with 15k miles but still worth checking on your WRX's. The symptoms were exactly as you describe.
Incidentally, Optimax fuel turns spark plugs orangy brown. Not many people know that.
Happy New Year.

 

have you tried fitting the little rubber insulators on top of the plugs yet? as was a modification for misfire problems, better try a cheap fix prior to buying new coils....

 

Before you part with cash, try plug gaps. Ive got MY93wrx, and have had nitemares with it ...same symptoms as yours.

I replaced boost solenoid, MAF sensor ... did everything, thurned out to be plug gaps 0.7mm, instead of the 1.1 that the plugs were preset to.

For an hours effort, it worth a try and could save a tidy sum.

Frank

 

I too had a misfire under boost. Checked the plugs today and found one of them had a gap way too big. Re-gapped, re-installed and problem has gone away. Total cost......£0

 

thanks for all the info

 

redwrx,

I went to buy a set set of plugs to try and cure the stutter on WOT on my 94 WRX and the bloke in the shop told me they should be set to 1.1 according to the "fitting" book he had. I thought they should be .7 too.

 

Hi guys, just thought I'd stick my two-penneth in! I had a similar problem on my 95 STi - under full boost there was a slight misfire. Just had some HKS Iridium tipped plugs fitted (under warranty!!!) and the problem seems to have gone away. Very impressed with the people that imported the car for sorting this out under warranty though! (www.bluchip.gg)