muffking2

Hi chaps.
My mates 1993 WRX jap spec Impreza intermittently kangeroos when accelerating hard on boost. So far the garage have found no fault codes, have checked the fuel pressure from the fuel pump, changed the fuel regulator and changed the spark plugs, but the fault persists.

The mechanic also says that it's possible that they push extra fuel at post 60mph? If this is correct then could this affect the problem.

Can anyone help.

wah

Has he not had his coil packs checked ??? just an idea

muffking2

The ignition system has been checked for sparking power but they only have a 2wd rolling road so it's hard to say, although the local Subaru dealer say that coil packs are very reliable?

Tone Loc

iTrader: (1)

On a MY93 the first thing to check is the coil packs....... depends how they checked the spark. By taking the plugs out and grounding the spark they can look ok but the coil not actually up to the job.

Does your mechanic know Subaru's... 'they push more fuel post 60mph' sounds like he's trying to bluff he knows what he's talking about!!!

Tony.

muffking2

On that basis i'll stick a post in the general section to see if anyone in the lincs area can come to the garage with me to exchange the coil pack(s) to test it through substitution.
I had heared about the Sccobs pushing extra fuel past 60mph, although this will happen at a different speed (if happening at all) due to it being an import with a converted speedo. I don't suppose the de-limiter could affect this could it?

timmyajmy93wrx

iTrader: (27)

im with tony on this one, defo check coil packs mate, have same car with the same problem. edit to say - did have the same prob!
Also are the spark plugs good enough? the cheap plugs (champion type) i tried drove well until you gave it some then they could produce a good enough spark, hence more splutter....
I'm running denso IK24 iridiums at the mo, fantastic (so far) but have also used NGK PFR7B's - cant fault these either.

Tim

Tone Loc

iTrader: (1)

This push extra fuel depending on speed is bull ****. The fueling is controlled by the MAF only during open loop, i.e this determines the load and combined with rpm the level of fuel injected is determined. Road speed doesn't come into at all, whoever told you that is taking a wild stab in the dark!

Tony.

muffking2

If that's the case then it could well be down to an ignition problem rather than a fuelling problem. The reason why the mechanic suspected fuelling though was due to the fact that there were no fault codes stored in the ECU, but would the ECU detect a fault with the air flow sensor if this was the cause of the problem?

Tone Loc

iTrader: (1)

I wouldn't expect the MAF sensor to cause kanarooing..... if the coil packs were dying this also wouldn't cause a fault code. Money's still on these. How were thses checked, when mine went i checked them by taking the plug out and grounding it on the block then cranking. Spark looked ok but the coil pack caused my hesitation/missfire as the spark just wasn't strong enough on boost. Not sure i'd trust this mechanic after this 'push extra fuel' stuff

Tony.

timmyajmy93wrx

iTrader: (27)

have you got an afr gauge & a knock link fitted?

every now and again my afr will show full 'rich' and the car will splutter obviously its over fuelling, and only does it from cold start. Once i have warmed the engine up and driven a while the afr reads normal stoich and flicks back and to as it should on tickover. Have not manged to find the cause yet, i am thinking that my maf could be on its way out as i have had new plugs (twice now) new lambda, pressure duty solenoid, coil packs.

Its just an idea that you could have a similar prob, as i say if you have the afr it could give you an idea on the level of fueling, and the knock sensor will obviously show you ure det.

tj

edit to say - try taking your plugs out agin an seeing the state of them, and are they gapped right? If they all black carbon/sooted up then afaik you are over fuelling. (just my tuppence!)

LeeMac

iTrader: (1)

may be nothing, but my diesel does it and someone suggested the fuel control valve

just a thought

dnb

A coolant temperature sensor fault can also cause over-fuelling & spluttering and may not show a CEL.

The coil pack failure is far more likely though.

KLR16V

iTrader: (2)

Are you sure it is not fuel cut coming in as you say it happens under hard acceleration, this comes in when too much boost it being run and is a safety feature what boost is the car running ?

Mark

MadDogWRX

I had the same problem.

Changed all coil packs and upgraded spark plugs to NGK pfr7b`s.

That sorted it.

muffking2

KLR16V: It could well be fuel related. The car is running the factory boost setting (what ever that is at), but I will try to go with the coil pack and MAF sensor if I can find some to buy or borrow.

Does anyone know if they changed the MAF sensor on later models. Bear in mind though that this one is a 1993 Jap WRX import.

muffking2

Quick update.
I've managed to track down a suitable MAF sensor which I'm gonna try when it arrives, but if that doesn't cure the problem then I will get a coil pack from Grade A Subaru breakers in Derby for £40.25 delivered and let you know the result.

Greeno

I had a similar prob with my93 WRX...

I evetually found out that the cam timing was out, and the car was obviously missing, maybe something to think about...???

Does the car run ok on idle, and when holding constant revs etc...

Also has anyone mentioned spark plug gaps...???

G.

muffking2

Well the MAF sensor finally arrived today but made no difference to the problem so I will be ordering a coil pack tommorrow.

A better description of the symptoms however, are that it hesitates big time between 4000-5000 revs mainly in 3rd, 4th & 5th gears.