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Bought a s15 today but...

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Toby

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As above a 20hr road trip with 2 ferrys to go get it, however on the drive home 2 faults arrose.

When accelerating, after about 4k the car start missfiring badly and there is a huge loss in power


When following the car, when lifting off the gas on over run the car smoke, White in colour I think!!

Does anyone have any ideas?
 

Curryzz

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missfire could be a coil pack! white smoke,that cant be to good, where in hampshire are ya? i only no of one other one and me in hampshire? as too your problem,The lads on here are good so im sure someone will reply with some good advice mate
 
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Toby

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I'm on the isle of wight mate!

No it doesn't sound to promising!! A bit more info on the car

60k miles
fmic
turbo manifold, down pipe, decat and cat back system
standard boost, infact
probably a bit low given the full exuast - 0.5 bar
 

craig8585

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White smoke in the exhaust is normally a sign of oil, but not burnt oil so normally entering after the engine. So from that I would guess its something to do with your turbo 'oil seal'.
As for the misfiring, could be a number of things. Coilpack is a possibility as mentioned in curryzz post..

Where did you buy the car from BTW?
 
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Toby

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I see, how would I go about diagnosing either of these faults?

Yes car was from
Limerick I'm
s Ireland

Thanks for your help guys!
 

LuPix_S15

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As with everything first check all the boost pipes cos if one of the silicones around the FMIC hotpipe area leaks or pops out she will run like a dog. I had loads of smoke from exhaust and nasty petrol fumes when this happened but it's more likely black smoke as it's unburnt fuel being shatted out of the car!!

Then check coilpacks if there is nothing loose cos your other most likely misfire problem is a ciolpack failure as the guys mention above...
 

craig8585

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You should get a fault code on the ECU if you have a failing coilpack. Does it idle normally or does it sound like an Impreza?

As for the smoke.. I don't know how you can positively confirm that. Theres not much else it can be really though but I would sort the misfire out first and then worry about the smoke.
 
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Toby

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Update!

today i went to do a compression test.

Upon removing the plugs i found the 1st 2 had half of them missing, were very black too, the 2nd 2 were fine.

with the engine hot, the reading were quite consistent at 140psi, and one cylinder maybe about 10psi down.

with new plugs in it there was no missfiring untill about 7000rpm but its still happening.

With a friend following he said there was hardly any smoke issues now, so assuming it was unburn't fuel since the spark on 2 of the cylinders would have been very poor?

The ecu light is working fine, but does not come on....

Idle etc is also fine it only untill you give it it stink under load.

Another thing i found is the boost solinoid had a plug on it and it was unplugged! seems to have made no effect plugging it in though!
 
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tooley

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Missfire at 7000 rpm?? odd does it have a uprated fuel pump? With the mods you have listed you MUST/SHOULD have an uprated one fitted.


The spark plug tips would have broken due to detonation. What make were the plugs?

What do you mean by missfireing?

Is it boost cutting? Fuel cutting?

However by reading this thread i would strongly say detination is the fault. I am supprised the engine hasnot failed.
 
T

Toby

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The car still pops and bangs, would it do this is it was running that lean?

Boost is also only .5bar so from what I've read a fuel pump would be reccomended, but not essential? - I will have a look tonight and see before I buy one.

The Plugs were NKG's I'm not sure on the heat range, will check.

The miss fire is like a coil pack is out, yes its upsetting the boost, but the boost is certainly not causing the missfire.

Before I fitted the plugs, it was doing ti as early as 4000rpm, now it does it at 7.

Thanks again everyone :)
 

tooley

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Hmmmmm, Well if its definatly boosting at 0.5 bar then detonation risk is lowered which is a good thing. However you are still getting detonation which will kill your engine. Try not to rev it to high RMP untill your confident you have a fix.

Yes if you car is running lean then it will definatly cause it to missfire. Which would inturn explain why your plug tips have burned off. Since a lean burn means a hotter burn. So you fuel air mix will ignight before you piston has reached top dead center (TDC) so both flame fronts are meeting eachother resulting in detionation and knock.

Have your plug ends burned off or snapped off?
 
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Toby

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I wouldn't know how to tell?

I'll get some pics up after work though!
 
T

Toby

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Pucker!

I am reading up on sxoc about the plugs, as clearly the 6's the car has and i replaced with are going to be to cold for my current set up.

Some people are saying NGK 7's are good to stage 3 and others say you should just go with 8's - I'm inclinded to do the latter unless there is any reason why running a spark thats too cold will damage the car?
 

tooley

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if you run a cold plug say on a standard engine then you would just be at risk of fouling the plugs as they wont get hot enough. more carbon build up etc since it wont burn it off.

But if your running a bar of boost im sure you will have nothing to worry about. I cant remeber what grade are on mine. Think mine are grade 8 or 7 iridium will have to double check tonight after work.
 

craig8585

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Might be an idea to get it RR'd too so you can get a good A/F ratio graph. This will give you a lot of info as to what's going on in there!
 
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Toby

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The initial plan is to get the car up to stage 2a. I just need to decide the best route to go down ECU wise, and to buy a boost controller - but that a another story!
 

craig8585

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If you get it RR'd now you can use the results to aid a diagnosis for your problem though. The graph that would be of interest would be the A/F ratio one. It will show if your running lean which could be causing your problems. IIRC the fuel in Ireland is a much lower octane than ours. I don't know if this would contribute to your problem or not..
 
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Toby

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I see your point, but If i spent the ££ now to have everythig in place it would save 2 trips up to a dyno.

All i need i belive is

new plugs
fuel pump
B/C
Nismo 555c's
Some form of mappable ecu Nismo tune / Apexi PFC

One thing I have not mentioned is I can't actually use the car for about 3 - 4 weeks while the plates get transfered to UK ones you see.

BTW please correct me if I'm wrong on any of the above, i'm a bit behind with all this, but working on it :)
 

tooley

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thats a point!!! what fuel are you using??? as the cars from japan are mapped to 102 ron fuel so even putting 99 ron fuel in is worse, that need the timing tweaked.
 
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