Car not running right

M

Matt

Guest
Im having a problem with my Impreza.
Its running fine under steady driving and idling fine.
I replaced the maf with a new one to rule that out also.
But when accelerating hard, it seems to hesitate and pull timing at about 5000rpm and upwards.
It is still boosting upto normal levels on the Defi guage.
Also no check engine light.
Is it possible it could be the o2 sensor? Doesnt seem like the knock sensor symptoms i had one before :dontknow:
 
ok thanks.
ill check the pack and leads tomorrow. I did replace the coil pack about 18 months but its worth a look :thumbsup:
 
Put new plug leads on the car today and checked the plugs but the problem seemed to get a bit worse. Went out for a quick drive and was getting missfires.
So i put an old set of plugs i had into the car and tried again and it was worse, misfiring at idle and nearly stalling.

Thought at this stage it might have been the coil pack, so one at a time i removed the leads from the coil pack with the engine on to make sure it was creating a spark for eack of the 4 leads.
Suffering 4 pretty painful shocks proved the coil pack is working.
Im going to get new plugs tomorrow to try but if that doesnt work,i dont know what the story is.

Any ideas?
Thanks
 
Hope you get her sorted man!
It's very frustrating stuff!
Dan
 
Yeah heads wrecked having done 2 spark plug changes in one evening.
Im hoping its just the plugs.
Ill let you know how i get on tomorrow :thumbsup:
 
Matt I have a set of new ngk 6's if you want to try them out mate. :thumbsup:

Just torule that out if it is the plugs so you dont have to buy a set to check. :dontknow:

Here is my number if you want to. 0877664376 :thumbsup:
 
Thanks for the offer Keith, much appreciated but i got a set today :wall:
Not to worry, ill use them anyway
Just changed them and started the car up and let it sit for 10min. Idle'd perfectly no missfires but went for a drive and im getting like fuel cut even at low revs when driving gently.
Didnt even try to get the revs up to see what happened, dont think it would have gone anyway.
Think it might be drinking fuel too but hard to say as ive not really driven far enough.
Im wondering is it the 02 sensor, replaced this just over a year ago but with a spurious one.
Not getting any check engine light :dontknow:
 
When my o2 sensor went it didnt show any check engine light, the only thing i noticed that it was drinking more fuel, i replaced it with a genuine one, i doubt its the o2 sensor causing problems :ponder:
 
Check for air leaks/cracks on any rubber/plastic hoses between airbox and engine.Sorry don't know the technical name for if.But it is there near air flow sensor that i had the same symtoms on a bmw a while back.
 
ok cheers ill have a look but i think everything is ok as i had the airbox out changing the plugs and everything looked fine.
From what ive read, its looking like the o2 sensor may well be the culprit.
Its definitly not the maf
99.9% its not the coil pack
Replaced the knock sensor last year and got engine light when that was faulty and slightly different symptoms so i dont think its that.
whereas the 02 sensor can give the symptoms my car has without any check engine light. :dontknow:

Found this info

If the lambda sensor continually reads high (rich), it will cause the engine computer to lean out the fuel mixture in an attempt to compensate for the rich reading. This can cause lean misfire, hesitation, stumbling, poor idle and high hydrocarbon emissions (from misfiring).
 
Hi Matt,

I would change the Lambda sensor for a genuine one and see how you get on :thumbsup:
Also have you changed the fuel filter?

Alan
 
Thats some good info about the o2 sensor when it reads high, i never knew it would cause them problems :smile:

As p1 Alan said get a genuine one, you can get them cheaper than main dealer prices, from justlambda im sure there is other sites, i paid around 290 euro , from main dealer :wall


have a look at this link, your part number might be on that list :thumbsup:

http://www.justlambda.co.uk/
 
Tried a new o2 sensor in the car just there and still the same.

Symptoms are:

Car difficult to start, needs to turn over for much longer than normal and then just catches and splutters to a start.
Then it will idle a bit rough and missfire intermittantly.
If you press the accelerator the revs will build but it sounds a bit rough and gives the occasional pop sound from the air box.

At this stage it seems like a fueling issue
I changed the fuel filter only 10k ago.
It has a walbro fuel pump in it about 20k

Is it possible the fuel pressure regulator or injector(s) are giving me trouble?
My heads wrecked at this stage :angry1:
 
[quote author=Matt link=topic=15825.msg196007#msg196007 date=1245429172]
Is it possible the fuel pressure regulator or injector(s) are giving me trouble?
[/quote]

I think with all the other things you have tried, that is probably where you should be concentrating your efforts.

Is the fuel pump priming OK? Get someone to turn the key but dont start the engine and you get on your knees around one of the rear wheels and listen for the pump priming.
 
Its priming ok but the car wouldnt start there without me pressing the pedal. It then spluttered to a start but was lumpy and popping when i pressed the pedal again.
Before i got it to start and i turned the key off after attempting to start the car and the pump did make some funny noises then :dontknow:
 
Re: Car not running right(Sorted)

Got the car back today.
After spending a week working on it myself trying to fix it and help from Jp and Keith i lost my patience and gave it to Dave in STI Tuning.
He found the problem to be the fuel pump when he took it out to inspect it.
It turned out id fitted a new age walbro pump to my car not knowing it wasnt the right one for my classic.
Different size fitment in the tank or something.
Also id managed to fit the pump the wrong way round, like it was turned 180 degrees so facing the wrong way :icon_redface:
It worked, but was only a matter of time before it went wrong as the fuel line was under strain :653: :angry1:
So the fuel line had snapped at the pump causing my fueling problem.
Sorted now anyway :thumbsup:
 
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