anyonewilldo

Right guys , hello to start off and then thank you in advance if you help solve my problem !!!

Cars spec is as follows , eBay item number 120954459960 !!!
Please look at the listing as there is way way too much to write !

Anyway now for the problem , I took the car to London to work with me (230 mile) as I had just bought it and fancied showing it off at work ! Anyway on the 4th day taking it to work I went round a round about not at great speed but accelerated hard when leaving the roundabout and for a couple of seconds the car halted power it was like a fuel shortage so I released off the throttle and changed gear and the car drove fine !
After my stint at work I drove the car home and stopped at northhampton on the way and all of a sudden the car began to idle erratically jumping up and down , after a quick splurt on the throttle and a few minutes it seemed to rectify itself and idled as normal , the check engine light was also on during this but went out when it sorted itself ! I carried on my journey home and was held up behind traffic so changed down gear but as I did so I realised that the revs where staying high like the throttle was stuck or some sort of choke was on , I tried to tap the throttle to see if it was sticking but no good ! This also sorted itself out !!!

Now I'v been out again today and the idle was fine and the revs dropped as normal when releasing the throttle but under hard accelaration it jerked again as tho there was no fuel !

Now I understand a boost leak could be a possible cause so from what my guage is telling me the car boosts to 1.0-1.1 and at idle sits at -0.5 but sometimes flicks to -0.6 and today while releasing off the throttle after hard accelaration it was -0.7

I haven't really got a clue about cars so if you can explain everything slowly and clearly with pictures lol it would be appreciated

Just like to note the car doesn't always do this and seems to boost normaly and goes like **** off a shovel but twice it has felt as if it was starved of fuel so there must me something on its way out ? And the revs has happened a couple of times although only noticed the check engine light the last time and as I said it went out when the car sorted itself

anyonewilldo

AnyOne ???

Shaks-STI

iTrader: (7)

Check all your boost lines fro mthe gauge to the engine bay, sounds like there is a air leak somewhere.

anyonewilldo

What makes you say that ? By the level it sits at on idle ? Should it be sitting at 0 and not in the minus ?

spender(again)

iTrader: (1)

Anyway on the 4th day taking it to work I went round a round about not at great speed but accelerated hard when leaving the roundabout and for a couple of seconds the car halted power it was like a fuel shortage so I released off the throttle and changed gear and the car drove fine !


Sound like fuel surge - were you on less than quarter of a tank?

Shaks-STI

iTrader: (7)

I had the same issue yesterday and the gauge was sitting on 0 and wouldnt move until i found a pipe that was disconnectd.

Shaks-STI

iTrader: (7)

would read minus when there is vaccum on the lines and 0 when nothing is detected on the lines. 0 is a standard position on the needle.

anyonewilldo

Well if it's reading -0.6 there's deffo vacuum then and it boosts to 1.0-1.1 so that can't be the problem and yes spender I was on less than quarter of fuel

JusticeEmpire

I don't mean to hijack your thread, but I was about to post something identical.

I noticed a 'power cough' when taking to subaru for MOT, said they would check emissions, but couldn't see anything wrong. Last week, I was in 4th doing about 65 up hill, when I went to squeeze the throttle, it 'coughed' again and since that, it has felt that this is less power. However, I have also noticed that sometimes, on idle, its REALLY wobbly, and the whole car is shaking side to side........

Just about to ring Subaru so that can check it out, as I advised of the fault under warranty and its not been rectified

anyonewilldo

Can you let me know please

JusticeEmpire

Its going in next tuesday....., guess I have to wait until then...

debbiesonic

iTrader: (7)

There is a definite possibility you have had 2 separate faults there. The loss of power coming off the roundabout sounds like fuel cut (where the ECU shuts fuel off due to an overboost situation). At 1.1 bar the Z4 is very close to it's fuel cut threshold, and there is no mention of a fuel cut defender on the advert so on a cool morning it is very possible it exceeded it momentarily. An easy test for this would be to simply turn the boost controller down so that max boost is set to 1 bar or less.
The idle problem can be caused from a variety of things, maf, tps, icv. But since the check engine light came on you will have a code logged in the diagnostic memory. So you will need to read the memory to ascertain the ECU code, this will in turn point you in the direction of the part at fault. Reading the memory is a simple procedure, see the link below for instructions.
http://www.saxonfields.freeserve.co....iag%20Page.htm

debbiesonic

iTrader: (7)

JusticeEmpire, your fault sounds much more like a simple misfire. The MY02 has coilpacks iirc, rather than HT leads. That would be my first check point, remove them and check around the rubber that fits over the spark plug, any cracks or deteriorate in the rubber will allow the spark to short to the heads rather than be fed to the plug. If they are all ok, check your plug gaps. It the fault has escalated and is permanent rather than intermittent it will be much easier to locate, a spark tester will let you see if any of the cylinders have a weak spark.

JusticeEmpire

Well mine has come back from Subaru, no fault found, although they are sending my data to Subaru for secondary analysis.

Thanks for the info debbiesonic, now that my warranty has expired, all work will be done by me so that's good advice