Need some help, my scoob is starting to drive me up the wall.I thought I had the problem fix , but I was wrong.

The car was booked in for a full service nearly 2 months ago, car was working 100% perfect before it went in. I specified I wanted NGK PFR7B sparkplugs installed with the service. Ive only noticed this problem about 3 weeks ago, as I dont use the car that much. When driving the car hard, at 4000rpm to 5000rpm there is a lack of boost, the boost stops at 0.5bar, then climbs upto 1.0bar after the revs climb past 5000rpm this is in all gears. If I drive the car sensible, its still there but not as noticeable. The car has been back at the garage twice in the last 2 weeks and cant find anything that stands out.

So far the car has had :

4 brand new coils packs fitted
brand new lamba sensor fitted
the NGK PFR7B sparkplugs double checked, gap is 0.7
2nd hand maf put in, checked the maf by pulling out plug and it stalls
cleaned out boost soleniod
reset the ecu & left battery disconnected for 1hr
garage has checked for air leaks, oil leaks, fuel leaks, cant find any


The car was in the garage the other day to get the decat fitted, now ive noticed the boost problem is 4000rpm to 5750rpm now, its getting worse.
Ive just went a bought a set of NGK PFR 6B SPARKPLUGS, to see if this cures the problem. Is this fuel cut ?.What is fuel cut anyway ?
There is no sudden loss of power, its like its smooth if you get what I mean, you dont do the windscreen head-butt thing. If you please take time to look at my specs, the car is tweaked a little. Im at a complete loss now. The only thing I havent done is remove the 'mines z4 ecu', Ive got a spare '2c ecu' but not tried it.

So what basically I am asking has anyone got any ideas how to cure this. As the car is booked in with Andy F on the 19th, so I need this fixed.

 

sounds like the coil packs but if you have fitted new then it cant be,i fitted pfr7b to mine and got the same as you so i went and put some 6b's in instead and it ran fine once back on the 6b's.alot of people use 7b's with no problem though, mine was running 1.2 bar but didnt like the 7b's for some reason.

 

 

I have a similar issue. I had a new ecu fitted and mapped and ever since I have had an intermittent missfire/light fuel cut type thing with loss of power for a moment. The only thing added was some NGK 7's before that I had 6's and an apexi mapped by AF and it never missed a beat.

 

**UPDATE**

Tonight I tried the 2 ecu's
reset the 'mines z4 ecu' shows no problems, flat spot 4000rpm > 5500rpm
reset the '2c ecu' shows no problems, flat spot 4000rpm > 5000rpm

looks like I can rule out the ecu's as the cause. Strange how there's a difference in the flat spots though.

Any thoughts people ?

 

bump for the night

 

dont worry your not the only one ive got same problem,mine shows code 45 so ive replaced pressure sensoe and pipes and it still there so im going to change the map sensor,
have changed coils
spark plugs
pipes
swaped ecus
cleaned every thing
have to see what happens when the map is changed,
matt

 

Mine does the exact same thing in 1st and 2nd gear, it sort of bogs down for a second around 4K, then shoots up to the redline. Tried Z5 and 2C ecu's to no avail. Beginning to accept it now! A few other people on here have the same problem. Mine is a my94 wrx.

 

Got to the bottom of this, it was the NGK PFR7B sparkplugs. Looks like my scooby just doesnt like them.

{tried the following gaps, 0.6 / 0.65 / 0.7}

 

What did you change to? 6's

 

could have been a dodgy set?

 

yes went back to NGK PFR 6B SPARKPLUGS

 

not dodgy, mate put them in his STI and work perfect

 

That is very very weird. As the 7's are colder plugs, perhaps they're fouling up briefly as you go into boost, maybe the 6's are staying clean? I could be talking out of my **** though.

 

Maybe so, my car ran clean until I fitted the 7's but I had an ecu fitted at the same and thought this may be the issue. I think I'll try a plug swop and see if it sorts mine out.