could do as they have more mesh in the filter and if you look at both togather you will see the differenceand the stock one could be clogged up as they sit right on the bottom of the tank might be worth taking out and have a look and if you have the walbro filter put it on really easy to do can be done in a 1/2 hour??

 

Dont you need to take the tank off, exhaust etc?

Anyway, I went for petrol at lunch time, but before hand reduced the duty by 2% to set it at 47. Warmed her up then put my foot down in 2nd and it boosted fine. Filled up with petrol, came back to work. Put my foot down in 2nd when going straight on off a roundabout and I *think* it overboosted and kicked me back. It was like a jolt/shudder and a small bang/pop from the exhaust (I think it was a bang but I might have been hearing things).

Confused, as the first day I got it back, the drive home was faultless and it was running superb with no problems like this at all

 

no you don't there is a cap with 10 or so nuts in the boot on drivers side you undo that and the pump is in that if you are going to do it release all fuel pressure first and no smoking as far as what you just posted that sound like a plug or wire is yours a classic or new age it will be miss firing at higher rpm and ok at low rpm or if you accellerate slow it will not do it right???

 

I came off the roundabout and floored it, the revs and boost increased and it kicked me back on boost rather than rpm. (ie it was nowhere near the rpm limiter. Or at least I dont think it was anyway. If it was then it redlined pretty damn fast!)

Full spec is :

2000 Impreza P1
Full decat 3" - 2.5" Afterburner
K&N 57i Induction Kit
Front Mounted Intercooler
Apexi PFC mapped by Andy F a couple of weeks ago
NGK PFR7B's (or 6B's, cant recall. They were the ones recommended by Andy)
Walbro 255 Fuel Pump
AP Racing clutch

I'll do a run later and check to see what the peak figures are on the Apexi controller handset.

 

hi mate it will cut out around 5000rpm i would check plugs or wires to be sure it could also be fuel cut what injectors do you have>>>???

 

if it is spark related it will kick you back as soon as the boost comes in hard mine did it yesterday and I had a broken coil pack.could also be the sensor mounted on the strut wall on drivers side it is upside down with a part number on it there is also another one beside it it could be that to do you know how to get fault codes of it???if not pm me with a landline and I will tell you..

 

440's. Thing is, it was fine when Andy mapped it and on the way home.

I've decided to do a run down of whats happened since I got her back. Its a bit long winded but will hopefully help in diagnosing further :

Once again, spec :

Full spec is :

2000 Impreza P1
Full decat 3" - 2.5" Afterburner
K&N 57i Induction Kit
Front Mounted Intercooler
Apexi PFC mapped by Andy F a couple of weeks ago
NGK PFR7B's (or 6B's, cant recall. They were the ones recommended by Andy)
Walbro 255 Fuel Pump
AP Racing clutch

* Apexi ECU mapped by Andy Forrest on Esso Supreme 97RON (they are no Shell VPower stations within 25 miles of where I live, but Tesco are set to release the 99RON up here soon, so it will be back to Andy to be mapped on that when available)

* Andy suggested I re-attach the engine tray underneath, as when the FMIC was being fitted, the tray looks like its been cut back to suit. The downside being travelling at over 55mph forces the tray to hang down and flap on the ground due to the pressure and air flow. The tray is being removed tomorrow, rather than re-attached again at the centre. This was recommended by a few people on P1woc.

* On way home, stopped and filled up with BP Ultimate 97RON as there were no Esso, unfortunately.

* Had a good few sprints of acceleration, including a turn left at a roundabout and floored it. Acceleration was amazing, and no hint of boost problem at all (obviously I would have been unaware at this stage of any anyway)

* The next day, I took my mate out in it. Cant remember the quantity of petrol in the tank, but definitely less than half. Took the 3rd exit from a roundabout (full right turn) and put my foot down in second. Wham, kicked back as if I'd redlined, only far too early. Changed up a gear, 3rd, 4th and 5th all superb speed and pulled amazingly. Not a sausage wrong after that.

* A day later I believe, me and my girlfriend went for some food and the petrol light was on. Took a left at a junction and put my foot down in second. Wham, kicked back again. Changed to 3rd gear and accelerated and it felt like it was trying to force too much air through the exhaust system. It popped a little and contined on, a bit sluggish, however, kind of laggy.

* Got home, had the food and decided to go for some petrol and test the car (after a few threads I'd read on similar problems). However, started car and after about 15 seconds it died on me. I started it up again, and it coughed a bit and then conked out again. Tried again, same. It was at this point I thought I'd done something seriously wrong.

* I decided to use my girlfriends car (an Evo 6, oh the shame) to go for a bit of petrol in a can. Filled up with about £5 worth, which was all I could fit in. Came home, filled up the P1 as best I could. Gave it a couple of minutes and started it up. Spot on. Started fine. Went for £20 worth of more petrol and came home and parked up.
Now this was alarming, because the petrol light must have been on for about 5 minutes, tops. Before the map and modifications, including the Walbro fuel pump, the light could stay on for a LOT longer, as a lot of people will know. It really confused me as to why it had run out of petrol so quickly after the light had came on.

* At the weekend, I took the step of trying to protect my K&N Induction kit from the rain, as recommended by Andy. I have open meshed 22B bonnet vents on the car, so any water could easily have been taken in by the 57i. I used the original blanking plate so now its protected. However, water could have gotten in during the time it wasnt fitted.

* Found out today that the sock filter on the Walbro Fuel pump is from the new pump itself, yet I've now been told its best to use the original sock filter.

* Took car out at lunch time for some petrol. Accelerated in 2nd gear. Boosted to around 1.3bar and didnt kick back. Filled up with petrol, drove back to work. Went straight on at a roundabout, upon exiting I put my foot down in 2nd. Wham, kicked back, shame I didnt manage to check the boost figure. I've just found out now that I can check the peak figures from the latest drive using the Apexi Controller handset, so I'll take it out later and have a play around.

Now its still doing the same thing on occassion. Not all the time, but on occassion, and usually in 2nd gear. With the above information, I've got into my head various suggestions from forum boards and people's takes on the situation :

* Overboosting
* Fuel Starvation
* Fuel Surge
* Maf failing
* Fuel Pump - Position of?/sock filter being newer version, not original
* Coil Packs
* Boost solenoid
* Spark plugs not gapped correctly
* Injectors not up to the job (440's)
* Hoses not connected properly
* A number of other things.

Its good to have a collection of possible problems and symptoms etc, but I'd rather know the route of the problem right away than having to check the spark plugs and all the fittings etc etc and not knowing if changing things will make any difference. Its one of those impossible questions, really, as without seeing the car and how its running, you dont know what it is. Thats why I've tried to break things down above as to give more clues in to what could be going on.

Many thanks to everyone who's tried to help. I hope the information above adds to your thoughts.

 

ya but you have to go through a list to narrow it down as it can be a number of things here are 2to 3 sensors to check and the coil packs are the first place I would go yours is doing the exact same thing as mine did yesterday and found a split coil it will work fine untill you come into boost then it cuts out..

 

Yeah I understand you have to narrow it down. Thats not a problem, I was just trying to get the point across of how annoying it is. lol

Wouldnt a split coil or spark plug issue cause problems with boost in all gears and not just the lower ones such as 2nd? It comes on boost very strong and spins right round to at least 1.3bar, but then gets to a certain point and cuts out. Other gears are fine. Thats why I thought it could be overboosting, but there are so many different things it might be other than that, like you say

 

no mine did it in 2 3 4 5 now in then depending on how hard i accelerated more common in 3rd

 

Mine has been fine in the higher gears, thankfully. The sensors that the Apexi controller checks are all fine, too. I know there are probably a lot more that it doesnt check, but its a start

 

the sensors don't pick up everything I would have to say it is fuel cut there are a couple of more sensors on the srut (driversside) that can be checked there is one upside down with a number on the top and also the one that mounts beside it those 2 are boost related the only way to check them is to change them unless you have them checked at the dealer or your wastegate on the turbo is faulty but not likely???

 

Ok guys, I took the car out with just under half a tank of petrol.

Turned left at a junction, put my foot down in 2nd and got these peak figures on the Apexi controller handset :

Duty : 75.3
Revs : 4986
Temp : 61deg
Air Flow : 4345
Boost : 1.31kg/cm sq
Knock : 16
Water Temp : 94 deg

The car didnt stutter or hesitate at all. Was fine.

I did another couple of tests. Took a right turn at a junction, and on a long straight and private road (actually being serious too) I put my foot down in 2nd gear again and it hesitated and hit the invisible limiter as though it had overboosted. Figures :

Duty : 54.1
Revs : 4107
Temp : 45deg
Air Flow : 3985
Boost : 1.19kg/cm sq
Knock : 6
Water Temp : 91 deg

so it cant have been overboosting, surely, at 1.19?

I went to the bottom of the road, did a right hand U turn and did the test again with the same outcome. Figures were almost the same, except boost :

Boost : 1.06kg/cm sq

Hmm, seems like it could be a fuelling issue perhaps? Like I said though, I had just under half a tank full. Saying that, it could still be a number of other things. Its only in 2nd gear it seems though, once up into 3rd or even accelerating in 3rd is fine.

On the way home I was on a long stretch of open road, so accelerated in 2nd and it boosted to 1.34bar with no problems at all. That was from no turning or junctions.

Also did a left hand turn at a junction and accelerated again, no problems. Really confused.

Hope this all helps with the diagnosis

 

Pretty certain its to do with fuelling now, and could well be the fuel pump location and/or filter used. 1/2 tank should eradicate the problem but didnt.

 

Also, is a knock detection of 16 ok? I dont know what the normal is?

 

A knock of 16 isnt bad, Andy would have set the car up (ptobably) to flash the CEL at a level just below where he would have heard knock during the mapping. I sometimes get in the 20's just by starting my car!!

Looking at the readings on the commander that you have posted, your no where near maxing out the injectors which I thought earlier you may have been, and your maf isnt maxing out either. What is interesting though on the first run your water temp is showing as 94, that seems a bit high to be honest unless you had really been giving it some (but in this weather it is still surprising)

With your tank running dry, there is a chance that there is muck in your fuel lines. Possible change the fuel filter

 

In fairness, the first test was done with a bit of travel on the go (maybe 12 or so miles driving). The second time was after only about 2 miles after the car had been parked up while we went shopping

I'll try and change the filter sock at the weekend. Hopefully this might alleviate the problem slightly.

Thanks mate.

 

Also, this might be way off, but my last service (or service prior) suggested that I might need a new lambda sensor as the emissions were out. Could fitting the decat etc along with this 'needing replaced' lambda add to the problem mentioned?

 

lambada problems shouldnt give the problem that you have been having, as when its happening the lambada wont be doing anything with regards to the fuelling. there is something you can do on the commander to bypass any labada control. It does sound definately like a fuelling // ignition related problem. changing the fuel filter will not harm the car though either, just in case there is muck in the lines

 

Yeah, and I need to do this anyway as it has the new filter sock on with the uprated Walbro, and not the original, which is the correct one I should be using. I'll change it over at the weekend. Its going to the bodyshop tonight until Friday to get FMIC sprayed, bumper cut to suit and mesh fitted along with engine tray removed.

Cheers Jay

 

I'd still say it's fuel starvation. Going around a tight right hand corner, most fuel will flow into the left hand side of the tank. Boot it hard in 2nd gear and what's left will flow towards the back.

If you are very low on fuel (nearing empty), then you would probably get it going around left hand corners also, as there's a cahcne the fuel pump could briefly suck in some air for a fractin of a second, enough to cause the engine to cough.

John

 

Thanks John. Like I've said, I'll be checking it all at the weekend, and replacing the sock filter with the original

 

Changed the sock filter on the Walbro to the original one (which was much bigger - couldnt believe how small the uprated sock was).

Filled up with petrol and its been spot on. Not a hint of hesitation and the acceleration is brutal in every gear