bigfarlz

iTrader: (9)

Hi guys,

Newbie on the site and have only been a Scooby since Sunday! I bought an x plate impreza 2000 turbo. Absolutely loving the car but have noticed under hard acceleration the power seems to keep be on and off as in with the pedal to the floor it accelerates then eases off then comes back again, this happens in all gears. As far as I'm aware the only mods are a cat back exhaust and a hks dump valve. Can't say for definite as I'm no mechanic but it is very loud do u think it could be decatted? Any help much appreciated as I'm new to cars of this type!

Thanks

prodriverules

iTrader: (52)

has it been remapped mate cause if its got decat it needs it and id swap back to the standard dv/recirculation valve also as the atmo types can cause idle issues and some problems like your suffering also.

dave247

Sounds like the maf sensor, if it's decat without a remap it can **** the maf up. About £80-£90 from dealer.

bigfarlz

iTrader: (9)

Really? I always thought atmospheric dump valves were ok on these cars and if I'm honest I quite like the sound! Lol also I've noticed that sometimes when I change gear it seems to violently jolt when this power problem occurs, been thinking about booking it in at Scooby clinic or pole position in willenhall as I'm from the midlands.

Eternal Rage

iTrader: (7)

Could be a few things. Split hose, MAF on its way out, fuel pump on its way out, Dodgy map. Unfortunately, what you said is prob the best bet, take it and get it diagnosed by the Pro's.

Splitpin

No, they're not, at least while you're running the standard engine management. Search is your friend if you'd like more info on why this is.

That is quite likely to be a side-effect of the atmospheric venting dumpvalve. Chances are reverting to the factory fit one will at very least alleviate it, if not cure it completely. If you are getting boost oscillation under flat out acceleration then it is possibly a result of the decat, but more likely to be caused by something else on that model car.

Getting it looked at certainly wouldn't be a bad idea. As above there are other potential causes for this sort of symptom and some, in particular a failing mass airflow sensor, can have very expensive consequences. As such it's much better to get it diagnosed sooner rather than later.

Possibly, possibly not.

No, that isn't correct. The OP may have a dodgy airflow meter, but if he has the decat won't have contributed to or caused it. Don't know where you would have got that idea.

bigfarlz

iTrader: (9)

Tbh, I'm feeling a little bit sceptical about what the guy I bought if off said with regards to just having dv and cat back as I found a used tubosmart manual boost controller in the glove box

More_Boost

Could be that he started an upgrade,then stopped short at the remap.

dave247

When I put a decat on mine within a few weeks my maf went, I was told on here that this would have been the cause.


Check the error code

http://www.5ive-o.org/forum/faq.php?...aq_item_errors

bigfarlz

iTrader: (9)

Ok then guys, thanks for the input. Puttin new discs and pads on the back on Sunday then will probably book it in at pole position a week today as it's my day off work. I'll let u know the diagnosis!

Thanks again

The Trooper 1815

iTrader: (31)

The moral of the story is, never buy a Scoob without getting advice first.

If it's "pulsing" when under hard acceleration it may be the Boost Solenoid. I had a similar problem with a Newage Bugeye, had it mapped at Powerstation and a few days later when giving it some beans the turbo seemed to "pulse" when on boost. It turned out I needed a 3 port boost controller solenoid fitting.

MrNoisy

iTrader: (28)

Unfortunately, it could be all or none of the above.
On my bugeye when I had a similar issue, it was just the spark plugs.
I had changed the MAF, cleaned the boost solenoid etc etc, but to no avail - had a look at the plugs - looked like they hadn't been changed for a while - gapped a new set and threw them in and hey presto - no more problem.

I would recommend doing what a few members have suggested and plugging in a diagnostics tool if you can get one and see if any fault codes have been thrown up. If not, you can always try re-gapping your plugs, and testing with a friend's MAF.

New MAF sensors are insanely expensive and you want to try and avoid having to replace it if you can (I was lucky and managed to pick up a second hand one for £25, but my local dealer wanted more than £200 for the part)!

Eternal Rage

iTrader: (7)

if there is a used MBC knocking about check the pipes from turbo housing to actuator and the ones that go across to the boost solenoid. if they have been removed or messed about with it is easy to get a small hole in one, i did on mine, spent hours messin about with stuff, was so annoyed when i found it was just this. If there is just a tiny pin hole, it can lead to boost spikes coming on boost.

Splitpin

Whoever told you that doesn't know what they're talking about. There's no conceivable way the addition of a decat can affect the airflow meter one way or the other. If your meter failed after you fitted the decat, the bottom line is that the AFM was failing anyway and the other modification was totally unrelated to it.

Bigfarlz - as per Eternal Rage's excellent post, have a look at the boost control pipework currently on the car, and if in doubt, make a point to get it checked out when you have the car looked at. If a manual boost controller has been fitted in the past, there's an obvious question as to what has been put back on in its place. If, for example, the standard dark grey pipework has been replaced by the nasty silicone stuff sold by ye olde chav tuning shoppe, this sort of tubing can balloon under pressure and muck about with the boost control. Similarly if the standard stuff has been taken off in the past, there's a question over whether the correct air restrictor has been used, and whether it's been put back in the right place.

bigfarlz

iTrader: (9)

Thanks I'll make sure to have a look in the morning.

*UPDATE* I was driving back from work earlier and the high pitched sound of the dump valve has turned into a more faint sounding chatter/flutter. To say I'm even more concerned is an understatement!
Help!!!

rookymatt

iTrader: (15)

Sounds like the dump valve isn't opening, causing the boost to surge back up the wrong way and hit the spinning turbo fins.
Take it off, and fit an oe dump valve mate.
It will improve gear change responsiveness, and also help improve fuel economy.
I would look on e-bay.
or the for sale sections on here. (just remember you need to be a paid up member to do this)

bigfarlz

iTrader: (9)

Will I still get the sound? I know this sounds sad but it's the first turbo car I've owned and
I was kinda enjoyin it!

pinkypurkhardt

iTrader: (9)

no mate

rookymatt

iTrader: (15)

You'll like it......for a while.
Then the little nasty looks you'll get from everyone and their mum on the street, as you simply change gear. will really start to become frustrating.
Trust me, the subtle note of the flat four rumble on part throttle, i find, is far more sexy than a "chav horn" announcing you've backed off the throttle or selected another cog.

pinkypurkhardt

iTrader: (9)

agree with the above i had 1 on mine when i first bought the car liked it at first then got fed up with it

Splitpin

^ Couldn't have put it better. It certainly sounds from what you're describing that the valve is sticking Bigfarlz. Your engine will run a hell of a lot better with a good OE valve. As far as the noise goes, do you want the car for its performance, or the noises? Nothing wrong with choosing the latter, as long as you're doing so on an informed basis.

bigfarlz

iTrader: (9)

Both really but I supposed I'll grow out of the dump valve! Update though had a look this morning and the tube had came off the dump valve so all is well on that front now! Still got my pulsing acceleration and I've noticed the maf sensor is the one with the green stripe is this ok? Also I've a feeling this car has been messed with more than in was told as a friend who's quite knowledgeable on these things thinks it's much quicker than standard. One last thing I've bought new discs and pads for the rear which I'm planning on fitting tomorrow, I'm not gonna need any specialist equipment for an impreza am I?

Thanks in advance all

leecalcars

iTrader: (37)

regarding new rear discs just make sure you do one at a time so as to look back if you have any problems with springs and adjusters going back in the right place, i removed all of my discs suspension months before i re-fitted it all and forgot where it all went doh... good luck

leecalcars

iTrader: (37)

oh and a small tip get a can of clear laqure from halfrauds and spray round the centre part of the disc as this rusts like hell look shiney new for longer.

More_Boost

Look nice there matey !

bigfarlz

iTrader: (9)

Yeah so having found that I had the wrong restrictor pill size fitted I've got the correct one in now, and it doesent pulse as much on hard throttle but still on low throttle it's quite apparent. Since starting this post I've changed maf, boost solenoid, plugs vacuum hoses etc. It's been suggested by someone that if there's a slight knock on the engine even if u can't hear it the knock sensor would make the ecu back off, is this true? Also been told lambda sensor and fuel filter, but tbh I don't want to keep changing things trial and error it's costing money! Also been suggested I may need a 3 port boost solenoid but I don't really know why? HELP?

f1_fan

iTrader: (9)

Lose the dv, go back to the OE one and then if that doesn't sort it have a mapper take a look at what map it is running. I am willing to bet if you restore the dv and have it properly mapped you will have a much better car and your engine won't evenetually go bang either.

GarethE

iTrader: (1)

I'm amazed that after all the earlier advice about the vent to air DV possibly being the problem, that you've changed all the other items, but not the one that's most likely to cause the problem.

Its hardly surprising its costing money - by all-means if you'd changed the DV first and still had the problem and love the VtA DV sound then put it back on and try the other options.

The standard cars come with recirc DVs and most well modded cars use the same - there has to be a reason for this.

Hope you get it sorted, and while I can't offer first hand advice about the problem, I'd certainly be taking the advice of those who have offered it - and I've been driving Imprezas for 12 years.

Good luck.

bigfarlz

iTrader: (9)

Sorry I forgot to mention it's took me a while to find one at a decent price but I have an oem recirc to put on now and will do this week and hopefully I'll be ok!

Fuzz

This