stevo1970

iTrader: (1)

I posted this question a week or so ago:

https://www.scoobynet.com/general-te...0-classic.html

Since then I have tried a few things without sucess. It appears now there could possibly have been two faults.

The first was the rough running off boost, this has been vastly improved by the fitting of a new MAF, but it isn't 100% still.

The second is a hesitation/holding back/fluctuation on boost. When cruising at part throttle say around 3000rpm i.e just onto boost the power fluctuates or pulses with say a one second frequency. If I push to WOT the car accelerates then appears to hold back as if you'be lifted off the throttle a little. This isn't noticable in second gear but is pronounced in the higher gears. In fifth it appears to take a long time to wind up to full boost.

I have also noticed that the idle is perfect and when cold it appears to be much smoother as it picks up onto boost, obviously as it is cold I don't go any further an certainly not WOT.

I have checked a few things in addition to the MAF change, the boost solenoid has been cleaned, most of the pipework checked, different fuel. The ECU was reset each time.

Has anyone an further ideas what the problem could be?

Is it possible to take the standard dump valve to bits to clean it? Any thoughts on fuel filter, plugs, leads etc?

I don't think its a major problem but it is difficult to trace .

Thanks

TonyBurns

iTrader: (3)

IS the car standard (in that I mean no other additions to the PPP like decat downpipe).

Tony

stevo1970

iTrader: (1)

Completely standard apart from PPP, standard dump valve, air filter element, exhaust.

Forgot to mention I cleaned the idle air valve too.

Splitpin

Time to get it diagnosed - or to put £20 in the direction of a diagnostic cable (assuming you have a laptop) and spend some time learning how to make sense of real time performance data.

DIPSY

Select monitor check at the dealers or independant specialist

midnight

iTrader: (10)

Also no need to take std dumpvalve to bits,as it is a sealed unit and has only a few components inside.Might be worth cleaning with brake cleaner,just for piece of mind.

stevo1970

iTrader: (1)

What is this select monitor?

Is it the device the dealership would use to interigate my cars ECU for faults, I take it its much more accurate than just doing the flashing CEL test at home. Any advice would me really helpful.

I don't suppose anyone knows of a specialist in Cumbria do they? My closest dealer is 40 miles away.

Splitpin

Not quite. It isn't that it's any more accurate at reading fault codes - it's exactly the same in that respect as connecting the black plugs. What it can do is, as per previous post, display live engine performance data - which can be very helpful in determining whether a sensor or engine component is misbehaving.

Obvious one that springs to mind would be TEG, although how much they do with road cars at the moment, I have no idea. Probably not too much, but if you don't ask, you won't find out.

As per previous post you can emulate a select monitor with a laptop, some freely downloadable software and a few quid on a diagnostic interface.

stedee

iTrader: (4)

sounds a bit like a knock sensor or maybe temp sensor, did you do the cel check btw

stevo1970

iTrader: (1)

The knock sensor was replaced just over a year ago after it showed the code on the CEL.

What temp sensor?

TonyBurns

iTrader: (3)

It could also be the O2 sensor, but you need a dealers diagnostic equipment to find that out, because unlike some monitors, this bit of kit will carry out a test on said sensors to see if they are within the correct calibrated working range.

Tony

stevo1970

iTrader: (1)

I've had a good look around again and changed the fuel filter. While the intercooler and many of the induction pipes were off I noticed a small nick in the induction pipe that feeds the turbo on closer investigation I think I can see damage and a piece of pipe hanging down at the bottom of the pipe, difficult to see though, so before I take the inlet manifold off (I need to acording to other posts on here) to remove the pipe I was wondering if this could be the cause of the symptoms i've described?

If air is being metered by the MAF and is then leaking before it goes into the turbo to be presurised would confuse the ECU and mal adjust the fueling? Or visa versa if the air was being drawn in after the MAF and before the turbo (which seens more likely to me) then you would bet the same result. Either way air at turbo/engine not as metered.

Make sence?

Splitpin

You've already received an answer to that question Steve, the second paragraph of this.

Yes and yes. Hence the original suggestion to check it. Any opportunity for air to escape from (or get into) the inlet tract after the mass airflow sensor can cause measurement errors.

Before you take the inlet manifold off, I'd suggest you pop down your local Halfrauds/Machine Mart/dentist's etc and pick up a small mirror you can use to inspect the pipe in situ (with help of a torch). Where the OE induction pipe fits onto the turbo, there is meant to be an extra little strip of plastic designed to hold the jubilee clip in place. This may be what you can see hanging off - see if you can get a closer look. The other thing you can often find is that the pipe wears through or splits near the turbo because either the jubilee clip has been overtightened, or because of the constant vibration and slight flexing.

If there is a "nick" or hole through that pipe though, it needs renewing.

stevo1970

iTrader: (1)

Are these likely to be any good?

http://cgi.ebay.co.uk/Silicone-Subar...item335b6546df

Is it a false aconomy?

Sorry posted before I realised, can I post this here?

Splitpin

That particular item will be no use to you at all as, although the picture appears to be of a 99-00 compatible part (albeit with an elbow that would struggle to fit past the PAS reservoir), according to the description, the picture is "for reference", and whatever you will be buying is for 97-98MY cars and thus won't fit your MY00 at all.

In general those unbranded silicone induction pipes are a lottery as many of them are weakly/cheaply made and, fit problems aside, are prone to collapsing under high throughflow. You can mitigate that by sticking jubilee clips around the middle to reinforce them but it's a faff better avoided if you have the opportunity.

If it does turn out that your current pipe has been punctured, the obvious path to a replacement would be a good condition OE item from a breaker. At least then you can put it all back together expecting it to function normally.

stevo1970

iTrader: (1)

At last the problem is solved. I;ve posted the cure to add to the knowledge base of the site.

Thanks to splitpin and everyone for their advice.

Anyway this was the fault, damage to the inlet pipe as it connects to the turbo, was probably damaged when a new short motor was installed in 2006 and it got progressivly worse until it began to pass air buggering up the metering and fueling.

Ely1482

bloddy well done for finding the problem been keeping an eye on your posts as i seem to have same ish fault looks like i need to strip off the inlet track just orderd lamber sensor too as think its over fueling but any way good for you mate

rob84

iTrader: (5)

It looks worse now off the car than it did when I was inspecting it lol

Splitpin

Nice one Steve. As per #14, overtightening the jubilee clip is not an uncommon problem.

Don't forget to show your other half so she knows the original symptoms weren't psychosomatic.