Finally found my problem

[Prawn]

Well chaps, yesterday I finally found the cause of my long term boost loss issues!

I was fitting my decat, and whilst I had the downpipe off, I thought I'd take a few pics inside the exhaust housing. visually looking in with a lead lamp these couldn't be seen, but looking on the pc later on told a different story

Now, it's pretty clear that the circle on the left is a nice crack in the housing next to the wastegate, which is obviously going to be causing a sizeble loss of boost, but what about the right hand oval I've drawn?

Is that some sort of casting mark, an unfortunate black line, or a monsterous crack?

I think it's safe to say a new turbo is needed! Although how soon I'm just not sure. the car hasn't changed it's performance for over a year, so I can safely assume it's been like this a long time!

I guess I'll have to join the long que of others on the lookout for a ko3s again This'll be my third!

 

[S3 HODGE]

Ouch, Why not upgrade to a K04? :icon_thumright:

 

[audi18tdan]

that explains everything!!
Well atleast you can now stop wondering what's causing it and if it wasn't for the de-cat idea you wouldn't have found out.
So we can have a pretty good guess at the fact you should have alot more boost with a new turbo running with de-cat.

Its a neever ending story!! hopefully when you eventually get a new turbo it'll be running sweet.

 

[Prawn]

thing is, I'm now not sure what I should replace this with.....

if I get another ko3S, is it not just as likely to crack again? if I save and go for a CRT ko3/ko4 hybrid, that'll still have the same exhaust housing, so isn't that just as likely to crack, if not more likely due to the higher boost and flow going through it?

I don't want to go KO4 really, as I've only just splashed out on a new 3'' downpipe and decat for the ko3S, plus, the performance is fairly good as it is now, and having Dans (above) stage 1 AUM last night, despite recording lower peak air flow, the midrange boost made it feel FAR quicker than mine, if mine felt as quick as his I'd be more than happy.....

hmmmmmmmm
decisions.....

 

[Westy]

This is the problem with these engines. The smallest of cracks or splits anywhere can cause major issues. At lease you've solved it.

 

[simch]

I ma not convinced! I've seen K 03s with worse cracks than that and no "boost issues" at all! But it cannot be helping matters!

 

[grathies]

Gutted for you mate, on the plus side atleast you should have found the solution to your boost problems

 

[Prawn]

Cheers chaps, I'm really hoping it is the cause, I can't see how this wouldn't be stopping boost really.

Simch, do you really think it's possible for the turbo to boost properly in that state?

What boost was the cracked ko3S you know of producing? Mine will still make 15-16psi, just not the requested 22psi it was mapped for originally.....

 

[Broken Byzan]

I ma not convinced! I've seen K 03s with worse cracks than that and no "boost issues" at all! But it cannot be helping matters!

^^ I am with him^^

I am shortly fitting a turbo to mine with a crack like that in it. Its not through so doesnt leak.

 

[ianysm]

It makes sense, a small leak will prevent it from giving its absolute optimum (which at 22psi, is what's being asked of it)

Seems a shame to have to buy another K03S if that one will just do the same. Abit like constantly replacing a fuse instead finding the cure, or replacing with a higher rated one!

 

[Prawn]

Well, to throw another spanner into the works, here are some logs I did last night, on my car, and a mates.

these are to be taken with a pinch of salt, as they're based on the bhp=MAF/0.8 equation, with torque calculated from those values and RPM, but as a direct comparison between two cars, I think it's fairly accurate.

First log is mine, which to be honest felt REALLY slow, despite what the graph suggests:

Then this second log is of a mates car, which is a stage 1 AUM with an FMIC and catback exhaust:

The figures are lower, as I'd expect them to be, but his car felt WAY faster, in every gear, at all RPM's too.....

Which leads me to think, if these graphs are based solely on airflow, it would appear mine is sucking in the air to make the power, but where is it going?

there is no audible boost loss, is it possible I'm loosing boost back into the PCV system via the check valve under the inlet mani? could that account for as much as 9psi lost from peak boost?

 

[emery1990]

Ahh thats sh*t for you mate. Is there know way you can test the turbo for leaks to be absolute sure. Couldnt you take it out and see if the crack has gone the whole way through the turbo ? I

 

[1animal1]

Prawn.....one of my mates has just bought a GT28 to replace his low mileage KO3S, unsure when hes fitting it but he will defo be selling it.... let me know and ill ask to see when it will be available, roughly

defo has no cracks....the lads a mechanic and wouldnt have fitted it otherwise

 

[Prawn]

Cheers Tim, that'd be awesome if I could get one from a 'known' source. I'm in no hurry either, as it's been broken for so long anyway! let me know

I think you'd be more than within your rights about now to point out that an S3 can make this sort of power years on end without cracking turbos on an annual basis!

 

[1animal1]

haha never kick a man when hes down......

had a quick chat and reckon its gonna be months rather then weeks before he attempts the GT28 so will keep my eye out...if by the time it comes 'off' ya still looking then ill PM ya with his details

Tim

 

[Prawn]

that's cool dude. I'm in no position to do ANYTHING for 3 weeks absolute min, as that's next payday, although seeing as it drives fine now, I'd happily leave it a few months.

Drop me a PM when you hear it's up for grabs, and I very well may still be interested!

Cheers

Prawny

 

[S3 Paul]

Bad luck mate,
My old K04 went the same way,
Ive still got it somewhere,
When i sent it away to turbo dynamics for their opinion they said i could fit a new/ used un cracked exhaust housing and have it recon'd, The problem was finding an uncracked housing !
I was also lead to beleave that any crack would get worse because of the heat up cool down process everytime you drive it hard, That and the preasure of the exhaust gas's.
That said... My mate works at a known tuning company and he said atleast 60% of the k03 or k04 turbos he takes off are cracked, Many showing no symptems at all of boost drops,
I would try and check the manifold too for cracks... If its anything like a k04 set up... they are known for cracking too.

 

[Prawn]

Cheers Paul,

I know the turbo's are fairly famous for cracking, and after 191000 miles, 60 of those remapped, i guess it's entirely likely that my standard original exhaust manifold could be cracked too..... Would this cause a loss of boost too? it doesn't blow externally to my knowledge.

I think what I'm going to do, is bide my time for a cheap low mileage ko3S replacement, and also fit a THS HiFlow cast manifold whilst it's all off.

With any luck, that'll restore the performance I'm missing, and give me a little more top end. I just can't be bothered with the huge money and expense of any upgrade. to go ko4 would involve at least £1000 spend, and the same or more to go ko3/4 CTR hybrid.....

 

[1animal1]

hold onto your cornflakes Prawn...... due to a severe lack of use with the MCS (used once in three weeks) i'm trying to talk the misus into selling it and buying an A3 1.8T

 

[Prawn]

I decided that as my leaking pcv vacuum hose was split, the pcv system clearly hasn't been getting any vacuum aid for a very long time, so it wouldn't matter it I just cut the pipe, and plugged the end leading to the inlet mani, effectively stopping my boost leak.

i did this, and once the car warmed up I was instantly back to a solid 20psi

which I don't think it bad considering the ECU hasn't seen more than 16psi for the past 18 months, so I'm quite sure it's got a little more adapting to do.

The slightly less good news, is that since fitting the decat, there has been an audible rattle/slight whistle when blipping the throttle, before the turbo even comes into boost.

I just tried it with the bonnet open, and it's definately more of a rattle, definately comming from the turbo area, so it's entirely possible that the bearings are goosed, and the more free flowing downpipe makes the sound easier to hear. it's also possible that the 18 month boost leak has been working the turbo super hard to try and make the boost it's asked of, and as a result, destroyed the bearings.....

still, it's quicker now than it's been for a LONG time

 

[Prawn]

if the above post didn't make sense to anyone, Earlier today I found a huge split in the PCV hose that runs from under the inlet mani to the PCV check valve....

 

[Plunky]

glad you have found the problems mate, pitty about the turbo though! would be a great excuse for the hybrid i agree about the money involved though! when i sort my silcone hoses out for the IC we can do a comparison on mine aswell

 

[Westy]

Good stuff, must feel like a new car?

 

[castors wheels]

Wow...Very informative discussion. The problem stated in this discussion seems to be small to look. But creates a lot of mess. I saved all the information in this discussion for my future reference. Thanks for sharing with us.

 

[Welly]

Prawn, I used to have EXACTLY the same problems as you with boost not being what was expected.

When I took my old K03 off, it had cracks in identical places around the wastegate.

After a turbo change, this was all resolved and lovely, so I'd be pretty sure that it is your problemo.