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View Full Version : Boost pattern of a K04??



kermac
09-26-2006, 06:08 PM
Hi again, and thanks for your responses to my last post.

My problem (well ... today's problem [:D]) is that each time I get into a forum like this, I'm amazed at the sort of power others seems to be getting from their 1.8Ts with a similar setup to mine.

I'm running a GIAC chip (type unknown as it was customised - long story[:o]), K04, 3" exhaust from turbo back, GFB DV, N75J etc etc). Best result I can get on the dyno is around 150 hp. This looks pretty sad compared with some of the figures I see from similar setups on AZ. But read on ...

Ever since I installed my boost gauge a year or so ago, it has shown the following figures at WOT (ie it's completely consistent every time I check it, so malfunction seems unlikely:-

16 psi @ 3,000 rpm
20 @ 4,000
16 @ 5,000
13 @ 6,000
10 @ 7,000

I queried with the guy who did the installation whether it was normal for boost to fall off in this way with a K04 as I had thought the main reason for using the K04 was that it would maintain the boost as the revs rose in a way the K03 couldn't.

He said this was normal as the K04 was still a very small turbo (true!) and it wasn't capable of maintaining anywhere close to 20 all the way up the range.

Now I've just spoken to a local (Canberra, Australia) guy who runs a VW with the 1.8T engine and almost exactly the same setup as me apart from a different chip. He reckons my motor should be maintaining 20 psi all the way to the red line like his does. He has had the vehicle on a dyno (I think he said it was FWD, not AWD) and recorded over 185 hp. Reckoned with a bit more work he would see something like 210 atw. This makes my best run of 150 hp look pretty sick.

He said he found the K04 setup so satisfactory he wouldn't dream of stepping up to a Big Turbo with all the expense, the extra lag and the problems of finding software (for a non-DBW b5).

He queried whether I had a MAF problem, but as I said, the consistency of the boost pattern suggests there is nothing wrong mechanically.

I get the feeling someone's bullshitting me here. What does anyone think about my boost pattern? Should I be falling off to only 10 psi at red line?

Poopie
09-26-2006, 06:46 PM
boost leak maybe? I'll spike 21 really hard and fall to around 19 psi to redline. Your boost looks ok so It might just be a leak somewhere.

EuroA4
09-26-2006, 06:57 PM
I suggest getting a VAG and logging some data...its hard to assume since you are seeing boost readings on a gauge there is nothing wrong mechanically. The MAF starts to die a slow death by some people's account, and the first thing I'd check was for a boost leak...you should not fall to 10psi like that...15-16 at the most.

kermac
09-26-2006, 07:00 PM
Appreciate your opinion Poopie. But my boost doesn't 'spike' (if you mean the needle flashes up to a peak reading and then immediately falls again?). It rises progressively to 20 and then gradually falls away as the revs rise.

It's been doing this consistently, with the readings exactly the same, for over a year. Even going up a steep hill where the revs are not rising quickly, as long as she's revving around 3,800 to say 4,400 the gauge shows 20 psi. The boost only falls as the revs get closer to 5.

If there was a leak - first, I don't think it would reach 20 psi, and secondly I would expect the leak to get worse over time.

I wonder if there's something the chip vendor isn't telling me? I originally had 370cc injectors fitted but we couldn't get her to run smoothly so we reverted to the stock injectors. The vendor told me that with the smaller injectors she was leaning out above 6,000 so I shouldn't spend too much time above that level.

I'm starting to think he may have keyed in a falling boost level to discourage me from revving the motor, as well as to minimise leaning out.

kermac
09-26-2006, 07:08 PM
Thanks Euro.

See my response to Poopie ... that solution has been suggested, and I'm trying to get hold of an OBDII cable to diagnose any possible mechanical problems. Any idea how you check for a failing MAF?

But I think the same would apply to the MAF - if it was failing, would it not deteriorate gradually over time and mileage?

The unusual feature of my symptoms is that they have not changed by so much as 1 psi over a year.

As an aside, the MAF was suspected when my boost started disappearing altogether some weeks after I had my N75 valve replaced with a N75J. Turend out the brand-new J valve was the culprit ... never got around to testing the MAF [:D]

kermac
09-26-2006, 07:13 PM
Originally posted by EuroA4
I suggest getting a VAG and logging some data...its hard to assume since you are seeing boost readings on a gauge there is nothing wrong mechanically. The MAF starts to die a slow death by some people's account, and the first thing I'd check was for a boost leak...you should not fall to 10psi like that...15-16 at the most.
PS love your car - if I saw it in a car park I'd mistake it for my own. I fitted a set of Eibachs and grooved Bilsteins a few weeks ago, and as well as handling a whole lot better, it looks like a racer instead of a Toyota Landcruiser.[:D]

Alas - I don't have any photos yet. But she wouldn't look much different from yours apart from a set of slimline, bright red number plates. Wonder if these will confuse our Speed Cameras?[drive]