On a somewhat longer trip I took yesterday I noticed that in 4th and 5th I seem to get slightly fluctuating boost at WOT. By this I mean I can hear the turbo spool up repeatedly, but only slightly, like in the "upper-spool-up" range: on WOT there's the normal woooooosh long spool-up sound followed by a series of shorter woosh-woosh-woosh repeating sounds, but no "dump" sound, so I'm guessing that only the peak boost is affected. This can also be felt in how the car pulls: very good (by my standards) up to where the fluctuations start, then also very good but with a very slight jerking. It's not really THAT annoying, since the jerking can barely be felt, and the car really goes, but any ideas are welcome. I'm thinking of trying another n75 valve...

Also, as far as I can tell the thing manifests itself in upper gears, like 4th and 5th, not so much in lower ones...

On a somewhat longer trip I took yesterday I noticed that in 4th and 5th I seem to get slightly fluctuating boost at WOT. By this I mean I can hear the turbo spool up repeatedly, but only slightly, like in the "upper-spool-up" range: on WOT there's the normal woooooosh long spool-up sound followed by a series of shorter woosh-woosh-woosh repeating sounds, but no "dump" sound, so I'm guessing that only the peak boost is affected. This can also be felt in how the car pulls: very good (by my standards) up to where the fluctuations start, then also very good but with a very slight jerking. It's not really THAT annoying, since the jerking can barely be felt, and the car really goes, but any ideas are welcome. I'm thinking of trying another n75 valve...

Also, as far as I can tell the thing manifests itself in upper gears, like 4th and 5th, not so much in lower ones...

The reason It happens In higher gears Is due to the fact you are under load. The reason this Is happening, I don't know?? I have the same problem & It isn't a map issue as I can still feel It with the standard map, but only slight. I've changed the N75, DV & PCV, but It still does It. I can see on the boost gauge that the boost drops then picks up, drops & picks up again??

Is yours mapped??

Maybe the spring in the wastegate actuator has relaxed over time, or the spring has corroded slightly reducing its rate. Or it's just out of adjustment, and low on pre-load.

Sounds like the wastegate valve is lifting slightly at high P3 pressure, then closing and opening again as the pressure gets reduced by the valve opening.

Maybe the spring in the wastegate actuator has relaxed over time, or the spring has corroded slightly reducing its rate. Or it's just out of adjustment, and low on pre-load.

Sounds like the wastegate valve is lifting slightly at high P3 pressure, then closing and opening again as the pressure gets reduced by the valve opening.

If this Is the case what could be done?

Dial on some more pre-load or fit a new actuator.

I know Forge make new ones, not sure of anyone else. People like VW/Skoda buy the turbo's as complete units, and don't repair components on them, so doubt they'd be able to supply just an actuator.

Dial on some more pre-load or fit a new actuator.

I know Forge make new ones, not sure of anyone else. People like VW/Skoda buy the turbo's as complete units, and don't repair components on them, so doubt they'd be able to supply just an actuator.

Mine Is a replacement turbo from TPS that was fitted last October. I know It was a recondonitioned unit as they all are, but I suppose the actuator never got changed.

Yea mine is mapped also, i've 1.5-1.6 bar peak boost then 1.4bar. Wouldn't dialing in more pre-load on the actuator increase my peak boost? (in which case I'm kind of reluctant to do it myself )

Also, the turbo was replaced with a brand new one beginning of 2007 (the receipt says 1400 eur!)...i'm guessing it came with a new actuator, but can't really know for sure.

Edited 8 March, 201016 yr by jmf

I had this problem until I stumped up for a decent map. The generic one caused the issued you have and once Paul at RS tuning worked his magic, the problem instanly stopped. Previously to that, I'd changed various bits with no success assuming - as I'd been told - that the generic map wasn't the issue.

I had this problem until I stumped up for a decent map. The generic one caused the issued you have and once Paul at RS tuning worked his magic, the problem instanly stopped. Previously to that, I'd changed various bits with no success assuming - as I'd been told - that the generic map wasn't the issue.

I could understand that, but mine does It with the standard map???

Well, today I met with a friend to swap my n75 for his. Before I went to meet him I took off the 007p DV to clean: it was quite dirty, dirty oil mixed with the temp grease, the cylinder didn't go smoothly AT ALL when pushing it with my finger. So I cleaned it and oiled it properly, made it like brand new. When putting it back on I also noticed some misting around a clamp for the turbo pressure hose so I also tightened that clamp a bit.

Then I met with my friend, but before putting his n75 in I took him for a ride to show him the "symptoms". Guess what: they were gone! We drove for about 30km, nailing it VERY hard and it went like a rocket throughout, no hesitations, just straight pulling from 2500 to 5000 (i'm not going past that until I put bigger injectors in ). Then took a break while he worked on his brakes, then another ride, again perfect. Then another break (about 2hrs) and now on the way home (this time alone in the car) again trashing...wow it goes!

So I guess one of the two, either DV clean or clamp did it. Any ideas which it might be? I'm leaning towards the DV, since the clamp was pretty tight, and the oil misting was not so much, so I'm thinking the DV was probably not closing all the way or getting somehow stuck, allowing pressure to escape? Also, if it was the clamp I'd have thought the pressure loss would be constant, but for me it was intermittent, it was loading/dumping/loading/dumping, which is kind of DV-ish

Edited 8 March, 201016 yr by jmf

Another reason why I shall have to get round to fitting an oil catch can - the DV is another part of the intake system that gets well and truly clogged up with oil. When we took my mates Split-R off it was caked in the stuff :no: :no:

what setup you running with the k04???

i.e you done the fuel pump maf etc etc??

ell done for fixing it strange how silly things work lol

Who me? It's all in the signature (except the fuel pump and injectors and exhaust, which are pending... )

yes you lol didnt see the sig lol

what power is that running then ????

Don't know, dyno is expensive Receipt from the tuner says 240-260ps, which is kind of how it goes, compared to other cars (e.g. 1.8Ts with various maps, 2.0Tfsi stock, Focus ST stock, Focus ST mapped etc).

I've already changed my DV & It still does It :( You can see how bad It Is on my RR graph a month ago.

Well, i was going to try the other n75 then adjusting the wastegate rod so I guess those are still good leads for you to try. One other thing I can think of is a boost leak test at about the pressure your turbo is making, which is around 1.3bar as far as i can tell from the graph. What DV-s did you try btw? I've the yellow spring in the forge 007p.

What mods do you have? Those 252bph sound quite mighty

Edited 8 March, 201016 yr by jmf

the prob witht he above map is its trying to hold 1.3 bar throught the entire rev range on a k03s lol you will need shares in a turbo company with this map lol

oggy try the actuator rod 1 turn and then log the boost

It should probably peak at 18psi (1.3 bar) at about 2500 revs then fall to about 15psi (1.1bar) between 3000 and 5500 revs rather than holding the 18psi all the way up. What other mods does your car have Oggy? Would be interesting to have another look at Rob's Custom Code graph as that went all the way up to 21psi IIRC but don't know if it tries to hold that for long.

It should probably peak at 18psi (1.3 bar) at about 2500 revs then fall to about 15psi (1.1bar) between 3000 and 5500 revs rather than holding the 18psi all the way up. What other mods does your car have Oggy? Would be interesting to have another look at Rob's Custom Code graph as that went all the way up to 21psi IIRC but don't know if it tries to hold that for long.

Forge TIP, Forge 007P DV with yellow spring, Carboinio CAI, 100cel miltek sports cat, blueflame exhaust, FMIC & 4bar fuel reg.

Jesus Oz that's some boost you got going on there :S

@ JMF I'm surprised you've still got this car buddy, you've had a lot of probs with it but I'm glad your iorning them out P.s I'm now back on Yahoo

Edited 9 March, 201016 yr by vRSMart

@vRSMart: well with the help of a community such as this how can I NOT be ironing them out

@oggy You said you changed your dv: what with? Another 007p? It might be worth taking a look at your current one for dirt and/or lubricating it anyway.

@vRSMart: well with the help of a community such as this how can I NOT be ironing them out

@oggy You said you changed your dv: what with? Another 007p? It might be worth taking a look at your current one for dirt and/or lubricating it anyway.

I changed the DV for a new OE one to try, but no change, but the 007p was checked & serviced before putting back on & no change.

I see, well then I guess adjusting the wastegate rod is the last left option to try. I talked to a few friends who know their way around turbos and they also agreed that this might fix it.