Mk4 Golf GT TDi feels underpowered plus white smoke

[Rob_2i]

Hello everyone,

Recently my car has generally felt underpowered with a lot of turbo lag and it produces a lot of white smoke when accelerating even moderately when not fully warmed up, which it did not do anywhere near as much when it was running OK. When the engine has warmed up there is minimal smoke. The car is running a lot better than when I first bought it but definitely not as good as it was after I sorted out a few problems. The car has been recently serviced.

Below is a graph showing expected and actual for both boost and MAF and also the N75 duty cycle * 10. The log was taken in 3rd gear WOT on a flat stretch of road.

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Are there any other logs that I could do to help determine what the problem is?

The previous owner tried disguising sticking turbo vanes by increasing the actuator rod length, so when I realised the vanes were sticking and cleaned the turbo out with Mr Muscle and then got the car stage 1 remapped this caused a massive overboost (1.5 bar of boost) and limp mode. I then adjusted and checked the operation of the turbo actuator with a Sealey vacuum pump and now the rod starts moving at ~5inHg and stops moving at ~22inHg, so it is just in range and if anything should it be slightly underboosting with it being right at the stiffer end of operation? Which is strange considering I am getting more boost than expected and the N75 is maxing out by about 4k rpm when it should be more like 80%?

For a short while after adjusting the actuator rod the car was running really well, with hardly ever any smoke and plenty of smooth minimal lag power. But now its the opposite and I can't figure out why? The fault codes read by VCDS can be seen at the bottom of this post, but they have all been there since before I cleaned the turbo and adjusted the actuator so the car has been running fine with these codes.

The EGR has a blanking plate fitted (and it is disconnected) which I've read can be a cause for higher than expected MAF readings but the EGR has been blanked since before I had the car. I have tried reconnecting the N18 but it makes no difference. Even at idle the actual MAF reading is not far off double the expected.

I have had a look for boost leaks but cannot find anything, I replaced all the vac pipes with silicon ones a while back and the actuator holds vacuum no worse than it has before.

Thanks in advance for any suggestions!

Fault codes:

Engine
18062 - Please check DTC Memory of Instrument Cluster
P1654 - 35-10 - - Intermittent
17849 - EGR Valve (N18)
P1441 - 35-10 - Open Circuit or Short to Ground - Intermittent

Instruments
00562 - Sensor for Oil Level/Temperature (G266)
30-00 - Open or Short to Plus
01176 - Key
07-10 - Signal too Low - Intermittent

Central Conv.
01135 - Interior Monitoring Sensors
36-10 - Open Circuit - Intermittent
00943 - Heated Exterior Mirror; Driver Side (Z4)
35-00 - -

[Crasher]

The white smoke suggests oil in the exhaust, Mr Muscle is well known for damaging the oil seals. It happened to one of my mechanics on his own car and filled the exhaust with oil when it went properly.

[zollaf]

mr muscle is a useful product for cleaning ovens.

[Rob_2i]

Thanks for the help.

Today I shortened the actuator rod a mm or 2 and it now starts moving at about 8inHg and stops at about the same as before (22inHg). The car smokes a lot less when cold and its more white/grey than white now and there is no visible smoke when accelerating hard after half an hour or so of driving. Also the N75 only goes up to about 85% @ 4k rpm now.

Still feels held back though..

Something I didnt think about was that I was using 5W40 oil but recently I put some 5W30 long life oil in because I do a lot of motorway miles and was fed up with changing the oil every 7/8 months, so now I'm going to change it once a year/every 16k miles.

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[Crasher]

I think 16K is too long, every 9k on 5w/40 looks after your engine and turbo. I change my oil every 5k and I use 5w/30 Longlife.......