Exhaust smell, down on power...

[dubster99]

Injectors were in excellent condition, the flow rate was slightly different between all 4

I reinstalled everything and conducted a boost leak test again, and as expected, the injector seals are no longer the problem, the injector seats are leaking air.

Drivability is getting better. I have ordered some billet injector cups from Phenix Engineering and some slightly bigger o-rings they offer. This should nail the leaking injector seat situation.

Do these fit the injectors? I was going to order some but was afraid that my 386cc injectors wouldn't fit because they are larger

[Sirocco20348]

These cups are 100% identical to the plastic ones that are currently in our AGU.

1.8T Injector Cups - Large Port - Phenix Engineering

They are available from many companies, but I bought from Phenix, as they were very responsive on Facebook Messenger with all my questions.

I had a hairy moment yesterday, as the car would not start. For some reason the engine was flooded with petrol, perhaps because I stopped and started it so quickly yesterday.

To solve this, I pulled the fuel pump fuse and keep cranking until it sputtered to life.

I drove around last night very leisurely as I haven't boost leak tested my car since I put it back together.

I'll type up some more findings soon, but the cabin fumes have been greatly reduced.

[Sirocco20348]

Update:

The injector cup replacements have solved the exhaust smell in the cabin.

The performance problem is still there, but I think I am onto something. N75...... This assholish valve.

I replaced the n75 a year ago with a new genuine E valve, so it has not been on my radar.

I am currently running the E valve, but I swapped it out for the F valve I have lying around (I replaced this last year due to suspecting it was faulty)...

The difference was magical. Not 100%, but way more power, boosting 20psi etc. Vagcom confirmed 99.6% duty cycle. It was so strange thou, similar boost achieved but smoother, stronger performance.

But that didn't last long, as expected performance soon became even worse but not too far off what I had previously with the newer E valve (providing about 15psi, but it felt like it was dumping the boost out).

I then unplugged the n75 from the turbo actuator, and I could maintain 22psi no problems.

The ohms test for the n75 is very misleading I find. The valve resistance reading could be in range but clearly faulty.

I'm going to replace the n75 again. $130 from dealer. I bought off eBay last time.

[Sirocco20348]

I just realised I had a thread created for n75 potential problems in 2014, but resolved via boost leak fixes haha.

Diagnosing a malfunctioning N75

I have boost leak (plus smoke tested at mechanic) tested this stupid car until the cows have come home. Surely I have them covered.

[jmcc]

Is it just when it gets up to temperature? I saw something yesterday on the UK mkiv Facebook about overheating the actuator? Seems unlikely, it's built to be connected to the turbo, they had to have engineered it for heat right?

[Sirocco20348]

Is it just when it gets up to temperature? I saw something yesterday on the UK mkiv Facebook about overheating the actuator? Seems unlikely, it's built to be connected to the turbo, they had to have engineered it for heat right?

I'm not sure exactly when it plays up, there have been so many different scenarios so far I'm confused in my mind. Every time I drive the car out does something different.

The drive home today was much better. So close to full potential. It was boosting to 20psi. Not too bad, but still not 100%.

I have subjected this actuator to very hot temps, I doubt it would be of concern.

Part of me still thinks it's a boost leak. I might test it again. N75 most likely a waste of money.

[jmcc]

Yeah I didn't think it'd be likely but was worth a shot.

Maybe the map needs tweaking?

From what I've read a small amount of boost leak should't have a huge impact on performance? Maybe the reliance on the MAF and the narrowband 02 make it worse though. You almost need a haltech or emerald just to get enough data to properly diagnose the problem.

[Sirocco20348]

Time for another update:

I partially removed the cat section of the exhaust and viewed the cat from the rear. It looked clean as a whistle. I kinda regret not dropping the while section out while I was at it, but I shined a torch into it and I didn't see any congestion.

I drove the car with the rear of the exhaust removed and ut drive exactly the same, except was very loud as expected.

Still no codes from the ecu...

In the interim I have ordered a fuel pressure tester. I always wanted to check the pressure anyway.

[Sirocco20348]

Fuel pressure testing:

I received my kit and I only tested idle pressure atm as I don't have a way of viewing the gauge while I am on boost.

"The 1.8T fuel system has a base fuel pressure of 58Psi (Approx. 4Bar).

This is the value seen when the vacuum line is disconnected from the FPR.

Vacuum at idle will cause fuel pressure to sit closer to 50Psi or 3.5Bar."

This is what exactly what I observed.

[Sirocco20348]

MAF observations:

I purchased a brand new bosch MAF about 2 years ago. It solved my problem as my previous MAF was completely stuffed.

However, I was reading a thread on audi-sport.net, https://www.audi-sport.net/xf/thread...109831/page-12

This guy is mentioning the exact same problem as me (AGU block) and it ended up being his already replaced MAF?!?!

Exact thread post talking about his solution Prawn and BigAls A3 Track Car

Here is a vagcom log of my current bosch MAF... do the values seem excessively high for a k03s turbo? I always thought I had exceptional MAF values because it was a brand new MAF.



I do not really want to buy a new MAF if it doesn't solve my problem.

IS THERE ANYONE IN THE BRISBANE/GOLD COAST AREA THAT WILL HELP ME BY LETTING ME SWAP OVER THEIR WORKING MAF TO TEST IN MY VEHICLE. Please....

Even if someone is interstate and have a spare one lying around I will pay for postage to and from and ill give you something for your help.

[Sirocco20348]

MAF update:

VW don't sell new MAF sensors as of 2012.
The part number 037906461C was superseded by 037906461CX. The X denotes it's a exchanged item.

So it's someone's old ****ty MAF that has been 'refurbished'. What ever that involves, the guy at VW doesn't know exactly.

The dealer wants $498 for a refurbished MAF sensor, plus they want my MAF to refurbish.

I replaced mine 2 years ago with a brand new Bosch 0280217117 MAF.

I don't understand why VW is concerned with refurbishing MAF sensors, if Bosch makes them new?!?

I wonder if there is an actual difference in quality between the 2 parts....

Here is a picture of the actual sensor part number in my 0280217117 Bosch MAF.

It would be interesting to compare the sensor numbers in a original MAF...alas I threw mine out 2 years ago.

Anyone have a busted one they want to check out the sensor number for me?

[Sirocco20348]

The Bosch 0280217117 is the replacement for Bosch 0986280201....I wonder if it's a refurb... To be continued

[h100vw]

MAF observations:

I purchased a brand new bosch MAF about 2 years ago. It solved my problem as my previous MAF was completely stuffed.

However, I was reading a thread on audi-sport.net, https://www.audi-sport.net/xf/thread...109831/page-12

This guy is mentioning the exact same problem as me (AGU block) and it ended up being his already replaced MAF?!?!

Exact thread post talking about his solution Prawn and BigAls A3 Track Car

Here is a vagcom log of my current bosch MAF... do the values seem excessively high for a k03s turbo? I always thought I had exceptional MAF values because it was a brand new MAF.

[ATTACH=CONFIG]40932[/ATTACH]

I do not really want to buy a new MAF if it doesn't solve my problem.

IS THERE ANYONE IN THE BRISBANE/GOLD COAST AREA THAT WILL HELP ME BY LETTING ME SWAP OVER THEIR WORKING MAF TO TEST IN MY VEHICLE. Please....

Even if someone is interstate and have a spare one lying around I will pay for postage to and from and ill give you something for your help.

180g/s is supposed to equate to 225hp at the crank. So i'd say its not far off. Might be a little late in the rev range, Which could indicate a soft actuator.

I fix a lot of mk6 gtis by tweaking actuators, lazy spool up. Can make 20kw difference if it's really a really bad one.

[Sirocco20348]

I feel confident enough to mark this thread as SOLVED. Thanks to everyone that replied to the thread and supplied information. I am going to give credit to Gavin (h100vw) for pointing me in the direction of the wastegate actuator.

I have full history of this Ko3s turbo as I bought it brand new and it now has 40,000kms on it. My car was originally set to 3 turns of the actuator locking nuts. Which gave me wastegate cracking pressure of 3PSI.

I originally tried to add tightness by using some external springs as per the Spring Mod on VWVortex. VWVortex.com - Wastegate Actuator Spring Mod

After countless times going back and forward to Bunnings, i concluded that this mod has minimal worth. People claimed to achieve wild cracking pressures by doing this. But even with the springs that I finally used which were tight (..however overextended the working range of the extension spring) I only ever got approx 1 extra PSI of tightness. Maybe I was doing something wrong.

So spring mod jumped the cracking pressure upto 4PSI, However I could already feel a positive difference with the car with the car coming onto boost sooner and higher WOT boost.

I unwound the tightening nuts, reset the waste gate into a closed position and ultimately tightened it up 4.75 turns with the addition of my spring mod. (I experimented many times with increasing the nut from 3 turns upto 4.75 turns (1/4 turn increments) with the spring attached) Many late nights...

4.75 turns and spring mod gave me a cracking pressure of approx 5.5-6psi. My car is now spooling up to 22psi psi and is back to being what I remember.

I took my car for a drive yesterday (WOT in 2nd, 3rd and it was the same fun I used to have in the car with 22psi bumping in every gear. I logged in vagcom, and its still registering a rich mix. But my friend driving behind me was saying there was no black smoke from my car at any time.

I also replaced the 02 sensor after all this was done and I felt as thou my partial throttle boosting was smoother. Not very technical testing. On the AGU the o2 sensor is a critical part of the ecu calculations and i bought a brand new Bosch sensor for $100 off ebay and took minimal time to install on my aftermarket dump pipe. This is the one I bought.

Genuine BOSCH Oxygen Sensor 0258005081 | eBay

[jmcc]

Congratulations! You made it.