help with a3 8l 1.8t (mk4 golf platform)

[Zornyan]

Hey chaps bit stumped here, first off car details.

Audi a3 1.8t 20v 8l 52 plate, AUM engine code, k03s turbo, standard map.

Aftermarket exhaust from turbo back
2.0t coil pack conversion
New copper ngk plugs gapped correctly
New maf from audio
New turbo so long I'd (n249 I think) from audio
New dump valve from audio
New pancake one way valve from audio
New pcv valve under inlet from audio
Throttle body cleaned and calibrated in vagcom, new gasket
All new pcv hoses (every single one)
New IAT sensor from audio
Boost pressure leak tested to 25 psi (no leaks)
New battery
New fuel filter

Issues it's having
On and off cold/hot starts car feels lumpy, idle is hesitsnt, requires more throttle than usual to pull away.

Rev counter doesn't sit right, as in at idle the revs seem to 'bounce' around, not huge numbers, but enough that the needle never sits still (around a few hundred rpm dips)
Turning OFF THE aircon, which makes it idle lower, the idle seems noticeably lumpier.
Some days, get in the car, warm it up, rag it and it pulls hard, other days feels like I could get out and push faster.
A loud audible 'whistle' when driving hard, SOUNDS like a pressure leak, but tests aren't showing anything (including a smoke test)

Getting engine codes
BANK 1 LEAN
o2 sensor out of range (along those lines)
Pressure drop between turbo and manifold


Known issues.
There's a small ticking sound when accelerating, think possibly turbo to mani gasket?
When doing the exhaust swap, we noticed a Crack in housing near wastegate, this was about a year ago, although at the time it didn't seem necessary to change.
Cam cover has an oil leak, need to swap the gasket.

Sooooo anyone got any ideas?

[Hosky]

When the throttle body was cleaned, was it reset? It may have a Cable operating it, but it still needs to have the basic settings put back into it

[boustie]

All those fault codes would indicate air leak. The most common being the VAC pipes under the intake manifold. Symptoms def like an air leak

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[Zornyan]

When the throttle body was cleaned, was it reset? It may have a Cable operating it, but it still needs to have the basic settings put back into it

It's fly by wire, and yes reset/calibrated in vagcom

[Zornyan]

All those fault codes would indicate air leak. The most common being the VAC pipes under the intake manifold. Symptoms def like an air leak

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Read my post dude everything under the inlet manifold is spanky new silicone hoses.

Also done the SAI delete so there's no rats nest under the plate for dipstick, and there DV is a regular mechanical operation.

[boustie]

Has it only done it since you've done all that.

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[rich damms]

Coolant temp sensor. Vw's bad for them, our old mk3 golf ran poor and lumpy due to incorrect fuelling caused by the sensor. Might be worth changing it for what they cost

[Zornyan]

Coolant temp sensor. Vw's bad for them, our old mk3 golf ran poor and lumpy due to incorrect fuelling caused by the sensor. Might be worth changing it for what they cost

Did 6 months ago for genuine item matey.

[Zornyan]

Coolant temp sensor. Vw's bad for them, our old mk3 golf ran poor and lumpy due to incorrect fuelling caused by the sensor. Might be worth changing it for what they cost

Did 6 months ago for genuine item matey.

[Zornyan]

Has it only done it since you've done all that.

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The mods have been done over 2 years, the various parts have been done over the last year, things like spark plugs etc a couple weeks ago.

It's been a slow progressing issue, that regardless of what I do gets worse. Hence my wondering if tubby could be the cause?

[R3K1355]

The fault codes look like it's unhappy with it's O2 sensor, is bank 1 lean to do with injectors or are there multiple O2 sensors on the engine?

[R3K1355]

Also why do you buy some much stuff from Audio

[Zornyan]

The fault codes look like it's unhappy with it's O2 sensor, is bank 1 lean to do with injectors or are there multiple O2 sensors on the engine?

There's 2 dude, front one is a wideband, rear is just a regular lambda, rear has had a spacer fitted for about a year (due to decat) and never thrown a code up relating to this sensor before.

[rocketbenny92]

I had similar problem with my 8L S3 turned out to be i couple of things, 1) intake pipe to turbo had a big gash in it
2) there was a vac leak from the N249 breather system that sits on the cam cover wich you can bypass , unsure if your code will be same as mine was, mine was APY


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[rocketbenny92]

Or could also be a faulty N75 valve, turbo to downpipe gasket failure is also extremely common mine went twice that will also loose you power.


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[Zornyan]

Or could also be a faulty N75 valve, turbo to downpipe gasket failure is also extremely common mine went twice that will also loose you power.


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N75 is genuine and new, correct code too.

[rocketbenny92]

Have you checked your intake pipe? From airbox to turbo?


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[Zornyan]

I had similar problem with my 8L S3 turned out to be i couple of things, 1) intake pipe to turbo had a big gash in it
2) there was a vac leak from the N249 breather system that sits on the cam cover wich you can bypass , unsure if your code will be same as mine was, mine was APY


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N249 (sai) has been removed correctly and resistors put in place, I get a fault code for the pump not being there, but it hasn't effected performance before.

I'll double check intake again, although we did pressure test and smoke test the system with no leaks found.

[rocketbenny92]

Also check your turbo to down pipe bolts arent loose, heating up and cooling down over time they come loose separating the 3 layer gasket, can cause whistling and noticeable performance loss, you should also be able to smell exhaust fumes round back of the engine bay.


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