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Audi s3 8p performance issue

ChristianSwe Apr 29, 2020

  1. ChristianSwe

    ChristianSwe Registered User

    Hi everyone!

    I have an Audi S3 8p, year 2008 with engine code BHZ that seems to have some performance issues since it doesn't seem, or feel atleast to pull as hard as it did when I got the car. Seems that the turbo/power is kicking in at higher rpms like 4000 rpms or so. A few weeks after I got the car it was idling and all of a sudden just stalled and when doing so it was difficult to start the car. After this happened the car didn't feel as powerful after that. It hasn't stalled any more or thrown any DTCs.I also had a battery drain issue after I bought the car and my question is that let's say the car was tuned to stage 1 and if the battery drained out would it revert back to stock map? Because if so then that could be the issue as to why the car isn't as powerful as it were because I don't know or have proof that the car was tuned or not when I bought it.

    I've also got a weird rattlesnake noise when doing a hard acceleration which you can hear in the video that I've linked in this thread. Would an open air intake cause this noisy "rattlesnake" sound? (Don't mind the rattle noise in the beginning of the video since the blower fan in cabin is noisy).

    Beside that I also sometimes(not very often) receives a DTC for a misfire and when reading live data with OBDeleven and VCDS I can see that the misfire counter is counting on cylinder 2 and 3 when car is idling which you can also hear from the exhaust if you're close to the rear of the vehicle since it's sputtering a little. Perhaps this issue is connected to carbon build-up or faulty injectors?

    Down below you will see what repairs and mods that have been done.

    Revo open air intake
    DV+ diverter valve (performance issue and rattlesnake noise was there with the upgraded oem DV also)

    Replaced PCV with an aftermarket one(have ordered a oem from maindealer)
    spark plugs
    ignition coils

    These repairs didn't help with this issue.

    What repairs is coming for this car?
    I will do a carbon cleaning(walnut blasting) and have also ordered new gaskets and 2 new injectors for cyl 2 and 3 just in case
    Replace the PCV again with oem from maindealer.
    Replace fuel pressure valve with RS4 valve (If i want to go stage 2+)
    Replace the piston for the HPFP.
    Upgrade the clutch to a Sachs performance cluth kit that should be good for around 550 Nm and good for daily driving also.
    Replace the rear breather/pcv hose with oem
    Try with another new oem DV

    Link to video for the "rattlesnake noise":

    So what do you all think could be the issue to the performance, slight misfire on idle and the "rattlesnake" sound?

    Best regards,
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  3. e9_mustii

    e9_mustii Registered User

    No you won't loose you're map if you remove or replace your battery only if you take it to audi and they preform a ecu reset, rattle mean something may be loose you may not be getting full boost hence the feeling of it being slower so check you piping for i/c intake etc maybe its come loose, could be dodgy coil packs, dirty maf sensor ideal you need to have it scanned and maybe logged whilst driving to see what Reading change under what circumstance heavy hard acel ect.

    Sent from my SM-N976B using Tapatalk
    ChristianSwe likes this.
  4. samuelh_888

    samuelh_888 Registered User

    Hi @ChristianSwe, welcome to the forum. If the cam was mapped by REVO and you disconnect the battery then their map will reset to their base (stock like) map. You can get you map back with the SPS tool but changing the settings - but this assumes you have a REVO map. Otherwise it’s very unlikely the battery change has impacted it.

    As for the rattlesnake sound, I can’t hear anything from the video other than the DV+ dumping between gears. The sound (which I cant hear) could be compressor surge, which these turbos are known for. Compressor surge is where too much air is being fed in and the turbo can’t keep up (crude explanation) but a decent tuner will normally map around this.

    If it was me I’d do the following - replace PCV (as you are), replace DV+, check that the intake it tight at the turbo, there is an Oring where the turbo outlet pipe joint the intercooler bayonet. If this is damaged then it will suck air under boost - the company who fitted my IC damaged the Oring (common amateur mistake apparently) so the car wasn’t boosting correctly, sucking air and generally no power - replacing this Oring resolved the issue. Until then my turbo was working overtime to try to generate boost - don’t know, worth a check maybe?

    If you’re taking the injectors out to replace filters then get them ultrasonically cleaned while they’re out. This should help with the miss fires.
    ChristianSwe likes this.

    CHRIS SPIJKER Registered User

    I had similar problems when i had my standard pcv valve, the rubber oring had a split in it, replaced it for a new one solved the issue

    Sent from my SM-G975F using Tapatalk
    ChristianSwe likes this.
  6. ChristianSwe

    ChristianSwe Registered User

    Thanks all for your replies!

    I've just recently bought a new oem DV valve from dealership but haven't replaced it since I remembered that I had to get new screws for oem dv since the dv+ screws are a little bit shorter.

    I have checked that the intake pipe is connected tight and firm to the turbo which it is. Seems to be a little movement in the rubber pipe from the turbo to the intake pipe but I assume that is normal right? The clamp is secured tightly anyways. I haven't checked the o-ring between the outlet pipe and intercooler but will check this.

    I've logged some readings with obdeleven and according to the readings i have peak boost of 2600 mbar, can that be correct regarding boost? Let's say that I have a boost leak in a pipe to the intercooler for example, would the car still displaying that amount of boost even tho there is a leak? And if there is a boost leak, wouldn't that usually be a dtc for it?

    Another thing that I've also noticed is that when the car is idling and I'm reading the live data for Camshaft adjustment (intake): Camshaft adjustment intake b1 (actual) it's reading around 46 degrees when the solenoid for the camshaft adjustment is unplugged(DTC also of course) and when plugged in it's displaying 34-35 degrees but should have 28 degrees as specified value. How many degrees + or - is ok to have from 28 degrees if that is the correct value at idle? What's also strange is that I cannot use the function to do an basic setting/adaption, it just says test off even tho the readings are within the limits but maybe it's too high in idle and that is the reason.

    And oh, I've also replaced the aftermarket PCV with a new oem pcv from dealership but didn't change much in regards to performance or smooth idling. I've also replaced the map/boost pressure sensor with a new oem one from dealership too.

    The rear breather/PCV hose has also been replaced with oem from dealership which for my car was just a regular hose going to the turbo from the cylinder head cover since there was no valve in the hose. Did fix what seemed to be a minor oil leak tho as the old hose had quite a bit of oil. Might have been old oil tho who knows :D
    Last edited: Jun 7, 2020
  7. Daveyonthemove

    Daveyonthemove Well-Known Member VCDS Map User

    Have you tried logging 'Actual boost' Vs 'Requested boost'?
    It's hard to make out in the video clip, but the 'Rattlesnake' noise sounds like a flutter noise to me. It only seems to be on boost, so that suggests it may be DV related (not holding boost correctly) or Turbo related.
    Was the car remapped in your possession or did you inherit the Remap when you bought the car?
  8. nluk100

    nluk100 Registered User

    Check your lower intercooler pips for signs of oil seepage as this is another common fault with these cars. If the ECU detects the boost is being lost due to a leak it will try to add more boost so you may not notice any real power loss, just the car will feel laggy. As above try and log actual vs requested boost across a few gears to see what the delta is between them. 2600mBar on OBD11/vcds is 1.6Bar which is about right for a mapped car.
  9. ChristianSwe

    ChristianSwe Registered User

    As far I can see when looking through the documents I can't see anything about remap and the car was purchased at a auto company. It's just that when I got the car it felt like it had a little bit more punch compared to now.
  10. ChristianSwe

    ChristianSwe Registered User

    Okay I will do that. If there is oil in the lower intercooler pipes that means that there is an issue with the turbo right? Is there a common with the K04 turbos with leaking seals?

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