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Low power 1.8T bex :(

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Paul_A4_UK, Dec 7, 2013.

  1. Paul_A4_UK
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    Paul_A4_UK Member

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    I set out this morning looking forward to having my car remapped and whilst I've made some healthy gains I'm a little concerned.

    I have an Audi A4 1.8T BEX engine which should be around 188hp standard. Car has only done 66k miles so it may have lost a few but on the dyno standard it made 167.9hp and 190ft/lb of torque. So torque is slightly up over standard figures but power is 20hp down?! Most confused, especially as it is a coolish day so I thought I'd see good results. I was a little gutted when they said what power it made standard.

    So after a stage 1 revo I now have 197.6hp and 246ft/lb torque. So torque is spot on but what the hell is going on with my power? It is niggling at me as I've never had any vehicle dyno 20hp down on standard figures.

    Guys who did the map said the car is running really nicely and not to worry that it is down on standard power. I'm a man who likes his numbers to be right though!!

    Anyone else had a BEX engine put out low figures? Something can't be right surely?

    I'm wondering if my ECU had a map on it for the lower power 1.8T? How would I find this out?

    My ECU number is 8E0 909 518 AS and revision 0003

    Cheers

    Paul
    #1
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  2. AlexGSi2000
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    AlexGSi2000 Well-Known Member

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    Could be down to a number of things.
    These cars are getting on abit now, so ensure all vac hoses and lines are not split / perished.
    N75 valves can become lazy over time.
    Most importantly, check your boost hoses - same story as with the VAC lines, these can perish and split too.
    #2
  3. Paul_A4_UK
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    Paul_A4_UK Member

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    I'd have thought the guys where I had the car remapped would have checked that kinda thing when it popped up at 167.9hp. They said that 1.8T bex engines do make low figures like these sometimes but do they really? I mean 20hp is a fair amount. 4-5 maybe but not 20.

    How does a revo remap work? I have read in the past that 1.8T BEX engines have left Audi with the incorrect map installed as standard. I am wondering if this may be my case? If the revo remap is a complete new map though and not just a tweak to the standard map I should be up to the 220hp-225hp mark.

    I'm just a bit confused as it makes such great torque figures. Why does it achieve those but such pants power figures.

    I will take a look at my hoses myself though to be sure.

    I've read about the N249 delete, what does the N75 do? if this was lazy would my torque figure still be as good as it is?

    You'll have to excuse the dumb questions as I'm quite new to owning / fettling a turbo engined car.

    Cheers

    Paul
    #3
  4. Rodders.
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    Rodders. Member

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    Buy a better car
    #4
  5. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    As a rule most generic flashers are not responsible for checking the health of your car, they are just reflashing the ecu software. The health of the car is up to you. Fault finding takes time that you are not paying for.

    You need to get yourself vcds and start some logs off to see if we can detect where you start. Do you have a boost gauge?
    #5
  6. Paul_A4_UK
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    Paul_A4_UK Member

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    No boost gauge no. Rodders and I do own a vcds so we'll have to get some logs once we've figured out how to use it properly. As ever Rodders you always have the perfect answer!

    Let the fault finding begin!
    #6
  7. Paul_A4_UK
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    Paul_A4_UK Member

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    Just been looking at my dyno print out and I think boost is OK. Post remap it peaks at 1.5bar_g then tapers down to about 0.7bar_g. Stock was 0.8bar_g peak then stays pretty much around the 0.5 to 0.6bar_g. Sounds about right from what I've read online?
    #7
  8. Paul_A4_UK
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    Paul_A4_UK Member

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    Here is my dyno chart

    [​IMG]
    #8
  9. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    theres a boost leak in there somewhere, i'd expect your turbo to hold better than that tbh
    #9
  10. Ian2012
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    Ian2012 Member

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    Well i can offer some advice, check your diverter valve is working and is newish, don't bother with aftermarket the audi part 710n designated is the one to fit, the coolant temp sensor can also hold things back and finally based on very recent experience a failing fuel pump will very much hold the car back, you can if you have a fuel pressure gauge plug into the rail to check pressure. Having just fitted a new pump our BEX engined car is running unbelievably well.
    #10
  11. Paul_A4_UK
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    Paul_A4_UK Member

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    Thanks for the replies. I was actually planning on having the DV replaced with a 710n next service, which is due soon. The original clamps are still on the one I have so I'd say it is on the original DV still. I'll see if I can source a fuel pressure gauge, it should be at 4bar in my car yes?

    I'll also get to checking for boost leaks and reading up on how to do that. Lots to learn still after owning NA vehicles up until now.
    #11
  12. Paul_A4_UK
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    Paul_A4_UK Member

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    Random thought, what if Audi only fitted a K03 to my A4 instead of a K03s?

    Is there any easy way to tell which turbo I have without getting under the car? I've had the air snorkel off but the can't see the bit I'm looking for to indentify if it is a K03s I have fitted from the top. I found some images online and the K03s has a silencer (I think that is right) on one part and it is this I am trying to see but can't Don't really want to have to pull the TIP off to count the blades if I can help it.

    Highly unlikely it is this but the thought popped into my head this morning.


    Cheers
    #12
  13. pauldazzle
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    pauldazzle Member

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    Very unlikely Audi would do that.
    Much more likely that you have split boost/vaccum pipework or the DV seal is failing.
    #13
  14. madmike01uk
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    madmike01uk Member

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    A descent tuner should have checked to see what was up. R-tech would have been my choice. Hope you get it sorted mate.
    #14
  15. Paul_A4_UK
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    Paul_A4_UK Member

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    Yeah I was a bit miffed why they loaded a map when it only made 167hp stock. The reason I was given was that it wasn't unusual for this engine to kick out low figures like this?! Then I was told it was running really nicely and I shouldn't worry that it's 20hp down. Hey ho, I should have pressed the point more at the time I guess.
    #15
  16. Paul_A4_UK
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    Paul_A4_UK Member

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    I've been checking through the service history of my car and the green coolant temp sensor was replaced in 2011 with another that has part number S058198025A which I believe is a genuine part. I've got no error codes for that and the car has only done about 10k miles since then so I'd hope it hasn't gone awry already. Last service (62k and its now on 66k) it had all new filters including new fuel filter. It also had new plugs fitted, NGK 6458. Only thing I can see I don't like the look of is the oil used. They put in Comma Syner-g 5w-40. I've some Castrol edge 5w-30 to put in at the next service. I don't believe that would cause any power loss though.

    New 710n DV should arrive tomorrow. Just wondering what size and type of clips will I need to fit it?
    #16
  17. Ian2012
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    Ian2012 Member

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    I have to say that the part number for the coolant temp sensor does not sound like an audi part no, it's a shame you can't take it back to standard with un messed ecu, i can't help feeling the people that did remap have somehow managed to mask an existing problem prior to it being mapped, i would only map a healthy car that has been tested to give close to what it should do from the factory.

    So in essence i think you should go back to go forward if that makes sense? Oil and filters won't make huge difference. Trey to get it put back to standard or get a used BEX ecu that hasn't been played with and as the americans say "start over"
    #17
  18. Ian2012
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    Ian2012 Member

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    Sorry hose clips are half to 3/4 inch approx make sure you fit it the right way round
    #18
  19. Ian2012
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    Ian2012 Member

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    is your fwd or quattro?
    #19
  20. Paul_A4_UK
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    Paul_A4_UK Member

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    I know. I wish I'd been there when he'd done the before run as I would have called a stop to it there and then. Hindsight hey! The remap got me the 30hp extra it should I just need to shunt the whole lot a bit higher. Still can't figure out why I made great torque (245ft/lb) but low power. Maybe I do just have a bit of a naff engine. Are the cams on pullies that can be adjusted slightly in these engines? If so maybe one of those is out slightly?

    Hoping to get the use of the VCDS cable I purchased with some friends soon so I will be able to get some logs to see what is happening as I drive.

    I don't think I was classed as a high value customer where I went for the remap based on being told that it isn't unusual for the BEX engine to give out low stock figures like mine is (just to get me on my way without asking too many questions). I however do not have access to other peoples results so cannot really argue that point and I do know that some cars give out crazy stock figures (Focus RS for example). I can only base my thoughts on input from people on forums like this one as to whether it isn't unusual for the 1.8T bex to only put out 167hp stock.
    #20
  21. Paul_A4_UK
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    Paul_A4_UK Member

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    Mine is fwd so transmission losses should be less, though not sure that this matters?
    #21
  22. A4cloth
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    A4cloth New Member

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    Hi sorry to be a bit thick how can you tell wot engine type you have??? Mine is a 1.8 SE 163 model?
    #22
  23. Paul_A4_UK
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    Paul_A4_UK Member

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    Mine has the letter BEX stamped onto the top of the engine under the plastic cover. I think the engine number itself has BEX in it on mine too. Check your logbook to see what yours says.
    #23
  24. Ian2012
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    Ian2012 Member

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    Got any codes stored?
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  25. Paul_A4_UK
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    Paul_A4_UK Member

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    When I checked before it had the remap it had a speaker error and a central locking one. The speaker one can be explained by the fact my window regulator was changed recently and potentially the car was powered up without the speaker plugged in. It is working fine. Can't explain the central locking one, it said alarm was triggered in boot and both rear doors wont de-safe. My central locking is all working fine however?

    There were no dates on these codes so I could not see when they appeared. I reset them last Thursday myself. I will re-check when I get the VCDS cable back. I do not think either of these errors would be the cause of loss of power however.
    #25
  26. Paul_A4_UK
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    Paul_A4_UK Member

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    If it turns out that I have a boost leak and I fix it, does that mean I should get the car re-run on a dyno to be sure it isn't running too lean? I'm unsure how they apply the Revo map and whether they would have made adjustments to get my AFR as it is now? In my head it says that if I cure a leak then more air will be being forced into the engine than it currently is thus it will run leaner than it currently does. Last thing I want is it to be running too lean at the top end.
    #26
  27. dualmono21
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    dualmono21 Active Member

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    leave the oil alone , you actually have the better spec oil in at 5w40 ignore the name

    divertor valves and n75 are both problematic on these engines
    the standard bosch divertor valve is plastic and not upto scratch especially if running higher boost levels
    check which n75 valve you are running as there are different revisions 'f' is known for going faulty at higher boost levels
    #27
  28. Paul_A4_UK
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    Paul_A4_UK Member

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    Looks like I should have ordered an N75 to replace at the same time. Would a dodgy N75 explain why my boost curve peaks then drops then rises then drops? I'd have thought it should peak and then simply tail off without rising again?

    Which N75 valve do I want? Do I want another F or do I want a J?
    Last edited: Dec 11, 2013
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  29. olly quattro
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    olly quattro Member

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    dont DD dynos always read power at teh wheels as oppose to flywheel?,,, your losses are mere transmission losses i'd of thought..
    #29
  30. Paul_A4_UK
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    Paul_A4_UK Member

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    197hp at the wheel? That's crazy high for a stage 1 only surely? Butt dyno says its an at the flywheel power based on my previous car being about 188hp-198hp depending on which dyno it was run on. Those were at the flywheel figures.

    What are transmission losses on the FWD Audis? I'd have thought 20%ish? That is a bit of a guesstimate though.
    #30
  31. Paul_A4_UK
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    Paul_A4_UK Member

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    Have the VCDS cable back and managed to do one log this evening which from what I can see only gives me my mass flow reading. Anyway here is what I the results are:

    Mass_Flow.jpg
    I take there must be other things that can be logged? What else should I look to log to check everything is running as it should?

    I contacted Revo today and the dyno I was run on is known as the 'heart breaker'!!
    #31
  32. dualmono21
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    dualmono21 Active Member

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    n75 version j will work fine but if your after more of a punch then try a c version this is used on the old b5 s4
    #32
  33. pauldazzle
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    pauldazzle Member

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    Wrong way round dude. C is the standard 1.8T valve, & J will give a steeper boost spike.
    #33
  34. Paul_A4_UK
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    Paul_A4_UK Member

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    Steeper boost spike? hmmm. As I'm only FWD it is struggling to put down power as it is at the moment. The roads are pretty slippery at this time of year though. I don't really need it to be any more aggressive so might just stick with OE with regards to the N75 then.
    #34
  35. dualmono21
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    dualmono21 Active Member

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    i was going off my experiance with the 1.8 leon cupra which has a very similar engine the std one was f and if you wanted a steeper curve you used the c version off the old s4
    #35

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