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Hesitation/Misfire problem

RichA3Turbo Jan 20, 2006

  1. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Yep...Already snapped one! lol. Luckily ECS do them for $3! /ubbthreads/images/graemlins/smile.gif
     
  2. HTC

    HTC Active Member

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    DOH!

    £2.83 from Audi, so not too bad there.
     
  3. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Well. on my way home this evening, i did the CC screen to show the coolant temp... And it was near enough to the dash panel to tell me the sensor is OK... However, the car would not go above 76oC, which tells me the 'stat is screwed! i've oredered a new one from GSF anyway, so will change that and see what happens.

    Rich
     
  4. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Did it again this morning (hesitation/mis)... Bloody thing! Getting really annoyed with it now!

    Rich
     
  5. Markb

    Markb Active Member

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    Interesting reading this.

    Never really bothered about it before, but yes mine has got a slight hesitation at about 2.5-3k RPM. Although due to mine running standard power it's not really much of a jolt!

    Hopefully getting mine back tomorrow after it's been stood for a month. So I'll see how she's running then (Like a bag of nails probably!)

    Mark.
     
  6. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    I was visiting Ed and Nathan at Automotive Performance Services on friday (www.autops.co.uk) and was speaking to them about this issue... They were pretty helpful of suggestions for possible causes... One of which was the ABS system and wheel speed sensors .etc. This can cause issues apparently if wheel speeds .etc dont match.

    Its something i think i shall be looking into! Going to clean the ABS rings and the hall sensors for good measure!

    Rich
     
  7. HTC

    HTC Active Member

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    The electronic diff lock (EDL) function does indeed use the ABS to apply braking to individual wheels if "spinning" is detected.

    This system only functions up until 50mph. Does your problem occur above this speed?
     
  8. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Will need to check on that. Its primarily in 1st-3rd gears around 3000rpm.

    Rich
     
  9. Khufu

    Khufu Well-Known Member

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    [ QUOTE ]
    The electronic diff lock (EDL) function does indeed use the ABS to apply braking to individual wheels if "spinning" is detected.

    This system only functions up until 50mph. Does your problem occur above this speed?

    [/ QUOTE ]

    Mine only works up to 15mph IIRC /ubbthreads/images/graemlins/confused.gif
     
  10. benk

    benk Member

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    I thought that the system engaged at about that speed (15mph), and that this caused the slight "clunk" you sometimes get when first setting off in the morning, etc?
     
  11. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Mine has only ever kicked in in first gear..makes an odd noise, and does little else. Utter waste of time! lol
     
  12. HTC

    HTC Active Member

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    Can't say I've ever noticed it on mine.
     
  13. Khufu

    Khufu Well-Known Member

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    sounds like a grinding noise. its only useful if you have one wheel in the mud and the other is on firm ground.
     
  14. cybrey

    cybrey Member

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    [ QUOTE ]
    Mine has only ever kicked in in first gear..makes an odd noise, and does little else. Utter waste of time! lol

    [/ QUOTE ]
    Mines kicks at the point I would normally spin the tyres getting away from a junction.

    BTW with regards to the problem I don't think its do with the ABS. Mine ( when it happens at around 3000rpm) feels like a complete loss of power followed by it coming straight back in again which gives the surging feeling.
     
  15. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    [ QUOTE ]
    Mine has only ever kicked in in first gear..makes an odd noise, and does little else. Utter waste of time! lol

    [/ QUOTE ]
    Mines kicks at the point I would normally spin the tyres getting away from a junction.

    BTW with regards to the problem I don't think its do with the ABS. Mine ( when it happens at around 3000rpm) feels like a complete loss of power followed by it coming straight back in again which gives the surging feeling.

    [/ QUOTE ]

    I dont think it has anything to do with it either...But its something i may try and rule out.

    Rich
     
  16. AL_B

    AL_B Well-Known Member

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    Rich,

    As you have probably read in the other thread, even a new MAF has not solved the hesitation for me.

    I just don't know what to try next.

    Thinking out loud...its as if the DV is sticking open...but that can't be because its a Forge 007P (they don't stick do they?)....what controls the DV....on my car the N249. If the DV was to be stuck open....then you could press the accelerator all you want...boost would be created, but it would be immediately recirculated. But surely I'd hear that? So in this scenario it could be either the DV or the N249.

    Likewise...the N75 controls the vacuum which operates the wastegate. My N75 is new, but perhaps the wastegate is sticking?

    It could be the throttle position sensor or throttle body. One or the other could be sticking, or producing a strange value, causing the ECU to get confused.

    Finally, it could be a vaccum or boost leak somewhere. Perhaps as the engine gets put under load, the engine will move, flexing/moving the pipes (we've all seen it on the dyno how much the engine moves)...so perhaps when the engine moves, its opening up the leaking pipe somewhere?

    End of my ramblings. I'm sure there's other things it could be too. What a nightmare.

    AL
     
  17. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Al,

    Going to service my DV and check... But think its OK. I dont have an N249, just a simple DV>inlet manifold vacuum line.

    N75 is a possibility which i will replace and see what happens

    Wastegate is unlikely...that would be 3 different turbo combos - not likely.

    TB/TPS - a possibility, but at the price they are, id leave that til last! Also swapped my TB a few months back as my old one, the TPS had failed.

    A leak is unlikely as it wouldnt really give you hesitation like that...just a lack of power. Take it from someone who when fixing one leak, causes another! lol.

    Rich
     
  18. cybrey

    cybrey Member

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    I think its very unlikely to be a leak as it occurs as random times where as a leak would either be always at a specific rev range or a dimished power throughout.

    I think its most likely to be a fault in the ECU programming. Do all the people have the same model / engine codes ?
     
  19. cybrey

    cybrey Member

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  20. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Which goes back to what i mentioned earlier.
    im going to get a price for it/them and see if they solve it.

    Rich
     
  21. benk

    benk Member

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    Interesting that these 2 threads have both come back to knock sensors.
     
  22. AL_B

    AL_B Well-Known Member

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    Rich,

    You said your hesitation mainly occurs in lower gears, 1st, 2nd, 3rd.

    I know you';ve already looked at the race logic system, but I was thinking this morning, is worth completely disconnecting it, AND pulling the fuse on the ABS system (or which ever fuse disables EDL etc.).

    Worth a try maybe.

    AL
     
  23. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Yeah, i am definitely going to bypass racelogic...just to check. its just a real pain in the arse to disconnect!

    The last few days, the hesitation has not been there... It has also not been cold the last few days...But with a cold snap coming up, it will soon be apparent if there is a problem with it. I think it will wrap the racelogic box in some foam insulation to keep it warmer.

    Rich
     
  24. Jodi

    Jodi Starsky

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    Not wanting to worry you, but have you thought about doing a compression test on your cylinders. I don't know if you saw my thread around Christmas time, but I had a misfire problem that was only really noticeable at idle with a slight loss of power at speed. After changing plugs coil packs and changing the coolant temp sensor (I too got the warning light at start up). Eventually I took it into a recommended garage for them to have a look (I had lost patience and time).

    Unfortunately I had lost compression in the cylinder. Ouch! I don't want be a scaremonger, but it might be worth a check.
     
  25. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    I'll check compression on the weekend... thanks

    RIch
     
  26. AL_B

    AL_B Well-Known Member

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    Whats the solution if compression is low?
     
  27. god_thats_quick

    god_thats_quick Numptie of the highest order

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    piston rings normally, can end up being new block or re-bore though - that's how my engine troubles started.
     
  28. HTC

    HTC Active Member

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    Not always piston rings. Sometimes valves can fail to seal.

    You need to do wet and dry compression tests to tell where the problems lie.
     
  29. god_thats_quick

    god_thats_quick Numptie of the highest order

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    [ QUOTE ]
    Not always piston rings. Sometimes valves can fail to seal.

    You need to do wet and dry compression tests to tell where the problems lie.

    [/ QUOTE ]

    good point hadn't thought of that!
     
  30. AL_B

    AL_B Well-Known Member

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    Rich,

    Whats the latest for you?

    AL
     
  31. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Its not been doing it recently...dont nkow why! Its not been as cold which i think has something to do with it. Did it the other morning when it was a little frosty but other than that. has been OK.

    Rich
     
  32. AL_B

    AL_B Well-Known Member

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    Similar thing here.

    Motorway up to Scotland and back, car was fine. The little stint down the country road following David in his Porsche...bit of hesitation at high revs 3rd gear.

    Then Monday, Tuesday, Wednesday this week, car is fine. Going like an absolute rocket - for a standard car of course. MAF readings of 186-191g/s. Feels great. Just don't understand it.

    AL
     
  33. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Well i think we are getting somewhere - Its temperature dependent!
     
  34. Khufu

    Khufu Well-Known Member

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    Its the cleaner air up here LOL
     
  35. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    So my car was misfiring the entire way home last night!!

    So o go to start it this morning and its doing the same thing. I have not bypassed the racelogic, and still doesnt work! wont actually start at all. I've taken the plugs out and cleaned them with brass brush and that didnt achieve anything.

    The connectors that i use to bypass the racelogic/use it were a little smap so i think my issue is water! they were waterproof connectors!! So cars sat on drive at home, not working. GREAT!! /ubbthreads/images/graemlins/frown.gif
     
  36. imported_ZeroK66

    imported_ZeroK66 Guest

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    You mention at one stage it wouldnt rev over 2k...

    I had that once... the G60 management had a sensor for "throttle closed" where it ran the idle program.

    This was bypassed for my setup - but I accidentally taped this up once and so no matter what I did with the throttle it would just run the idle programme and run lean when I put my foot down - would not get over 2k.

    Just a thought maybe your motronic uses something similar and there is a dodgy connection/sticking switch somewhere on the throttle.

    Long shot I know - but another idea in the hat.

    Cheers,
    Leon
     
  37. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    Im pretty certain that if i make the connections with the racelogic permanent, that it will solve my issues - Cant be bothered /ubbthreads/images/graemlins/swear.gif around with connectors so just going to solder the connections and double heat shrink them.

    Rich
     
  38. darnich

    darnich Member

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    Rich,

    I really think you have to double check the coolant sensor...
     
  39. RichA3Turbo

    RichA3Turbo ...Watching you! Staff Member Moderator

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    teh coolant sensor wouldnt cause it to not even start though.

    Rich
     
  40. darnich

    darnich Member

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    Not really!
    My car refused to start last summer....
    I had to have the car on WOT and keep the ignition turning for a good 60 secs before it finally started... coughing black smoke from the exhaust...

    I immediatelly took it to my mechanic who without even plugging the car to the diagnostic equipent said it is probably a faulty coolant sensor. We replaced it and no probs ever since.

    The reason for refusing to start was (as the mechanic eplained)...
    that the ECU has to adapt the mixture according to the temp (richer mixture when the temp is colder). When the sensor is dodgy it will read whatever and the mixture will get all mixted up.
    In my case when the car was plugged in the coolant sensor read -9c when the outside temp was +35c and therefore the ECU choked the motor with very rich mixture.

    I had similar starting probs before but it wasn't easy to trace because the sensor was not really out of range.

    I really think you have to check the coolant sensor...
     

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