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Thread: WRC-inspired track build

  1. #321
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    crazy build.... attention to details and the build in general is immense.... lovely car dude...

  2. #322
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    I had the car on the hub dyno a few weeks ago, and unfortunately another disappointing day. I had the dyno booked for the whole day but we didn't make it very far....so it was a costly and unproductive day sadly.

    There's massive det on cylinder 3, for no obvious reason. The other three cylinders are fine. Romain tried running all 8 injectors, also just the top rail and also just the bottom rail but it made no difference. As soon as any boost was present, the spikes were huge and we had to abort with suspected mechanical issues.

    However - I've compression tested the engine and it's good (125-130psi across all four) and I've had the injectors tested (again) and they're all fine. We removed the plugs and three are fine, but the plug from cylinder 3 is showing signs of a clear lack of fuel and high temperatures. The adjacent cylinder is getting fuel, so I can't see it being a fuel supply issue.

    We've had a fibreoptic camera in the bore and there's no signs of det, no damage and nothing out of the ordinary.

    I need to investigate possible electrical issues, but if anyone has experienced something similar or have any wisdom I'm all ears...


  3. #323
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    So was he all ears too ?

    ie is he just relying on what the knock sensor is seeing, or did they actually listen for detonation with the det cans ?

    Just how bad were any spikes, and exactly when ? And how often ?

    I assume he did adjust noise levels for that cylinder etc ?

    You say there was massive det on cylinder 3....but are you really saying there was visible noise seen via the ecu, or you're actually saying there was 100% confirmed detonation ? The two are not the same, and if actual detonation, this would be a far greater concern.
    speed didnt kill me, but taxation probably will

  4. #324
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    Quote Originally Posted by stevieturbo View Post
    So was he all ears too ?

    ie is he just relying on what the knock sensor is seeing, or did they actually listen for detonation with the det cans ?

    Just how bad were any spikes, and exactly when ? And how often ?

    I assume he did adjust noise levels for that cylinder etc ?

    You say there was massive det on cylinder 3....but are you really saying there was visible noise seen via the ecu, or you're actually saying there was 100% confirmed detonation ? The two are not the same, and if actual detonation, this would be a far greater concern.
    There are two knock sensors on the car, both were reading accurately.

    I saw one of the plots of the det, the other three cylinders were normal and cyl 3 was showing significant spikes. To the extent the car misfired at 5k rpm and the ECU pulled the timing.

    The plugs are a good indicator, the plug from cyl 3 was like it had just been removed from the packet, the other three were black.

  5. #325
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    Quote Originally Posted by Rich View Post
    There are two knock sensors on the car, both were reading accurately.

    I saw one of the plots of the det, the other three cylinders were normal and cyl 3 was showing significant spikes. To the extent the car misfired at 5k rpm and the ECU pulled the timing.

    The plugs are a good indicator, the plug from cyl 3 was like it had just been removed from the packet, the other three were black.
    Knock sensors are just microphones, they listen for noise. All noise, it's what the tuner/ecu then does with that noise that matters....but it's up to the tuner to calibrate things so they make sense

    But saying that 3 plugs are black and one clean....is this new plugs after a pull ? That has to be a huge red flag.

    You compression test was even....was that all warm ? throttle open ? Leakdown test ?

    When running, with an infrared temp gun, is there any sign that cyl 3 is not firing ? ie measure exhaust on each cylinder.

    Does it matter what boost or rpm ? Does the engine ever behave as if it is all good ?

    If you alter fuel on only cyl 3 on the ecu ....does it have the expected change in running and wideband readings etc ? Try swapping wiring from cyl 3-4 ?

    Proven ignition system all working and good ?
    speed didnt kill me, but taxation probably will

  6. #326
    Senior Member Justin A's Avatar
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    Also check for inlet manifold leak around cylinder 3, I had a similar issue once, car ran fine but once up to temp and any boost then it would appear to run on 3
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  7. #327
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    Quote Originally Posted by stevieturbo View Post
    Knock sensors are just microphones, they listen for noise. All noise, it's what the tuner/ecu then does with that noise that matters....but it's up to the tuner to calibrate things so they make sense

    But saying that 3 plugs are black and one clean....is this new plugs after a pull ? That has to be a huge red flag.

    You compression test was even....was that all warm ? throttle open ? Leakdown test ?

    When running, with an infrared temp gun, is there any sign that cyl 3 is not firing ? ie measure exhaust on each cylinder.

    Does it matter what boost or rpm ? Does the engine ever behave as if it is all good ?

    If you alter fuel on only cyl 3 on the ecu ....does it have the expected change in running and wideband readings etc ? Try swapping wiring from cyl 3-4 ?

    Proven ignition system all working and good ?
    Thanks Stevie I appreciate your input.

    Yes new plugs when the engine was built, it did an hour on the dyno to run the engine in, and then the next dyno session where we ran into the issues. The car starts and runs perfectly well on four cylinders, it's only when we started to introduce some boost that things were clearly not right. No other signs beforehand of an issue.

    The compression test was with a cold engine, throttle closed. A leakdown test is possibly the next step.

    The engine sounds sweet, no audible warning signs. In fact no signs that would otherwise make me hesitate in booking a full day on the dyno and having three tins of race fuel at the ready!

    We saw 1.5bar and about 5k rpm and that was enough to show significant det so at that point we called it a day, it's not really the time or place to start diagnosing faults when the car's on the dyno and the meter is ticking, so we didn't investigate further than pulling the plugs.

    I can swap the injector wiring from 1-3 but the problem I've got is the car behaves perfectly normally at idle and I can't diagnose much outside of a mapping session on the dyno...

    I'll probably drop the car off somewhere next month for a leakdown test and further investigation.

    Cheers,
    Rich

  8. #328
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    Quote Originally Posted by Justin A View Post
    Also check for inlet manifold leak around cylinder 3, I had a similar issue once, car ran fine but once up to temp and any boost then it would appear to run on 3
    OK great thanks - I'll double check.

  9. #329
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    Compression test should always be done with throttle open....if there is no or restricted air to compress, you can get false readings.

    Swapping injector plugs 3-4 will at least test the ecu/wiring. If the problem stays on cyl3, then you're into mechanical/engine issues.

    If the problem moves 3-4, then you're potentially into wiring/ecu problems. But it's a simple and free test.

    Even if you re-configure the ecu to tell it you've swapped 3-4 that's ok...as it's the same physical wiring and same ecu driver so still a valid test to see if the problem moves.

    Switching injectors pri/sec as you've already done, at least proves the fuel injectors are not the problem

    Air leak on boost as Justin says is also worth looking at. Wouldnt be the first time I've seen people not tighten up manifold bolts correctly etc.

    but again i ask is this real and verified detonation with your ears, or perceived detonation via noises seen from the knock sensors. The two are not the same.
    Likewise, and it's truly more a yank/old school thing....reading plugs.

    Fit a new plug or plugs ( cheapy copper will be fine, correct heat range ) and make a pull on the dyno. This should also help verify if there is actual detonation or not. It isnt something I'm experienced in, but the yanks swear by it and there are many online guides.
    But it must always be new plugs and plugs pulled directly after the power run ( or in their case usually at the end of a 1/4 mile after shutting the engine down )

    http://ultimateaircooled.com/engines...ugs-101-a.html

    http://www.wallaceracing.com/plug-reading-lm.html

    But the fact you say with a borescope there is no evidence of detonation, you can see why I'm querying things. You're saying as fact there is detonation, with only questionable evidence of it....but the engine is noisy on that cylinder. Which could be A N Other problem or could be detonation. The old faithful DIY det cans are excellent for listening to confirm or dispel one way or the other.
    Although given the info so far...I'd assume they have done this already ?
    speed didnt kill me, but taxation probably will

  10. #330
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    Every time i have seen Romain map a car, he has used det cans and correlated the sensor readings.

  11. #331
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    That would be the sensible thing. But if it was detonating as heavily as suggested, there would be evidence on the plug and piston crown

    But for it to be on only one cylinder....makes little sense.

    Timing/ignition should be checked on that cylinder to ensure timing is what you expect it to be and also injector/wiring swap as mentioned ( and also swap coil wiring in a similar fashion, and if need be coils too. ) etc

    But a new set of plugs installed and checked after a pull when this problem occurs would also yield some info after doing the swapping cylinder tests.
    speed didnt kill me, but taxation probably will

  12. #332
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    Quote Originally Posted by stevieturbo View Post
    Compression test should always be done with throttle open....if there is no or restricted air to compress, you can get false readings.

    Swapping injector plugs 3-4 will at least test the ecu/wiring. If the problem stays on cyl3, then you're into mechanical/engine issues.

    If the problem moves 3-4, then you're potentially into wiring/ecu problems. But it's a simple and free test.

    Even if you re-configure the ecu to tell it you've swapped 3-4 that's ok...as it's the same physical wiring and same ecu driver so still a valid test to see if the problem moves.

    Switching injectors pri/sec as you've already done, at least proves the fuel injectors are not the problem

    Air leak on boost as Justin says is also worth looking at. Wouldnt be the first time I've seen people not tighten up manifold bolts correctly etc.

    but again i ask is this real and verified detonation with your ears, or perceived detonation via noises seen from the knock sensors. The two are not the same.
    Likewise, and it's truly more a yank/old school thing....reading plugs.

    Fit a new plug or plugs ( cheapy copper will be fine, correct heat range ) and make a pull on the dyno. This should also help verify if there is actual detonation or not. It isnt something I'm experienced in, but the yanks swear by it and there are many online guides.
    But it must always be new plugs and plugs pulled directly after the power run ( or in their case usually at the end of a 1/4 mile after shutting the engine down )

    http://ultimateaircooled.com/engines...ugs-101-a.html

    http://www.wallaceracing.com/plug-reading-lm.html

    But the fact you say with a borescope there is no evidence of detonation, you can see why I'm querying things. You're saying as fact there is detonation, with only questionable evidence of it....but the engine is noisy on that cylinder. Which could be A N Other problem or could be detonation. The old faithful DIY det cans are excellent for listening to confirm or dispel one way or the other.
    Although given the info so far...I'd assume they have done this already ?
    Thanks Stevie.

    I will try another compression test, I've heard of conflicting information regarding throttle open/closed but I need to check as I'm using DBW that the throttle is actually open...

    Once I've done that then a leakdown test is next on the list to try and rule out anything mechanical. I really don't want to pull the motor out so will try everything else first...

    I know that the eight injectors and the four coils are all powered via a 20A output on the PDM, as mentioned the car also runs and idles perfectly well. Swapping the injector plugs would need to be done on the dyno to get any meaningful results as to whether the det transfers to another cylinder.

    Yes I think Romain used det cans, bear in mind we were shut out of the dyno cell and couldn't see, but that is my understanding...I will confirm though. I don't think there was a question that actual det was present but I appreciate that the two are not necessarily the same...

    Cheers,
    Rich

  13. #333
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    At cranking speeds with DBW the throttle "should" be open enough for a valid test.....should, but really does depend how it's programmed. Holding pedal down may or may not open it further...again, depends how it's programmed. But it should be open for the test.

    http://www.pumaracing.co.uk/comp.htm

    But both tests really need done with engine properly warm. Although I'd be sceptical that it will reveal the problem, still worth doing them though. Pointless cold.

    If the problem is there all the time and repeatable...I'd be doing the spark plug test. You can do it almost for free and no dyno required. Likewise swapping injector wiring etc to see if the problem moves.
    Either via a visual on the noise traces for each cylinder, or colouration as to whether those spark plugs are actually firing or not.
    Again, always fit a new spark plug prior to doing a full load run, and pull it very quickly afterwards to get a better picture of how it was running when the problem occurred.


    Hell, you could even have shut that cylinder down completely on the dyno to see if the noise levels changed ( if perhaps it isnt already being shut down by a mistake somewhere in the calibration ? )
    You say the plug was clean almost new....that is a huge red flag there that combustion is not taking place

    Just follow a simple procedure. In this case you need to try and see if you can get the problem to move to another cylinder via wiring swaps, coil swaps, ecu output driver etc etc. All of which should be fairly easy to achieve with minimal work.
    speed didnt kill me, but taxation probably will

  14. #334
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    Also check cam timing, maybe get a visual on all the valves opening and closing too when the engine is turning over. Longshot, but free and easy to do in a garage.
    speed didnt kill me, but taxation probably will

  15. #335
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    I always tune cyl 3 a few percent richer and take out a few degrees ign timing. Purely due to the heat from the up pipe. I dont think thats your problem though. Good luck, sounds painful.

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