No announcement yet.

Solo_S14 Needs Help!! - Tuning Experts??

  • Filter
  • Time
  • Show
Clear All
new posts

  • #31
    Hey so I haven't yet found a good e-tuner, but I have been working through through some issues / troubleshooting.
    One of which was the "Enginebasics" article that called out the AEM EMS V1 as missing an amplification circuit that the stock Nissan ECU uses for knock sensing.
    His fix was an early Saturn Resonant type sensor vs our non-resonant type sensors. I wasn't connecting the dots as to how the typical 300-500 millivolt output from one of those sensors wouldn't need amplification also, so I asked AEM on a thread in their forum that was dealing with this question - except they had answered for Version 2 which has additional knock tuning capabilities.

    I haven't yet received an answer, but there are a few things that may be of interest to you guys there:

    Since I'd also typed out an update and some questions over there, I'll post it here for anyone interested.
    Also, if you know of any reputable tuners that could help me out remotely, I would like to find one!

    For reference, I am running an SR20DET Blacktop with 87mm pistons @ 9.0:1 CR (86mm stock bore @ 8.5:1 CR), slightly larger Tomei 265 Poncams, Ferrea valvetrain, GT2871R, 740CC Injectors (380cc stock), and have backed away from EBC to MBC on advice of my tuner while we try to sort out these "knock" issues. For reference, I dyno'd about 380WHP / 360 TQ (always picking up the "knock" between 5000-6500RPM) before pulling the engine apart and finding zero damage. This has been a 5yr on again, off again problem - so any advice will go a long way!

    In short, if you guys have any ideas on things I can troubleshoot to either verify that the knock volts I am seeing are fine, or change to sort out why for example, I get knock retard without knock voltage regularly, I would really appreciate the help. The shots below outline some logs and scenarios that I've captured as a baseline - but really need the questions about the V1 answered above before I think I can move forward.


    Last night I logged a 2nd gear, low load pull (-10psi to -4psi) from 3,000 - 7,000 RPM as a baseline for "noise".
    That highest reading was at 6480RPM, 0.16V which seems negligible if the amplification circuit works in the EMS V1. 6400RPM will be a common theme here:

    Here, I have a 2nd gear pull, full throttle, from 2000 - 7100 RPM.
    The AEM is pulling the maximum amount of timing (5deg) from 3850RPM (With Zero Knock Voltage?) onward.
    Most knock volts from 5600-6600RPM, with max readout of 0.76V at 6600RPM.
    ** Notice that at 1:49 there is a drop from 5700RPM to 5600RPM after a 0.3V knock event, then again at 1:50.5 from 7100RPM to 7000RPM.
    No such drop at the higher peaks of 0.33V at 6000RPM, 0.33V at 6450RPM, or 0.75V at 6600RPM. I am thinking this was just a one-time thing - but if you have any advice I am all ears.

    Then, a 3rd gear pull, with smooth RPM build - again the EMS pulls 5deg of timing from 3750RPM, with no Knock Voltage.
    A lot of high knock voltage events beginning at 5800RPM (0.4V), 6000RPM (0.95V), 6300RPM (0.8V), 6350RPM (2.85V), 6650RPM (2.55V), and 6900RPM (1.0V).

    For comparison, I tried a bit of a partial throttle sweep from 3500 - 7000 RPM in 3rd gear at up to 14psi of boost.
    A 0.33V reading at 4500RPM, the EMS pulled the maximum 5deg of timing through about 5,000 RPM.
    Then "relatively quiet" from 5,000-6,200 RPM, before spikes as high as 2.75V at 6470 RPM at 13psi.
    So the EMS is still pulling timing quite early, and we are seeing high knock volts throughout the power band, concentrating at ~6400RPM.

    One last 2nd gear pull, with peaks of more than 0.5V at 3900RPM (start of peak torque), 4800RPM (end of peak torque), 5550RPM (historic "knock point"), and 6450RPM (New favourite knock point).
    The EMS is pulling timing from 3900RPM onward - this time after a knock event vs the prior charts with timing pulled before knock events?? Still don't understand those ones.

    For reference, here are my current fuel and timing tables, as well as my last dyno graph(s) - all dyno plots at less advanced timing.
    Last night I added some timing to be more in the range of standard SR20DET tunes, but obviously it isn't helping me with the knock voltage.
    From what I gather, I can pull another 5-10 deg of timing, sacrifice the performance, and still "knock".....or sort out a better system to read and tune for verified knock events...

    Fuel - a few areas of ramp and hold, based on adjustments to logs

    Ignition - Early build, drop and hold throughout peak torque, then build again.
    Note that earlier dyno graphs would hold or drop timing following peak torque (fighting knock voltage / noise), with the exception of the 2008 tables which detonated an engine top death.

    Dyno Charts:

    2012 (Bold) vs 2013 (Thin)

    In Zipties We Trust....


    • #32
      Dyno graph and ignition table from 2008 - Original tune:
      - Tuned with 93 Octane pump gas
      - Car made 379 WHP and about 370 ft.lbs at 18psi
      - Power drops off from 5800 RPM until it curves back up near redline
      - Consistent area for a drop-off in power - possibly undiagnosed detonation issues?
      - I used this tune for about a year before losing the engine to detonation
      - Timing was still initially conservating at about 9-13 degrees advance at 18 psi

      Ignition table from 2012 - Melted Harness:
      - Tuned with 94 Octane pump gas
      - Car was only tuned to 5900 RPM due to detonation issues
      - Tune was basically stepped up in 1000 RPM increments to tune driveability and stopped here once we observed detonation
      - At this level, the car made 347 WHP and about 309 ft.lbs at 17psi (basically untuned at high boost)
      - Consistent area for detonation to begin at 5750 RPM

      - We ended up melting the clips on the coil pack harness CYL #2 & #3 - and thought that this may have been causing our ignition / detonation problems, and stopped tuning
      - Turns out this was because when they initially did the swap they cut off the grounding wire on the harness and wired the harness into an HKS "ignition amplifier". While troubleshooting we bypassed the HKS box and in doing this removed the only ground that the harness had. We finished the day thinking that we had diagnosed the detonation issue - but we were wrong
      - When we began detonating the timing advance between 5750 and 7000 was about 6-11 degrees (still conservative) at 17psi
      - When we finished it was much lower at about 2-8 degrees advance at 17 psi - Still detonating!

      Dyno graph and ignition table from 2013:
      - Tuned with 91 Octane pump gas (All that is available out East)
      - Car made 377 WHP and 362 ft.lbs at 19psi (Very Consistent with the 379 WHP and about 370 ft.lbs at 18psi from 2008 when they used 93 octane fuel)
      - Power stays flat from 5750 RPM to 6500RPM
      - Consistent area of detonation from 5750 RPM to redline - Consistent issue!
      - Timing is still very conservating at about 7-9 degrees advance at 19 psi

      More info here:

      Anything useful to help me calibrate / verify these knock events using the AEM EMS V1.......or anything odd you guys notice for SR20DET application in the tables / graphs I would love the feedback.

      Thanks all for the assistance!

      In Zipties We Trust....