16v ECU raised rev limiter - pics inside

Discussion in '16-valve' started by barny, Oct 14, 2006.

  1. Rusty Dan Forum Member

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    Good point, does it raise the peak torque level of the engine for optimum shifting?
    I cant see me needing 7800rpm in 5th on a 1/4 mile...
     
  2. websifus New Member

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    Is there any possibility for a tuner to modify the ignition-map itself and optimizing it to the AFR an the overall set-up of the engine?

    The opinions in the international forums are confusing and contrasting.

    - Many quote, that you can indeed only shift the rev-limit. The ignition-map itself is said to be stored in a non accessible eprom inside the processor.

    - Some tuners offer "optimized chips" for the KR-ECU
    http://www.bar-tek-tuning.de/Chiptuning+chip+VW+16V+KR.htm

    - Others offer complete sets as 268-Inlet-cam, mdodification of WUR and modification of VEZ and TSZ-h. WUR, VEZ and ZSZ-h have to send to the tuner for specific modification
    http://www.slstuning.de/f/vw/golf-ii/23467-1-8-gt-16v-102kw/stufe-1/

    How gets the engine adapted to for example a set of 268-Schrick-Cams?
    The injection should suit for this extra 10bhp just by setting idle and CO.
    Further optimization could get obtained by WUR-Mod.
    But the ignition? Only by turning a bit the ignition distributor?

    Cheers!
     
  3. alexkod22 New Member

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    I read all your posts(apreciate very much your sustained effort), I tryed everything and no good results. Changed the crystal in my 16v KE-Jetronic Knock Box with a 4500 Hz one and the rev limit is the same(around 7000 RPM), only change: the interval when it cuts fuel is shorter and it sounds more like fully electronic injection when hitting te rev limit. I also changed the crystal in the Oxygen Control Unit. It has 6000 stock and I tried 6150, no changes and a 4134.327 and the rev limit drops to around 5000 RPM. It won't go past 7k. The Knock box board is the green one so the nr.4 pin that is cut in the first pictures is for diagnostic and there is ni logical reson for doing that. Any idea?
     
  4. Nm8932 New Member

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    Hi,
    newbie here looking to resurrect this old thread to try to gain some info on the kr Rev limit.
    Looked at the pics and ordered a 4.608mhz crystal as reqd but am confused by the pic showing the wire and the cut pin.
    Is this necessary to gain the extra rpm??
    Is the frequency of the crystal that alexkod22 used ineffective because it's the wrong frequency(I.E. Will only the 4.608mhz actually work?)
    I'll explain what I'm trying to achieve.
    I've got a kr on r1 carbs running pretty much stock everything with Newman 16v championship control cams.
    This is a race engine in its 1st phase of development and for phase 2 I want to flow the head and add the wildest cams I can whilst retaining the hydraulics(for cost reasons). Piper and Kent advertise the cams I'm after and quote a usable Rev range upto 7500rpm. This would suit the gearing on my car ideally as currently on the gearing I'm running it drops too low between gear changes, I've already got a different diff ratio ready to fit and if I can get the revs up I'll change 5th gear too.
    Already done all my sums and worked out max speeds in relevant gears and shift points etc I just need to get to 7500rpm whilst producing useable power.
    So back to the question, anyone out there got a working ecu with just the crystal change or is the wire mod also reqd?
    I have both types of ecu too do if anyone wants to chip in wether grey/white or green is best feel free.
    Sorry if this is dragging up ancient threads but it's something I want sorted in the next few weeks so I can get back on the rollers and get busy prepping the car for next season(this season finished at the weekend)
    Cheers in advance guys.
     
  5. rubjonny

    rubjonny Administrator Staff Member Admin

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    pretty sure the wire is due to some other issue, maybe to bypass a cut trace or whatever. just swapping the crystal is all you need to raise the rev limiter.

    squinting at the picture and diagram it may correspond to the spark trigger pin 12 which fires the TCI unit, or it could be pin 5 which is the ignition live feed to power up the ecu
     
  6. Nm8932 New Member

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    That's exactly what I had hoped.
    Thanks.
    The new crystal should be here soon but it'll be a few weeks before I can get the cams and head done but I will post again when have results.
    I may buy another ecu as well and back to back the modified one and 2 standard ones to get an answer if white or green ecus actually make a difference.
    Also be interesting to see from the power curves what effect the crystal has over the whole rev range too.
    Not sure if this is particularly relevant now given the cost of mega jolt and similar systems but I'm keen not to have an exposed crank sensor as I've seen cars cut out in wet races recently due to water getting on crank sensors. Ultimately I'm willing to sacrifice a few ponies for reliability.
     
  7. rubjonny

    rubjonny Administrator Staff Member Admin

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    I did try both a grey and green ecu in mine and couldnt feel any difference, a rolling road might have picked something up I guess!
     
  8. Erik Christiansen New Member

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    I know this is an old thread, but I wanted to post up some information a friend and I have recently figured out relating to modifying the rev limiter. This is based on my experience with a USA spec 1.8l 16v “PL” Oxygen Control Unit (ECU) and knock box. I don’t know if the KR fuel and ignition management used in Europe are the same, but if they are different it might explain why US and UK 16v seem to respond differently to the crystal swap.

    For PL engines, there is a rev limiter built into both the ECU and the knock box. They both kick in at ~7,200 rpm. The ECU rev limiter sends negative current to the Differential Pressure Regulator (DPR). This cuts fuel to the injectors in the same manner used for deceleration fuel shut-off above 1600rpm when the throttle is closed. Meanwhile, the knock box rev limiter functions by opening the ground to the fuel pump relay.

    To raise the rev limiter you need to defeat or modify the rev limiters built into both the ECU and knock box. As previously described in this thread, you can swap the stock 4.194304 Mhz crystal in the knock box with a higher frequency crystal, in order to effectively trick the knock box into a new rev limit = 7,200 * [(new crystal) / 4.194304]. I have a 4.433618 Mhz crystal installed right now for a rev limit of 7,611 rpm. This will stretch out the ignition map, possibly leading to some loss of mid-range torque, but I haven’t felt any seat of the pants difference. When I get a chance I plan to dyno both stock and modified knock boxes back to back.

    The ECU rev limiter is a bit trickier to get around. I haven’t even attempted to modify the ECU itself so I don’t know if that is possible. But, a friend of mine built an add-on “Power Module” that over-rides the DPR current when the full throttle (WOT) switch is closed. It uses an Arduino to do closed loop feedback control of DPR current using the analog signal from an AFR meter (MTX-L Plus) connected to a wideband oxygen sensor. The primary purpose of the power module is to eliminate lean conditions at high rpm, but it also conveniently lets us raise the rev limiter by simply replacing the crystal in the knock box. The module only functions at WOT, so the rev limit is still 7,200rpm at part throttle, but I’m not concerned about part throttle operation between 7,200 – 7,600 rpm.

    I’m curious if anyone knows if the KR ECU also has a rev limiter built in?

    Also, I still do not understand what the jumper wire is for in the pics in the original post on this thread. Has anyone figured that out?

    I hope this information is helpful. I learned a lot from this thread!
     
    Toyotec and Sirguydo like this.
  9. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Glad you were able to build on the information shared.

    Thanks for your update.
     
  10. rubjonny

    rubjonny Administrator Staff Member Admin

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    the KR ecu is doing the same job as the PL knock box, handing the ignition side of things just without a knock sensor attached so this is why the solution is the same :)

    other than that there is no ecu for the fuel system as its purely mechanical but with the addition of a controller for the ISV instead of the AAV found in earlier 8v.

    dont think anyone figured out what that wire was for, certainly isnt there in the other modified ecu which was posted up so it may just be to fix some other issue inside that cropped up in the past
     
  11. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    PL has closed loop lambda control as was used in countries like Germany and North America. It is a pollution controlled engine, like a 9A, 6A and ACE.
    While it was produced alongside the KR, I am not sure what was carry over for electronics.
    UK did not get them.
     

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