Announcement

Collapse
No announcement yet.

Subaru MY01-05 camshaft control

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    We are using the LIC. I am not sure the bearings are OEM quality. I have implemented annual engine refresh program for these engines, durability is something to consider for a road car.
    He gets his lap dogs to do his talking for him. Buzzard is a good example.

    Comment


    • #17
      Thank you both for your suggestions.

      Comment


      • #18
        Thank you very much for the suggestions, my motor has just been reassembled with the LIC eccentric pulleys and the engine builder is very pleased with their effectiveness.

        I have done some research since my original post and there is some extremely useful material elsewhere on these forums. The first thing I had overlooked is that there is an rpm inhibit value below which the system doesn't control camshaft position. As the default setting for this parameter is 1500 rpm, this means that the system will not even be attempting to control camshaft position at idle.

        There is a good description of the origins of cam position error at idle here, and even how it changes while the engine warms up here.


        Comment


        • #19
          I got LIC pulleys myself after this thread, but they are just laying there on the shelf waiting for the next rebuild - then i will get adjustable exhaust sprockets and will finally degree my cams!

          you don't really need to control cams @ idle, besides there is little oil pressure which is required for the AVCS to be operational in normal conditions

          however, I have had A LOT of unsuccessful experiments trying to mimic the OEM AVCS mapping at low loads - if I advance my cams beyond 110 degrees (~15 degrees advance in OEM language) I would get very unstable and jerky low load driving (1000-2000 RPM)... I've tried different ignition timing, AFRs... nothing seems to work. I have no idea why 30-40 degrees advance work fine on OEM ECU, but not Autronic

          Comment


          • #20
            My ECU was recycled from another WRX and I don't know the history of its cam control map. It would appear to be gobbeldygook. So I have decided to start again. This is the base map that I most recently downloaded with the Autronic programming software:

            Base map cam table.JPG

            This seems to match your observation of applying no more advance than 15 degrees under Autronic control.

            I'm presuming that it doesn't make sense to advance the cams under full boost so here is the table I'm currently trialling (this time expressed in terms of advance rather than absolute degrees):

            cam table 2018 04 10.JPG

            I'm still running the engine in so have yet to explore how the car runs under 20 pounds of boost.

            How does this compare to your experience?

            Comment


            • #21
              I am yet to book a dyno session to figure out optimal numbers, but I am advancing cams by 40 degrees in the lower RPM range up until 5000 when I start closing them slowly, and I have a feeling I need to retard them later

              you can also use your butt dyno, because loss of torque is felt right away when you regard the cams

              Comment


              • #22
                Your comment about 40 degrees advance (compared to the 15 degrees in my map above) caused me to do a bit of searching for a standard AVCS map. I found this:

                EJ255 2006 WRX standard AVCS map.JPG

                Is this closer to the OEM map that you have been trying to mimic?

                Comment


                • #23
                  2.5 liter engine has different AVCS mapping from the 2.0 liter, something about cams being more advanced physically
                  either way, JDM engines run up to 45* AVCS

                  Comment


                  • #24
                    here is 2.5 vs 2.0 OEM AVCS maping

                    Attached Files

                    Comment


                    • #25
                      Thank you very much for posting this, but unfortunately the image is in very low resolution and I can make much out (I think the website has converted it to a 'thumbnail'). I'd be very grateful if there is another way I could see this file in its original resolution.

                      I have been trying to better understand the objectives of advancing the inlet cam. From the reading I have done to date, three themes emerge:
                      1. A generic observation for all engines that advancing the inlet cam in the mid-range will improve power/torque at full throttle, and elsewhere advancing the inlet cam is likely to be counter productive for maximising power/torque.
                      2. Some advice that advancing the inlet cam will assist the engine in coming on boost, but I have yet to see a good explanation.
                      3. A heap of advance at light throttle/no boost can minimise 'pump work', improve fuel economy and reduce emissions. See the area in the OEM map for the EJ25 I posted earlier that shows the maximum 40 degree advance centred around 2200 rpm and 0.60 load. The fuel economy benefit is apparently achieved by creating a heap of overlap resulting in the combustion chamber still containing exhaust gas when air should be admitted, generating less vacuum so more throttle is required for the same torque. More explanation here. Presumably this also creates an internal Exhaust Gas Recirculation and so reduces oxides of nitrogen emissions. All these things are 'good' from an OEM perspective. This approach may have only been implemented in the Drive By Wire versions (MY06 and newer) of the engine as I guess it would make the engine feel soggy and unresponsive in this zone - Drive By Wire could presumably compensate by opening the throttle more aggressively in this area.
                      Of course these are all very theoretical assertions and what happens in practice is probably very specific to the individual engine. That's where the 'right' OEM map might provide a good starting point. When the weather improves here I'll try a few things out, but I'm obviously keen to understand what others have learned.

                      My engine is a EJ25 running forged internals, ported heads, E85 and what appear to be mild cams (shame that they seem impossible to identify precisely). Given that I have a Spec C inlet manifold, there is the remote possibility that I have Spec C cams. Even if they are, they will probably just have a bit more duration and no more lift than stock. I'm running a frankenstien Garret GT3076 on a twist mount, so obviously the car will com on boost much later than stock, and so if advancing the cam assists in coming on boost I might need to modify the OEM map in this area as a minimum.
                      Last edited by AndrewS; April 15th, 2018, 10:05 AM. Reason: Inserted links

                      Comment


                      • #26

                        Comment


                        • #27
                          Thank you very much - very interesting. Is the 2.5 l map on the left? If so, it seems quite different to the one I posted and this might mean that there were a number of different OEM maps for different variants/countries (e.g. WRX vs STi, JDM vs Aus etc). I wonder if the area centred around 2800 rpm and load 1.0 fulfils a similar fuel economy/low emissions function to that described in item 3 of my post above?

                          The map on the right seems a much 'safer' starting point.

                          Do you know the model/spec of the cars these maps were downloaded from? The load extends way up to around 5, way beyond factory boost levels. As ever, it seems to get quite complex when we try to reverse engineer what a manufacturer was doing, and we'll always have a lot of unanswered questions!

                          Comment


                          • #28
                            207 on left, 255/257 on right
                            area around 2800 is emissoins, I always skip that

                            whichever HEADS and CAMS you have, is what decides what AVCS numbers you should run.

                            when measured, 257 cams are more advanced physically when compared to 207, hence lower numbers in the mapping table

                            those maps are OEM maps, load is calculated through a formula using MAF values

                            Comment


                            • #29
                              I put in LIC eccentric pulleys today, spend a lot of timing adjusting them trying to hit all marks
                              I did the best I could with the engine installed, and logged the car to see what has changed - my GPC adapt values now are incredible low (0.5% and 0.8%), however the cam position orientation degree did not change (well, perhaps by 1 degree) and they are still not even

                              I thought compensating the decked block my using eccentric pulleys would even the cam idle position even, am I wrong?

                              I know in motec to zero out the cams you need to run the engine with the solenoid connectors disconnected, wondering if there is a trick here too

                              Last edited by Hyper; April 23rd, 2018, 05:51 PM.

                              Comment


                              • #30
                                I'm not sure many others are following this thread. I'm not much use at the moment - a failed rear wheel bearing last week has stalled my ECU tuning efforts for the time being, and also have a short holiday planned, so I won't be able to offer any comparisons for a month or so.

                                Comment

                                Working...
                                X