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E30 2.9L Stroker ITBs etc build...

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    Did you get the fuel situation sorted?
    Transaction feedback: Here, here and here. Thanks :D


      Well, I can't duplicate the lean out we saw on the Dyno. Been driving and logging and see nothing like that.

      I was stopping the motor between pulls (should have left it running).

      Also I should have setup the fans differently.

      I think we had a heat soak situation?

      I need to do some more diagnostics then we can try the Dyno again...


        Originally posted by mrlucretius View Post
        Hey @Delanoso,

        I know we have been messaging regarding your 2.9L build, but I forgot to add: wideband O2 sensor is mandatory. Also a variable TPS should be mandatory.

        Right now I am running a MAP only tune but will go to Alpha-N or blended at some point (ie, needing variable TPS); Rama @ RHD says this is very important to improve load resolution, which I believe as MAP signal goes from full vacuum (throttles closed) to atmosphere (throttles partially open) in maybe 1/3 of full throttle travel...

        Alex, thanks for the extra details here. I bought an LC-2 from DIYautotune and it came to me dead trying to work that out with them now. Also, I have an M5x TPS ready to go in and GM air temp sensor in a aluminum sleeve all set.

        So you're saying I should go Alpha-N to start with as long as I've got the TPS?

        ForcedFirebird Alex set me on you. As soon as I get my wideband situation corrected and I'm ready to install the MS ECU, I plan on hiring you to help me get the car up and running.


          I forget, do you have ITBs or not on your build?

          With ITBs, the MAP signal is nearly binary, either the throttle is closed or open (not truly, but it is limited in range).

          I think if you have a standard single throttle body intake for example the MAP signal is probably much smoother throughout the whole throttle range.

          So with ITBs running MAP this means the ECU does not know the difference between say 60% throttle and 100% throttle.

          Supposedly this lack of resolution limits the tunability and ultimate performance.

          When you run TPS and Alpha-N, you get a true 0-100% throttle signal, which then can improve the tune overall since there is a larger and more accurate range of engine loads as signaled by the TPS position.

          To be honest, the MAP only tune runs and drives great... I have just had people recommend using the TPS via Alpha-N or Blended mode can improve overall performance (since you can map out the whole VE table, instead of about half of the table which is what I get, ~0.35-0.85 atmospheres in MAP mode.

          At some point I will do the experiment: get it running on Alpha-N and do another dyno session and see what I get.



            I'm currently still running the stock intake manifold. The plan is to step through some intake upgrades since I can do that with spending a fortune. I spent about $50 getting a sleeve fabricated to put the IAT in. that connects the stock boot to a cold air intake from KA Motors, which was about $150 or so. I'm hoping moving from the 2" square opening in the stock air box to a full 3" round opening along with the swapped out ECU will handle what I need. The next step would be ITBs and after reading Digger's thread with yours as confirmation I'd go straight to the RHD.

            I have a based line dyno runs scheduled for later today. Planning on posting those and comparing them against yours to see how much work I have.


              ^^^I am going to make an educated guess with 184whp, 192wtq. :P
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                I wish. There's something seriously wrong with this picture and I spent some on the phone today give the guy who built my engine a piece of my mind. When I picked the car up from him, he told me it made 198whp/210wrq on a dyno but I knew it wasn't true. We're going to start with a smoke check and see what happens.

                Do you think it's worth trying to drop the MS ECU in at this point? Could a bad tune on a chipped stock ECU cause that much chaos? Or do you think the internals are less than what I was sold?
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                  198 is a little optimistic, but not out of the realm of possibility. One of our clients is making 208/189 with our head, stock size ST valves, 288 cam, b25 crank and 12.5:1 pistons (lightened/balanced everything).

                  Oh, stock ECU? Put the air box back in. That little funnel on the front of the AFM is worth 5whp on a bone stock engine (-5whp when removed).

                  Yeah, those numbers are way off. My stock Spec-legal rebuilds make ~160-65whp with a stock chip. We have two race cars with JY hodge-podge 9.4:1 b27's and they both make almost exactly 180/180 at the wheels, one is on MS dyno tuned, the other is using a chip I wrote during the dyno tune (stock ecu, stock injectors).

                  You have a major drop in the curve at 4500 rpm. The stock ECU pulls timing there.

                  Who's chip are you using? Can you get the AFR graphs for that dyno pull?

                  EDIT: also noticed the dyno curve getting "wiggly" after ~4500. Might want to check your ignition system, they tend to break up starting there when there's an issue. The CPS likes to break where the wire goes into the sensor, the wire likes to rub on the back of the water pump pulley, or the ECU is unhappy with the air gap. The two 13mm hex head screws that hold the CPS in place can be slightly loosened and the bracket can move around to adjust. Use a .030" feeler gauge, or thick business card for a shim. Make sure the CPS reads 540ohm, and have a helper wiggle the wire where it goes into the sensor while doing the ohm test. And finally there's supposed to be a plastic conduit on the timing cover to house the CPS and oil sensor wires. On the race cars, we run the wire over the timing cover just to avoid these issues.
                  Last edited by ForcedFirebird; 07-04-2020, 05:28 AM.
                  Transaction feedback: Here, here and here. Thanks :D



                    1) I would try to run the mega squirt with the wide band O2. I did this on the stock motor and it ran and pulled much better than with a stock ecu. I can help you get all the settings right. I would not trust a "tuned" stock ecu. With the mega squirt you can take logs and see afrs and all the sensors to help you get everything setup right. With stock ecu you are running pretty blind.

                    2) I had issues with ignition. Your dyno plots look kindof like ignition issues. ForcedFirebird may have some hints to use stock ignition (same or different plugs with smaller gap IIRC?). I went overkill with wasted spark and coil pack and drivers.

                    3) Separate note: I got my motor running in "Blended / ITB" mode (MAP and Alpha-N combined), after manually adjusting some of the VE table, then driving around on auto tune, then manually smoothing out the VE table. Seems like it runs and drives a bit better and I definitely now have full load resolution with the TPS... The original attempt to run alpha-n just needed VE adjustments that I did not know how to do at that time. Now I have it sorted.

                    So I am ready for another dyno session... Next time I want to burn some more dollars!

                    Last edited by mrlucretius; 07-05-2020, 12:31 PM.


                      I wouldn’t expect more than 170-180whp with stock head and intake with baby cam. Torque should be 180-190. One way or another you’d want to ditch the motronic
                      89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                      new build thread


                        Started my own thread so Alex can have his back - sorry for the hijack!