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4 minute(s) of a 31 minute read
10-24-2014
Didn't get a good pull. Fouled the plugs during tuning, so we attempted to tune another customers' 944t, but his ECU installer botched the wiring. Wasted a few hours of dyno rental with no results on either car. Got another appt later today.
10-26-2014
We were trying to sneak between appts on dyno, as the owner is a friend of mine, but they all ran over their slot on Friday, so we just used the time to iron out the M1.3 Alpha-N, and ended up giving up. Int the M1.3 code, Bosch used a transfer function map to save valuable space on he 256k chip and dies to the nature of the formula, airflow could not be transferred to a linear table. One might be able to get it to work, but it will never be street-able. Since there is an exponent in the formula, the final air flow calculation can never be linear (as the TPS is putting out that replaced the AFM).
Standalone will be at the shop tomorrow afternoon, and it will be tuned with a P&P MS from Whodwho (Keith).
We kept fouling plugs trying to get the M1.3 to behave, but it simply wasn't working. Just pulling the car from trailer to the dyno on the stock ECU with a free-rev tune fouled the plugs. Changed them, got it to pull a couple times, but could never get over 135whp, and after each run, there was a dead cylinder from a fouled plug - laser thermo on header primaries was always showing the dropped cyl at 120 degrees, the rest were in the upper 200's when the dyno brake stopped the wheels. We would change the plugs, then it would happen again and not always on the same cylinder, and at times it dropped 2 after a pull. I went out of town for the weekend for a planned family visit, just ran out of time.
If one had a LOT of time to change plugs and change the AFM transfer function multipliers in the Motronic, you MAY be able to get it to behave, but then it would still be finicky. When you tune the part or wide open throttle, the other suffers. Idle was never good, even putting the stock throttle switch on it to revert back to idle maps since the AFM tranfer is still calculated in.
I know this may as well be Chinese to some, but trust me, it's nearly impossible compared to the Motronic 3.x (413 and 506 ECU's) we were able to run in Alpha-N. If one was to start with an M50 Vanos harness and M3.x ECU on the M20 with ITB's, I feel it would be a better starting point.
10-30-2014
Didn't hit 200, but it's healthy. Before and after.
With spacers. Wanted to try with them and hood closed, then without hood closed, but already over stayed the welcome on the dyno as it was. First few pulls, it was breaking up over 4500rpm, had to adjust the CPS closer to the wheel. Whodoo was kind enough to answer the phone and gave the tip. Figured it may be failing, but guess the MS is more sensitive than the stock ECU.
To add, judging by the graph, I feel a larger cam would have kept pulling and not drop the lower end power by much, or maybe adjust timing instead but we used a stock fixed gear on this build.
My JY m50b25 with 45mm ITB's vs the modified head/cammed m20 with 40mm ITBs...
I will take the single cam all day
