I have posted before about difficulties with the throttle response of my 09
2.5 NA in a 82 Westy diesel, 5spd, installed by SC. I have about 2.5K miles
on it now and have been unhappy with the way the throttle responds, being
too much power in the first third, less in the second third and almost no
new power in the last third. This made it difficult to drive smoothly and
gave a very nonlinear feeling. Others have reported the same difficulty with
late throttle-by-wire Systems, especially in off road driving. I was gearing
up to do a complicated remapping and reprogramming of the ECU to try to get
a more linear response.
But then I seem to have stumbled on a fix, at least for my system. One thing
I like about TBW is the ease of installing Cruise control-no vacuum
actuators, cable or any of that. It's all done by the ECU thru the
electronic throttle. Someone has already figured all this out and posted it
in Files. He had almost the same setup as me, and ran into the same
problem-his ECU was for an auto trans although he was running am MT as I am.
And the CC couldn't be hooked up because the CEL was on all the time due to
a code P0600, generated by the fact that the ECU is looking for a AT control
computer that isn't there. This also prevents the CC from working and makes
hooking up the CEL a waste of time. When I read his article in files I went
and checked, and sure enough I had the same PN ECU, designed for an AT and
throwing the same code. The fix is to get an MT ECU-just one number in the
PN is different. Just one ECU wire has to be grounded (C15) (this is a
signal wire to tell the ECU that an MT is installed.) and all these problems
are solved. I got one for $90 on ebay and installed it and found it also has
a different throttle response more appropriate to an MT. The response is
linear all the way to full throttle now and it sure seems like I have more
power. Problem solved!
All this makes perfect sense, that Subaru MT and AT would use different
throttle response MAPS. MT Subs would probably be jerky too if you installed
an AT ECU.
The article in Files, with the PNs can be found here
ntrol/
Dennis
