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Old 09-18-2012, 06:37 PM   #93
roger 04 rt OP
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Joined: Nov 2011
Location: Massachusetts
Oddometer: 2,371
I got out today with the GS-911 attached and a PC in the Top Case for a 100 mph run up a section of posted 50 mph highway that runs through a flat swamp nearby. I didn't get past fifth gear before running out of highway. I continue to operate at 52 psi fuel pressure and a mixture of 13.8:1 no BoosterPlug or any other modification to my '04 RT.

The idea was to see when and where the Motronic runs the Closed Loop program. I've got some charts coming but here are a few observations. Keep in mind that the max 95HP is at 7250 RPM.

--Closed Loop was operational at 100 mph (The engine seemed very smooth here)

--Closed Loop was operational in 2nd, 3rd, 4th gears at nearly 6500 RPM.

--Closed Loop was operational at 48 degrees throttle (80 degrees is wide open) going 100 mph

--In 3rd gear, while accelerating to 70 mph the Motronic was Closed Loop a lot of the time. Same in 4th gear to 90 mph.

--In 5th gear, WOT Motronic stayed mostly Open Loop from 65 mph to 100 mph. But as soon as I "relaxed" the throttle to about 3/4 open at 6400 RPM, Closed Loop kicked in. Amazing!

Given the amount of time and operating areas where the Motronic will enforce lean Closed Loop, I think it gets easier to see the advantages of mixture richening by using a Wideband O2 to shift Lambda from 1 to something less--0.94 in my case.

--At 6000 RPM & WOT the injector was on for 7.2 milliseconds. One revolution of the engine only takes 10 milliseconds at that RPM. At 7250 RPM (max horsepower) each revolution is only 8.3 mS. The injectors would be open 90% of the time!

(The air temperature was 90F today; had it been 20F the 7.2 mS injector pulse would lengthen to 8.1 mS. Were I to boost my fuel output using a -20C air-temp shifter on a 20F day, that pulse would lengthen to almost 8.6 mS. More than 100% on-time! Fuel pressure is a better method for boosting injector output (compared to IAT shifting or PCs or Techs) since it doesn't require the injector pulse to be lengthened.)

That's the raw data. I'll try and post a chart tomorrow after I've thought about it further.
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