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Guest Message by DevFuse

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*Dyno* 1997 Outback Sport ECU comparison Results

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2 replies to this topic

#1 Myxalplyx


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Posted 11 February 2004 - 11:07 PM

Car: 1997 2.2ltr Subaru Impreza Outback Sport Wagon (AWD/Autotranny)

Dyno: Dynojet *AWD Dyno*
Place: Xotic Motorsports
Current Mods: Underdrive Pulley and 2.25" axle back exhaust (Remus-dual) That's it!

Tests: Tested 3 different ECUs for my car. Did 6 dyno pulls total. The first 3 were 3rd gear pulls up to around 6000rpm. ECUs where changed and reset (Pocketlogger) after each run. The 2nd 3 dyno pulls where from 1st gear all the way up to the top of 3rd gear at 6000rpm. This way you could see the hp/torque and even shift characteristics of each ECU to compare.

ECUs Tested:

Part#AC831 This the ECU that comes stock in my car according to the vin number (lost my original ECU, don't ask).

Part# AD61A This is a 1999 2.5ltr Legacy GT ECU. I used this while I was running turbo/nitrous for years. Just took it off the car last month.

Part# AD400 This is a 1997 2.2ltr Impreza ECU. It's not for my car but other models of Impreza in 1997.

The first 3 runs where done in 3rd gear starting between 65mph-60mph. It's really difficult to get a decent run in this gear without having the tranny downshift into 2nd gear. Sudden mashing of the throttle even this high can make the tranny downshift even if it has only 200rpm left to go before shifting into 3rd. The pics are way to big to post and show here.

3rd Gear Run

Sorry for the huge file sizes as I'm still getting used to changing the dyno files over into pdf and then to jpg format. Note my stock ECU makes less horsepower than the Legacy and the other 2.2ltr ECU. My stock ECU also seems to run richer than the rest. I tested my stock ECU first, the 'other' 2.2ltr Impreza 2nd and the Legacy ECU 3rd. I didn't let the car cool down for no more than 5 minutes in between each run.

If someone can make these files smaller for me, please let me know. I'll delete what I have up and submit a smaller size. I'm not good at these things.

Next up: 1st to 3rd gear run of each ECU.----------------->

#2 Myxalplyx


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Posted 11 February 2004 - 11:10 PM

This file is the 1st-3rd run of all the ECUs.

Part# AC831 is my stock ECU,

Part# AD400 is a 1999 2.5ltr Legacy GT ECU and

Part# AD400 is the 'other' 1997 2.2ltr Impreza ECU for other models made in 1997.

1st-3rd gear run

Just for further analysis, I'll post up each gear of all these runs, hp/torque and air/fuel ratio and leave it at that.

I know there are a ton of things (like the size of the pics) that could be done better dyno wise but this is my 2nd time on the dyno. I'm not rich so I plan to spend as little time there as possible with each dyno session BUT I feel like I'm on Dyno-Crack now. I have to be there as much as possible. I've already made more appointments to test out little stuff.

Before posting the dyno charts of each gear, notice the hp/torque spikes in each gear. This is the valve body shifting pretty hard (just the way I like it). I tried to describe the feeling to folks as 'it-throws-the-car-forward while shifting. At least the full dyno run in to 3rd gear shows why. Torque shoots up in between gears. Pretty cool eh?

1st Gear of Full Run

2nd Gear of Full Run

3rd Gear of Full Run

Looks like the Legacy ECU makes the most power, then the 'other' 1997 2.2ltr ECU, then my stock Ecu. The air/fuel ratio looks interesting. The Legacy is LEAN. Can't see how I got away using that ECU doing what I did. I'll stop here.


#3 blitz



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Posted 12 February 2004 - 09:18 PM

Cool info, thanks for posting. It looks like the ECU's are not radically different with regards to fuel delivery. I'd imagine that the spark curve differs between them to some degree as well, but you got no data to indicate those differences. That would be good info to know on account of the spark map being 3-dimensional, meaning it's controlled by (all) throttle openings as well as RPM (not only WOT open-loop as is fuel mapping).

It looks like you've got a couple ECU choices to swap-in as you add airflow to the 4k-and-up range via cam/headwork, etc.

You may already know this: a simplistic but totally effective way of controlling A/F ratio & spark lead is by manually adjusting the resistance in the IAT circuit.

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