Welcome to the North American Subaru Impreza Owners Club Thursday September 18, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Subaru Models > Baja Forum

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 06-03-2005, 12:36 AM   #1
dhstein313
Scooby Newbie
 
Member#: 88445
Join Date: Jun 2005
Chapter/Region: SCIC
Location: SoCAL
Vehicle:
2005 Baja Turbo
dark blue

Default Turbo and Premium Fuel

IN the process of purchasing a 2005 Turbo Baja and am getting conflicted reports whether premiujn fuel is REQUIRED or RECOMMENDED. If one would choose not to USE Premium what would the consequences??

DHSTEIN
* Registered users of the site do not see these ads.
dhstein313 is offline   Reply With Quote
Old 06-03-2005, 12:47 AM   #2
Hawk296
Scooby Specialist
 
Member#: 14555
Join Date: Jan 2002
Chapter/Region: MWSOC
Location: Troy, MI
Vehicle:
1995 Impreza L
Baja

Default

91 octane is required. If you use anything lower you may run into issues with detonation. THe ECU will detect knock and retard the ignition timing, This does decrease engine performance and there is a limit to how far it can retard the timing. So its very possible that the computer will not be able to compensate enough.The manual says 91 is minimum, Follow the instructions.
Hawk296 is offline   Reply With Quote
Old 06-03-2005, 07:07 AM   #3
jason.bogdan
Scooby Newbie
 
Member#: 82812
Join Date: Mar 2005
Location: wny
Vehicle:
2005 Baja Turbo
Monterey Gray

Default

Heck it says 91 right on the inside of the gas cap. Around here not a lot of places offer 91, they jump right to 92,93 and 94 - I probably use 93 the most.
jason.bogdan is offline   Reply With Quote
Old 06-03-2005, 07:45 AM   #4
KC
Scooby Guru
 
Member#: 442
Join Date: Oct 1999
Chapter/Region: NESIC
Location: SE Mass/RI
Vehicle:
2013 Crosstrek XV
00 Honda S2000

Default

Quote:
Originally Posted by jason.bogdan
Heck it says 91 right on the inside of the gas cap. Around here not a lot of places offer 91, they jump right to 92,93 and 94 - I probably use 93 the most.
Yep. Here it's 87, 89, 93. 91 is a rarity, so I put in 93.

--kC
KC is offline   Reply With Quote
Old 06-03-2005, 06:22 PM   #5
pdiz
Scooby Newbie
 
Member#: 82424
Join Date: Mar 2005
Chapter/Region: SCIC
Location: Riverside, CA
Vehicle:
2005 Baja Turbo
Black Onyx

Default

Here in So. Cali. it's 87, 89, and 91. Kinda sucks because my Honda RC51 (bought here) says it requires 93, but what can you do?

Quote:
Originally Posted by KC
Yep. Here it's 87, 89, 93. 91 is a rarity, so I put in 93.

--kC
pdiz is offline   Reply With Quote
Old 04-21-2008, 01:49 PM   #6
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

Resurrecting an old thread to comment and ask further questions:

I use 88 octane gasohol (10% ethanol) regularly in my '05 turbo. There has been no adverse effects whatsoever that I can detect. I have not towed the boat around this way (yet). I have hauled stuff and pulled our other small trailer this way.

New question:
Does the Baja's version of the EJ-255 (old STi motor) really require premium fuel to run properly?
Internals are the same as the (older) STi, right? Same compression ratio? Cars101.com doesn't list a Baja CR. Same cams? Lower boost levels though, right? Smaller turbo (TD04 vs. VF-39, right?) pushing fewer lbs/min and lower pressure.
So, let's say for the sake of discussion that the (older) STi engine runs its max boost satisfactorily on 91 octane fuel. Since the Baja pushes less air in and at lower pressure, why in the world would it require an equal level of knock resistance in the fuel? It should require less anti-knock to run properly given the lower output from the same CR and cams.

So, what EXACTLY is different between the Baja and the (older) STi motor internally? Not talking about turbo and I/C. Talking pistons, heads, cams, etc. How does the ECU programming compare? What's different, and where is it different?

I'm not advocating anyone go against their owner's manual. I'm not advocating anything. Still, I think the discussion would be engaging and possibly even useful. Anyone know the answers or care to discuss these questions?
bulwnkl is offline   Reply With Quote
Old 04-21-2008, 03:47 PM   #7
deadlydave
Scooby Specialist
 
Member#: 131119
Join Date: Nov 2006
Chapter/Region: Tri-State
Location: Waterford, NY
Vehicle:
1996 Impreza LWRXSTI
91 BMW 318is

Default

Quote:
Originally Posted by bulwnkl View Post
Does the Baja's version of the EJ-255 (old STi motor) really require premium fuel to run properly?
The 2.5 Liter STi engine code is ej257, is it not?

Quote:
Originally Posted by bulwnkl View Post
Internals are the same as the (older) STi, right? Same compression ratio? Cars101.com doesn't list a Baja CR. Same cams? Lower boost levels though, right? Smaller turbo (TD04 vs. VF-39, right?) pushing fewer lbs/min and lower pressure.
As far as I know, all the ej255's run a higher compresison ratio than the STi's 257 to compensate a little for the smaller turbo (td04) and less boost. I highly doubt the cams are the same. Again, I'm pretty sure that No USDM STi's use the 255 block.

Quote:
Originally Posted by bulwnkl View Post
So, what EXACTLY is different between the Baja and the (older) STi motor internally? Not talking about turbo and I/C. Talking pistons, heads, cams, etc. How does the ECU programming compare? What's different, and where is it different?
That's just it though: what does the STi have that's different? A larger intercooler is one of those things. Cooler, denser air also helps guard against knock(detonation from pre-ignition), right? Your ECU is tuned for the higher octane gas too, so to get re-tuned would cost cash just to lose performance. It can't change the timing enough by itself to run on 87.

Ultimately: What's the point of going to a cheaper gas if you get crap for gas mileage and power. That's why these cars have the octane reccomendation above all else. You'll burn more fuel and get less power on lower octane gas on a car that's meant for higher. Also, If you did this in high altitude or the middle of a desert, your ECU would have to compensate even further for the lack of air density.

I'm not saying your ideas are dumb--not by a long shot. This is a serious issue. Our cars have the aerodynamics of a brick, weigh 3500+ pounds, and suck premium gas at a healthy rate. I'm working on making mine lighter: so far, every upgrade I have done has replaced the factory part with a lighter peice. Someone here is working on Aerodynamics. All different approaches to the same problem. You just happened to take the hardest one ;-). Kudos for having the cojones.
deadlydave is offline   Reply With Quote
Old 04-21-2008, 06:23 PM   #8
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

Quote:
Originally Posted by deadlydave View Post
The 2.5 Liter STi engine code is ej257, is it not?
Don't know, actually. Everything I can recall reading from those who appear to have a clue what they're talking about here and at Scoobytruck say the engines are the same internally but turbo, I/C, ECU programming, and maybe U/P and exhaust are different. I don't know, though. It seems plausible to me that the difference between EJ-255 and EJ-257 could be the turbo, I/C, and up-pipe, but I've no idea whether Subaru does things like that or not. It also wouldn't be tough for them to simply spec a slightly thinner HG for a slight CR increase. Again, no clue whether they operate this way or not.

Quote:
Originally Posted by deadlydave View Post
As far as I know, all the ej255's run a higher compresison ratio than the STi's 257 to compensate a little for the smaller turbo (td04) and less boost. I highly doubt the cams are the same. Again, I'm pretty sure that No USDM STi's use the 255 block.
It is possible that the rumors are false re: block internals. IIRC, my owner's manual (it's out in the car right now) says 8.8:1 CR. Cars101 claims 8.2:1 for the '04 and '05 STi. I have to say it sounds unlikely to me that separate pistons would be developed just for the Baja, but they could well have done just that. Also, cam differences could easily erase a small CR difference like that, but again it strikes me as unlikely we'd see that level of effort for a low-volume vehicle like the Baja. Especially given how widely Subaru shares parts in everything else. Unless, of course, they never envisioned it as being so low-volume...


Quote:
Originally Posted by deadlydave View Post
That's just it though: what does the STi have that's different? A larger intercooler is one of those things. Cooler, denser air also helps guard against knock(detonation from pre-ignition), right? Your ECU is tuned for the higher octane gas too, so to get re-tuned would cost cash just to lose performance. It can't change the timing enough by itself to run on 87.
My experience thus far says the ECU can, in fact, adjust enough (if adjustment is even happening) to deal with 88 octane. Haven't tried lower, and probably won't. I can buy 88 gasohol for the same money as 85 octane in straight gasoline. Like I said, perhaps pulling the boat will reveal problems, but I don't see any peak boost reductions for very short bursts (i.e. on-ramp, etc.). I don't have my own scan gauge, and borrowing one from work for an evening is probably not possible, so I can't watch timing adjustments nor fuel trims. I do agree that a turbo that's more efficient at higher airflow rates and a larger I/C will help resist knock at high boost.

Quote:
Originally Posted by deadlydave View Post
Ultimately: What's the point of going to a cheaper gas if you get crap for gas mileage and power.
Well, that's just it: I have a hard log of all miles and gallons since shortly after I bought the truck last summer. The lower octane is not harming mpg (though the cold weather sure kills it!) nor my performance if/when I use it. To be sure, most all my miles are a commute in which any Subaru ever sold here will live perfectly well forever on low-octane fuel. You only need the anti-knock when pulling hard. It is possible that my relatively high altitude is helping me because the lower-density air results in lower absolute pressures in the CC than I'd see down at sea level. Still, the turbo should be able to move enough air to correct for this; most turbo cars have enough reserve built in to do so.

Quote:
Originally Posted by deadlydave View Post
I'm not saying your ideas are dumb--not by a long shot. This is a serious issue. Our cars have the aerodynamics of a brick, weigh 3500+ pounds, and suck premium gas at a healthy rate. I'm working on making mine lighter: so far, every upgrade I have done has replaced the factory part with a lighter peice. Someone here is working on Aerodynamics. All different approaches to the same problem. You just happened to take the hardest one ;-). Kudos for having the cojones.
I appreciate your feedback and the discussion, deadlydave. I know I don't take any offense to your input, and hope you wouldn't either from any of my replies. I'd like to keep going if there's anywhere to go with this. Partly to determine for certain whether/what differences there are internally between us and the STi (or other turbo Subies), and partly to further knowledge of how these things run and what we might be able to do to deal with the cost of just getting to work and back while keeping one of the coolest, most useful vehicles ever made.
bulwnkl is offline   Reply With Quote
Old 04-21-2008, 09:04 PM   #9
Hawk296
Scooby Specialist
 
Member#: 14555
Join Date: Jan 2002
Chapter/Region: MWSOC
Location: Troy, MI
Vehicle:
1995 Impreza L
Baja

Default

The EJ255 in the baja has been proven to be the same short block as the earlier STIs. This means same block, same crank, same pistons etc. To go either further, the heads, cams, valves, fuel injectors etc are also the same. And I am pretty sure the compression ratio is the same. The EJ255 in the earlier STIs had the VF39 turbo, different Y-pipe and larger intercooler. They had a catless uppipe, I believe the center exh. manifold crossover piece is slightly larger, and the intake manifold is painted red.

All EJ255s are not the same though. The EJ255 in the legacy has a totally different IC, turbo manifold combo (made of plastic) and is pretty much the setup the 08 wrx uses now. Another difference is that the 06 and on WRX that also uses "EJ255" does have different heads as well as increased compression ratio. an air pump was added and sodium filled exhaust valves removed (this started in 07 for the STI)

Either way, ECU calibrations are quite a bit differnt. there are several areas where the baja runs a noticeable amount more timing advance than the sti. Fueling is also different, as is everything else

What altitude are you running that gasahol at? That makes a difference too.

If you log the data from the ECU I would not be surprised if the ecu is detecting knock and pulling timing.
Hawk296 is offline   Reply With Quote
Old 04-22-2008, 10:04 AM   #10
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

4800 feet is the altitude on the river plain. The mountains go up from there (obviously ), but I spend the bulk of my time down low.

I'd really like to be able to log data, but just don't have the hardware, etc. Clearly, the lower octane should be perfectly fine for nearly all commuting situations since I have no on-ramps nor freeway time. It's just city, county, and state roads. I thought I detected some anomalies once going up into the hills, but that wasn't at very high boost. I can push and hold much higher boost pretty well as and when I choose.

I've been running 88 octane for months, and will switch back to 92 gasohol next tank as a control/check.

EDIT: Hawk, how much timing difference is 'a noticeable amount?' A degree? 5 degrees? 10? How much fueling difference is there? 10:1 vs. 12:1 AFR under max boost? 10:1 vs. 10.2:1? (I don't know what either runs, I just made those numbers up). BTW, what is the boost difference between the early STi and the Baja? PSI, but I also mean lbs/min.

Last edited by bulwnkl; 04-22-2008 at 11:06 AM.
bulwnkl is offline   Reply With Quote
Old 04-22-2008, 11:37 AM   #11
deadlydave
Scooby Specialist
 
Member#: 131119
Join Date: Nov 2006
Chapter/Region: Tri-State
Location: Waterford, NY
Vehicle:
1996 Impreza LWRXSTI
91 BMW 318is

Default

bulwnkl, are you running factory boost? Have you made any changes?

I couldn't boost above 11psi flat until I replaced my wastegate actuator (stock is 11.4 or 11.8?). If you were running lower than stock boost, perhaps the computer could compensate enough timing for you to be able to run what you're running.

STi's I beleive run ~14psi stock compared to our ~11psi. My friend with a shot boost control solenoid was only running 9psi on his till we changed it.
deadlydave is offline   Reply With Quote
Old 04-22-2008, 04:33 PM   #12
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

No changes to the truck at all. The only gauge I have is the factory boost gauge on the steering column, which I cannot calibrate nor cross-check. I got rid of my nice Autometer gauge a year or two ago. ...now that I think of it, maybe I didn't. I'll have to look in a drawer I thought it got tossed from...
Anyway, the factory gauge will show me a little over .075 MPa max. I've seen nearly .080 a couple times, but it seems to depend upon weather and whether I'm towing more than anything else. That's certainly within margin of error for the stock gauge and 88,000 miles, don't you think?

OK, so to back up to the theoretical for a moment:
If the STi runs higher pressure with a turbo which should be more efficient at moving the additional lbs/min of air and moves it through a larger I/C, where does that leave us? Higher efficiency turbo = more lbs of air moved per psi at design flows, and the larger I/C should cool the greater airflow. So, one might suppose that intake air temps are similar between the two machines. To be able to verify: where is the IAT sensor on these? Upstream or downstream of the I/C? The STi owner's manual specifies 91 octane (R+M/2 method) minimum, right?

On a purely theoretical level, given:
Identical long blocks and
Similar (or even lower) IATs,

The Baja should have a lower octane requirement than the early STi unless AFRs and/or ignition timing are more than trivially different.

Are the assumptions above correct? Are they easily verifiable or even reasonable? Back to the other question: Exactly how different are the AFRs and timing maps between the Baja and the early STi?
bulwnkl is offline   Reply With Quote
Old 04-22-2008, 05:50 PM   #13
Hawk296
Scooby Specialist
 
Member#: 14555
Join Date: Jan 2002
Chapter/Region: MWSOC
Location: Troy, MI
Vehicle:
1995 Impreza L
Baja

Default

I beleive the IAT sensor is actually part of the MAF sensor. If thats the case then it is before the turbo, right off of the airbox.

When I get home from work I will post stock maps of each. They are scaled differently so you cannot directly compare them, but you will get the idea. Not crazy different, but not identicle. The STI also uses multiple sets of maps where the Baja only uses one set.

I am not doubting that your car runs fine. But am thinking not everyone will have your results depending on location, driving conditions and weather.

2005 Baja turbo base timing map, rpm on the left, engine load across top
Code:
 	0.25	0.3	0.4	0.6	0.7	0.8	0.95	1.05	1.25	1.35	1.5	1.6	1.7	1.9	2.1	2.3
600	13.05	15.16	15.16	15.16	15.16	15.16	4.96	0.04	-3.83	-3.83	-3.83	-3.83	-3.83	-3.83	-3.83	-3.83
800	14.1	17.97	20.08	20.08	20.08	19.02	9.88	3.91	-2.07	-2.07	-2.07	-2.07	-2.07	-2.07	-2.07	-2.07
1200	20.08	25	29.92	28.87	28.87	28.16	19.02	10.94	9.88	8.12	4.96	4.96	4.96	4.96	4.96	4.96
1600	38.01	38.01	38.01	38.01	35.9	34.14	26.05	20.08	9.88	9.88	8.12	8.12	8.12	8.12	8.12	8.12
2000	40.12	41.88	45.04	45.04	42.93	41.88	35.9	26.05	15.86	15.86	13.05	13.05	13.05	11.99	9.88	8.12
2400	40.12	41.88	45.04	45.04	45.04	45.04	39.06	28.16	19.02	16.91	15.86	14.1	14.1	11.99	9.88	8.12
2700	40.12	41.88	45.04	45.04	45.04	45.04	39.06	33.09	19.02	16.91	15.86	14.1	14.1	11.99	9.88	8.12
3100	40.12	41.88	45.04	45.04	45.04	45.04	39.06	36.95	26.05	22.89	19.02	15.86	14.1	11.99	9.88	8.12
3400	40.12	41.88	45.04	45.04	43.98	42.93	39.06	34.14	27.11	25	21.13	19.02	14.1	11.99	9.88	8.12
3600	40.12	41.88	45.04	41.17	41.17	41.17	38.01	34.84	27.11	25	21.84	20.08	16.91	13.05	9.88	8.12
3800	40.12	41.88	45.04	45.04	43.98	41.88	40.12	35.9	28.16	26.05	22.89	21.13	17.97	15.86	13.05	10.94
4200	40.12	41.88	45.04	45.04	45.04	41.88	40.12	35.9	28.87	27.11	23.95	21.84	20.08	17.97	15.86	14.1
4500	40.12	41.88	45.04	45.04	45.04	41.88	40.12	36.95	30.98	28.87	23.95	22.89	21.84	19.02	15.86	14.1
4800	40.12	41.88	45.04	45.04	45.04	42.93	40.12	39.06	34.84	32.03	28.87	28.16	27.11	23.95	19.02	17.97
5200	40.12	41.88	45.04	45.04	45.04	42.93	40.12	40.12	35.9	34.84	32.03	30.98	28.87	27.11	25	23.95
5600	40.12	41.88	45.04	45.04	45.04	42.93	41.88	40.12	35.9	34.84	33.09	32.03	30.98	28.87	26.05	25
6000	40.12	41.88	45.04	45.04	45.04	42.93	41.88	41.88	40.12	38.01	35.9	34.84	34.14	32.03	30.98	29.92
6600	40.12	41.88	41.88	41.88	41.88	41.88	41.88	41.88	41.88	41.88	38.01	36.95	34.14	34.14	34.14	34.14
And 2005 STI base timing
Code:
	0.25	0.4	0.55	0.7	0.85	1	1.15	1.3	1.45	1.6	1.75	2	2.25	2.5	2.75
800	16.91	21.84	27.11	16.91	11.99	8.12	4.96	2.85	2.15	2.15	2.15	2.15	2.15	2.15	2.15
1200	21.84	21.84	29.92	26.05	21.13	15.16	8.83	7.07	6.02	6.02	6.02	4.96	4.96	4.96	4.96
1600	27.11	29.92	29.92	35.9	28.87	21.13	15.86	8.83	7.07	6.02	4.96	4.96	3.91	3.91	3.91
2000	33.09	38.01	40.12	40.12	34.14	29.92	22.89	15.86	11.99	7.07	6.02	4.96	4.96	4.96	4.96
2400	35.9	42.93	46.09	43.98	38.01	34.84	28.87	22.89	19.02	15.16	11.99	7.07	6.02	6.02	6.02
2800	38.01	46.09	46.09	43.98	39.06	34.84	30.98	26.05	21.84	17.97	15.16	8.83	8.12	7.07	7.07
3200	40.12	46.09	46.09	43.98	39.06	36.95	33.09	28.16	23.95	21.13	16.91	13.05	9.88	8.12	8.12
3600	40.12	46.09	46.09	43.98	40.12	38.01	34.84	30.98	26.05	21.84	19.02	14.1	11.99	8.12	8.12
4000	40.12	46.09	46.09	43.98	40.12	38.01	34.84	30.98	27.11	22.89	19.02	15.16	13.05	10.94	10.94
4400	40.12	46.09	46.09	43.98	40.12	38.01	34.84	30.98	27.11	25	21.84	17.97	14.1	11.99	11.99
4800	40.12	46.09	46.09	43.98	41.88	39.06	38.01	35.9	32.03	27.11	23.95	20.08	17.97	15.86	13.05
5200	40.12	46.09	46.09	43.98	41.88	39.06	38.01	36.95	34.14	30.98	27.11	22.89	19.02	16.91	14.1
5600	40.12	46.09	46.09	43.98	41.88	39.06	38.01	36.95	34.14	30.98	27.11	22.89	20.08	16.91	15.16
6000	40.12	46.09	46.09	43.98	41.88	40.12	38.01	38.01	35.9	33.09	29.92	25	20.08	17.97	15.86
6400	40.12	46.09	46.09	43.98	41.88	40.12	40.12	39.06	36.95	34.84	32.03	27.11	21.84	17.97	17.97
6800	40.12	46.09	46.09	43.98	41.88	41.88	41.88	39.06	38.01	35.9	32.03	29.92	26.05	22.89	21.84
7200	40.12	46.09	46.09	43.98	41.88	41.88	41.88	39.06	38.01	35.9	32.03	29.92	26.05	22.89	21.84
7600	40.12	46.09	46.09	43.98	41.88	41.88	41.88	39.06	38.01	35.9	32.03	29.92	26.05	22.89	21.84
baja max timing advance table
Code:
	0.25	0.3	0.4	0.6	0.7	0.8	0.95	1.05	1.25	1.35	1.5	1.6	1.7	1.9	2.1	2.3
600	0	0	0	0	0	0	3.87	3.87	3.87	3.87	3.87	3.87	3.87	3.87	3.87	3.87
800	0	0	0	0	0	0	3.87	3.87	3.87	3.87	3.87	3.87	3.87	3.87	3.87	3.87
1200	0	0	0	0	0	0	5.98	5.98	7.03	7.03	7.03	7.03	7.03	7.03	5.98	5.98
1600	0	0	0	0	0	0	5.98	5.98	7.03	7.03	8.09	8.09	8.09	7.03	5.98	5.98
2000	0	0	0	0	0	0	3.87	5.98	5.98	5.98	5.98	5.98	5.98	5.98	5.98	5.98
2400	0	0	0	0	0	0	1.05	4.92	5.98	5.98	5.98	5.98	5.98	8.09	7.03	7.03
2700	0	0	0	0	0	0	1.05	2.11	5.98	5.98	5.98	5.98	5.98	8.09	7.03	9.14
3100	0	0	0	0	0	0	1.05	2.11	7.03	7.03	5.98	7.03	7.03	8.09	7.03	9.14
3400	0	0	0	0	0	0	1.05	5.98	5.98	4.92	3.87	4.92	7.03	8.09	7.03	9.14
3600	0	0	0	0	0	0	2.11	4.92	5.98	4.92	3.87	4.92	5.98	7.03	8.09	9.14
3800	0	0	0	0	0	0	2.11	4.92	4.92	3.87	3.87	3.87	5.98	4.92	5.98	7.03
4200	0	0	0	0	0	0	2.11	4.92	3.87	3.16	3.87	3.87	4.92	4.92	4.92	4.92
4500	0	0	0	0	0	0	2.11	4.92	4.92	3.16	3.87	3.16	3.16	4.92	7.03	9.14
4800	0	0	0	0	0	0	2.11	3.16	3.16	3.16	3.87	3.87	3.87	3.87	5.98	7.03
5200	0	0	0	0	0	0	2.11	2.11	2.11	3.16	3.16	3.16	3.87	4.92	4.92	3.16
5600	0	0	0	0	0	0	0	2.11	2.11	3.16	4.92	4.92	4.92	3.87	3.87	2.11
6000	0	0	0	0	0	0	0	0	0	0	2.11	3.16	3.16	2.11	2.11	2.11
6600	0	0	0	0	0	0	0	0	0	0	3.87	3.87	3.87	3.87	3.87	3.87
sti max timing advance
Code:
	0.25	0.4	0.55	0.7	0.85	1	1.15	1.3	1.45	1.6	1.75	2	2.25	2.5	2.75	2.9
800	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
1200	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
1600	0	0	0	0	0	0	0	0	2.11	3.16	3.87	3.87	3.16	3.16	3.16	2.11
2000	0	0	0	0	0	0	0	0	3.16	7.03	7.03	7.03	7.03	7.03	7.03	5.98
2400	0	0	0	0	0	0	0	0	2.11	5.98	7.03	9.14	7.03	7.03	7.03	5.98
2800	0	0	0	0	0	0	0	0	2.11	4.92	7.03	7.03	7.03	7.03	7.03	5.98
3200	0	0	0	0	0	0	0	0	0	2.11	3.87	8.09	9.14	7.03	5.98	4.92
3600	0	0	0	0	0	0	0	0	0	0	3.16	4.92	7.03	7.03	5.98	4.92
4000	0	0	0	0	0	0	0	0	0	0	3.16	3.87	7.03	7.03	7.03	5.98
4400	0	0	0	0	0	0	0	0	0	0	3.16	5.98	7.03	7.03	5.98	4.92
4800	0	0	0	0	0	0	0	0	0	0	2.11	4.92	7.03	4.92	7.03	5.98
5200	0	0	0	0	0	0	0	0	0	0	2.11	4.92	5.98	4.92	7.03	5.98
5600	0	0	0	0	0	0	0	0	0	0	3.16	5.98	4.92	4.92	5.98	4.92
6000	0	0	0	0	0	0	0	0	0	0	2.11	5.98	4.92	4.92	5.98	4.92
6400	0	0	0	0	0	0	0	0	0	0	2.11	5.98	4.92	4.92	3.87	3.16
6800	0	0	0	0	0	0	0	0	0	0	1.05	3.16	2.11	2.11	1.05	0
7200	0	0	0	0	0	0	0	0	0	0	1.05	3.16	2.11	2.11	1.05	0
7600	0	0	0	0	0	0	0	0	0	0	1.05	3.16	2.11	2.11	1.05	0
Baja base fuel (in AFR)
Code:
	0.25	0.3	0.4	0.6	0.7	0.8	0.95	1.05	1.25	1.35	1.5	1.6	1.7	1.9	2.1	2.3
600	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7
800	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7
1200	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7
1600	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	13.94	13.73	13.73	13.73	13.73	13.73	13.73
2000	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	13.73	13.73	13.73	13.73	13.73	13.73	13.73
2400	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	13.84	13.44	12.98	12.98	12.98	12.98	12.98	12.98
2700	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	13.84	13.44	12.98	12.8	12.8	12.8	12.8	12.8
3100	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	13.94	13.73	13.16	12.89	12.46	11.83	11.83	11.83
3400	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.7	13.94	13.44	12.89	12.54	12.06	11.54	11.2	11.2
3600	14.7	14.7	14.7	14.7	14.7	14.7	14.36	13.84	13.25	12.89	12.71	12.38	11.98	11.4	11.07	10.81
3800	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.04	13.25	12.89	12.54	12.22	11.83	11.4	11.07	10.63
4200	14.7	14.7	14.7	14.7	14.7	14.04	13.73	13.34	12.98	12.38	11.83	11.54	11.54	11.2	10.63	10.63
4500	14.7	14.7	14.7	14.25	13.73	13.44	13.16	12.89	11.98	11.69	11.33	11.2	11.2	10.94	10.63	10.63
4800	14.7	14.7	14.7	13.84	13.73	13.16	12.46	12.06	11.69	11.47	11.33	11.2	11.2	10.88	10.63	10.63
5200	14.7	14.7	14.7	13.34	13.25	12.89	12.38	11.83	11.54	11.54	11.47	11.33	11.13	10.81	10.63	10.63
5600	14.7	14.7	14.36	13.16	12.98	12.71	12.14	11.76	11.54	11.54	11.33	11.13	11.13	10.81	10.63	10.63
6000	14.7	14.7	13.73	12.71	12.38	12.22	11.76	11.47	11.33	11.13	10.94	10.94	10.94	10.63	10.63	10.63
6600	13.16	12.89	12.71	11.83	11.76	11.47	11.2	10.88	10.63	10.63	10.63	10.63	10.63	10.63	10.63	10.63

STI base fueling (in AFR)
Code:
	0.25	0.4	0.55	0.7	0.85	1	1.15	1.3	1.45	1.6	1.75	2	2.25	2.5	2.75
800	14.7	14.7	14.7	14.7	14.7	14.7	14.25	14.25	14.25	14.25	14.25	14.25	14.25	14.25	14.25
1200	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.25	14.25	14.25	14.25	14.25	14.25	14.25	14.25
1600	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.25	14.25	14.25	14.25	14.25	14.25	14.25	14.25
2000	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.25	14.25	13.54	13.34	13.34	13.34	13.34	13.34
2400	14.7	14.7	14.7	14.7	14.7	14.7	14.7	14.04	14.15	13.54	13.34	12.8	12.71	12.54	12.46
2800	14.7	14.7	14.7	14.7	14.7	14.7	14.25	13.94	14.04	13.63	13.34	12.54	12.06	11.98	11.83
3200	14.7	14.7	14.7	14.7	14.7	14.7	14.25	14.04	13.63	13.63	13.34	12.38	11.98	11.83	11.76
3600	14.7	14.7	14.7	14.7	14.7	14.7	14.15	14.04	13.63	13.63	13.25	12.38	11.76	11.54	11.47
4000	14.7	14.7	14.7	14.7	14.7	14.25	13.54	13.34	12.89	12.46	12.22	11.83	11.54	11.33	11.2
4400	14.7	14.7	14.7	14.7	14.25	14.15	13.34	12.98	12.63	12.3	11.98	11.27	11.13	10.94	10.94
4800	14.25	14.25	14.25	14.25	13.73	13.16	12.71	12.63	12.3	11.98	11.54	11.2	11.13	10.94	10.94
5200	14.25	14.25	14.25	14.25	13.34	12.89	12.46	12.38	12.14	11.83	11.4	11.13	11.07	10.94	10.94
5600	14.25	14.25	14.25	13.63	12.8	12.38	12.22	12.14	11.83	11.47	11.33	11.13	10.88	10.88	10.63
6000	13.34	13.34	13.34	12.8	12.38	11.83	11.83	11.69	11.47	11.27	11.2	11	10.88	10.63	10.63
6400	13.34	13.34	13.34	12.71	12.06	11.76	11.61	11.47	11.33	11.27	11.2	10.81	10.81	10.63	10.63
6800	12.98	12.98	12.98	12.46	11.83	11.47	11.33	11.2	11	10.94	10.88	10.81	10.63	10.63	10.63
7200	12.98	12.98	12.98	12.46	11.83	11.47	11.33	11.2	11	10.94	10.88	10.81	10.63	10.63	10.63
7600	12.98	12.98	12.98	12.46	11.83	11.47	11.33	11.2	11	10.94	10.88	10.81	10.63	10.63	10.63
now that I have thrown some fuel into the fire.... lets discuss.

Last edited by Hawk296; 04-22-2008 at 10:14 PM.
Hawk296 is offline   Reply With Quote
Old 04-23-2008, 10:17 PM   #14
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

Sorry, Hawk, I didn't see all the stuff you'd added 'til now. I found someone to lend me an OBDII scan tool for the evening. It'll give me near-real-time readings (updates a couple times per second or so) on ignition timing in degrees BTDC, short- and long-term fuel trims (STFT & LTFT) in percentage adjustment from base, IAT, ECT, MAF, MAP, O2 sensor voltage and current, O2 sensor STFT in percent adjustment from base, calculated engine load in %, TPS, OL or CL ECU operation, and some other stuff I forgot. It won't give boot pressure, but MAP could be used to derive that, I suppose.

Anyway, I need you to explain what a bunch of those numbers you posted mean.

What is engine load expressed as in the table? I don't understand, for example, what engine load of 2.3 means.

Base timing is expressed in degrees BTDC, correct?

Is max timing advance also degrees?

I guess my main thing is what engine load is expressed as?

If load 1.0 = 100%, then the maps look quite similar, though the Baja appears programmed to run slightly more advanced timing sometimes? Hard to tell since there's no load=1 for the Baja and some of the differences between 0.95 and 1.05 are significant. Baja seems programmed to run richer from mid-high rpm on up, doesn't it?

I watched a couple things on the way home and, for example, I see 20-22 degrees BTDC ignition timing at 100% engine load, ~6,000 rpm, between 90 & 100 mph (don't recall what gear it was in), and STFT is -8% to -9.5% there. Timing advance appears steady (not variable or wavering) and increases as rpm increases.

That timing figure argues that my ECU is pulling ~20 degrees of timing out IF the engine load figures above are 1.0=100%, which will make the control tanks of 92 octane that I'll start in a couple weeks very interesting to see indeed (yes, it takes me 2-3 weeks to run a tank clear dry).

Couple things I didn't know are that the ECU reports that it remains in closed-loop at WOT all the way to redline, and that it reports going to open-loop when coasting. O2 sensor voltage goes to 0 when that OL switch happens down until about the time the torque convertor unlocks. Complete fuel cut?

Last edited by bulwnkl; 04-24-2008 at 12:11 PM. Reason: spelling
bulwnkl is offline   Reply With Quote
Old 04-24-2008, 08:29 AM   #15
deadlydave
Scooby Specialist
 
Member#: 131119
Join Date: Nov 2006
Chapter/Region: Tri-State
Location: Waterford, NY
Vehicle:
1996 Impreza LWRXSTI
91 BMW 318is

Default

bulwnkl, do you plan on re-setting your ECU upon filling up with the 92 octane, or are you going to let the computer 'learn' on the new fuel?

And I only have a very basic knowledge of whats in the above posted charts. Engine managment is new and interesting territory for me :-).
deadlydave is offline   Reply With Quote
Old 04-24-2008, 12:18 PM   #16
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

Not sure about the ECU reset, deadlydave. I'm new to electronic engine mgmt. adjustments as well. I've thought of each option, and will probably let it learn. Thing is, my LTFT is negative in most areas, and I know that when I disconnected the battery to swap plugs last fall/winter, mpg went right into the toilet the very next tank. I'm sure the winter cold was a big contributor, but even so it appears to have taken a while for the ECU to learn and lean things out. So, it seems to me that it'd be learning either way, and I'd just as soon let it start from where it's learned to operate. Make sense, or does a reset make more sense?

I should note that I'm a little skeptical that the engine would be running 40-45 degrees BTDC ignition timing under full power, especially at high rpm. I know the Tahoe I drive at work is only roughly half that. Still, I'm willing to be surprised by the Subies.

Last edited by bulwnkl; 04-24-2008 at 12:23 PM.
bulwnkl is offline   Reply With Quote
Old 04-24-2008, 01:30 PM   #17
deadlydave
Scooby Specialist
 
Member#: 131119
Join Date: Nov 2006
Chapter/Region: Tri-State
Location: Waterford, NY
Vehicle:
1996 Impreza LWRXSTI
91 BMW 318is

Default

Quote:
Originally Posted by bulwnkl View Post
So, it seems to me that it'd be learning either way, and I'd just as soon let it start from where it's learned to operate. Make sense, or does a reset make more sense?
I see your point. The ECU, if reset, would be learning from it's base tune. Moving up in octane with the ECU in it's current state (adjusted for lower octane)will at least be safer. Hell, it may even be faster. Subies are full of surprises.

It's really up to you, both chioces make sense for different reasons. The altitude you said you were at makes me lean towards not resetting the ECU though.
deadlydave is offline   Reply With Quote
Old 04-24-2008, 01:45 PM   #18
Hawk296
Scooby Specialist
 
Member#: 14555
Join Date: Jan 2002
Chapter/Region: MWSOC
Location: Troy, MI
Vehicle:
1995 Impreza L
Baja

Default

For what its worth, I have on a few occasions logged spark advance up to 50 degrees BTDC on my baja back when it was stock. That was running 93 octane fuel here in MI. I have since then retarded the timing a bit as i have increased boost to around 18-19 PSI.
Hawk296 is offline   Reply With Quote
Old 04-24-2008, 03:25 PM   #19
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

50 degrees at WOT and high rpm? I was seeing ignition timing in the mid to high 40s yesterday a number of times, just not at WOT and high rpm.

What does the engine load number mean in your tables, Hawk?
bulwnkl is offline   Reply With Quote
Old 04-24-2008, 10:58 PM   #20
Hawk296
Scooby Specialist
 
Member#: 14555
Join Date: Jan 2002
Chapter/Region: MWSOC
Location: Troy, MI
Vehicle:
1995 Impreza L
Baja

Default

Quote:
Originally Posted by bulwnkl View Post
50 degrees at WOT and high rpm? I was seeing ignition timing in the mid to high 40s yesterday a number of times, just not at WOT and high rpm.

What does the engine load number mean in your tables, Hawk?
Engine load measured in g/rev

I said a max of 50 degrees. I have to dig through logs to find what RPM, Throttle position and engine load that was at.
Hawk296 is offline   Reply With Quote
Old 04-24-2008, 11:02 PM   #21
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

I'm sorry, Hawk, I still don't quite comprehend engine load numbers (g/rev). g=grams or gravity in the context I'm used to.
bulwnkl is offline   Reply With Quote
Old 04-25-2008, 12:52 AM   #22
Hawk296
Scooby Specialist
 
Member#: 14555
Join Date: Jan 2002
Chapter/Region: MWSOC
Location: Troy, MI
Vehicle:
1995 Impreza L
Baja

Default

Edited because I was stupid and double posted.

Last edited by Hawk296; 04-25-2008 at 12:03 PM.
Hawk296 is offline   Reply With Quote
Old 04-25-2008, 12:57 AM   #23
Hawk296
Scooby Specialist
 
Member#: 14555
Join Date: Jan 2002
Chapter/Region: MWSOC
Location: Troy, MI
Vehicle:
1995 Impreza L
Baja

Default

Quote:
Originally Posted by bulwnkl View Post
I'm sorry, Hawk, I still don't quite comprehend engine load numbers (g/rev). g=grams or gravity in the context I'm used to.
http://forums.nasioc.com/forums/show....php?t=1294424

and http://forums.openecu.org/viewtopic....8330aa48c20da7
all the answers you seek are probably hiding in nasioc somewhere in fact this very topic has probably been covered too but its more fun to discuss.
Hawk296 is offline   Reply With Quote
Old 04-25-2008, 09:27 AM   #24
bulwnkl
Scooby Specialist
 
Member#: 41070
Join Date: Aug 2003
Location: Arizona
Vehicle:
2005 Black Tiger
(Black Turbo Baja)

Default

Crap, it IS grams! Thank you Hawk, for your patient help. More reading to do, but we started fumigating today, so little time for a few weeks...
bulwnkl is offline   Reply With Quote
Old 04-26-2008, 12:53 PM   #25
TeaBag
Scooby Newbie
 
Member#: 124161
Join Date: Aug 2006
Location: Valley Center,CA
Vehicle:
2005 Legacy + Supra
White legacy, Blue Supra

Default

All the timing and technical facts aside, running the Mfg required fuel is a little more at the pump, but its a small price to pay considering the damage that detonation can ultimately cause to your engine.

The Mfg is usually correct on all vehicle service and operating recommendations and I have personally seen what neglect and trying to save a few bucks to do to a car.

$.10 more per gal at the pump or repairing melted/cracked pistons, bhg's, and burnt valves?
TeaBag is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Stock looking more HP with just turbo and injectors/fuel pump? bigfishs Factory 2.5L Turbo Powertrain 11 02-07-2010 12:10 PM
Prosport Premium Fuel Pressure, Premium EGT, and Air/Fuel ender87i Interior/Dressup/Audio & Security 2 09-28-2007 01:10 AM
2006 WRX TD04 turbo and stock fuel pump..6500 miles riggs Private 'For Sale' Classifieds 4 01-24-2006 07:43 PM
Turbos and Air Fuel Ratios Kevin Thomas Factory 2.0L Turbo Powertrain 29 05-21-2001 01:29 PM


All times are GMT -4. The time now is 03:59 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.