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Old 11-17-2005, 11:09 AM   #1
Hitokiri
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Default 99RS ECU Findings !great for AFI!

I was helping another member recently, and in the process of datalogging through SSM off his ECU I made a very interesting discovery. Very interesting especiallly for us AFI people.

The 99RS ECU might be somewhat similar to the 98RS ecu, but as Japan changed ecus in 99 the 99ecu has a good probability of standing on itss own programming wise. I have been working with tuning piggyback on it for more than a year now and tuning has always been very easy especially with the emanage ultimate eliminating MAF correction. Due to the recent release of great ECU datalogging software, I have been able to tune fuel trims down to almost nothing with the ultimate, and explore many aspects of the stock ECUs control that we have never seen prior.

This car has a stock WRX turbo which spools very quickly. It has an SAFC and WRX injectors and is more or less untuned at this time, but while working on cruising fuel trims I noticed that the car's closed loop to open loop transition is triggered by the boost sensor!!!

Closed loop / open loop transition criteria is the most important part of tuning boost onto an ECU which does not expect it. This transition represents when you have free control over fueling without the ECU trying to correct around your efforts to stabilize a desired AFR. It was previously thought that RS ECUs in general go open loop (not lisening to the o2 sensor at all) at around 3700 RPM, or so it has been stated many times, but what I have found is that it may go open loop at that time under some conditions and on some ECUs, but the transition to boost seems to kick the MY99 ecu into open loop at any time!

This is PERFECT for AFI tuning with piggybacks. You essentially want the ecu to run stock off boost (and it does ALOT to achieve this through its learning - you realize the extent that it helps when you start tuning standalone systems), and be able to tune it to run the way you want on boost. The fact that the 99ECU seems to hit open loop as soon if not slightly before (which would make sense as it was designed for NA) the car sees boost is by far the best ECU program a tuner of AFI systems could dream to have. It is no wonder my car is so easy to tune! The ECU lets me tune the car however I want whenever the car is in boost, and it makes that transition seemlessly and automatically for me.

All those with 99ECUs out there you are lucky. Its the perfect ECU for turbo applications.

Here are some datalogs showing the transition to open loop happening as the car transitions to boost. Notice in both logs the car is at relatively low RPM and relatively low Engine Load. You can see the short and long term fuel trims go to zero as the car enters boost - this is the transition to open loop. The car no longer makes any correction to its program.. it just blindly sends whatever fuel you ask it to (with piggyback).

Todd

Code:
Engine Speed (RPM)	Air/Fuel Learning #1 (%)	Air/Fuel Correction #1 (%)	Engine Load (g/s)	Front O2 Sensor #1 (V)	Mass Air Flow (g/s)	Ignition Timing (BTDC)	Knock Correction (BTDC)	Fuel Injector #1 Duty (%)	Air Flow Sensor Voltage (V)	Manifold Relative Pressure (PSI)
1947	-13.28	-3.91	4.31	0.775	15.36	13	0	2.91	1.4	-11.608
1937	-13.28	-1.56	3.14	0.095	12.71	23	0	2.48	1.4	-11.608
1931	-13.28	-0.78	3.53	0	14.48	29	0	2.47	1.46	-11.318
1929	-13.28	0	7.45	0	32.79	33	0	4.53	2	-10.447
1965	-16.41	1.56	12.55	0	53.62	33	0	7.54	2.48	-8.706
2049	-20.31	0	27.45	0	112.37	15	1	17.48	2.8	-2.757
OPEN LOOP TRANSITION!!!!!!!!!!!!!    OPEN LOOP TRANSITION!!!!!!!!!!!!!    										
2106	0	0	30.98	0.035	124.27	13	1	20.67	2.84	-0.145
2316	0	0	38.04	0.765	155.16	12	3	25.69	3.08	0.871
2484	0	0	45.49	0.805	183.06	13	2	30.21	3.3	2.176
2633	0	0	52.55	0.83	211.96	12	1	34.82	3.4	3.773
2814	0	0	61.18	0.83	245.07	11	-1	40.23	3.52	5.078
3059	0	0	67.06	0.83	264.82	11	-1	43.72	3.56	5.078
3344	0	0	72.16	0.82	286.83	12	0	49.22	3.68	5.078
3484	0	0	75.69	0.81	303.37	11	0	51.28	3.72	5.078
3676	0	0	80.39	0.79	320.39	11	0	54.9	3.78	5.078
3916	0	0	85.1	0.785	341.88	13	0	58.48	3.86	5.078
4119	0	0	89.02	0.775	356.1	10	-2	61.5	3.9	5.078
4333	0	0	95.29	0.765	378.25	12	-2	64.7	3.98	5.078
4596	0	0	100	0.765	392.39	16	-2	69.61	4.04	5.078
4814	0	0	100	0.76	411.83	19	-2	72.91	4.08	5.078
5013	0	0	100	0.76	419.47	25	0	74.86	4.08	5.078
5208	0	0	100	0.75	423.96	24	0	76.67	4.1	5.078
5439	0	0	100	0.755	432.9	26	0	78.89	4.14	5.078
5622	0	0	100	0.745	436.99	26	0	80.36	4.14	5.078
6093	0	0	64.71	0.76	206.26	22	0	1.3	3.14	2.467
5756	0	-2.34	47.06	0.615	186.97	20	0	1.23	3.28	-6.675
5459	0	-2.34	47.84	0.5	187.64	20	0	1.16	3.18	-9.722
5155	0	0	49.41	0	190.64	39	0	31.89	3.2	-9.576
4889	0	0	75.69	0.03	306.33	24	0	54.24	3.88	-3.627
4185	0	0	87.84	0.74	348.93	10	-5	61.61	3.88	2.467
4211	0	0	89.02	0.735	353.92	11	-5	60.19	3.86	5.078
4266	0	0	91.76	0.73	364.14	11	-5	61.89	3.94	5.078
4422	0	0	94.51	0.725	374.2	13	-5	63.21	3.98	5.078
4483	0	0	95.69	0.725	376.53	14	-5	64.07	3.98	5.078
4604	0	0	96.86	0.725	379.96	15	-5	65.81	3.98	5.078
4690	0	0	98.43	0.72	390.72	16	-5	67.04	4.02	5.078
4735	0	0	98.04	0.725	382.29	18	-5	65.66	3.92	5.078
4407	0	-2.34	41.96	0.655	166.25	20	-2	0.94	3.1	-3.627
4378	0	-2.34	52.16	0.735	205.71	20	-2	0.93	3.26	-9.431
4155	-17.97	-2.34	43.53	0.685	170.25	20	-2	0.89	3.04	-11.027
3555	-17.97	-2.34	31.37	0	124.88	20	-2	0.76	2.76	-11.173
3298	-17.19	-2.34	26.67	0	102.82	20	-2	0.7	2.62	-11.027
3044	-17.19	-2.34	23.14	0	89.89	20	-2	0.65	2.5	-11.173
2793	-17.19	-2.34	20.39	0	81.19	20	-2	0.6	2.34	-11.173
2549	-17.97	-2.34	17.25	0	69.26	20	-2	0.54	2.26	-11.173
2323	-15.63	-2.34	16.47	0	65	20	-2	0.5	2.26	-11.463
2095	-15.63	-2.34	15.29	0	61.14	20	-2	0.45	2.14	-11.608
1859	-20.31	-2.34	14.51	0	52.2	20	-2	0.4	1.4	-11.608
1642	-16.41	-2.34	6.27	0	25.24	20	-2	3.5	1.66	-11.463
And another example:

Code:
Engine Speed (RPM)	Air/Fuel Learning #1 (%)	Air/Fuel Correction #1 (%)	Engine Load (g/s)	Front O2 Sensor #1 (V)	Mass Air Flow (g/s)	Ignition Timing (BTDC)	Knock Correction (BTDC)	Fuel Injector #1 Duty (%)	Air Flow Sensor Voltage (V)	Manifold Relative Pressure (PSI)
2234	-14.84	8.59	12.16	0.765	48.68	35	0	7.15	1.98	-8.706
2275	-14.84	7.03	12.55	0.77	50.48	35	0	7.28	2.04	-8.706
2341	-14.84	5.47	12.55	0.78	50.25	35	0	6.99	2.08	-8.851
2397	-14.84	3.91	12.55	0.775	51.28	35	0	7.16	2.12	-8.706
2433	-14.84	2.34	13.33	0.765	52.75	34	0	7.27	2.1	-8.706
2486	-14.84	1.56	13.33	0.76	53.09	34	0	7.42	2.18	-8.706
2584	-18.75	0	22.75	0.745	93.43	29	0	12.13	2.86	-6.82
2647	-17.97	3.91	32.94	0	134.77	21	1	17.51	2.98	-2.902
2708	-17.97	7.03	41.57	0	166.25	16	3	20.79	3.14	-0.58
OPEN LOOP TRANSITION!!!!!!!!!!!!!    OPEN LOOP TRANSITION!!!!!!!!!!!!!    										
2974	0	0	52.94	0	213.56	16	3	33.62	3.34	1.741
3161	0	0	63.14	0.795	252.36	13	1	39.11	3.52	3.918
3317	0	0	66.67	0.815	270.67	11	-1	41.04	3.54	5.078
3498	0	0	70.59	0.82	282.81	10	-1	44.03	3.62	5.078
3761	0	0	76.86	0.81	305.5	11	-1	48.14	3.74	5.078
4011	0	0	81.57	0.805	322.92	14	-1	52.19	3.78	5.078
4167	0	0	85.1	0.805	341.2	8	-2	55.11	3.88	5.078
4363	0	0	89.41	0.795	356.8	9	-2	58.64	3.92	5.078
4621	0	0	94.51	0.785	374.75	13	-2	63.09	3.96	5.078
4744	0	0	96.08	0.78	383.76	16	-2	63.76	4	5.078
5061	0	0	96.86	0.78	383.32	25	0	66.93	3.98	4.788
5256	0	0	93.73	0.77	370.15	27	0	65.03	3.92	3.627
5427	0	0	92.55	0.77	370.09	28	0	64.83	3.92	2.612
5614	0	0	91.37	0.77	357.14	29	0	63.47	3.82	1.741
5241	0	-2.34	44.31	0.665	174.73	20	0	1.12	3.14	-5.659
5023	0	-2.34	49.41	0.65	195.31	20	0	1.07	3.22	-9.722
4705	0	-2.34	43.14	0.045	171.03	20	0	1	3.08	-10.737
4353	0	-2.34	36.47	0	141.24	20	0	0.93	2.88	-11.027
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Old 11-17-2005, 11:59 AM   #2
ai42
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Man that is cool. 99 is definetly the RS to turbo then with 9.5:1 compression and a niffty ECU.
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Old 11-17-2005, 12:35 PM   #3
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at what throttle position is that transition occuring?

Also, I am having a hard time reading the AFR stuff, is it reading in lambda or straight afr, and if so where is it?

Looks like it is maxxed out at 5.078psi, looks like we found the limit of that stock MAP sensor

I am curious as to how this is better/different than other cars, cause all cars have closed and open loop transitions, I would venture a guess if you were able to data log other NA subarus you would see similar things.

good info though.

Ben
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Old 11-17-2005, 12:40 PM   #4
ai42
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Quote:
Originally Posted by PHATsuby
at what throttle position is that transition occuring?

Also, I am having a hard time reading the AFR stuff, is it reading in lambda or straight afr, and if so where is it?

Looks like it is maxxed out at 5.078psi, looks like we found the limit of that stock MAP sensor

I am curious as to how this is better/different than other cars, cause all cars have closed and open loop transitions, I would venture a guess if you were able to data log other NA subarus you would see similar things.

good info though.

Ben
99 RS is MAF based.
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Old 11-17-2005, 12:44 PM   #5
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yes, I know it is, but it still has a MAP sensor, look at the last column, that is the manifold pressure in psi, manifold pressure is still used for secondary things for the car. Thanks though.

Ben
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Old 11-17-2005, 12:49 PM   #6
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I had a feeling this was your post when I saw it on the main page. Nice findings, Toddsauce.
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Old 11-17-2005, 01:20 PM   #7
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That is not the limit of the stock sensor. I have personally seen it read up to 8.5psi on my car. This car is just running 5psi.

Forget about the AFR numbers. Its narrowband 02. and that reading is o2 voltage. But in my experience it's not accurate at all. Subaru switched to a much better o2 sensor in 00 which actually comes out as lambda in the logs.

I garantee that TPS isn't what is causing this transition. I didn't log it but I will next time I am tuning. It would make sense however and some have noted that TPS may be another condition for open loop, but having a boost trigger is much better tuning wise.

I have logged various other cars. I have 02RSt logs and when I get a chance I will post its transition as well.

I really hope that I find that boost triggers open loop on all NA subes, but I have a feeling this isn't the case
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Old 11-17-2005, 01:29 PM   #8
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Oh ok, yea I figured it was either the limit or only running 5psi, but I looked at your setup and figured you were not running only 5psi, but this is not your car?

likely on the MAP systems you wont see the same thing, here would be the thing to check is get another 99 that is stock, likely it is some combination of load and TPS value, or just one or the other. Cause if it was just boost, you would never transition to open loop on a stock RS. It must have some positive pressure type algorithm or fail safe programming in it that makes it go right ot open loop when getting positive pressure.

I have no idea really, just guesses.

Ben
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Old 11-17-2005, 01:50 PM   #9
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On MY00, I believe there are 3 different conditions to get out of closed-loop - MAP reading, TPS reading, or RPM. It looks like Subaru has made some major changes in the sensors for 2000 - I believe we have a 1bar MAP sensor (that will go slightly over 1bar, I have it clamped at 1.1). It will do open loop as soon as the MAP reads above 1bar absolute (No LT & ST). I have seen some cases where there is still a LT but no ST at all which would have suggested that it's open loop as well (because I'm on a stand-alone).

To me, if you're not running some big over-sized injectors, it seems that piggy back is better - when you're not boosting, you should have no problem letting the stock ECU run the ignition and injection, it's only when you're boosting you need to retard timing and increase fuel... great - one more route to think about if and when I ditch my Link
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Old 11-17-2005, 02:09 PM   #10
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And to add to this thread - imagine you're going a steep hill where you get 100% load on part throttle (on an NA car, that should mean a MAP reading > 1bar absolute). It would be bad to be running closed-loop under that situation (remember that closed-loop is strictly for emissions so it almost always target close to stoich) so TPS must not be the only factor in switching over to open loop. As for RPM switching - it's mainly for engine cooling since you could run too hot even on N/A if you keep running stoich.

Which kinds of bring me to the discussion of the reflashes for the RS - does anybody know if i-Speed manage to figure the closed-loop kick out? I hope they do because if they didn't, that would be a great reason not to market the reflash for an RS-T at this point - they would have to use a MAP sensor > 1bar and the stock ECU reads Voltage. Lots of opportunity here - my conclusion for an RS-T is that if you run WRX sized injectors and you don't go crazy on boost or power, you might be better off with piggyback that only controls ignition/fuel on boost. Your car would be cleaner when not boosting (good for emissions), and you have more power and the safety is thru the piggyback on boost. Stock injectors would be a little iffy since you're still working with the stock map and that might be why RalliTEK is advocating 5th injector on PP SMT6 for RS-T
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Old 11-17-2005, 04:07 PM   #11
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kgb- I agree. but adjusting the sensor scaling is doable with reflahing ability. They will have to have located those tables in the flash however. It'll get there.

There is another MAP sensor on 00+ MAP base RS ecus..... And it reads boost.... very accurately... If anything that sensor could be used in conjection with a sensor scaling on a reflash with good results. There is so much that needs to be understood in order to effecticly implement reflashing for the ecu to handle boost well however that I wouldn't hold your breath. It would be much easier for a 99 to be flashed as the load scales would just need to be changed to allow more resolution at higher MAF voltages. That I could see happening.

Rallitek is using a 5th injector because after the car goes into boost, there is no tuning ability as the sensor you are modifying is pegged. They had to add a 5th injector because its simply a hack to try and use sensor correction on a maxed out sensor. Now that the emanage ultimate is here hoever this is all changed. I would definitely recomend either a 5th injector setup or bigger injectors with an emanage ultimate if you wanted to go back to stock ecu. I am working on a 5th injector setup on another car with a regular emanage at the moment with a 02 ECU so i'll have a better idea how good of a solution that is soon.

Don't get me wrong though. A good standalone tuned by a good tuner is still the best solution at this point. I am just sheding some light on the stock ecus operation.
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Old 11-17-2005, 04:20 PM   #12
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I think my view is that without the ability to switch the MAP cross voltage, the stock ECU would only switch to open loop close to a 5V reading on the MAP. I don't believe the MY00+ has a MAP sensor that reads more than 1.2Bar, even if you're pass 1.1, you're looking at a CEL - hence the need for MAP clamp. I would agree that there is tunability once the sensor is pegged. I don't know - the stock ECU has a lot of a potential because of all of sensors it used to make decision. Off boost I don't think there is anything standalone that can touch the stock ECU in terms of balance - it's on-boost that concerns the RS-T owners. ecuExplorer was great in getting a good understanding of the MY00 ECU's working
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Old 11-17-2005, 08:22 PM   #13
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todd, which ecu did we try at your apartment that night? TJ's? what year is that one?
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Old 11-17-2005, 09:19 PM   #14
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My00rs
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Old 11-18-2005, 10:23 AM   #15
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The only thing I don't like about the '99s are the MAF sensor type. IF only it was still the older ones. '99 MAFs suck.
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Old 11-18-2005, 11:43 AM   #16
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99 MAFs may break all the time, but they are a godsend for tuning and AFI.
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Old 11-18-2005, 02:29 PM   #17
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MAF is better compensated to weather change, because they actually measure the mass of air that is sucked into the engine. It's just the choice of MAF they put on the 99 that makes it suck - the WRX and STi have no problem with the MAF sensor. The only problem with MAF is that it kind of restricted the size of intake
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