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Old 04-29-2009, 10:30 PM   #1
sorrowfulkiller
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Default Effect on moving stock o2 sensor to post turbo?

I know the stock wideband in the wrx atleast is only good to read down to about 11.25-11.5 correct?

My question is, what if the sensor was re located post turbo? would it still be as accurate or would it change?

The only reason I'm asking is because my LC-1 crapped out on me and shortly after my backup wideband which is a JAW 1.03 (www.14point7.com) then crapped out on me shortly afterwards... the JAW I may be able to fix... the lc-1 is probably completely shot and I just got my injectors and maf properly scaled but I can tell the car is running too rich for e85 because I'm backfiring way more than I was when I had wot tuned and was running a leaner cruise and idle afr due to fudged injector scaling.

I don't have the cash now to buy a new wideband, and I may or may not be able to fix my JAW unit, I'm simply curious if anyone has tried it and what your results were.

Thanks for your time
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Old 04-30-2009, 09:13 AM   #2
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Send the LC-1 back to Innovate.I remember a thread on Romraider about moving the 02 sensor.
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Old 04-30-2009, 09:48 AM   #3
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Send the LC-1 back to Innovate.I remember a thread on Romraider about moving the 02 sensor.
They'll replace the lc-1 huh?

That'd be awesome!
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Old 04-30-2009, 11:00 AM   #4
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I think I remember that the people who moved their stock O2 post-turbo ran into some CL fueling issues because of the added delay, but I don't have any threads for reference.
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Old 04-30-2009, 01:19 PM   #5
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I've got my stock O2 in the downpipe bellmouth and my car runs fine. Someone else on RomRaider (root is his name) did the same thing with no ill effects.

Mine only reads down to about 11.2 or something so I haven't put much effort into scaling it to be accurate outside of cruise. It's something I want to try eventually though just for grins. I have a wideband installed right next to it, so it should be possible to reasonably good readings down to 11.2. However MickeyD2005 at RomRaider says the stock sensor reacts slowly to changes in AFR so I'm not sure this mod can actually replace widebands.

I also strongly suspect that there's a way to hack the ECU to get it to read much lower. I'm hoping Merchgod finds it because I'm making no progress toward that myself.
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Old 04-30-2009, 10:13 PM   #6
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I've been running the stock front O2 sensor in my downpipe for over 2 years. It actually reads pretty close to my LC-1 down to around 11.14. No ill effects, stumbles, or adverse behavior. It reacts just as quickly as it did in the manifold.

FYI, the JDM twin-scroll turbo setups run the front O2 sensor in the downpipe as the OEM location.
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Old 05-01-2009, 12:06 AM   #7
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Yeah I know the stock twin scroll setups use it in the downpipe and I'm thinking that if I move my sensor back to the dp, then I'd be able to re-tune my car slightly leaner so I don't have the horrible gas mileage I'm currently getting and would run back up to 12 AFR like I was on my previous tune.

The car's running e85 fyi, just wanted to clarify that before anyone said anything about the 12 afr target.


Also doesn't the 02-03 wrx not have closed loop enabled? only open loop? If that is not the case is there a way to run strictly open loop?
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Old 05-01-2009, 03:12 AM   #8
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Quote:
Also doesn't the 02-03 wrx not have closed loop enabled? only open loop? If that is not the case is there a way to run strictly open loop?
I have no experience with the 02-03 WRX but my guess is that it runs closed loop in cruise for the sake of emissions and fuel economy.

I haven't actually tried this, but it's something to consider if you want a hack to get open loop all the time... with my 05 LGT, zeroing the open loop transition delays is supposed to leave only one factor that governs OL/CL: the fuel enrichment table. If it's lower than the "minimum open loop enrichment" value (I think that's the name) then the car goes to open loop. So if you set that to 14.7 (or 14.69 if necessary) and set the cruise region to 14.69 (14.69 if necessary), then you might full-time open loop. Again, I haven't tested this theory but it seems plausible. If you can log OL/CL status that should be enough to verify whether this works.
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Old 05-01-2009, 09:23 AM   #9
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I haven't actually tried this, but it's something to consider if you want a hack to get open loop all the time... with my 05 LGT, zeroing the open loop transition delays is supposed to leave only one factor that governs OL/CL: the fuel enrichment table. If it's lower than the "minimum open loop enrichment" value (I think that's the name) then the car goes to open loop. So if you set that to 14.7 (or 14.69 if necessary) and set the cruise region to 14.69 (14.69 if necessary), then you might full-time open loop. Again, I haven't tested this theory but it seems plausible. If you can log OL/CL status that should be enough to verify whether this works.
It will have to be richer than that. You'll have to look at the minimum OL active value for your particular ECU, but it is never 14.7:1. And yes, others have already tried this and it does keep you in OL all the time.
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Old 05-01-2009, 09:24 AM   #10
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Also doesn't the 02-03 wrx not have closed loop enabled? only open loop?
No, the 02-03 WRX runs in closed loop and open loop just like every other Subaru.
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Old 05-01-2009, 10:44 AM   #11
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It will have to be richer than that. You'll have to look at the minimum OL active value for your particular ECU, but it is never 14.7:1. And yes, others have already tried this and it does keep you in OL all the time.
Yeah, I think when I did it on my car I set the minimum open loop enrichment value to 20 or something ridiculous, then changed all of the 14.7 cells in my map to 14.6. Voila, permanent open loop.
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Old 05-01-2009, 04:14 PM   #12
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I have sensor in the downpipe on my 02 wrx. It's more accurate in the downpipe since it's not exposed to pre-turbo exhuast pressure. I log and tune the car by it and it works fine. I never tune any richer than 11.2 anyway for good power.
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Old 05-02-2009, 12:51 AM   #13
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Well this is all good to hear... I'l actually be able to tune my car a bit better then without a aftermarket wideband.

Did any one of you have to extend your wiring for the o2 sensor?

I think I'm going to try to fix my tune soon then, all I need to do is get a new m20 bung welded into my downpipe.

I suppose I'll make my car permanently run open loop as its completely pointless not to from what I can see. Although I'm not going to target as rich a mixture as 14.7. I've ran up to 17-1 safely with no sign of any issue what so ever, but I'll set it up for 16. I'll just fudge my injector latency on purpose to lean out on cruising and adjust my wot afrs to follow.

One issue though, the suicide eggroll, how did you modify your minimum open loop enrichment value to 20? I can only get it to go to 14.7

Last edited by sorrowfulkiller; 05-02-2009 at 01:00 AM.
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Old 05-02-2009, 01:28 AM   #14
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Another thing... I was looking at how the closed loop and open loop setting is figured.

If one would change the limits for closed loop to an afr like 20-22 would this not constantly put the car into open loop because it has no possible way to try to target such an afr when the closed loop afr value only reads 14.7?

This way even if you mess with injector latency to lean out your cruising afr's past 14.7 then you should be able to do this while still in open loop, correct?

I don't like how either rom-raider or ecuflash do not let people target leaner afr's than 14.7 in open loop. It annoys the living hell outta me and it has for quite a while
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Old 05-02-2009, 05:03 AM   #15
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Your 02 WRX might be different than my 05 Legacy but in my case the stock O2 sensor's wiring was just the right length to relocate it. PLX/Bosch on left, stocker on right:



Also, I think the 14.7 limit for open loop cruise is a function of the ECU code, not RomRaider or EcuFlash. Internally it's a number that basically means, "how much richer than stoich." But as you mentioned, it should be easy to target whatever open loop AFR you want just by tweaking the injector or MAF scaling.
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Old 05-02-2009, 02:09 PM   #16
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Originally Posted by NSFW View Post
Your 02 WRX might be different than my 05 Legacy but in my case the stock O2 sensor's wiring was just the right length to relocate it. PLX/Bosch on left, stocker on right:



Also, I think the 14.7 limit for open loop cruise is a function of the ECU code, not RomRaider or EcuFlash. Internally it's a number that basically means, "how much richer than stoich." But as you mentioned, it should be easy to target whatever open loop AFR you want just by tweaking the injector or MAF scaling.
if i targetted an afr thats leaner than 14.7 however wouldnt that star going into closed loop again when its over the pre determned afr threshhold?
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Old 05-02-2009, 02:24 PM   #17
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Here's what I had in mind:

14.7 * 0.85 = 12.5 (15% lower)
Set the target AFR in your cruise area to 12.5.
Then multiply your injector scaling by 1.15 (15% higher)

The car will use IPWs calculated to give you 12.5 (15% richer than stoich), but since your injectors are flowing 15% less fuel than the car thinks, you should end up with 14.7.

Then raise the values in the fuel table until you get the 16:1 AFRs you're looking for in cruise. The numbers in the fuel table won't match reality but in open loop the engine doesn't know or care. You'll have to scale them in your head when you make changes.

Definitely verify the results with a wideband before you go crazy with this. I'm making this **** up as I go along.
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Old 05-02-2009, 03:28 PM   #18
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One issue though, the suicide eggroll, how did you modify your minimum open loop enrichment value to 20? I can only get it to go to 14.7
Maybe it's a 32-bit only thing? I just did it again, works fine.
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Old 05-02-2009, 05:16 PM   #19
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Anything leaner than 14.7:1 in the editor for that minimum threshold, which you can enter for the 32-bit ECU (but not the 16-bit ECU), is irrelevant. 20:1, 17:1, 14.7:1 is all equivalent to 14.7:1.

The whole idea of manipulating the ECU so that you can run open loop all the time because your wideband o2 is broken and you want to use the factory sensor to tune fueling and then manipulate the injector scaler so you can tune leaner than stoich seems to me to be a hell of detour in attempt to solve your problem -> get the sensor replaced. If you can't afford a new sensor, then frankly, I'd be running the most conservative tune I could and not start jacking with stuff and get the wideband as soon as you are able to.
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Old 05-02-2009, 05:36 PM   #20
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i have the stock o2 after the turbo because i have the JDM twinscroll setup and that is where it is from the factory
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Old 05-02-2009, 07:59 PM   #21
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Anything leaner than 14.7:1 in the editor for that minimum threshold, which you can enter for the 32-bit ECU (but not the 16-bit ECU), is irrelevant. 20:1, 17:1, 14.7:1 is all equivalent to 14.7:1.

The whole idea of manipulating the ECU so that you can run open loop all the time because your wideband o2 is broken and you want to use the factory sensor to tune fueling and then manipulate the injector scaler so you can tune leaner than stoich seems to me to be a hell of detour in attempt to solve your problem -> get the sensor replaced. If you can't afford a new sensor, then frankly, I'd be running the most conservative tune I could and not start jacking with stuff and get the wideband as soon as you are able to.
uh.... what?

I just want to use the stock o2 sensor since I'm not running richer than 11.5 at WOT there is no reason for me to replace the wideband unless it gets fixed by innovate. and the reason for me to run open loop... well that's just because I don't like closed loop, it pisses me off immensely.

Also, you can't run leaner than stoich unless you trick the ecu anyways... I don't care if my numbers match up on my fuel table to my actual trims, as long as the actual afr is right I don't care at all.
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Old 05-02-2009, 09:23 PM   #22
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uh.... what?

I just want to use the stock o2 sensor since I'm not running richer than 11.5 at WOT there is no reason for me to replace the wideband unless it gets fixed by innovate. and the reason for me to run open loop... well that's just because I don't like closed loop, it pisses me off immensely.

Also, you can't run leaner than stoich unless you trick the ecu anyways... I don't care if my numbers match up on my fuel table to my actual trims, as long as the actual afr is right I don't care at all.
Is this on an 02 WRX as in your profile? Only the DBW cars (32-bit ECU) have a wideband for the front o2. The DBC 16-bit ECU use a narrowband front o2 so it will be useless for anything outside of normal closed loop (i.e. stoich). And yes, you can run leaner than stoich in closed loop. You can directly modify the CL target for the 16-bit ECU in RomRaider as well as the allowable limits.
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Old 05-02-2009, 10:23 PM   #23
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Is this on an 02 WRX as in your profile? Only the DBW cars (32-bit ECU) have a wideband for the front o2. The DBC 16-bit ECU use a narrowband front o2 so it will be useless for anything outside of normal closed loop (i.e. stoich). And yes, you can run leaner than stoich in closed loop. You can directly modify the CL target for the 16-bit ECU in RomRaider as well as the allowable limits.
From what I'm reading on romraider that is not true... it may or may not be a wideband. It just depends on what kind of sensor the stock one is and what it's output at idle would be
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Old 05-02-2009, 10:47 PM   #24
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From what I'm reading on romraider that is not true... it may or may not be a wideband. It just depends on what kind of sensor the stock one is and what it's output at idle would be
Your reading a recent post on RR by someone who deals with non-USDM Subarus. The consensus has always been that at least the USDM 02-05 WRX uses the identical front o2 and that it is a narrowband. I guess that could be wrong - no one has attempted to prove it either way that I know of.
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Old 05-03-2009, 12:13 AM   #25
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I suppose then I'll just have to use my buddies aem wideband and log both once I get it tuned to see actually how well the stock one works
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