rampster
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- May 5, 2021
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in @Grease Monkey's Hustler clone thread, John had made some interesting comments (shown above) about O2 corrections & that got me to thinking........... its been quite a long time since Ive touched anything EFI related & all of what I did was drag racing or street car related, was wondering how things have changed..... I didn't want to bugger up the other thread with tech questions..........I never run an 02 sensor in my cars for multiple reasons. My personal car either but after the last few days I have decided to do it to my own. Most Subarus I build has economy priced Ecu’s so it’s not really an option. But GreaseMonkey and mine run an AEM ecu. The infinity series, their top of the line. So I installed a base map from a previous build and it started and ran good. I turned on the lambda and made a pull right out of the box and had fabulous AFR through the whole pull. Then I turned off lambda and I was surprised at what I saw. Base maps are just that. Base maps. Too many variables that affect it so to run the same map on two different cars is not a reality (with no tuning) what I saw was how far off the base map was to my target AFR. This 02 was doing way more corrections and at a very fast rate than I had thought it could do. Yesterday I got the base map on the money sans 02 sensor and then when I was done I turned it back on. I already ordered one for mine.
These are great questions. Let me answer them as best as I can. Wide band O2 sensors were very expensive as they were never produced in huge quantity and their use was limited but with more stringent smog laws and need to have O2 sensors go into closed loop, the OEM car manufactures have made these sensor more common and cheaper. The AEM Bosch 4.2 that grease monkeys car uses is just a tad over $100! They were also plagued to short life too with leaded racing gas. That is still an issue with my O2 sensor on my dyno because I tune lots of cars with leaded gas. But E85 won’t hurt these sensors so other than maybe abuse(shock) to these sensors I expect them to last years! And I only run one sensor for my 6 cylinder cars. 02 sensors are now so effluent that newer cars can go into closed loop well under 30 seconds. Years ago this would take 5 minutes or more! Just to make sure we are in the same page closed loop is when the ecu is able to adjust fuel demands by monitoring the exhaust coming out of the tail pipe. Thereby it’s always correcting or trimming the mixture to optimize AFR. Open loop would be where a sensor is monitoring the exhaust but can’t do any corrections/trimming to the current AFR. This would be like buying a stand alone AFR gauge to watch/monitor exhaustin @Grease Monkey's Hustler clone thread, John had made some interesting comments (shown above) about O2 corrections & that got me to thinking........... its been quite a long time since Ive touched anything EFI related & all of what I did was drag racing or street car related, was wondering how things have changed..... I didn't want to bugger up the other thread with tech questions..........
When you (@John@Outfront) turned on the O2 correction & saw how much it was trimming, was it "learning" those new spots & adjusting the map or was it just continually trimming to "fix" spots it did not like?
related to the above question....... can you put it in a "learn" mode so it will adjust the base maps so you can turn the course trim correction off & it will be super close to spot on w/o correction?
How robust are the O2 sensors now days? used to be the WBO2's were uber expensive & were not super robust. Especially when we were running leaded gas...
Is this functionality how most EFI's work now days? I think that @Fullthrottleguy, does a number of different tuning stuff & was wondering if the other MFG's operate similarly to what the AEM Does??
John one thing I see on LS engines with"reasonably priced" (real Bosch) WBO sensors is that we tend to have them "closer to the engine" and running boost either SC or Turbo and making "power" you tend to get hotter headers (ever see a header glow so red you can see through it ...and because they are in the hot header - life gets shortened quite a bit (the heater fails), not as bad as running leaded gas of course but friggin annoying. One of the best tuners I know gace me a suggestion and I do it now on High boost engines =Basically make a heat sink under the 02 by taking a 6" by 6" piece of .090 Copper plate and throwing some bends in it and drilling a hole and placing under the 02 - doing that the sensors are lasting a couple seasons instead of 1/2 a season ,,,These are great questions. Let me answer them as best as I can. Wide band O2 sensors were very expensive as they were never produced in huge quantity and their use was limited but with more stringent smog laws and need to have O2 sensors go into closed loop, the OEM car manufactures have made these sensor more common and cheaper. The AEM Bosch 4.2 that grease monkeys car uses is just a tad over $100! They were also plagued to short life too with leaded racing gas. That is still an issue with my O2 sensor on my dyno because I tune lots of cars with leaded gas. But E85 won’t hurt these sensors so other than maybe abuse(shock) to these sensors I expect them to last years! And I only run one sensor for my 6 cylinder cars. 02 sensors are now so effluent that newer cars can go into closed loop well under 30 seconds. Years ago this would take 5 minutes or more! Just to make sure we are in the same page closed loop is when the ecu is able to adjust fuel demands by monitoring the exhaust coming out of the tail pipe. Thereby it’s always correcting or trimming the mixture to optimize AFR. Open loop would be where a sensor is monitoring the exhaust but can’t do any corrections/trimming to the current AFR. This would be like buying a stand alone AFR gauge to watch/monitor exhaust
Great idea. As you can see like on GM carbI always put them post turbo. Learned long time ago from a MoTec guru that pressure actually affects the O2 sensors reading. That MoTec actually had a compensation table to correct so you would get an accurate reading in the pressure side of the exhaust. So for that reason and yours I place it post turbo. You just can’t get to close to end of tail pipe either. If you always put pre turbo placement and didn’t know that pressure skews the reading then if you were a good tuner you would unknowingly compensate still searching for max power, However if you try to extrapolate your readings and apply “your target AFRs” to a motor that has sensor post turbo you may find it likes a different reading then you are used toJohn one thing I see on LS engines with"reasonably priced" (real Bosch) WBO sensors is that we tend to have them "closer to the engine" and running boost either SC or Turbo and making "power" you tend to get hotter headers (ever see a header glow so red you can see through it ...and because they are in the hot header - life gets shortened quite a bit (the heater fails), not as bad as running leaded gas of course but friggin annoying. One of the best tuners I know gace me a suggestion and I do it now on High boost engines =Basically make a heat sink under the 02 by taking a 6" by 6" piece of .090 Copper plate and throwing some bends in it and drilling a hole and placing under the 02 - doing that the sensors are lasting a couple seasons instead of 1/2 a season ,,,
Have you ever plumbed one pre and post turbo on the same car to see what the real time difference is?Great idea. As you can see like on GM carbI always put them post turbo. Learned long time ago from a MoTec guru that pressure actually affects the O2 sensors reading. That MoTec actually had a compensation table to correct so you would get an accurate reading in the pressure side of the exhaust. So for that reason and yours I place it post turbo. You just can’t get to close to end of tail pipe either. If you always put pre turbo placement and didn’t know that pressure skews the reading then if you were a good tuner you would unknowingly compensate still searching for max power, However if you try to extrapolate your readings and apply “your target AFRs” to a motor that has sensor post turbo you may find it likes a different reading then you are used to
No but it’s not a delay it’s a skew of the actual AfR….so I was told. Great idea but I’d rather always have it post anyway. Just think what one is subjected to at high boost!Have you ever plumbed one pre and post turbo on the same car to see what the real time difference is?
I ask only out of curiosity. I have tuning zero experience.No but it’s not a delay it’s askew of the actual AfR….so I was told. Great idea but I’d rather always have it post anyway. Just think wha one is subjected to at high boost!
sorry i never saw this, i have since changed that "removable tow bar" that you saw--maybe i can find a pic from olds pics i haveHey John, in the old (lost) build thread you posted your rear tow hook setup, what bolt you used and how you welded it to the rear of your car. Would you re-post that info for us? Thx
I think I need to do the exact same thing... IDK how more of these cars don't have this exact symptom, or perhaps they're just not running engine management that monitors/logs/and alerts fuel pressure.#1 regardless of how efficient my 24 gallon tank is at control slosh with multiple baffles up and down and right to left my car can corner so hard that when i have about 7-8 gallons left i can starve my fuel pump and takes a few seconds to recover. going to install an external fuel sump with internal fuel pumps. i will use my current pump to just supply my sump (it was too small for high boost anyways). then my sump will have 2 fuel pumps to meet the demand of my motor. they will be set up sequentially, the second one coming on during some amount of boost. so yes three fuel pumps/monthly_2023_12/IMG_1271.JPG.85b3c142d0ce3b9250a98789b4f6d930.JPG
i think its a function of the driver and how aggressive the cornering is and how low the tank is. i dont like the idea of having to be topped off all the time because of this issue. on one run i can go from full until the issue occurs--so like a 15-16 gallon run. thats bogus that means i basically carry 8 extra gallons of fuel all the time (50 lbs) when if the issue was fixed, i could run lower fuel levels (and weight). no matter how good the tank design you cant argue with a fuel sump. lots of pics to comeI think I need to do the exact same thing... IDK how more of these cars don't have this exact symptom, or perhaps they're just not running engine management that monitors/logs/and alerts fuel pressure.
-TJ