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Old 12-03-2017, 08:07 PM   #21
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Default Re: intermitten p1174 (Fuel Trim Balance)

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Originally Posted by fdryer View Post
Jumping into port injection diagnosing can open a new can of worms. As to stuck O-rings on injectors, try some oil. Oil will eventually seep in and as engine heat warms it up, it should coat and lube them enough to allow injector removal when you find replacement O-rings. I would presume O-rings are oil and fuel resistant but harden over time so you have hardened ones with oil to help soften them. The plus side is if oil helps to soften and expand them as well as provide a temporary seal against some vacuum leaks. If seals are seriously damaged with air leaks the squirting oil around the base of injectors with the engine idling may induce exhaust smoke as oil is ingested into each cylinder and burned up with a smoky exhaust while idling.

Unless you can prove fouled injectors with a home made setup to pressurize a fuel line to feed solvent like kerosene into a clear container while applying 12v to observe spray patterns, your left to guess which are fouled or faulty without sending them to places setup for injector refurbishing tests. Either threads already covered this topic with part numbers or you may have to search for injector replacement sites to find more info about them. Members here may point you in the right direction.

Be aware that injectors rely on regulated fuel pressures so the PCM can make accurate injector pulses based on sensor signals. There comes a time when chasing your tail becomes a problem if you're not keeping a perspective of what's going on while lost in minutiae.
Got a new can of Gunk Carb Cleaner and it was much more pressurized and re-cleaned the injectors and made a 150 mile trip with no CELs and passed all I/M readiness test on that trip. For ****sngiggles I swapped the one giving me the p0304 into the bank #3 and got a p0303 instead telling me it was the injector. I made special care to clean it, and got me 5 syringes and made a harness adapter to clean all the injectors at the same time into individual test tubes with markings of the amount of fluid coming through them. When I finally had everything even and a nice spray pattern, I put them back in and drove. Watching for pending DTCs and the fuel trims very carefully. Now I'm at -2, +2 stft and 0.0 ltft !! and car drives like a new vehicle! I'm thinking that my first cleaning I didn't have enough pressure left in the bottle of carb cleaner I used, but after I redesigned it I wanted even flow because after I got to thinking the p1174 basically means that the cylinders don't have the same flow of gasoline into the combustion chamber meaning the wave pattern is altered for stft's and will later indicate a misfire on a certain cylinder if not corrected. I feel like all the injectors are pretty well balanced now and didn't cost me nothing but a can of carb cleaner and some spare parts and medical equipment i had laying around Now I did notice that faulty injector had a weak spray when I first blasted it and it took 4 or five good alternations between forward/reverse blasting to get it to spraying and clicking audible like the other 3 injectors. Finally it came to life and broke loose whatever the problem was, and I was catching all the cleaning solution after it had ran its course, I can't believe there isn't an in-line filter on these Saturn Vue's that is serviceable without removing the tank!! That crap was dirty.

Anyway if the misfire or the p1174 comes back I'll finally just break down and order all 4 new injectors and seats/seals to go back in and I'm about 99.99% sure the problem will be resolved then. This has been kinda fun to say the least and I'm sure it might help others stumped with the p1174 issue too. If your O2 sensor is causing p1174 I think it would be much easier to diagnose with the live data of the O2 output. If the post-cat o2 sensor plays any role in this I still would like to see some official documentation saying so. If a vaccum leak was causing the issue you would notice + stft output at idle which would drop back toward Zero during load / acceleration when vacuum falls off. When it is clogged injectors you will see near normal stft at idle, but they will go lean and even more lean the more load/acceleration that gets applied. This is my best way of describing the way to troubleshoot this if you have the p1174 and trying to figure out the cause. Get a good scan tool that does live data (The CenTech from Harbor Freight does well) and just monitor the conditions I mentioned above and you will narrow it down to the cause like I did. If its a fuel pump you'll notice misfire codes or p0300 on multiple cylinders alike, I'd suggest check your fuel rail pressure if you think your fuel pump is weak, but its most likely not the cause.

Hope this helps you guys out a little, I'm glad to have gotten somewhere today!!

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Old 12-03-2017, 09:08 PM   #22
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Default Re: intermitten p1174 (Fuel Trim Balance)

Well done!? Any way to show your home made injector bench testing equipment when you were observing spray patterns. I'm all for diy equipment that can isolate a problem using some ingenuity. From your descriptions and careful before and after observation of spray patterns may have given you enough info to try swapping injectors around and following error codes that can point to injector, plug or valves. Excellent fault isolation techniques without spending money in true diy fashion.

Perhaps one of the reasons for zero bleed down of fuel pressures after engine shutdown is to reduce the chances of engine heat accelerating fuel vaporization, leaving miniscule deposits over a long period of ownership. If pressure bleed down occurs before an engine cools off, fuel vaporizing may leave deposits and may be what you collected when using carb cleaner. Gasoline is already a solvent with a chemical concoction only chemists know. Fuel filtering serves one major purpose, ensuring large crap won't jam injectors otherwise the world wide fuel distribution network with EFI systems everywhere would have a history of fouled injectors. Filtering right up to each vehicle providing final filtering can't be faulted for fuel pressure bleed down and vaporization processes that may lead to build up over time. Since gasoline is already a solvent, the merits of adding injector cleaner from time to time may have merit. With so many variables, there isn't any right or wrong procedure of when and if to treat a fuel system with additives. Results vary.

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Old 12-03-2017, 11:07 PM   #23
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Default Re: intermitten p1174 (Fuel Trim Balance)

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Well done!? Any way to show your home made injector bench testing equipment when you were observing spray patterns. I'm all for diy equipment that can isolate a problem using some ingenuity. From your descriptions and care....................

............................................ may have merit. With so many variables, there isn't any right or wrong procedure of when and if to treat a fuel system with additives. Results vary.
Yea you are right about the left over residues in carb cleaners, however I researched my options and went with a non-chlorinated carb cleaner just because of this. My first round was a regular carb cleaner plus the can was about 1/4 way full and i was trying to make it last to do all 4 injectors. It just didn't have enough pressure to deep clean them properly and like you said it probably left some deposits behind because it was not the non-chlorinated type. I just drove around again for a good hour (however long it has been since my last post - minus a few minutes with family) Still no misfires, still excellent fuel trims and still no DTCs. I could always recreate the p1174 dtc by accelerating steady at 55 mph for approx 3-5 minutes and then slowly decelerating. It would always throw that fault when it was going to. What you said about the deposits with carb cleaner makes perfect sense about my p0304 misfire after the cleaning the first time though but I also noticed the p1174 on my trip back home last night which was prolonged to the normal time period. However I monitored the fuel trims throughout both trips of both cleanings. The fuel trims stayed way positive on LTFT almost always except at idle they'd hover around +1 to +3 but on any acceleration they'd immediately jump to +8 to +16 and would slowly change too. My stft and ltft work hand in hand now and both are changing almost immediately in sync. For instance if i get a +10 ltft I'll see a -10 stft pull it back down to ltft -9 then stft will go back to -5 or so and ltft will be +5 until they both balance at 0. this never happened ever while I've been battling this p1174 because my stft would almost always be between -3 and +3 at idle and on acceleration would be always above +5 and usually around +7 while cruising, and LTFT would just usually stay steady around +12.5 This whole cylinder to cylinder fuel trim balance makes perfect sense to me now and when I watch the graph log of the stft and the pre-cat o2 data the rich/lean switching is done in a much more smooth form.

I wish I could just snap a picture of the setup I used today to clean the injectors, but it consisted of so many baster/syringe tubes and wires, when I got done I disassembled it and stored it away in case I need to do it again. I could reassemble it all again but I'd like to do that tomorrow or some other time if that would be ok.

I put a 20 oz bottle of Techron in the tank tonight ( I had a 16 oz bottle of seafoam in the tank friday and put 10 gallons on that) I had ran all that gas out and put the techron in after I got these injectors working good and then filled it up to half a tank. I'm hoping that it will keep cleaning the injectors where I left off instead of pushing more debris into them. But is there any idea how hard it is to get to the fuel filter that is on the pump assembly ? I'd like to add an in-line filter and replace the in-tank filter after I run this techron through and clean the tank really really good. And keep all this fuel system as clean as possible.

I really think this car is going to be a decent car if I keep maintaining the small things. I just done the timing chain/balance shaft chain rebuild, new cam actuators, new vvt gears, new timing oiler, the throttle body rebuild, cleaned the pcv system in the intake manifold, decarb'd the intake via the brake booster method with both marvel mystery oil & seafoam, running brand new AC Delco OEM plugs, purolator oil filter, new k&n drop in filter. Compression Check is right at 160 across all 4 cylinders too. Hybrid Battery system seems to hold perfect charge, charge/assist functions wonderfully as well as autostop. At this point I have no complaints at all about the operation of the vehicle as it drives and runs perfect, especially after cleaning the clogged injector(s) (Only 1 was bad enough to cause the misfire - but I'm sure the balance issue was related to all 4)

The things that scare me is the previous owners maintenance on things like the transmission. The manual says to change the Transaxle fluid and filter every 25K miles, which I doubt has been done, but if it has I am hoping that they used the OEM AC Delco or Equiv Dexron 6 as recommended. I'd hate to go by the book and come to find out the tranny had been completely rebuilt and used DexIII instead of DexVI when they filled it back up or some other non recommended fluid. Because thats when I'd really end up with some issues when I'd be trying to do it just like its suppose to be done, but end up screwing it up by having 2 incompatible fluids in the system. DexVI may work with DexIII but i know DexIII is not recommended on this tranny, anyway I'm just using an example. I can't really afford to to a complete emptying of the tranny and refilling it as well as the TC. I just don't have that kind of money. That's why I try to do most things myself because I'd rather fix things for nothing and have the same results, as pay someone else to do something and have no idea if they actually did it right or skimped around at what they did. If I make a mistake I know who is to blame. I don't believe in shortcuts, I believe in doing it right, but you have to make use of what you have and what you are able to use so creativity has to take place - as with my injector cleaning setup and my Throttle Body repair.

I think I have like $40 to my name right now after we done our xmas shopping last night. I could have spent $40 and got 1 injector, and still had a imbalance on my car as 1 injector would have been clean and the others would have been semi-dirty. Or I could have cleaned all 4 of them equally and evenly ensuring that the spray pattern and spray volume per duty cycle were very close, so with that in mind I just got to looking around at what I had and came up with the best way I could to do it and keep them controlled where the cleaning could take place simultaneously and the output could be monitored in the amount each injector pushed. To be honest it does not look like nothing you'd want to sell or anything fancy, its just a home brew setup that attempts to do what a cleaning service would do. Now if this car is still running this good in 2 or 3 weeks I may revise my little setup and actually make it look nice and create an electrical control box for pulsing the injectors, and a compressed cleaning solution holding tank to use something better than Carb Cleaner for cleaning. Who knows with a little work I could offer some injector cleaning services - But honestly unless you aren't the type of person who would remove/install your own injectors I see no point in a cleaning service as the service would cost nearly as much as just getting new injectors. I guess if you had some very high dollar racing injectors then a cleaning service might be an option, but to daily drivers I'd suggest either do what I did and design your own cleaning system or save some $ and get new injectors!

I know I've been all over the place in this post, I hope I'm not out of hand I'm still new to this forum, not quite sure what the tolerated post guidelines / required etiquette is, but I'm really just very enthused about what I've accomplished over the last couple of weeks with this car and if these injectors gum up or fowl up in a day or two after this cleaning at least I still learned what the problem was and what needs to be done.

I am going to do another thing later on probably within the next month or so. I'm going to put a test pipe where the CAT is, and I'm going to use the anti-fowler method plus steel wool and keep the rear O2 sensor so that it can keep my CEL off. But after talking with Satlite440 I'm really just trying to play with fire on this one. First of all I'm going to just plug the test pipe's o2 sensor bung off and let it set the p0420 code as usual and run it normal and see if it changes anything at all to do with the before/after ltft/stft and if i get this p1174 back due to messing with the post-cat O2. If he is right I will definitely get the code back and I will definitely throw my fuel trims out of whack. Honestly I think the guy is smart and has some deep knowledge of mechanics and with OBD systems, but I think there is some confusion somewhere about this particular vehicle using the post-cat O2 in fuel trim balance calculation, but if I am wrong I will be the first to admit it. I was really wanting to delete the CAT anyway but after he stated his theory/belief on the post-cat o2 playing an important role in balancing the cylinder to cylinder fuel trim by the ECM keeping snapshots of data logged from in in read-only memory - It really makes me want to put it to the test! I know several vehicles use a downstream O2 sensor to verify efficiency of another O2 sensor directly in the CAT or very near it, and I know that some other vehicles use 2 post-cat O2 sensors for a different method, one being exactly like he mentions is involved in comparing s1b1 data with s1b2 data. But in all systems where that is involved it must consist of at a minimum of 3 O2 sensors on a 4 cylinder system. 1 up stream for closed loop management of course, 1 down stream control , 1 down stream verification. As he says though the P1174 code if it is set due to the downstream o2 sensor being removed, it has no impact on the ECMs actual changing of fuel trim, it is mostly just for information. So it will not impact the actual fuel trims them selves either way, worse case you get a CEL with p0420 as well as p1174. I just have a feeling that you'll only end up with p0420 though on this particular vehicle. Later in March when tax refunds come I'm going to buy HP Tuners VCM Suite for tuning these 2.4 ecotec pcms, I'll really get down to the bottom of it then when I can actually see what all p1174 depends on to be executed and what all it modifies if anything other than CEL.


Sorry for the very long post guys! Thanks for reading and I really enjoy chatting here with you guys, you seem like some well educated users. Most other automotive forums aren't so fortunate to have this type of userbase! We could actually get a long way if we put all our minds together here!!

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Old 12-15-2017, 04:34 PM   #24
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Default Re: intermitten p1174 (Fuel Trim Balance)

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so this dtc is basicly a random sampling of pre and post cat o2 reading when a specific cyclinder is 4 degrees after tdc ignition..it is a predicted model based of of one of the 3 intake performance models that is in read only memory..the concept is basicly we randomly take a picture of cyc 3(for our example) over the course of a few drive cycles(note that this is constanly doing this for all cyclinders constaly every time the moter is running and closed loop hence the reasone it will show up in as few as 2 or as many as 5 drive cycles) and see if a pattern of rich or lean mixture shows up..this is very important in sidi(spark ignited direct injection) meaning for those unfamiliar with what this is..the injecter is in the combustion chamber like a diesel and operates at around 22,000 psi..the theory is we use less fuel than intake ported injectors of old.the down side is rail pressure cannot be measured mechanicly.and your at the mercy of the rail pressure sensor reading acuratly..so by monitoring each cyclinder for rich or lean condtions we can start to pick out a clogged or poorly performing injecter.. versus say maby you might have a sticky valve as all the oil&carbon builds up on the base of the valve stem.i have seen hard and chunky to sticky/gooey build up on them a bad valve guide leaking oil makes it worse.stays gummy and when cold or low rpm can stick and cause a lean misfire but not slow the crank speed enough to set a p0300..all ecm's from 07 up have a ethonal counter.that takes into account crappy fuel/oxegenated fuel and of course ethonal..occasonaly the counter needs to be manuly reset.. so I doubt its the fuel. a map will defiantly cause this though..
Sorry to bring this back up Satlite440, but I didn't mention the year/engine size in the beginning. This is the 2007 2.4L ecotec LE5 engine. So we aren't dealing with SIDI/GDI/Direct Injection. Cleaning the Injectors fixed the p1174 issue. I also replaced the seals and cups that are in the head. Still not tripped the code again since I did the injector cleaning / seals approx 2 weeks ago. Which saturn engines and years used the SIDI style injection system? I've not seen much about SIDI on the ecotec 2.4 except for GM/Chevy years 2010+

Also I'll be putting your theory of the downstream O2 sensor effecting/causing the p1174 here pretty soon as I'm going to be replacing the resonator with a flowmaster super 10, and using another super 10 in place of the 2 cats, but will be using 2 non-fowlers to prevent the p0420 from occuring. Not sure why people who do delete their cats increase the stock pipe size, and end up with bad engine drone and humming (not to mention losing their torque curve). I'll be keeping stock diameter, and using 2 super 10s in place of the 2 cats and deleting the resonator. I hope to get a little more throttle response, and have a good sound that isn't too loud but sounds a bit better than stock (keyword better), and get the cats out of the way from causing future issues.

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Old 12-15-2017, 05:22 PM   #25
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Default Re: intermitten p1174 (Fuel Trim Balance)

Please do not go to any extra effort to setup your bench fuel injector cleaning since it was disassembled. Any simple bench setup in working condition with a picture or two to post is one way to share and isn't necessary until you need to do it again. As a member, you can post thumbnails in a thread or create an album to collate all your pics into one file in a area this site.

One other member here in the S-series forums used a simple 6 or 12 volt ac transformer (120vac input, 6 or 12vac output) as his injector exercising equipment and dipped injectors into a solution (poor man's ultrasonic cleaner?). He was promptly put down by know-it-alls that couldn't prove anything wrong with a diy cleaning. Even when providing before and after info of engine running performance, the naysayers were negative to this. I haven't forgotten it as another idea to try if I'm ever faced with injector issues. There's merit in anyone capable of successfully thinking outside the box of conventional wisdom, know-it-alls and naysayers that haven't come up with solutions for diy work to keep money from lining someone else's pockets. There are YouTubers all over the world presenting their home grown inventions. Some are questionable where safety may be an issue while many are positive in addressing issues with what's laying around without spending money and create a solution that works.

In my limited time here, only two members state the downstream O2 sensor affects fuel mixtures. Every Saturn service manual states the downstream sensor is used to measure catcon efficiency. No mention of contributing to the EFI system fuel mixtures where the upstream sensor is relied on for emissions/fuel control. No one has ever presented documentation yet stating the rear sensors are contributing to fuel management. I have four O2 sensors and would wonder how all four are used if they all contribute to my V6 engine performance. I'm of the belief that only the front O2 sensors affects fuel mixtures since they're directly front of the exhaust stream coming from each cylinder bank in the two exhaust manifolds. How anyone claims the post catcon O2 sensors contribute to fuel mixtures is beyond my comprehension of EFI systems. I claim no expertise in EFI systems if anyone asks. If the catcon converts exhaust gases to harmless byproducts and is measured by the downstream sensor, how can signals from the downstream sensor be used to supplement the upstream sensor?

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Old 12-15-2017, 08:37 PM   #26
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Default Re: intermitten p1174 (Fuel Trim Balance)

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Please do not go to any extra effort to setup your bench fuel injector cleaning since it was disassembled. Any simple bench setup in working condition with a picture or two to post is one way to share and isn't necessary until you need to do it again. As a member, you can post thumbnails in a thread or create an album to collate all your pics into one file in a area this site.

One other member here in the S-series forums used a simple 6 or 12 volt ac transformer (120vac input, 6 or 12vac output) as his injector exercising equipment and dipped injectors into a solution (poor man's ultrasonic cleaner?). He was promptly put down by know-it-alls that couldn't prove anything wrong with a diy cleaning. Even when providing before and after info of engine running performance, the naysayers were negative to this. I haven't forgotten it as another idea to try if I'm ever faced with injector issues. There's merit in anyone capable of successfully thinking outside the box of conventional wisdom, know-it-alls and naysayers that haven't come up with solutions for diy work to keep money from lining someone else's pockets. There are YouTubers all over the world presenting their home grown inventions. Some are questionable where safety may be an issue while many are positive in addressing issues with what's laying around without spending money and create a solution that works.

In my limited time here, only two members state the downstream O2 sensor affects fuel mixtures. Every Saturn service manual states the downstream sensor is used to measure catcon efficiency. No mention of contributing to the EFI system fuel mixtures where the upstream sensor is relied on for emissions/fuel control. No one has ever presented documentation yet stating the rear sensors are contributing to fuel management. I have four O2 sensors and would wonder how all four are used if they all contribute to my V6 engine performance. I'm of the belief that only the front O2 sensors affects fuel mixtures since they're directly front of the exhaust stream coming from each cylinder bank in the two exhaust manifolds. How anyone claims the post catcon O2 sensors contribute to fuel mixtures is beyond my comprehension of EFI systems. I claim no expertise in EFI systems if anyone asks. If the catcon converts exhaust gases to harmless byproducts and is measured by the downstream sensor, how can signals from the downstream sensor be used to supplement the upstream sensor?
Thanks for sharing the info because I was quite hesitant to post pics due to the quality of my benchtop system, as I know it is a bit redneck, but it works. I have the clear DTCs to prove it and my fuel economy is up tremendously as well. As for the downstream O2 sensor, I'm don't know about on all vehicles, but with the ones I'm experienced with, the downstream sensor is just used to help diagnose a 'lazy' upstream o2 sensor, as far as contributing to the fuel trims and other I have seen no proven documentation to that on any make/model vehicle. I'm about 99.99% sure with the 2007 Saturn 2.4L Ecotec that I have the only o2 sensor used with any fuel trim calculations is the post-cat (upstream) o2 sensor, and the p1174 code for these vehicles has no dependency on the functionality of the downstream o2 sensor, despite what other members may claim, I'd have to see some documentation to prove otherwise. On a more modern vehicle with SIDI technology it is possible it is used for fuel trim balance, but really it would all boil down to checking and verifying the laziness of the post-cat / upstream o2 sensor and vice versa.

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Old 12-15-2017, 10:17 PM   #27
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Default Re: intermitten p1174 (Fuel Trim Balance)

With many things already known about the 4-stroke cycle engine, thermodynamics, emissions control, electronic fuel injection, O2 sensors and catalytic converters, there isn't much of the unknown to figure out. This leaves less to invent insofar as engine management. I remember a time when muscle cars used multiple carburetors, mechanical or electric fuel pumps (both low pressure systems), no catalytic converters and made hundreds of horsepower when high compression was incorporated. They died as soon as the EPA mandated emissions control programs to reduce pollutants, including removing lead in leaded fuel (this reduced/eliminated knock). Many cried the passing of these muscle cars. What the car manufacturers didn't want to do and was forced into doing was eventually adopting electronic fuel injection, rethinking materials engineering, developing the O2 sensor, use high pressure fuel pumps and develop catalytic converters. We now have muscle cars again with even more horsepower yet still pass tight emissions control programs. This was unthinkable for many years until engineering sciences simply continued to evolve and adapt new materials to muscle cars made by every manufacturer competing for our dollars. The '60's factory muscle cars were limited to around 400 hp while cars now are equipped with 500-800hp, all stock. This couldn't happen without the engineering and sciences to adapt whatever is needed to create monster cars that are street legal and emissions compliant.

My understanding of O2 sensors is that the range of emissions are well known so its programmed into memory. Custom programming that tunes a specific engine and power while meeting emissions requirements from the front feedback o2 sensor compares known emissions (in memory) against what an O2 sensor outputs. The comparison is made to determine if a sensor is within its operating range or not. When out of range, other programming determines what fault it is and triggers an error code. I do not think one sensor is compared to another as the known operating parameters are in memory for simple comparison. Self checking continually without external testing, brought about by electronics and programming in small computer systems. Many do
not believe OBD II is a self contained rolling emissions testing system in every USA operating vehicle. Electronics brings lab testing to every vehicle with OBD II.

The downstream O2 sensor has well known parameters and the output is compared to parameters in memory to determine operating within range, determine if the catcon is worn out, deteriorating, shorted, open, and trigger error codes when necessary. Without any more documentation to prove otherwise, the post cat O2 sensor isn't compared to the precat sensor and isn't necessary since allocated memory is set aside for this purpose. If the precat and post cat O2 sensors were compared to each other then what if one or both are faulty? How does engineering deal with this simple problem?

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