o2 sensor code 1153 won't go away???
02-02-2019, 01:00 PM
#61
I have tuned many many LS engines with LT headers-----The reason they are Illegal in most states is because of the further aft mounted front 02's they do not read correctly when the fromt 02's are now as much as 3' back---They do not heat up correctly and read wrong----They always read RICH !! There is no 100% fix for this however what most tuners do is this
1 Install a set of the rear 02's onto the front locations ( the rear 02's are far more sensitive and will read more accurately)
2 Re scale your 02 switching points----LT's will make your engine run rich at P/T so to compensate you need to LOWER the front 02 switching points --Try 1st by lowering the entire switching point table by 100 points------The check to see if the 02 voltages are in line they must have an AVERAGE voltage between .400 and .500 millivolts
The higher the average the richer the P/T fueling will be----Typically with LT's the switching point averages will be beyond .500 to .600 millivolts This is a trial and error process with the data logger as each application may be different
1 Install a set of the rear 02's onto the front locations ( the rear 02's are far more sensitive and will read more accurately)
2 Re scale your 02 switching points----LT's will make your engine run rich at P/T so to compensate you need to LOWER the front 02 switching points --Try 1st by lowering the entire switching point table by 100 points------The check to see if the 02 voltages are in line they must have an AVERAGE voltage between .400 and .500 millivolts
The higher the average the richer the P/T fueling will be----Typically with LT's the switching point averages will be beyond .500 to .600 millivolts This is a trial and error process with the data logger as each application may be different
The down stream after cat sensors on board heaters do NOT heat up even close to what the up stream 02s do. So if I did as you suggest I will likely get not only a P1153 but a P1133 as well. So I am going to pull the LTs back off and install 02 bungs in the number 7 and 8 primary tubes in the factory stock location that should work. If it doesn't work anybody want to buy a nice set of slightly used headers?
This is NOT a problem with the 4 02 sensors it is ONLY a problem with their location. And I do NOT want to have some tuner shut off the fault code. That is like placing black electric tap over the CEL. It does NOT fix the problem.
The oxygen sensor must be hot (about 600 degrees or higher) before it will start to generate a voltage signal, so many oxygen sensor have a small heating element inside to help them reach operating temperature more quickly. Think of it like this the closer you hold your hand over the stove the more it burns. And if you hold your hand as you say "3 feet further away" your hand is NOT going to get burned.
I agree with you when you say "The reason they are Illegal in most states is because of the further aft mounted front 02's they do not read correctly when the front 02's are now as much as 3' back---They do not heat up correctly and read wrong----They always read RICH !! There is no 100% fix for this however what most tuners do is this."
From what I have read they read lean and the computer over corrects causing a rich condition but my 2002 C5 does not appear to be running rich but lean right now judging by how clean the spark plugs look, (NOT black at all).
As I said. "I replaced the plugs because they were black from being too rich and it started perfect in the AM for about 1 day (autolite double platinums) I pulled a couple of them and they look like they just came out of the box clean as new after about 225 miles on them. So it is no longer running rich but lean."
As you say. "when the front 02's are now as much as 3' back" So the solution is to move them 2 and a half feet closer to the cylinder head/exhaust port. The original cast iron manifolds are just tubes the LTs are just tubes their is no "mechanical or programing" changes to the car the ONLY difference is 02 sensor placement/location. I do NOT see ANY reason why relocating them will not solve the problem 100%
Only thing is I will NOT be getting the average reading from all 4 cylinders off each head but only a reading off the single #7 and #8 primary tubes. What would that hurt? How big is the possibility of burning a hole on my pistons from an undetected lean condition from not sampling from all 4 cylinders per side only the two #7 and #8? And wouldn't a lean running fuel injector set off a code?
Some guy at LG headers said "by doing this the computer would not detect an unmonitored lean running cylinder and I could burn a hole in one of the unmonitored cylinders."
Bassani Long Tube Headers keep the 02s in the factory locations but are only monitoring 2 cylinders on each bank and I have NEVER heard of any problems from people running Bassani LTs except for poor quality welds they leak. Please see the 2 photos of Bassani headers below to see the 02 locations and best of all no wire extensions are needed wit these headers. But Bassani no longer manufactures them.
Last edited by ricksright69; 02-02-2019 at 02:18 PM.
02-03-2019, 10:15 PM
#64
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St. Jude Donor '13-'14-'15
There are other fixes for problamatic front 02 readings------
1. turn OFF the LTFT corrections to your fueling at P/T Only after you have cleared up all your LTFT's to read "0" or slightly negative up to about 7500HZ on yout MAF table
this will prevent your ECM from making fuel corrections via false 02 readings
2 You may have a wiring issue with your front 02's Check online and it will tell you what each wire should read with the key on and No start---I beleive 1 is a ground- 2 is 12v 3 is 0-5 volts and I can't remember what the 4th should be--Check all these wires from the pigtail of the front 02's with them dis connected
3 On certain hi modded engines you are left to run a OLSD tune where the fronts are not used at all however this requires some wideband testing to verify your P/T AFR ratio---This will make your engine run in OPEN LOOP all the time with no corrections not a big deal on a troublesome combination-----PE still works as designed
1. turn OFF the LTFT corrections to your fueling at P/T Only after you have cleared up all your LTFT's to read "0" or slightly negative up to about 7500HZ on yout MAF table
this will prevent your ECM from making fuel corrections via false 02 readings
2 You may have a wiring issue with your front 02's Check online and it will tell you what each wire should read with the key on and No start---I beleive 1 is a ground- 2 is 12v 3 is 0-5 volts and I can't remember what the 4th should be--Check all these wires from the pigtail of the front 02's with them dis connected
3 On certain hi modded engines you are left to run a OLSD tune where the fronts are not used at all however this requires some wideband testing to verify your P/T AFR ratio---This will make your engine run in OPEN LOOP all the time with no corrections not a big deal on a troublesome combination-----PE still works as designed
