We have a customer with a 2000 that has had our header system on his car for at least five years now. I think the code was PO135 (not pos), but it was for the PS front o2 sensor. They had the car in to dealership who verified everything passed including the wiring loom and connectors. We also did visual for any soot type leaks by AIR connections and flanges. This started at the end of last year when they replaced the o2 sensor. Code came back this spring and I think they changed it again with another Denso to no avail. They did all the other obvious checks like clearing codes in memory and then driving again. He ended up, out of curiousity, putting an old one in he had retained from a few years back and the cel went away but then the car cut out sometimes under heavy accel. Any ideas. could a fuel filter cause any of this. Had to cut this short because I have to run. Be back tomorrow.
Chris at Melrose
P0135 is for the driver's side---but you may have gotten the codes mixed up--
The biggest problem with 02 sensor issues are LT headers--because the 02 bungs are further back than the stock manifold locations--they often do not heat up properly or are very slow reacting at lower RPM's especially-
I would 1st check both sides with a scanner and after the engine goes into closed loop (warmed up) see how rapidly the 02 voltages oscillate--
When correct--they should bounce very rapidly from .100 to .900 millivolts--try this at idle where most likely the code is being set--then at like 1000 RPM and then 1500 RPM--see if the movement changes any----Good news is that a tuner an correct this for you--With LT's the stock commanded AFR of the stoich. 14.68 is now more likely pig rich in the 12.0 range--Several ways to correct--I have had the best luck with 1st checking the true AFR with a wideband--Stick it in the tailpipe and see where you are --If in the 12.0 range--then i always subtract 20% from the VE table up to 2800 RPM's 1st--- and then work on the "02 switching point table" Start by removing 50 ponts at a time to the entire table --checking it with each change to see if you are getting close to 14.68--
P0135 is for the driver's side---but you may have gotten the codes mixed up--
The biggest problem with 02 sensor issues are LT headers--because the 02 bungs are further back than the stock manifold locations--they often do not heat up properly or are very slow reacting at lower RPM's especially-
I would 1st check both sides with a scanner and after the engine goes into closed loop (warmed up) see how rapidly the 02 voltages oscillate--
When correct--they should bounce very rapidly from .100 to .900 millivolts--try this at idle where most likely the code is being set--then at like 1000 RPM and then 1500 RPM--see if the movement changes any----Good news is that a tuner an correct this for you--With LT's the stock commanded AFR of the stoich. 14.68 is now more likely pig rich in the 12.0 range--Several ways to correct--I have had the best luck with 1st checking the true AFR with a wideband--Stick it in the tailpipe and see where you are --If in the 12.0 range--then i always subtract 20% from the VE table up to 2800 RPM's 1st--- and then work on the "02 switching point table" Start by removing 50 ponts at a time to the entire table --checking it with each change to see if you are getting close to 14.68--
Thanks for the advice. I really wish we had a local tuner I could trust. The odd thing about all this is why the old one didnt throw CEL. Have you seen these o2 sensors have a variance in their sensitivity even if they are for the same application?
Thanks
Chris at Melrose
Yes---even between brand names on new sensors you can see differenes----I like the GM sensors the best---ALSO---Many people have installed the REAR 02 sensors into the FRONT locations---They are way more semsitive and i think have longer pigtails which for headers is great--Try researching this on the forums---I have never tried it--- But you must have a tuner delete all the rear 02 codes
Yes---even between brand names on new sensors you can see differenes----I like the GM sensors the best---ALSO---Many people have installed the REAR 02 sensors into the FRONT locations---They are way more semsitive and i think have longer pigtails which for headers is great--Try researching this on the forums---I have never tried it--- But you must have a tuner delete all the rear 02 codes
Are the GM sensors Denso's that come in a GM box cuz the dealership installed a Denso in the car?
Corvette Store
C5 o2 sensors- customer w/ odd happenings
i had the same problem with my 00 c5
