Keep killing 02 sensors every 1-2 years
10-03-2012, 03:01 PM
#4
I OBD1 swapped as soon as I started playing with the car so maybe I am missunderstanding the OBD2 codes. It says both front sensors voltage high. I thought generally a "bad O2" was lack of switching???
Then you have a heater failure.
Are the codes displayed numerically or in the order they present?
I wonder if the heater circuit failure is a clue.
What program are you using to scan? Have a new smartphone myself and want to play, my car may be OBD1 but there are still 3 OBD2 vehicles in the driveway.
Then you have a heater failure.
Are the codes displayed numerically or in the order they present?
I wonder if the heater circuit failure is a clue.
What program are you using to scan? Have a new smartphone myself and want to play, my car may be OBD1 but there are still 3 OBD2 vehicles in the driveway.
10-03-2012, 05:15 PM
#6
I OBD1 swapped as soon as I started playing with the car so maybe I am missunderstanding the OBD2 codes. It says both front sensors voltage high. I thought generally a "bad O2" was lack of switching???
Then you have a heater failure.
Are the codes displayed numerically or in the order they present?
I wonder if the heater circuit failure is a clue.
What program are you using to scan? Have a new smartphone myself and want to play, my car may be OBD1 but there are still 3 OBD2 vehicles in the driveway.
Then you have a heater failure.
Are the codes displayed numerically or in the order they present?
I wonder if the heater circuit failure is a clue.
What program are you using to scan? Have a new smartphone myself and want to play, my car may be OBD1 but there are still 3 OBD2 vehicles in the driveway.
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11-23-2012, 02:27 PM
#8
Have Pacesetter long tubes and if I let mine idle a while and pull the O2's they are pitch black. Is it possible they are not hot enough at idle? BTW: Both heaters are good and powered, they are AC's.
Al 95 Z28
Al 95 Z28
11-23-2012, 03:43 PM
#9
I wonder if open loop at idle tuning could lean it out and help. I know one of my friends who is very good with carbs says that all the high overlap injected stuff is too rich at idle and so long as the tune is ballpark the pcm aims for 14.7 as seen by the narrowbands but the overlap could be interfering with that.
Longtubes will shed more heat than stock manifolds so yes the exhaust is likely cooler even with ceramic coated longtubes and this could contribute to longer warmup for the engine and quicker fouling of the O2s.
11-23-2012, 08:43 PM
#10
So it used to take 6 months to get the code now you are getting it intermittently after a few weeks? Sounds like something changed even beyond the previous undesirable short life.
I wonder if open loop at idle tuning could lean it out and help. I know one of my friends who is very good with carbs says that all the high overlap injected stuff is too rich at idle and so long as the tune is ballpark the pcm aims for 14.7 as seen by the narrowbands but the overlap could be interfering with that.
Longtubes will shed more heat than stock manifolds so yes the exhaust is likely cooler even with ceramic coated longtubes and this could contribute to longer warmup for the engine and quicker fouling of the O2s.
I wonder if open loop at idle tuning could lean it out and help. I know one of my friends who is very good with carbs says that all the high overlap injected stuff is too rich at idle and so long as the tune is ballpark the pcm aims for 14.7 as seen by the narrowbands but the overlap could be interfering with that.
Longtubes will shed more heat than stock manifolds so yes the exhaust is likely cooler even with ceramic coated longtubes and this could contribute to longer warmup for the engine and quicker fouling of the O2s.
11-23-2012, 09:22 PM
#11
What about the heater ground? If memory serves it is grounded back into the harness somewhere?
I might be reaching a little there but the fact the light came back on so quickly with the new sensors says either something is up with the car or the new sensors are much more fickle.
I might be reaching a little there but the fact the light came back on so quickly with the new sensors says either something is up with the car or the new sensors are much more fickle.
11-23-2012, 09:54 PM
#12
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I wonder if open loop at idle tuning could lean it out and help. I know one of my friends who is very good with carbs says that all the high overlap injected stuff is too rich at idle and so long as the tune is ballpark the pcm aims for 14.7 as seen by the narrowbands but the overlap could be interfering with that.
Last edited by 1961ba427; 11-24-2012 at 07:41 AM.
11-24-2012, 07:47 AM
#14
I've been wondering about this myself. My small cc503 and stock injectors smells very rich at idle, even though my plugs look okay, o2 readings are normal, and everything else about the tune seems fine. Alot of other guys with modded efi cars say that it is completely normal since my catalytic convertors are removed and that it is just overlap. I don't understand that when I grew up with carbs (which are much less tuneable than fuel injection I would think) and camshafts with ALOT more overlap than this little 224/230 - 112 LSA HR. I couldn't strongly smell gas inside those cars with the windows up at stoplights (and those old cars had alot more places for fumes to enter the cabin).....or walking near them while it is idling in the yard.
You read the forums and you will see a LOT of folks who talk as if the O2s read fuel, they don't they read O2 so anything that causes there to be unburned air in the exhaust the pcm reads as lean and commands more fuel. The narrowbands are only accurate at 14.7:1 so that is what the pcm revolves around in closed loop. With a wideband setup it might be as easy as telling it 15.5 or something to account for the unburned air coming through on overlap but it isn't that easy with a narrowband, doable but not as easy.
11-25-2012, 01:42 AM
#15
Overlap makes for fresh air and fuel going out the tailpipe, the fresh air is the "problem" because the O2s can read it and think the AFR is lean and cause the pcm to command more fuel.
You read the forums and you will see a LOT of folks who talk as if the O2s read fuel, they don't they read O2 so anything that causes there to be unburned air in the exhaust the pcm reads as lean and commands more fuel. The narrowbands are only accurate at 14.7:1 so that is what the pcm revolves around in closed loop. With a wideband setup it might be as easy as telling it 15.5 or something to account for the unburned air coming through on overlap but it isn't that easy with a narrowband, doable but not as easy.
You read the forums and you will see a LOT of folks who talk as if the O2s read fuel, they don't they read O2 so anything that causes there to be unburned air in the exhaust the pcm reads as lean and commands more fuel. The narrowbands are only accurate at 14.7:1 so that is what the pcm revolves around in closed loop. With a wideband setup it might be as easy as telling it 15.5 or something to account for the unburned air coming through on overlap but it isn't that easy with a narrowband, doable but not as easy.
I'm tempted to go speed density, I know my tuner was trying to sway me to do it before, but since he met up with me at 1am off the highway last time he didn't have the time do do it.
11-25-2012, 07:22 AM
#17
if it only took 15 minutes this time like I said before I would look for a newer aggravating factor. Like I threw out an O2 heater ground issue or something. Not saying the tuning is perfect but for the time period it took to get a code to change so dramatically something else is going on.