Lt's stuck at 25 when not cruising
03-25-2010, 08:22 PM
#1
Staging Lane
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Lt's stuck at 25 when not cruising Hey guys, I'm getting the following codes while tuning the VE tables. The first is of course expected, but the o2 appears to be causing some issues:
P0103 - Mass Air Flow (MAF) Sensor Circuit High Frequency (ignore this)
P0135 - HO2S Heater Performance Bank 1 Sensor 1
From 2400 & >, I get LTs in the 6-7 region. (My first scan was pretty bad). I know that the goal is to get the LTs in the -5 to +5 area. But I noticed that unless I am cruising at highway speeds or idling, my LT's shoot up to 25 and stay there when the throttle opens. I thought it was a warmup issue (I'm using the Bosch 13111). I first noticed that it takes 10-15mins before my FTs go below 25, but I now realize that the time I noted is how long it takes for me to get on the highway. So in essence, my FTs remain at 25 until after a few mins of highway cruise.
I thought it could be due to one of 2 reasonse. a) The aforementioned P0135(I'll explain below) or perhaps because b) the 13111s warm up slower, or c) because of where I welded the front o2 bungs.
a). Since i have longtubes, I had to weld on bungs for the front o2's. After welding the left side, I noticed that it is at about a 45degree angle. I have a 1.5" drop, and trying to backout of my driveway cause the new leftside o2 to scrape, and perhaps bend a little. So this is may be the reason for the code.
c). I welded the bungs about 2feet from the rear o2's. Is this too close, which may cause the readings to be close?
Current fuel economy is about 17-18mpg with about 80% highway use. Shitty? Hell yeah! The nitrous is off, so there's no excuse for that. I havent tuned the spark tables, because I was trying to first get the LT's to where they should be. I have essentially stopped tuning until I figure this out. So pitch in and help where you can. Is the cause for the hight LTs when not at highway speeds, a,b or c?
Another question: what are the rear o2's for? Should I just remove them, tune them out, and plug the front o2's in its place?
P0103 - Mass Air Flow (MAF) Sensor Circuit High Frequency (ignore this)
P0135 - HO2S Heater Performance Bank 1 Sensor 1
From 2400 & >, I get LTs in the 6-7 region. (My first scan was pretty bad). I know that the goal is to get the LTs in the -5 to +5 area. But I noticed that unless I am cruising at highway speeds or idling, my LT's shoot up to 25 and stay there when the throttle opens. I thought it was a warmup issue (I'm using the Bosch 13111). I first noticed that it takes 10-15mins before my FTs go below 25, but I now realize that the time I noted is how long it takes for me to get on the highway. So in essence, my FTs remain at 25 until after a few mins of highway cruise.
I thought it could be due to one of 2 reasonse. a) The aforementioned P0135(I'll explain below) or perhaps because b) the 13111s warm up slower, or c) because of where I welded the front o2 bungs.
a). Since i have longtubes, I had to weld on bungs for the front o2's. After welding the left side, I noticed that it is at about a 45degree angle. I have a 1.5" drop, and trying to backout of my driveway cause the new leftside o2 to scrape, and perhaps bend a little. So this is may be the reason for the code.
c). I welded the bungs about 2feet from the rear o2's. Is this too close, which may cause the readings to be close?
Current fuel economy is about 17-18mpg with about 80% highway use. Shitty? Hell yeah! The nitrous is off, so there's no excuse for that. I havent tuned the spark tables, because I was trying to first get the LT's to where they should be. I have essentially stopped tuning until I figure this out. So pitch in and help where you can. Is the cause for the hight LTs when not at highway speeds, a,b or c?
Another question: what are the rear o2's for? Should I just remove them, tune them out, and plug the front o2's in its place?
03-26-2010, 06:07 AM
#2
1st I'd put a bung plug in that o2 hole and drill and put a bung in higher and new sensor (to be sure)
I take it you do not have a wideband and are tuning withyour fuel trim? If you are don't forget to clear and reset fuel trim after you flash/calibrate
I take it you do not have a wideband and are tuning withyour fuel trim? If you are don't forget to clear and reset fuel trim after you flash/calibrate
03-27-2010, 02:53 PM
#3
Staging Lane
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LC1 is in my other car. I'm tuning with fuel trims only. Initially, I was resetting the fuel trims, but not in the last 3 flashes.
Regarding the 15mins before the Lt's drop below 25, I think I found the answer. Another thread spoke extensively about slow switching o2's, and the 3yr old thread still has no answer. My guess is that the o2's are not heating up sufficiently due to their location. I may move and weld them another foot closer to the collectors.
As far as the P0135 code, I think its because the left o2 is slightly damaged, preventing it from heating up as well as it should. If it were due to the o2's position, I would have been getting a code for the right side as well.
Regarding the 15mins before the Lt's drop below 25, I think I found the answer. Another thread spoke extensively about slow switching o2's, and the 3yr old thread still has no answer. My guess is that the o2's are not heating up sufficiently due to their location. I may move and weld them another foot closer to the collectors.
As far as the P0135 code, I think its because the left o2 is slightly damaged, preventing it from heating up as well as it should. If it were due to the o2's position, I would have been getting a code for the right side as well.
03-27-2010, 07:05 PM
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tuning with LTFT's works but if your facing slow reading 02's you will be wasting your time. With LT headers try switching to 00-up Corvette Rear 02's. Or just get a wideband and follow the Greg Banish Instructions. Then you know its right!!!
03-27-2010, 10:35 PM
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Currently using the rear corvette o2's - Bosch 13111's
03-27-2010, 11:03 PM
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I believe that is the hottest operating o2 you are going to get for LS1,6 applications. so i dont know what to tell you if you are still getting a slow switching rate. Possibly try plugging the exsisting bung and having a new one welded in somewheres else. (Closer to the Heads)
Or just leave the slow switchers in, get a wideband and tune it to your stoich on idle/cruise for MAF/VE. then set your PE to whatever AFR you want
Or just leave the slow switchers in, get a wideband and tune it to your stoich on idle/cruise for MAF/VE. then set your PE to whatever AFR you want
03-28-2010, 08:52 AM
#7
45* angle?? Given you say it hits the curb, I assume it's at sme angle like 4 or 8 o'clock??
At that angle, the sensor will be contaminated w/ startup moisture, and eventually fail. This can be the reason for the long heatup time.. they are full of water....
Above the 3 to 9 o'clock line is where you should have them installed.
As others have mentioned.. move the bungs.
At that angle, the sensor will be contaminated w/ startup moisture, and eventually fail. This can be the reason for the long heatup time.. they are full of water....
Above the 3 to 9 o'clock line is where you should have them installed.
As others have mentioned.. move the bungs.