When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
CC503 issues. High o2 volts after warmup, fuel trims disappear
Something just isn't right with my car that I'm trying to figure out. I'm going to try to explain some trends I've noticed.
96 lt1 m6, 140k miles. Just installed cc503 cam and 1.6 rrs. Has long tubes on it as well.
I have had issues with high voltage codes to my o2 sensors. I viewed them on torque pro and sure enough they were at some points glued to .9 or 1 volt.
So, I changed o2 sensors for brand new ac Delcos. Same intermittent problem. Then, I checked all my grounds. The grounds to the driver side head to my understanding are where the o2 grounds are. I re did that ground.
Problem seemed to have been fixed... But then the code came back on about a week later, and again, glued to 1 volt or so on each bank.
*********more updated info below*********
Last edited by slikrider20; 09-19-2018 at 12:30 PM.
I've replaced both o2 extensions and i'm getting power to heater wires on both sides and the ground checks out. However, on my driver side o2 bank, i'm getting high voltage that just basically stays at .8 or .9v and doesn't move. Therefore it's running really rich and goes down to 12.2 commanded AFR in PE mode when it's set for 12.8.
I've noticed that when I pump the brakes I can get the o2 volts to come down on that side temporarily as I pump the brakes, but then they go right back up and stay there. Another thing I can do is make a vacuum leak by unplugging the FPR or HVAC lines and the voltage goes down and bounces around like it should, and the commanded AFR goes to 12.8 instead of 12.2 in PE mode with that line disconnected, and feels so much stronger when it's still in open loop. I've also went through a couple of different FPR's with same result. I checked all my plugs/wires and they were good as well. I cannot find any vacuum leaks anywhere and i've replaced probably half of the hoses anyway hoping to find something.
It runs better with the driver o2 disconnected and I've changed both o2 sensors for brand new Delcos, even swapped them left to right and I still get the same result on the driver side bank. I'm really out of ideas.
Last edited by slikrider20; 09-15-2018 at 07:37 PM.
With the exception of the heater in the O2 sensor, the voltage you see is strictly a result of the mixture if the harness is not at fault in some way. So...the O2's are just responding to the mixture it's seeing.
What are your long term fuel trims looking like during this issue? Did you get the car tuned after the cam install?
Can you data log the car during the problem and post a log?
Edit: One more question....was it running fine before the cam install?
It was tuned by Solomon. It's always ran "fine" but I didn't start looking at o2 volts until after cam install.
I have a lot of logs on my computer but i've also fiddled with a bunch of things. Let me take a new one tomorrow. I'm starting to wonder if I just have a bad/clogged fuel injector on the bank 1 side.
I did end up renting Solomon's kit to log/flash myself that gets here tomorrow so hopefully that will help trace things down.
Last edited by slikrider20; 09-17-2018 at 04:32 AM.
You still have cats? What are your post cat O2's doing during the trouble? If you don't have cats, the post cat O2's should be mirroring the pre-cat O2's. If a cat fails(my driver's side has failed), you'll see them doing the same thing on the failed side.
Does it smell rich?
What is the P0 number of the code? I'll look it up in the factory service manual.
For the radio acting up at the same time...I suppose that could point to a voltage issue. I didn't give it too much thought at first because my radio is acting silly now(turning on and off at random)....I suspect capacitors are going bad in it given it's age. FM is not working right anymore.....CD player works fine....other than it cutting on and off randomly.
May not hurt to monitor the voltage on the radio circuit as the trouble happening. You may have to scope it to see what the voltage wave is doing(ripples in the DC).
No cats. Rear o2s are tuned out. They always read .445 volts or something like that.
It seems as though the left o2 bank bounces around fine on a cold start until it gets to operating temp. Then, it just gets glued to .8 or .9volts while the right bank o2 works fine.
Solomon told me my coolant temp was high, it usually tops out around 210 to 215, not sure if that would have any affect on it? I'm not sure why it goes that high anyway. Fans are on.
I'm starting to wonder if it has something to do with my EVAP system. I remember when I put the cam in I broke the long plastic tube that goes under the TB to the fuel line bundle.
There is quite a bit of pressure in the gas tank when I open the door to fill up for gas.
I'm starting to wonder if it has something to do with my EVAP system. I remember when I put the cam in I broke the long plastic tube that goes under the TB to the fuel line bundle.
There is quite a bit of pressure in the gas tank when I open the door to fill up for gas.
same thing happened to me. I broke that line and have lots of pressure when I open the gas tank. I don't have any of the other issues that you are experiencing though.
Don't both o2s share the same ground? I just don't get why the problem is only on one side. And it doesn't really act up that much until operating temp is reached.
Sounds like it's most likely giving you trouble in closed loop mode. A log of it from a cold start to operating temp may help diagnose it.
My coolant temp went up after installing the CC503. Especially my cruise temp. Would regularly hit around 210-215 in 6th gear, light throttle, 65mph. Stock, it would never get above 190* at cruise. A 160* LT1 thermostat solved that issue. Runs a little cooler than stock now. However, that does tell me the CC503 is running leaner at cruise. I've got no drivability issues with it at cruise.....so I have not put any time into trying to sort it out other than installing the cooler 160* stat.
Get a infrared thermometer at an autoparts store. Take the temp of the individual header pipes just after exiting the head. See if there is a difference on any of the cylinders when it's up to temp.
Really need to see a log......things like.... throttle position, map, maf, short term trims(both banks), long term trims(both banks), o2 volts on all sensors, IAT temp, coolant temp, voltage, ignition voltage, calculated load, timing, injector pulse width(both banks), etc.
Here you guys go. It was bizarre, because the o2's were working just perfectly even into closed loop, but then all of a sudden.....bang. They start freezing. You can really see it from like line 2500 on, especially at the end. Lots of times where the right bank is switching back and forth and the left just stays at .8 or .9.
You'll also notice a few times I get on it, when the o2's are acting right it goes to a commanded AFR of 12.8. When they start freezing, it goes down to 12.2. My fuel trims also seem to disappear when the o2's start freezing as well. What gives?
It's weird because at first both o2 volts bounce around, whether i'm at idle, or on the throttle. But at the end, it's the left bank that gets stuck at high volts during normal cruising and idle. But when I release the gas during DFCO, both will drop to 0.
At idle, if I force a vacuum leak (ie unplugging HVAC connection on intake) I can get both banks to drop. Or, if I pump the brake fairly hard a couple times I can also get the banks to drop. I can't find any vacuum leaks, and this doesn't explain why they only act up after it's been running awhile. Over my head.
Last edited by slikrider20; 09-19-2018 at 12:22 PM.
Was your SES light on during any of the logging? I suspect the disappearing fuel trims are from the PCM seeing the O2 sensors stuck high....so it knows something is screwed up in the fueling and is shutting off the trims. That DTC(O2 high voltage) will kick it back to open loop.
Didn't see the injector pulse width or the IAT temp. Need to see what they are doing. There is also a gap in the log from where it appears to be running right and when it screwed up(csv line 2409). That's pretty important info that we needed to see and don't have it. According to the timestamp, there is a 20 minute gap missing.
There are times in the logging, when you are off the throttle, the O2s go dead lean(0V). Either the fueling really is going lean or you do have an electrical issue that changes as you come off the throttle. That will have the effect of twisting the engine in the opposite direction moving the engine, thus the wiring.
Attached at the bottom of this post is the troubleshooting chart for high voltage(bank 1) from the 1996 factory service manual. They test the heater wiring by pulling the fuse and looking for a reaction from the O2 sensor.
Do you have the stock fuel pressure regulator?
Break in the log below.....all looks okay until this point...
At idle, if I force a vacuum leak (ie unplugging HVAC connection on intake) I can get both banks to drop. Or, if I pump the brake fairly hard a couple times I can also get the banks to drop. I can't find any vacuum leaks, and this doesn't explain why they only act up after it's been running awhile. Over my head.
This right here would seem to point to the O2 sensors working okay and that you really do have an overly rich problem. You are adding air to what would appear to be an overly rich mixture. To the explanation, not sure what it is, but it appears to be some kind of heat induced issue that is over fueling the engine.
If it was running okay before the cam install....it has to be something that happened during the cam install.
I'm gonna have to get logger analyzer, looks like it's 40 bucks?
And I got this email from Solomon.
" I checked again and saw that your “stock” tune that was in your PCM when you first sent it to me had the bad HPP tune applied to it. That has a weird dip in the MAF sensor table near stock WOT area, so I’m sure that was affecting your tune before. I’ve fixed it with a stock MAF table"
07-15-2018, 02:48 AM
CC503 issues. High o2 volts after warmup, fuel trims disappear 
