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My check engine light has been on for quite sometime. I was hoping maybe somebody on the forum can give me a few pointers on what to look for. Even though the light is on, the car is running better than new, it has a ton of power and seems to drive normally.

All parts below where replaced. Some more than one time:

  • All four oxygen sensors (one was coding - failed - and was replaced a second time)
  • PCM (first replacement - reprogrammed twice, due to car would shake intermittently stopping at the stop light. Then replaced again due to check engine light)
  • both catalytic converters
  • Flow Valve

I purchased a BlueDriver OBDII scanner, the codes which are posting are:

P2096 - Post Catalyst Fuel Trim System too Lean Bank 1
P2099 - Post Catalyst Fuel Trim System Too Rich Bank 2

A while back I ran a few reports and also put together a report of the full voltage range the sensors were posting during the scan. See below:

Bank 1 - Sensor 1 - Voltage consisted of values between: 0 - 0.908
Bank 1 - Sensor 1 - Short Term Fuel Trim values ranged: -7.6 - 23.8
Bank 1 - Sensor 2 - Voltage consisted of values between: 0 - 0.877
Bank 1 - Sensor 2 - Short Term Fuel Trim values ranged: -62.9 - 99.2

Bank 2 - Sensor 1 - Voltage consisted of values between 0 - 1.242
Bank 2 - Sensor 1 - Short Term Fuel Trim values ranged: -79.7 - 21.7
Bank 2 - Sensor 2 - Voltage consisted of values between 0 - 0.923
Bank 2 - Sensor 2 - Short Term Fuel Trim values ranged: 39.8-99.2

The hyperlink will direct you to the original post I created on the Crossfire Forum

Any help is very much appreciated!

Its been awhile! I was had the dealer look at all the grounds. and clean them and reattach them to the car but, the light is back on again. I also was able to pull new readings as of Friday.

Reading from 4-21-17

enter image description here

  • 1
    Did you take down the long term fuel trims by any chance? Also I've never heard of a STFT going as high as 99. I thought they were capped much lower than that.
    – Zshoulders
    Nov 18, 2016 at 15:53
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    See attached images I included the Mode 6 report and also the readings while driving. I highlighted the anomalies. Its not the full report just the times the reader posted issues. I will run the diag tool today to see if anything has changed but, this is a normal reading since the car's MIL has been on. Nov 18, 2016 at 16:25

1 Answer 1


very well formed question.

At any point did you test your fuel injectors? if you got some crud in your fuel line one injector on one side might be dripping while another might be going rich.

Does any of your spark plugs look white or black. I would expect to see a white one on bank one somewhere and a black sooty one on bank 2 some where.

Can you hear any exhaust leaks especially on bank 1

seems like we have a pattern. Also you missed the 0mph to an immediate 105mph inside of 2.3 seconds. Got to ask, with that kind of power what's your quarter mile time or do you just like peeling out in 4th gear? ;)

It seems that the issue happens when slowing down and breaking. Can you get a readout of your brakes by any chance?

This leads me to think it's either a strange crossed circuit that is touching while breaking or possibly a loose ground. Below should isolate if its physical movement causing the problem or actually a faulty sensor or something.

If the lifted tests show the oddities we can skip the non lifted tests. It still could be a loose wire or something but much less likely. The only thing you could try if the anomalies show up differently while lifted as in not so severe is try the speed bump test and the slalom. These 2 tests effectively eliminate sensor changes and just vibrate the car.

Please be sensible with these tests. if done incorrectly some might damage your car like the speed bump test. use common sense. I am sure you will but wanted to make this clear especially if someone else reads this answer.

I think those are rear wheel drive cars so jack up the drive wheels so they are not touching the ground and make sure the car is stable on the jack stands. punch it let it run at about 60mph for a little bit then slow down reasonably quickly. This will test only the sensors under hard acceleration and hard braking without much motion at all.

While it is in the air you might want to do some normal startups and slow downs as well. Also try dropping your foot off the gas. these will test the sensors under normal driving conditions while eliminating much of the motion and vibrations. dropping your foot off the gas will cause rapid changes in airflow and might show us that the issue is not gforce related but sudden stopping of flow.

with it lifted pretend you're driving on the highway for a bit and be really smooth about your throttle position speed and rpm. this will test to see if we get any anomalies while everything is at a steady pace. If we do then either its engine vibrations which I suspect there isn't much of or something is reading incorrectly and glitching out.

with it in the air let it speed up slowly keep it there for a few seconds then slowly let off the gas and let it coast to idle again. This will tell us if the system reacts when there isn't any abrupt changes.

Can you do some really hard starts like wide open throttle then let it cruise for 20 seconds then slam on the brakes and stop really fast? Do this a few times. this is to get as much motion as possible and see if the sensors go wild. This could then be a reliable way to test fixes if we can reproduce what is above, messed up sensors while braking.

do some really slow startups and really almost coasting type braking try not to make any g forces at all and pick the smoothest spot you can. when slowing down quickly let off the gas on a couple runs and let off the gas slowly on a couple more. this is to eliminate motion from the equation.

do a couple runs starting up and slowing down as you normally would do. This is suspect as you can see most of the issues are happening right after braking. so it may not be a sensor issue it may be a ground issue or a something sloshing where it shouldn't be issue.

Get a section where you get up to speed something you feel safe slaloming with then steer hard to the left and right while maintaining the same throttle and speed. straighten out and drive for a bit again. This should keep nearly all the sensors running as they were while driving straight. keep track of turning left or right first and about what time. might want to video record it to match up with sensor data. This might tell us if something is sloshing or becomes loose when turning and which direction it becomes loose.

Get it up to some speed put it in neutral while maintaining the RPM's or keeping them between 1.5k and 3k and brake hard. This should eliminate mass air flow rate, throttle position, engine rpm, timing advance, intake manif pressure and sudden dips in exhaust flow from the equation

find a parking lot with some sharp speed bumps. Get up to and maintain 20mph or os and run over a few. keep everything as smooth as you can maintain throttle position engine rpms and speed. This should eliminate all sensors and possibly if something is loose we will get strange readings.

This should help determine if it is actually something loose, sensor related, or sudden change related. Basically a big process of elimination.

and upload the results to google docs and paste a link here.

the ABS might be due to the car dropping into failsafe mode. This means teh computer will activate different systems to keep the car limping along and to keep you safe. This of course is just a guess it could also be related to a loose wire or a bad reading from the brake pedal ... which if you can get brake pressure or position readings that might also show some pattern or strangeness.

resetting the computer and then having it flag while keeping a steady speed does support the bumpy road idea but it can also be a bad sensor glitching out. It makes that breaking / slowing down pattern you can see in your images less likely to be a main issue. hard braking still can cause the ground or loose wire to act up reliably each time.

The ac acting strange supports the loose wire / bad ground option. Check all the main big grounding straps going from the frame to the engine and the battery see if one of these are loos. Those being loose can make all sorts of strange things happen to the systems connected to them.

And you're welcome! :)

  • 1
    I must have miss typed (on both forums) its a purge valve they replaced. Nov 18, 2016 at 15:28
  • I am not sure how to upload a PDF on this site. Do you know how? Nov 18, 2016 at 15:40
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    Thank you! the dealer has checked the plugs which seem to be fine. Also, awhile back I paid for the dealer to service the fuel system. On top of that every 5k when I change the oil I add fuel injector cleaner. About two weeks ago they found a small leak in the exhaust system and patched it to see if that would fix the problem. But, the light came back on after three trips around town. Nov 18, 2016 at 16:01
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    All I could upload were JPGS.. not sure how to upload a PDF. I will run some reports today during my travels. Nov 18, 2016 at 16:26
  • @user3496471 updated answer with lots of stuff to try I think it revolves around braking / slowing down at least that is what the patterns hint at in your readouts.
    – Cc Dd
    Nov 19, 2016 at 5:46

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