P0101 and P0420

Boomer

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MAKE:Chevrolet
MODEL:S10
YEAR:2002
MILES:129000
ENGINE
:4.3
DESCRIBE ISSUE.... Driving home last night and the SES light came on. I got home and broke out my Scan tool. http://www.amazon.com/Actron-CP9580...qid=1457389242&sr=8-1&keywords=actron+cp9580a

The codes were P0101 and P0420. I've been doing some research and the article here at bat says on GM. Do a vacuum test for the 101. It's also referencing MAF sensor. For the 420, it's saying
Catalytic Converter Propane Test
Introducing propane into the car air intake will aid diagnosing the catalytic converter and O2 sensors. To run this test the car should be warmed up and running in a closed loop.

1. Connect the scan tool

2. Set the scan tool to monitor the upstream and downstream O2 sensors and the short and long term fuel trims

3. With the car running, introduce propane into the air intake (all your O2 sensors should respond with a high steady voltage)

4. Keep adding propane until the short term fuel trim is over -20%

5. Once a rich condition is reached (step 4), stop adding propane

6. Obtain a freeze frame of the O2 sensor response to the removal of propane

7. Analyze the O2 sensor response

Remember, a properly functioning catalytic converter will remove O2 from the exhaust gas. If your catalytic converter is doing its job, there will be a delay of more than 1 second in the downstream O2 sensor’s transition from the rich condition to the very lean condition caused by the propane test. If both the upstream and downstream O2 sensor respond immediately to the removal of propane by going lean, your catalytic converter is bad and is not removing O2 and hydrocarbons efficiently.

I'm pretty sure my Actron can monitor the 02 sensors. Not sure if it does fuel trim. I haven't used it much.

Question is, is this exactly how I should go about it or, is there a more direct troubleshooting tree I should follow. I have NO driveability issues. At least not yet. I've kept an eye on the coolant overflow jug for awhile and I'm not seeing coolant loss. Gas mileage on this truck isn't great but, almost seems worse than it should be. I'm going to be monitoring that now to see if anything looks amiss.
 

kev2

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#2
look at MAF first... this will skew mixture and a bad fuel trim would skew o2 readings.
start by cleaning it there is a MAF spray cleaner to use.
Do NOT use an oiled air filter. ie K&N - my guess this will help.
check for vacuum leaks After the MAF - use the old school carb spray trick. Need how to info?

let us know if scanner reads live data- MAF, MAP, FT's and o2 sensor voltages.
 

Gus

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Also watch the pre O2 sensor.......if it is not constantly changing, disconnect the MAF......if you get normal readings now, need a MAF......

You can also plot the pre and post O2 sensors.........If they mirror each other, that cat is not functioning....the pre should always be constantly changing, while the post should be slowwwwwwwwwly changing......
 

Boomer

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Hey guys, I did decide I would go out and find out what the scanner does. Looks like it's halfway decent. I then got the bright idea to record video of the data. As you will see in the video, the truck was warmed up. I know at least one video shows the coolant temp. I took 2 videos of settings and 4 videos of different sensor graphs. The light to this point has not come back on. I do hear a little bit of rattling in the cat though. Probably not a good sign. Let me know if the graph videos would be useful and I can upload those.

http://vid82.photobucket.com/albums/j262/Rocguy/02 sensors monitored_zpsf4kfowhx.mp4

http://vid82.photobucket.com/albums/j262/Rocguy/Run through settings_zpslqqnjsds.mp4
 

nickb2

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#5
Also watch the pre O2 sensor.......if it is not constantly changing, disconnect the MAF......if you get normal readings now, need a MAF......

You can also plot the pre and post O2 sensors.........If they mirror each other, that cat is not functioning....the pre should always be constantly changing, while the post should be slowwwwwwwwwly changing......
 

nickb2

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#7
I checked out the videos, all were in closed loop. In a closed loop, switching will be slow.

Fuel trims will be misconstrued and diagnostic off.

For a proper diagnosis, this will need to pass a drive cycle.
 

Boomer

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I checked out the videos, all were in closed loop. In a closed loop, switching will be slow.

Fuel trims will be misconstrued and diagnostic off.

For a proper diagnosis, this will need to pass a drive cycle.
What you are saying is, I will have to drive it a certain distance to really tell or, wait til the light comes back on?
 

nickb2

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#9
Yes, I think one of the features of this actron code reader is that it will give a green led light on when the drive cycle is done. However, I may be mistaken with a Equus code reader.

Maybe I wrote that wrong, but you need to get the readiness monitors all on the same page.

So since I am from Canada, we don't have US emission specs to go by. Up here we do not have secondary air injection to reduce emissions.

I have run into this before with VGA cars and trucks.

VGA in this case means "vehicule grandement accidente" We get those VGA's once in a while and mostly on a dime. They come through the border and we can pick them up at auction. But they are hell to play with as they don't comply with canadian regulation.

See snapshot below.

Screenshot (605).png
 

nickb2

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#10
This is not my writing, but this is what a proper drive cycle should look like for your application/truck.

General Motors Driving Cycle
A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.

To perform an OBDII Driving cycle do the following:

  1. Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
  2. Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
  3. Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
  4. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
  5. Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
  6. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
  7. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
  8. Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

Reprinted on OBDII web site courtesy of General Motors Corporation
© General Motors Corporation
 

nickb2

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#11
Pay special attention to step 7. That is where the cat monitor is doing it's thing. ;)

You might need to be patient and do 5 drive cycles. This is what we call a algorithm. The ECU needs to relearn it's curve, so to speak.
 

nickb2

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#12
This is where I have fun in my trade, I get to test drive and basically tell the client I have to go and ride the shyte out of your car. :):eek:

I have seen clients hanging on to whatever. What a laugh. They usually ask if this is necessary? Yes it is. One guy with his corvette, was most adamant to drive it himself. So I am in the pass side and he is asking me if he is doing the cycle correctly? I said pull over, we will see!!;)
 

nickb2

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#13
On a funny note, I chipped a tooth taking out the garbage. Hurts like a son of a b$tch. Details in life is what gets you.

How do you chip a tooth taking out the garbage? :confused:
 

kev2

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#14
did I read something wrong-
I see MAP as @10"hg....? seams low
I see MAF in LBS/M BUT I see there is a suffix right after the 0.70 that looks like g - could that be GPS grams per second?- both seam low
 

Boomer

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#15
Thank you Kev. Will do. I have a brand new can of that MAF spray on hand. Air filter like everything else is stock. I did have the air box out last week while changing the oil cooler lines that run to the radiator. Almost positive I got everything back right though.

Regarding the g you are talking about, that indicates graphing is available for that parameter. I learned a few things about that tool yesterday.