P0300

nickb2

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#17
Of note, stop resseting CEL light, and try to do a complete drive cycle to see which monitors will complete. Obviously the misfire I/M will not complete, but it will eliminate anything o2 or catalytic related, evap related etc.

Here is a typical gm drive cycle


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.
 

GM Guy

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#19
Thanks guys! I will try this diagnostic drive cycle.
My Giotto software is not the enhanced version. It has a screen where mode 6 info is given, but not it details that a shade tree like myself understands.
 

nickb2

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#20
Just post them in screen shot once you have successfully completed a complete drive cycle. If the drive was complete, all monitors will report back and give data, in PID form or something close to that, but in what you say, it is true, it is hard for a shade tree, but with some guidance from us here who do understand that, mode 6 is a VERY valuable data to get when chasing a multiple misfire such as your especially when not associated with lean or rich codes such as 171, 172, 174 etc.
 

grcauto

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#24
It's not warm.....ETS @124 degrees and open loop both sides. Get it into closed loop.
UPDATE: Are these taken after the drive cycle? Did it ever warm up?
 

GM Guy

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#25
That was the capture at time of SES. The 2nd capture is at full operating temp, 198.
Also the fuel pressures are; key on engine off=57-58 psi, engine running 52psi.
 

GM Guy

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#27
Here are the sensors with the engine at 194*F.
This is after shutting off engine and restarting it. NO SES, so there's no capture of the instantaneous conditions at the time of (no) fault.
The first test drive, the trans did not shift through lockup and the SES was set.
The second test dirve, the trans DID shift through lockup and the SES was NOT set, yet the sensor fuel trims were still at 99%. I was expecting in closed loop and no SES set, the fuel trims would be at a lower % operation. ??
 

Attachments

grcauto

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#29
Here are the sensors with the engine at 194*F.
This is after shutting off engine and restarting it.

So the captures are while engine is running. correct?

NO SES, so there's no capture of the instantaneous conditions at the time of (no) fault.
The first test drive, the trans did not shift through lockup and the SES was set.

SES equals Service Engine Soon? Had to think a minute....this is old OBDI terinology. This is OBDII compliant vehicle?
You can't get the freeze frame data?


The second test dirve, the trans DID shift through lockup and the SES was NOT set,

yet the sensor fuel trims were still at 99%.

I do not know what this means. Does your software explain what this is and how it's calculated? The rear O2's are for monitoring the cats ability to store O2.

I was expecting in closed loop and no SES set, the fuel trims would be at a lower % operation. ??

The trims you need to be concerned with are
#1 the LTFT and then
#2 the STFT both of which are in good shape. Your engine is doing very well with fuel control.
What monitors are you trying to set doing the drive cycles?
 

GM Guy

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#30
GM Guy said:
Here are the sensors with the engine at 194*F.
This is after shutting off engine and restarting it.

So the captures are while engine is running. correct? YES

NO SES, so there's no capture of the instantaneous conditions at the time of (no) fault.
The first test drive, the trans did not shift through lockup and the SES was set.

SES equals Service Engine Soon? Had to think a minute....this is old OBDI terinology. This is OBDII compliant vehicle?
You can't get the freeze frame data?
THE light on the dash says Service Engine Soon. SES.
OBDII compliant= yes.
Freeze frame data like my 1st attachment is recorded at the time of the P0300 code being set. The second drive there was no SES light on and the transmission shifted through all the gears, including lockup. This is determined by watching the tach. This was without clearing the P0300 code that there was no SES light on, although the code was stored.


The second test drive, the trans DID shift through lockup and the SES was NOT set,

yet the sensor fuel trims were still at 99%.

I do not know what this means. Does your software explain what this is and how it's calculated? The rear O2's are for monitoring the cats ability to store O2.
The last attachment shows both O2 Fuel Trims at 99.06%, and highlighted in red.


I was expecting in closed loop and no SES set, the fuel trims would be at a lower % operation. ??

The trims you need to be concerned with are
#1 the LTFT and then
#2 the STFT both of which are in good shape. Your engine is doing very well with fuel control.
OK, I'll revisit the ignition, it must be something I'm overlooking that is failing for a very short period of time while the engine is still warming up.

What monitors are you trying to set doing the drive cycles?
Well, not being as well versed as you professionals, I don't know the important sensors to watch nor what their respective data reflects. While reading the responses on here and watching some youtube vidoes that explain the relationships of the O2 sensors function to the fuel curves, I'm learning how the O2 voltage responds during rich and lean conditions and the respective fuel trims to try to maintain the +/- .450 mV signal.
That is the reason in my first post in this thread, I asked for guidance in the use of my software, which is not the enhanced version, not bi-directional. It looks like I need to get the enhanced. Gone are the days of Quadrajets and HEI and quality gasket materials that were reliable and easy the work on. Sorry, I'm rambling...