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john aka eaut, The Car Guy
Category: Pontiac
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Experience:  15 years as a auto tech
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2001 grand am 3.4L, new MAF, codes p0443 and p0449 for evap.

Resolved Question:

2001 grand am 3.4L, new MAF, codes p0443 and p0449 for evap. I only have a basic scan tool and a multimeter, but I have noticed this being a common problem on these cars and wondered if there was a simple solution
Submitted: 4 years ago.
Category: Pontiac
Expert:  john aka eaut replied 4 years ago.

 

po443

CIRCUIT DESCRIPTION
The Evaporative Emission () purge valve is Pulse Width Modulated (PWM) . The Powertrain Control Module (PCM) controls the EVAP purge valve duty cycle by controlling the amount of purge valve ON time. The scan tool displays the amount of ON time as a percentage.

An ignition voltage is supplied directly to the EVAP purge valve. The PCM controls the EVAP purge valve by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The PCM monitors the status of the driver. If the PCM detects an incorrect voltage for the commanded state of the driver, DTC P0443 sets.

CONDITIONS FOR RUNNING THE DTC

  • The engine speed is more than 400 RPM .
  • The system voltage is between 6-18 volts .

CONDITIONS FOR SETTING THE DTC

  • The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.
  • The above conditions are present for a minimum of 5 seconds .

ACTION TAKEN WHEN THE DTC SETS

  • The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
  • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

  • The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  • Use a scan tool in order to clear the MIL and the DTC.

TEST DESCRIPTION graphicgraphic


The numbers below refer to the step numbers on the diagnostic table.

 

  1. This step tests if the concern is active. The EVAP purge valve is Pulse Width Modulated (PWM). An audible clicking should be heard when the purge valve is commanded to 50 percent and should stop when the EVAP purge valve is commanded to 0 percent . The rate at which the valve cycles should increase as the commanded state is increased and decrease as the commanded state is decreased. Repeat the commands as necessary.
  1. This step verifies that the PCM is providing ground to the EVAP purge valve.
  2. This step tests if a ground is constantly being applied to the EVAP purge valve
Customer: replied 4 years ago.
I have found this on alldata, but my scan tool will not allow me to open or close anything or allow me to veiw freeze frame data. Is there a way, without doing those things, that i could fix this problem? Are there parts in this system that commonly fail and cause these codes? Im also getting a system too lean, and a sweet smell after driving.
Expert:  john aka eaut replied 4 years ago.
P0449

CIRCUIT DESCRIPTION
An ignition voltage is supplied directly to the Evaporative Emission (EVAP) canister vent valve. The Powertrain Control Module (PCM) controls the EVAP vent valve by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The PCM monitors the status of the driver. If the PCM detects an incorrect voltage for the commanded state of the driver, DTC P0449 sets.

CONDITIONS FOR RUNNING THE DTC

  • The engine speed is more than 400 RPM .
  • The system voltage is between 6-18 volts .

CONDITIONS FOR SETTING THE DTC

  • The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.
  • The above conditions are present for a minimum of 5 seconds .

ACTION TAKEN WHEN THE DTC SETS

  • The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
  • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

  • The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
  • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  • Use a scan tool in order to clear the MIL and the DTC.

TEST DESCRIPTION

graphic

graphic


The numbers below refer to the step numbers on the diagnostic table.

  1. Listen for a click when the valve operates. Be sure that both the ON and the OFF states are commanded. Repeat the commands as necessary.
  1. This step verifies that the PCM is providing ground to the EVAP vent valve.
  2. This step tests if the EVAP vent valve control circuit is grounded
Expert:  john aka eaut replied 4 years ago.

if you dont have a scanner to trigger the solemoids then replace the evap purge valve & the canister vent valve they are both common for failure on older gm s

a lean code is genarally codes are generally caused by vacum or intake leaks

or failed mass air flow sensors



Edited by john aka eautosales on 8/18/2010 at 4:16 AM EST
Expert:  john aka eaut replied 4 years ago.
where is the sweet smell coming from? check the intake manifold gaskets they are very common to fail on 3100 and 3400 motors
Customer: replied 4 years ago.
Relist: The guy just keeps sending me copies of charts on alldata (literally copies). This does not help me, and I can do that myself, i need expert experience and advise, not a dictionary. .
The guy just keeps sending me copies of charts on alldata (literally copies). This does not help me, and I can do that myself, i need expert experience and advise, not a dictionary.
Expert:  john aka eaut replied 4 years ago.

as stated above .....if you dont have a scanner to trigger the solenoids and a Smoke machine then replace the evap purge valve & the canister vent valve they are both common for failure on older gm s

a lean code is genarally codes are generally caused by vacum or intake leaks

or failed mass air flow sensors

where is the sweet smell coming from? check the lower intake manifold gaskets they are very common to fail on 3100 and 3400 motors

the proper way to diagnose is with a good scan tool like a solus or a modis or a tech 2

but the failures i stated are very very common



Edited by john aka eautosales on 8/18/2010 at 4:24 AM EST
Customer: replied 4 years ago.
I will try replacing these 2 tomorrow morning, and all the gaskets are new, and all the bolts were torqued to spec, i thought maybe the sweet smell was the motor running lean, but ill recheck everthing tomorrow morning. Sorry for the relist, It only showed me your first 2 posts. I'll let you know how it goes tomorrow, thanks.
Expert:  john aka eaut replied 4 years ago.

sweet smell is coolant, recheck for coolant leaks

Expert:  john aka eaut replied 4 years ago.
and the intake bolts are torq to yield aka stretch bolts and are suppose to be replaced when intake gaskets are done..........
Customer: replied 4 years ago.
It really smells like a fuel thing, and its only after we take the car out full throttle (too see if it will throw a light), I'll recheck all the gaskets, I didnt have the money for all new bolts, trying to save as much as possible. They are all 2 ft lbs higher than origional spec, tightened is proper sequence.
Expert:  john aka eaut replied 4 years ago.
checj for injector o ring leaks or regulator leaks
Expert:  john aka eaut replied 4 years ago.
any luck?
Customer: replied 4 years ago.
regulator was leaking, that got my starting issue fixed (long crank), i replaced the 02 because i had one laying around, and i believe that solved the lean code, now im down to only one code so far, though i didnt run it that long, which is the canster vent code. Im assuming this means the rest of my problem is just that vent piece needing to be replaced. I think a friend is coming by with either a brick or a modis tomorrow so we can try to open and close the valves independantly.
Expert:  john aka eaut replied 4 years ago.

you can trigger the solenoids i do it with a smoke machine also to open and close them and watch for leaks

should be under the car i believe drivers reargraphicgraphic

Customer: replied 4 years ago.
would a leak throw a leak code? or not always?
Expert:  john aka eaut replied 4 years ago.
99 perecent of the time a leak will throw a code but its generrally a small opr large evap code like a PO440
Customer: replied 4 years ago.
thats what i figured... we start tomorrow at 9am (central time) but I dont know when the guy with the scan tool is coming over, but i hope to take it for a drive tomorrow and still only have that one code.
Expert:  john aka eaut replied 4 years ago.
ok best of luck....any other info feel free to ask if i was helpful please hit accept, I have a large amount of time on this question....Thank you
Customer: replied 4 years ago.
all codes are back, and his scan tool was a brick, and we found out nothing...
Expert:  john aka eaut replied 4 years ago.

with out the proper tools and equipmenmt its a guessing game

if you replaced both evap components then you have a wire or ground issue or a connector issue or a failed ecm

Customer: replied 4 years ago.
didnt replace them yet, Im about to though, the lean code is gone thanks to the o2 im guessing, ill have the 2 components repalced very soon
Expert:  john aka eaut replied 4 years ago.
i would replace them they are inexpensive and the most probable cause
Customer: replied 4 years ago.
They are both new now, and the codes instantly pop up as pending, the p0443 and p0449 codes.
Expert:  john aka eaut replied 4 years ago.

its in the harness or the pcm then you need to check them with a solus or modis or similar scanner

john aka eaut, The Car Guy
Category: Pontiac
Satisfied Customers: 12953
Experience: 15 years as a auto tech
john aka eaut and 4 other Pontiac Specialists are ready to help you
Customer: replied 4 years ago.
Ok, thanks for all the time you put into this... If you happen to know how to find out what pcm goes in a car without the number on the computer id pay for that one too.

1987 Olds 98 regency brougham, have so spark, crank and cam sensors are new, ingition controll and coil are new, that was all provided at the time the guy gace me the car... the only thing left is the pcm, which has been replaced before and the sticker is gone. Apparently the difference between the two possible computers on this car is the final drive ratio, but we cannot find that out, weve checked the RPO's and the list does not include the "f" codes for the ratios.

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