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Question

We have a 2003 malibu 3.1. Car is bucking. tried replacing the egr valve but car still bucks as soon as it warms up. I remove the cable to the egr and car runs perfect untill it overheats. We have found a way to drive it,we disconnect the egr start the car,as soon as it begins to warm up we reconnect the egr cable and the car runs fine untill we shut it off then the problem is back,what can this be?

Submitted: 500 days and 22 hours ago.
Category: Chevy
Value: $9
Status: AWAITING CUSTOMER ACTION
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Optional Information

Optional Information:
2003 Chevrolet malibu 3.1

Already Tried:
replaced egr,cleaned out intake manifold,removing cable to egr and reconnecting when warm

Accepted Answer

Hello XXXXXXXXX,

When you disconnect & reconnect you are just playing hide & seek with the computer.Reconnect the valve ,scan the engine,take note of failure codes (except EGR,clear codes ) & test the engine system while looking at a scan tool (class 2 scan tool).Take note of the engine misfire data in engine data parameters.Most likely you have a bad plug wire or ignition coil.

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Expert: john
Pos. Feedback: 99.7 %
Accepts: 
Answered: 7/10/2008

Master A.S.E Automotive technician

A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician

500 days and 13 hours ago.

Reply

Reply to john's Post: already replaced the plugs wires etc. would a coil pack cause this? or the mip?

Posted by john 500 days and 13 hours ago.

Answer

Yes ,most definetly.

500 days and 13 hours ago.

Reply

Reply to john's Post: mip or coil pack?

Posted by john 500 days and 12 hours ago.

Answer

The coils can cause a misfire if they don't fire a spark that is enough to burn the mixture in the cylinder.Specs are 5-7 ohm .I check the amperage by measuring the length of spark it will jump.Use a test lamp & it should do a 1inch arc with no problem.I have worked for General Motors for almost 40 years & I don't believe I know what a "MIP ?" is.Can you elaborate on that.

499 days and 23 hours ago.

Reply

Sorry Should have said MAP not Mip.I hav po102,103,403,404,and 405 errors on the obd

Posted by john 499 days and 22 hours ago.

Answer

Ok,that make a whole lot more sense.Check the wiring at the MAF sensor & replace sensor(MAF)

P0102-PCM detects that Mass Air Flow voltage signal is less than 1200 Hz

P0103 - PCM detects that MAF is more than 11,500 Hz

P0403-

The PCM detects an electrical malfunction in the EGR solenoid high control circuit or the EGR solenoid low control circuit.
• The above condition is met for more than 20 seconds.

P0404 -
The difference between the EGR Position Sensor parameter and the Desired EGR Position parameter is more than 15 percent.

 

P0405 -

The EGR Position Sensor parameter is less than 0.35 volts.
• The above condition is met for more than 20 seconds.



Edited by john on 7/11/2008 at 9:37 AM

499 days and 22 hours ago.

Reply

Reply to john's Post: Ok I know where everything else is except the MAF Sensor, Where is that located on the 3.1. I appreciate your help on this.The sensor on the air duct to the intake?

Edited by XXXXXXXXX on 7/11/2008 at 9:46 AM

Posted by john 499 days and 20 hours ago.

Answer

Yes,

Mass Airflow Sensor Replacement

  1. Turn OFF the ignition.
  2. Disconnect the intake air temperature (IAT) sensor electrical connector.
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  3. Disconnect the MAF sensor (1) electrical connector.
  4. Remove the air inlet duct from the MAF sensor and the throttle body. Remove the MAF sensor from the air filter housing.


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  1. Install the MAF sensor (1) to the air filter housing.
  2. Install the air inlet duct to the MAF sensor and the throttle body. Connect the IAT sensor electrical connector.
  3. Connect the MAF sensor electrical connector.
  4. Start and idle the engine.
  5. Inspect the air intake duct for leaks.

498 days and 21 hours ago.

Reply

ok that did not help one bit but I did spend $120.00 on a useless part, any other thoughts? MAP Sensor? coil? I'm stumped, ready to trash this car.

Posted by john 498 days and 21 hours ago.

Answer

You are missing something.All the sensors are important to the correct running of your vehicle,but you have to find the fault.Plug in a scan tool & check for failure codes.Note whatever code,clear codes & go drive car.Do not unplug anything ! When the CEL comes on,we will check the code & proceed with the diagnosis.

498 days and 20 hours ago.

Reply

po102,300,403,404,405 and 300again with a symbol that looks like 2 p's reversed on top of each otherone inverted says mil on misfire fuel heater,02

Posted by john 498 days and 20 hours ago.

Answer

The wiring from the Mass Air Flow sensor & the EGR I believe is grounding out at the engine harness.Check the harness for burned or melted wires or any of the insulation has rubbed off.You have MAF,Misfire,EGR codes. If the wiring is not at fault I would suspect the Powertrain Control Module.

498 days and 20 hours ago.

Reply

you really don't think it's the MAP sensor?

Posted by john 498 days and 20 hours ago.

Answer

It could be ,but I do not want to waste your money.I know you need you vehicle repaired & I want to help you. We need to look for the root cause of your problem,whether it be a MAP sensor,wiring,or a computer.The most inexpensive & proper way to repair a vehicle is through proper diagnosis.To repair a vehicle with a computer,you really need to look at the sensor data list & check the voltages to make sure the calculations are right.

498 days and 19 hours ago.

Reply

ok

Posted by john 497 days and 16 hours ago.

Answer

Ok,I know you will find it.

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