Question about 2000 Pontiac Grand Prix

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2000Pontiac grand prix, code 304 misfire #4. Changed the spark plugs, wires, control unit for the plugs and the back 3 injectors, still have the same problem. Clear the code, comes back. slight ruff idle, but no problem acelerating. Check engine light flashes sometimes as I cruise and sometimes as I stop. had the injectors prof. cleaned, ran great for 5 mn, then came back. Any suggestions?

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6 Suggested Answers

6ya6ya
  • 2 Answers

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Posted on Jan 02, 2017

  • 81 Answers

SOURCE: cylinder 3 misfire

Make sure you're using the recommended spark plugs. When my car did that, I had put Bosch Platinum Plus-4 plugs in and got that same problem. Turns out the plugs are too hot and cause it to fire prematurely and kick the misfire code.

Posted on Jul 24, 2008

  • 1 Answer

SOURCE: I am getting a misfire

Here is a copy of the "Policy Adjustment" that I took to the dealer with me this morning. Hope this helps any of you.

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Subject: Special Policy Adjustment - Catalytic Converter #05551 -(09/14/2005)
Models: 2001-02 CHEVROLET IMPALA, MONTE CARLO
2001-02 PONTIAC GRAND PRIX
2001-02 BUICK REGAL
EQUIPPED WITH 3.4L (RPO LA1 - VIN E) OR 3.8L (RPO L36 - VIN K) V6 ENGINE
----------
Condition
Some customers of 2001-02 Chevrolet Impala, Monte Carlo; Pontiac Grand Prix; and Buick Regal model vehicles, equipped with a 3.4L (RPO LA1 - VIN E) or 3.8L (RPO L36 - VIN K) V6 engine, may experience a condition where the vehicle exhaust catalytic converter is replaced due to complaints of lack of power or illumination of the Malfunction Indicator Lamp (MIL). This may be due to the front endcone insulation from the catalytic converter breaking away and blocking the front of the first catalyst brick and preventing the free flow of exhaust gas through the converter.
Special Policy Adjustment
This special policy covers the condition described above for a period of 10 years or 120,000 miles (190,000 km), whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership. The repairs will be made at no charge to the customer.
For vehicles covered by Vehicle Service Contracts, all eligible claims with repair orders on or after September 15, 2005 are covered by this special policy and must be submitted using the labor operation codes provided with this bulletin. Claims with repair orders prior to September 15, 2005 must be submitted to the Service Contract provider.
Vehicles Involved
Involved are all 2001-02 Chevrolet Impala, Monte Carlo; Pontiac Grand Prix; Buick Regal model vehicles, equipped with a 3.4L (RPO LA1 - VIN E) or 3.8L (RPO L36 - VIN K) V6 engine and built within the following VIN breakpoints:
Year
Division
Model
From
Through
2201
Chevrolet
Impala
19100001
19378250
2001
Chevrolet
Monte Carlo
19100001
19378233
2001
Pontiac
Grand Prix
1F100004
1F275188
2001
Buick
Regal
11100004
11338085
2002
Chevrolet
Impala
29100001
29374833
2002
Chevrolet
Monte Carlo
29100016
29374832
2002
Pontiac
Grand Prix
2F100019
2F276927
2002
Buick
Regal
21100001
21288762
Parts Information
Parts required to complete this special policy are to be obtained from General Motors Service Parts Operations (GMSPO).
Part Number
Description
Qty/ Vehicle
10343187
Converter, Catalytic (L36 engine)
1
10343185
Converter, Catalytic (LA1 engine)
1
10328740
Gasket, Catalytic Converter (Converter to I-Pipe, both)
1
15286606
Gasket, Exh Manif Pipe (L36)
1
24505057
Gasket, Exh Manif Pip (LA1)
1
Customer Notification
General Motors will notify customers of this special policy on their vehicles (see copy of typical customer letter included with this bulletin - actual divisional letter may vary slightly).
Service Procedure
Catalytic Converter Inspection
Begin the inspection by reviewing the condition described by the customer. Refer to "Description and Operation," SI document 657895, to help you determine the correct symptom diagnostic procedure when a malfunction exists.

Posted on Feb 08, 2009

  • 2 Answers

SOURCE: 3.1 engine 96 misfires trough driving speeds and idle

i had a 94 that ran into problems like that with very rough idles and misses. i get about five different codes from injectors to oxygen sensor. turned out my negative wire from the battery was so corroded inside the insulation it was causing all sorts of problems. bought new cable and ends from canadian tire $40.00 and installed (had to clean the connection to the block with sand paper) but fixed all my problems after that.

cheers

Posted on Apr 17, 2009

davidg65
  • 26 Answers

SOURCE: Engine misfires under load when warmed up.

check the mass air flow sensor, does it idle back and forth between 500-1000 rpms? if yes mass air flow sensor is the problem.

Posted on Jul 04, 2009

SOURCE: Car coded yesterday p0303 noe check engine light flashing

The only thing left is the injector or a vacuum leak on the manifold gasket sucking air in and causing a lean condition. Thats is its the only common issue providing you dont have a head gasket issue leaking coolant on that cylinder and the compression and valves are not leaking. The old spark plug should show a coolant issue if present. The white part will be shiney if you have a coolant loss. If the coolant is looking real dark you should have the cooling system checked for gas being pushed into the cooling system on compression stroke thru the head gasket.

Posted on Nov 12, 2009

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Have you cleared the codes since replacing the parts? If so, are the codes coming back? Does the misfire still exist even after replacing the parts? You post is rather unclear on this.

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I have a 1996 ford contour i get the 304 code mice fire on cyl 4. i changed the plugs and the coil and they wires look good but the car is still sputtering and it back fired once. any ideas?


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Check engine light on . will not pass DEQ code po 304


hoopers51, Code 304 is for a misfire detected on cylinder #4. Check the wire and the spark plug for that cylinder. Make sure that there is no corrosion in the boots of the wire and see if the spark plug is fouled up, or wet with gas. If the plug is fouled (a normal firing plug will have a grayish color to it) clean it and replace it. If the wire is bad then replace it. Make sure that there is no corrosion on the coil terminal when you pull the wire off. You might want to test the coil if you have an inline spark tester. These can be purchased very cheaply at any auto part store. Also what you can try is to remove the plug on the #4 injector when the engine is running. DO NOT try this with the spark plug wire. (Do this when the engine is off) When you disconnect the injector you will hear a misfire if it is working properly and this will tell you that the injector is not the problem. If there is no change then you should check for power to the injector. (once again, when the engine is running) The injector on that cylinder may be weak and is leaking. This will dump too much fuel into that cylinder causing the misfire and you will have a wet spark plug. All of these, a bad wire, a bad spark plug, a leaky injector or one with no power, or a bad coil will cause a misfire and will increase the HC's on an emission test. Good luck with this.

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1 Answer

2006 pontiac grand prix recevied code P0303, changed spark plugs, wires, and fuel injector. Car still shakes and check enigine light is still on. Acceleration is fine.


Spark plugs,wires and injectors, have nothing to do with your problem

PO303 is a misfire on cylinder #3
You may have an individual cylinder coil for that cyl or a coil pack for
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You may also have other issues that are causing the shaking

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1 Answer

2002 grand prix 3.1 code says number 6 cylinder misfire detetected. I changed the coil pack spark plug and wire and alSo changed the board tat the coil sets on. Computer stillsays #6 misfire detected. The...


It's a possibility the injector is the problem. It may not have the psi it needs, therefore the cylinder could be misfiring, or the injector could be letting too much fuel in. Before I change the injector, I would try to have someone to clean the injection system to see how it works. The cleaning around in South Carolina is $99-$149 depending on where you go.

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1 Answer

I ran a scanner on my 2002 pontiac grand prix 3100 V6 and it reads out as multiple misfire i already changed the spark plugs,what could the problem be?


A code “multiple misfire” may mean that one or more of the following has happened:

•Faulty spark plugs or wires
•Faulty coil (pack)
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2 Answers

#4 cyl misfires/code 304


P-0304 indicates number 4 cylinder misfire. Are you using Toyota parts dept spark plugs? More often than not, non-toyota plugs make the v-6s run poor, right out of the box....
Try this:With the engine running, pull the connector wire off of the #4 injector. Note to see if there is any change with the idle quality. No change? You may have a bad injector.

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