2003 grand prix p0300

[larryjoe61]

44,000 miles, getting the p0300 code...has anyone experienced this condition? The code is very generic...causing the "transmission to slip"
no metal sounds...Should I take to have a diagnostic test ran? The service soon light comes on then off but the condition does not change.
I understand that with computerized systems one circuit effects other circuits....where should I start...or take it to a dealer and hope to win the lottery before time to pay.
Any suggestions appreciated

Larry

[kustomkid54]

Originally Posted by larryjoe61

44,000 miles, getting the p0300 code...has anyone experienced this condition? The code is very generic...causing the "transmission to slip"
no metal sounds...Should I take to have a diagnostic test ran? The service soon light comes on then off but the condition does not change.
I understand that with computerized systems one circuit effects other circuits....where should I start...or take it to a dealer and hope to win the lottery before time to pay.
Any suggestions appreciated

Larry

Are you sure your reading the right code? I'm coming up with this;
• P0300 - Engine Misfire Detected .

Let me know.

[larryjoe61]

Originally Posted by kustomkid54

Are you sure your reading the right code? I'm coming up with this;
• P0300 - Engine Misfire Detected .

Let me know.

Yes that is correct...the code does not specify which plug or wire or coil is causing the problem....is there a method to test plug wire?

[kustomkid54]

Originally Posted by larryjoe61

Yes that is correct...the code does not specify which plug or wire or coil is causing the problem....is there a method to test plug wire?

If their the plugs that came with it, change them all. I'd say it's one of the back ones, always is. And it's the cheapest way to the fix.
Pull the back plugs, check to see if any are cracked. But with 40,000 on them, what do you have to lose.

Good luck

[richtazz]

if you have an inductive pick up timing light, you can check the spark on each wire by firing the light at the underside of the hood, and watching the flash pattern. You didn't say what engine your car has, as there are some problems with intakes that can cause random misfires so changing plugs may not fix it.

[larryjoe61]

Originally Posted by richtazz

if you have an inductive pick up timing light, you can check the spark on each wire by firing the light at the underside of the hood, and watching the flash pattern. You didn't say what engine your car has, as there are some problems with intakes that can cause random misfires so changing plugs may not fix it.

I "automotive igorant" so I don't have a light....I thought these platium plugs were supposed to be good for 100,000 miles...but i guess anything can break...curious why it doesn't show the bad plug....p0301 or whatever unless it is a hairline crack and causing the voltage to drop slightly..enough to not fully fire..or would it?
I'll just replace the plugs.

Larry

[richtazz]

p0300 is a random/multiple misfire, meaning it isn't just one plug. I think your mileage is to low for the plugs to be worn out, so I would look into a possible injector failure.

[larryjoe61]

Originally Posted by richtazz

p0300 is a random/multiple misfire, meaning it isn't just one plug. I think your mileage is to low for the plugs to be worn out, so I would look into a possible injector failure.

And correct you are ! I had them cleaned by a quick oil change business (changed fuel filter also)a few months ago when the problem orginated....this a.m. I purchased some "stp" injector cleaner and wow! what a difference....in retrospect I should have using this product with every tank of fuel (I switched from medium grade fuel to regular(no additives) ..price difference. ....save money in one aspect but cost more in long term.
As a side note: the local GM dealer told me it was the transmission and would cost $1800 to repair. Mechanics wonder why the public ranks them at the top of their list(lawyers second) as most mis-trusted.

Now would someone explain how fouled injector would effect shift points?
Auto now shifts correctly!

[02gpdriver]

Trust me, the trouble is the catalytic converter. I had all the classic symptoms as everyone else and in the end it was the cat. P0300 is the cat. It causes backpressure to the extent the engine can not fire properly. That is why it does not show up as a particular cylinder misfiring. The engine is firing but not getting full power because it can not exhaust the previous cylinder fuel burn. It is not the secondary air pump, nor the 02 sensor, as I replaced all and still had the problem. Engine would not produce over 2500 rpm in driving condition. Felt lilke transmission was slipping. That is because transmission could not shift because motor was not developing enough power to get to the next higher speed.
The GM special policy number on the catalytic converter is 05551, which provides warranty on cat to 10 years or 120,000 miles. Good luck.

[BNaylor]

Originally Posted by 02gpdriver

Trust me, the trouble is the catalytic converter. I had all the classic symptoms as everyone else and in the end it was the cat. P0300 is the cat. It causes backpressure to the extent the engine can not fire properly. That is why it does not show up as a particular cylinder misfiring. The engine is firing but not getting full power because it can not exhaust the previous cylinder fuel burn. It is not the secondary air pump, nor the 02 sensor, as I replaced all and still had the problem. Engine would not produce over 2500 rpm in driving condition. Felt lilke transmission was slipping. That is because transmission could not shift because motor was not developing enough power to get to the next higher speed.
The GM special policy number on the catalytic converter is 05551, which provides warranty on cat to 10 years or 120,000 miles. Good luck.

Welcome to AF.

Please check the date of the thread and DO NOT resurrect old ones. This one is nearly two years old. So old one of the participants has already passed way.

If you have anything to add to this forum or would like to share your experiences then do so in another post, however, please note that we have plenty of old ones that address the issue of CAT convertors and mifires to include the GM special policy applicable to 2001-2002 model Grand Prixs. A copy of the notification from GM is posted at our Tips & Maintenance forum. See link below.

Click here


Thread closed.