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Amedee
Amedee, GMC Technician
Category: GMC
Satisfied Customers: 24774
Experience:  ASE Technician advanced level specialist
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I have an envoy 06 it has a P0300 it runs but very bad.

Customer Question

Hi I have an envoy 06 it has a P0300 it runs but very bad. There is a lot smoke getting out of the exhaust (kind of gray) I hear a little knock I already changed the spark plugs and the coils.
Submitted: 3 months ago.
Category: GMC
Expert:  Amedee replied 3 months ago.

Hello and welcome!

My name isCustomerand I can assist you with your question.

Customer: replied 3 months ago.
Hi
Expert:  Amedee replied 3 months ago.

Are there any other codes in the computer other than the P0300?

Is the rough running at idle, under a load or both?

Customer: replied 3 months ago.
No its only po300. Runs like crap
Expert:  Amedee replied 3 months ago.

Ok, have you checked for vacuum leaks or fuel pressure?

Customer: replied 3 months ago.
I have check leaks, fuel pressure an like I said I replaced the spark plugs and coils
Expert:  Amedee replied 3 months ago.

Excellent!

Do you know what the engine vacuum is at when the engine is at idle?

Customer: replied 3 months ago.
I didn't find any leak
Expert:  Amedee replied 3 months ago.

No sir, this is not related to vacuum leaks. I am talking about the engine vacuum reading.

Customer: replied 3 months ago.
I'm sorry you talking about the long and short term. ?
Expert:  Amedee replied 3 months ago.

It is a reflection of how the engine is brearthing. It is a good way to measure and see if this is a base engine mechanical problem. For example, if you have a sticky valve, the vacuum gauge or needle will fuctuate at idle compared to an engine that is running good the vacuum needle will be nice and smooth at idle.

Anyway, the most common cause for this condition would be an issue with the timing chain or variable valve solenoid or actuator.

Customer: replied 3 months ago.
Yesterday I was checking trying to check that but the computer wasn't reading. It didn't move from 0
Expert:  Amedee replied 3 months ago.

Here is a picture of the solenoid.

Expert:  Amedee replied 3 months ago.

Here is a picture of the actuator.

Expert:  Amedee replied 3 months ago.

You can also see the timing chain in the second picture. That could be an issue as well.

Customer: replied 3 months ago.
Do you think this is the reason I hear a little knocking ?
Expert:  Amedee replied 3 months ago.

Yes Sir I do

Customer: replied 3 months ago.
What should I replace first?
Expert:  Amedee replied 3 months ago.

I would check engine vacuum first. If it is low or unstable and there are no vacuum leaks, then the cheaper option would be to replace the camshaft actuator solenoid.

Customer: replied 3 months ago.
OK I'll do it this evening
Expert:  Amedee replied 3 months ago.

Sounds good!

I am glad I can help!

It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "5 STAR SERVICE" for assisting you today.

Please let me know if you have any further questions.

Customer: replied 3 months ago.
Hey bro do I sopuse be getting an other code for this selenoid?
Expert:  Amedee replied 3 months ago.

It may or may not set a code if it goes bad.

Customer: replied 3 months ago.
The spark plugs are a little wet with fuel else is this the reason for the smoke?
Expert:  Amedee replied 3 months ago.

Yes Sir

Expert:  Amedee replied 3 months ago.

Did you have any further questions?

Customer: replied 3 months ago.
Yea. Why my computer is not reading the vacuum it just stays in cero
Expert:  Amedee replied 3 months ago.

I am sorry but I dont understand what your asking?

What computer? Your scanner or the cars computer?

Customer: replied 3 months ago.
The scanner
Expert:  Amedee replied 3 months ago.

What reading is it? Does it say engine vacuum?

Can you upload a picture for me?

Customer: replied 3 months ago.
Well its gonna have to be latter because I'm working right now
Expert:  Amedee replied 3 months ago.

OK

Customer: replied 3 months ago.
Do you think that's a big issue?
Expert:  Amedee replied 3 months ago.

YES it is possible but I would need to know what exactly your talking about to say for sure one way or the other

Customer: replied 3 months ago.
Great a soon I take the picture I will send it to you
Expert:  Amedee replied 3 months ago.

Sounds good

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