Persistant Pinging Problem

[nme904]

This is my first post on this site but I have been reading about the issue I am having quite a bit. I have been having a problem with my '02 5.3 Silverado pinging. I had it at the dealer and they did a de-carbon procedure on the engine to clean it out but it is still pinging (not as bad). From what I understand, they used a high pressure machine to clean out the combustion chambers and intake manifold and fuel injectors.

 

The pinging seems to be somewhat better but I still hear it when the engine is under load and after the tranny downshifts and the engine is lugging along at low rpms. I am also using 91 octane right now because the dealer reccomended I run a few tanks of it. I called the dealer back and told them I was still having this problem and they told me to keep driving it for 2 weeks to let all of the carbon get out of the engine. Wouldn't this happen almost instantaneously?

 

Do you think I could still have any carbon buildup in the engine? What would be the next logical step for things to check? From searching on here it seems like this could be caused by several things including: bad egr, intake leak, dirty MAFs, bad knock sensor, bad o2 sensor, dirty MAP. The dealer did say that my ignition timing was being retarded so this makes me think the knock sensors are working.

 

Any suggestions will be greatly appreciated.

[nbscanuck]

what brand of fuel are you using? shell has LOTS of detergents in it, which cleans the engine and injectors but doesn't burn well, causes pinging.

 

How many miles? have the spark plugs ever been changed?

[nme904]

what brand of fuel are you using? shell has LOTS of detergents in it, which cleans the engine and injectors but doesn't burn well, causes pinging.

 

How many miles? have the spark plugs ever been changed?

 

I use Chevron gas mostly. The truck has 79K miles, and the plugs and wires were changed about 6 months ago.

[markw8]

Chevron is good, It is Top-Tier gas. Also the higher the octane the more carbon tends to form. This is because the higher the octane the slower the burn. Try adding Techron gas additive, this is made by Chevron, it's also in their gas. Do this over several tanks. Mark.

[nme904]

Chevron is good, It is Top-Tier gas. Also the higher the octane the more carbon tends to form. This is because the higher the octane the slower the burn. Try adding Techron gas additive, this is made by Chevron, it's also in their gas. Do this over several tanks. Mark.

 

Thanks for the suggestion. I may try that.

 

I am surprised that the carbon cleaning procedure that the dealer did didn't get all of the carbon out though. That's what makes me wonder if there isn't something else causing this.

[minibike132]

I agree with carbon issue. I can't really comment on the job the dealer did, you'll find as many different procedures used as you'll find technicians. Top tier fuel and an in tank additive are a good way to keep a clean engine clean but IMO a more aggressive approach is needed once it starts to ping. You'll find that alot of folks here swear by seafoam but I can't testify to it because I've never used it. How long was it in the shop? When I have a stubborn one I'll usually let the top engine cleaner sit overnight.

[nme904]

I agree with carbon issue. I can't really comment on the job the dealer did, you'll find as many different procedures used as you'll find technicians. Top tier fuel and an in tank additive are a good way to keep a clean engine clean but IMO a more aggressive approach is needed once it starts to ping. You'll find that alot of folks here swear by seafoam but I can't testify to it because I've never used it. How long was it in the shop? When I have a stubborn one I'll usually let the top engine cleaner sit overnight.

 

It wasn't there overnight. I guess I will be taking it back. I feel like I should haven't to pay for them to do this again if it should have been left to soak overnight in the first place. I also tried seafoam myself but I never noticed any difference with that. I used the brake booster line so I may have not been feeding all of the cylinders.