pinging/knocking on '02 C5 stock

[Javier Gonzalez]

2002 auto stock 65000 miles. I've been reading the forum for fixes to the pinging. Lots of info on decarbonization, etc. I also saw something about a re-flash for this issue. My VIN is 1G1YY22G825122413. My car seems to do the pinging (marbleing) when downshifting. Is there such a flash? best gas I can get here in CA is 91 octane and have been running Chevron. I have an appointment for a BG decarbon process this week but I don't expect much. I tried the seafoam and that didn't get rid of it. No codes come up and I don't trust my dealer.

[c4c5specialist]

Hi there,

Honestly, 2 things.

First, Seafoam and Techron do NOT decarbonize as well as 44k from BG products.

The 'process' should be to install 2 cans in your tank and fill it.

Drive it and see what happens.

HOWEVER, BECAUSE YOUR EXPERIENCING THIS NOISE ON DECELLERATION, IT CANNOT BE SPARK INDUCED PING DUE TO CARBON BUILDUP.

So, you need to start from square one. Accurate road test to determine where the noise is coming from.

Decarb will do NOTHING for a noise on decelleration.

It could very well be normal driveline characteristics.

Alllthebest, c4c5

[Javier Gonzalez]

I should have been more clear, the downshifting is when I step on it and the engine kicks down a gear or two. It amost seems that the PCM can't keep up with the timing.

[c4c5specialist]

HI there,

Start with the 44K to a full tank and reevaluate AFTER you use the tank up.

Also, the calibration would also be suggested to make sure you have the latest and greatest from GM as far as programming goes.

Allthebest, c4c5

[Javier Gonzalez]

Thank you, I just called the dealer and gave them the VIN and the guy I spoke with wasn't helpful regarding my question about the PCM calibration flash for my car. He kept saying that according to GM there were no recalls for my car. I just gave up talking with him. I have an appointment with a BG shop to have them decarbonize the top end. They use an adapter to the throttle body and inject the cleaner that way and then do the injectors via the fuel rail.

[LLC5]

Originally Posted by Javier Gonzalez

Thank you, I just called the dealer and gave them the VIN and the guy I spoke with wasn't helpful regarding my question about the PCM calibration flash for my car. He kept saying that according to GM there were no recalls for my car. I just gave up talking with him. I have an appointment with a BG shop to have them decarbonize the top end. They use an adapter to the throttle body and inject the cleaner that way and then do the injectors via the fuel rail.

It's not a recall you are after, it is the latest PCM update. Call another dealer if yours doesn't understand, or just plain doesn't want to help you. You could also contact GM customer service and let them know the kind of customer service you are recieving from your local dealer if they will not help you. Good luck with it.

[motorman]

there used to be a GM website where after putting in your VIN it would tell you if your vehicle has the latest computer updates.

[Javier Gonzalez]

Originally Posted by motorman

there used to be a GM website where after putting in your VIN it would tell you if your vehicle has the latest computer updates.

Yeah, I tried the site and it's no longer a valid link. The dealer service person I spoke with was clueless but nice. They must be slow in the service dept because he really tried to understand my question regarding the updated PCM calibration flash. If the decarb process doesn't take care of it, I'll look for a local tuner with a dyno and see if he can figure it out.

[Javier Gonzalez]

The pinging is gone for now. Here is what I did. I did the seafoam through the vacuum line at the brake booster. Then I cleaned the throttle body and also did the seafoam through the throttle body using the new method where you disconnect the air tube at the throttle body, insert the squirt tube from the seafoam spray can, reconnect the air tube, start the car and rev it to 1500 RPM and squirt the seafoam in (this is a new product), then return to normal idle and turn off the engine. Wait 5 minutes and then go drive it hard. This seemed to have helped a lot but I had an appointment at the BG service station so I took it in for the BG Fuel/Air Induction Service. The work order states that they charged me for a BG04-205-2 - BG Fuel/Air Induction Kit, a BG-03-4058 - BG Throttle Body Cleaner. " technician attached induction machine to engine, installed cleaner. Ran engine as part of service and cleaning process". I drove it hard today and could not get it to ping and the car is running as new. For overkill, I added a can of Techron concentrate when I filled up today.