Suburban Pinging

[98BLACKBURB]

My 98 Burb that has 149,000 miles started pinging,plugs and cap and rotor are'nt due until another 40,000 miles...........no codes/engine lights........any ideas? Thanks in advance..........I love this site..........

[pm26]

Yes, you could have a lot of carbon buildup on tops of pistons and on valves. Carbon gets red hot and causes preigniton, hence pinging. Or, your base ignition timing is advanced too far. Or the EGR valve could be failed closed.

 

Remedy:

 

First, check the base ignition timing and adjust

 

Test the EGR valve vacuum diaphragm with a vacuum pump. The vavle plunger should move when vacuum is applied. If it does not hold vacuum, the diaphragm is bad and valve needs replacing.

 

Test for the compression inside the cylinders. Abnormally high compression (about 180 psi) can indicate a lot of carbon buildup.

 

In the meantime, use premium gas to stop pinging.

 

My hunch is you have a bad EGR valve. If you need a new one, recommend you get one from a GM dealer. I once bought an aftermarket vavle for my 83 Pontiac, and it was a piece of junk that lasted only a few weeks. The GM valve fixed the problem.

 

Adjusting timing is easy, and if carbon is your problem, use GM Top engine cleaner (available from GM dealers) to decarbon your engine.

[98BLACKBURB]

Yes, you could have a lot of carbon buildup on tops of pistons and on valves.  Carbon gets red hot and causes preigniton, hence pinging.  Or, your base ignition timing is advanced too far.  Or the EGR valve could be failed closed.

 

Remedy:

 

First, check the base ignition timing and adjust

 

Test the EGR valve vacuum diaphragm with a vacuum pump.  The vavle plunger should move when vacuum is applied.  If it does not hold vacuum, the diaphragm is bad and valve needs replacing.

 

Test for the compression inside the cylinders.  Abnormally high compression (about 180 psi) can indicate a lot of carbon buildup.

 

In the meantime, use premium gas to stop pinging.

 

My hunch is you have a bad EGR valve.  If you need a new one, recommend you get one from a GM dealer.  I once bought an aftermarket vavle for my 83 Pontiac, and it was a piece of junk that lasted only a few weeks.  The GM valve fixed the problem.

 

Adjusting timing is easy, and if carbon is your problem, use GM Top engine cleaner (available from GM dealers) to decarbon your engine.

 

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[98BLACKBURB]

Thanks, I have no check engine light,have used sea-foam,marvel mystery oil in gas and oil ,changed fuel filter,tryed different octanes in fuel,Thanks I'll check that I'm guessing what you mentioned won't throw a code out huh?Thanks Again

[100R1]

Did you check for codes with a scanner ?

 

You may have codes stored that do not cause a "check engine light" to lalluminate.

 

MY bet would be like PM26 says EGR valve could be the cause of pinging

[Butch 02 Denali]

EGR is high on the list, so is a dirty mafs. I'd try cleaning that first, no cost and easy!