97 Yukon pinging badly under load

GMC guy · May 5, 2006

My 97 Yukon with about 180K, has developed a bad pinging problem when under any kind of a load. It gets severe on long hills, and the knock sensor calls the timing back until it runs rough and loses power. The tune up stuff is OK, and it does not display any codes. It has lost a little bit of coolant, and is a bit better with premium fuel but something has changed. I have seen similar problems in other posts but no real answers. Has anyone had any experience with this?

Thanks, Bill

catnfool · May 5, 2006

I know you were asking the expert and not me, but here goes... I had the exact thing happen and chased my tail for a while with timing,plugs,wires,ect and found it was carbon built up in my combustion chamber. They ran some high dollar injection cleaner through it, let it sit for a half hour, and repeated the procedure and PRESTO- it was cured!!

I thought they were taking me for a ride when they told me what it needed but they turned out being heros!

ratt454 · May 16, 2006

hey man, i've got an old big block that i had the same problem with. i would agree with the engine flush, but there is no need to pay a whole lot of money. you can buy the same stuff they use at advance autoparts for 6 bucks a bottle. its called Seafoam, and its just about the best product i've found out there. i would pour half the bottle into the gas tank and suck the other half through a vacume line. that should take care of your problem, if it is indeed carbon deposits.

bobcat5544 · May 5, 2006

do a decarb cleaning, but also take a can of brake clean or carb cleaner spray it around the intake area to make sure you dont have a vacuum leak, if the engine revs up while spraing then you have a vacuum leak

mmmikkke · May 5, 2006

That's what I was going to say too. Lost coolant? Pinging? Could be on part of your intake manifold gasket has corroded away, leaking coolant and allowing extra air into the mixture for one cylinder. One cylinder therefore runs hot and pings.