Does anyone know the cylinder compression of a 3.3L in psi? I've done a search through the site and found nothing of usefullness. My car is pinging like crazy and this is my last resort before I tackle the EGR valve. Thanks!!
I'd check out the EGR valve before checking the compression. One thing the EGR valve does is lower combustion temperatures to lower NOx levels, and in the process of lowering the temperatures it helps to reduce pinging as well.
125-160 is relatively normal for most "healthy" engines.
Try pulling the codes from the computer, and as froggy said, look for egr codes.
You can also try running some combustion chamber cleaner through it (I guess it's Seafoam in the States), but if there's enough carbon in there to raise your compression that high, I doubt it alone would clean it enough.
If you want to know if it is compression (carbon buildup) try running some high test through it and see if the problem goes away or if it is dramatically reduced. Higher octane fuels are more resistant to what most people call "pinging" (detonation usually).
I've often done what used to be called a "performance driving tune up" on carboned up cars (heavy city driving all the time). Run a can of combustion cleaner through it and then go for a nice long run on the highway with heavy acceleration (foot to the floor, safely though) up the on ramps. Helps to burn the carbon off.
I would bet on there being something out of adjustment or functioning incorrectly if the pinging is really severe.
Yeah, my guess would be the EGR valve too. I've got 218k on the car, so it's about time for it to go. It's just such a pain in the ass to get to and expensive, (for a poor college kid), to replace. The local Advance Auto has Seafoam in stock, so I'll go pick up a can and see what happens. While I'm there I'll pick up some cans of carb cleaner and see if I can clean the EGR valve and solenoid. Thanks for the help!
With that many miles, carboned up cylinders is a very likely culprit. How long have you been experiencing problems? Cylinders don't get loaded up with carbon overnight. Takes time. so if the problems you're having happened relatively suddenly, then I'd look at other things (like the EGR) before getting deeper into things. Seafoaming the engine isn't a bad idea, nevertheless. Might even run like a brand new car once you do it.
Great White is absolutely correct in his post. Higher octane does burn slower to resist spark knock, a.k.a. pinging, a.k.a. detonation. And you'll read it in many other places that some recommend bumping up the octan level of the gas you use when you've got a lot of miles on the car because built up carbon effectively raises the compression ratio and thus raises the octane requirements in the process.
One more thing, how's the weather been down there lately? Hot, cold, etc... Pinging seems to get more frequent when it starts getting hotter outside. Pull your spark plugs and see what they look like. If they're looking really white, then your engine is running on the lean side (which also leads to pinging) and probably running hot in the process.