Major Parasitic Power Loss in Specific RPM Band

[240nspec]

Any gear, any condition, most noticeable in heavy loads / wot. From 2.5-3k Great power loss, a very noticeable tin can noise is made while within these RPM boundaries. I already removed the top chain guide and fear even If i were to remove the other guide (side) this would not correct the problem. ECU not throwing codes, could this be a fuel or fuel/air problem? Injectors? MAF? Very confused at the moment. Already replaced Sparks, and Oil, no improvement.

[rockinthefans]

I know this is stupid but what octane fuel are you running? Low octane fuel will deffinately cause you to get some knocking and pinging. I know gas is expensive but its worth it when it comes to this. Try a new fuel filter and some better gas, maybe some fuel injector cleaner. Its worth a shot but cheap to do.

[Neil]

Borrow a light and double check your ignition timing... it shouldn't ping like mad and be a dog below 3000rpm JUST from running 87 octane, but yeah- if running premium eases it at all until you figure out what's up, then don't wear out your rod bearings any more than you have to.

[danielsan]

sounds like pinging to me. run some seafoam in the gas tank, vacuum lines. check distributor timing.

yeah the knock sensor will retard timing to help with the pre ignition but it sounds like its pretty severe.

[240nspec]

see this was what I originally believed however it ONLY bogs down starting at 2000rpm then power restores back at 2500 rpm. which let me to believe, possibly a fuel problem... even that sounded far fetched... so I replaced the fuel filter today, ran out the rest of the gas, ran cleaner, ran it for about 4-5 minutes, filled 10$ of 91 octane, no difference, ended up running out of the little fuel 10$ can get you nowadays, filled up back normal unleaded 87 octane, both fuels, after cleaner and filter result in the same weird noise + power loss at only those RPM's....

any further help guys, I appreciate it so far, the guy at autozone who said he's been his buddies unofficial mechanic has worked on 3 240's. He mentioned a clogged cat that could cause the rattle, but cmon such marked power loss?

im at the mercy to the pagan car gods...

[240nspec]

It's also not a consistent sound, it literally sounds like a bunch of tin cans being rattled around, a different sound eevrytime. that just leads me to believe resonance of some exhaust component, but its weird that I hear it only from 2000 to 2500 rpm along with the power loss... Idle to 2000 FINE ; 2500 to Redline FINE... only that "window" do I have problems... hey, also cleaned the Air sensor with some CRC MAF cleaner, it was as clean as a whistle before I sprayed it, but never could be too sure....

[Neil]

If it sounds like a dozen spraypaint cans being shaken, that's "pinging".

The actual sound you hear is the piston/conrod assembly smackng real hard against the crankshaft due to the combustion gasses igniting before they're supposed to, also called predetonation. It increases combustion temps which is bad for your pistons and the conrod smacking against the crank is bad for your rod bearings.

Did you verify your mechanical timing with a light?

[240nspec]

unfortunately I do not have a light at this time... will get someone over to my place if you trully feel this is a must. Detonation at only a small RPM range? I can verify my distrib. is still the same timing as I received the car as I marked it with a marker, could adjusting the ign. timing be of any benefit? My guess advance a small degree to ignite before pre-detonation?

[modulation]

Try running A WHOLE TANK of the highest Octane gas you can and see if that makes any difference. The Computer probably doesn't have enough time to adjust when you only put $10 in there of high octane.

Although plugs and wires probably aren't the problem they are cheap and you should see if replacing them makes any difference.

[240nspec]

appreciate it modulation, I will do that, also I just replaced the spark plugs to Bosch Platinum plus's, the old were covered in a white deposit which leads me to believe my car is running lean? am I correct?

[240nspec]

I'm very p***ed right now, after a nice long drive out 30, then 30 miles back I come home to get out to open the garage and low and behold engine knock. Im so upset right now, its my DD, and I have not the money to work on it. I have a DSM aswell however it has a head gasket leak, a few poorly seating valves and no gas or insurance in/on the car to boot. I'm in a wonderful predicament...

Time to hide behind the couch.