Has anyone been experiencing engine ping or knock with your TC? I've got over 4000 miles on mine and I've already changed the oil once. The ping/knock was heard while I was driving with the windows down and shifting into second on a hill. It was a brief knocking/pinging...like it hesitated. I then took it to a less traveled road and got on it a little, pushing the pedal to the floor. No knock. No ping. OK....so what the hell. I stopped at a dead stop and took off. I shifted hard into second, pressing the pedal all the way into the floor...an even shorter knock/ping was audible when shifting. I then took the car in to have the oil changed for the first time... I've read the manual and I know the car takes a minimum of 87 octane.
Since the oil change I've added a new tank of gas along with some fuel system cleaner. I only use BP fuel, by the way. I heard it again today only once, going uphill, shifting into 3rd. WTF? Maybe I need to be patient and let the cleaner do it's job. Maybe it is related to the slight turbo sound I hear when accelerating? (My previous posting questioning the winding/turbo sound has gotten feedback that it is normal.) Any feedback on this will be apprciated.
UPDATE! The Knocking is gone! I've run through a half of a tank of new gas with the fule system cleaner and it cleared it up. I guess if you are going to use 87 octane you need to execute the recommended 'ever 3000 mile' fule system cleaning.
Dammit to hell. It is doing it again. 7,000 miles, 89 octane....and I still get a spark knock when I shift from time to time. No knocking or pinging during regular or hard acceleration. ONLY when shifting and sometimes from take-off. Is this a 'feature' of an electronic throttlebody (drive-by-wire) or perhaps my computer f***ing up? Help anyone? I took it in to my Scion dealer and they told me to use 93 octane and to change my driving habits. BS! The car was made for 87 octane. There is nothing being reported to Scion so they have no 'fix' for it. I'm thinking there is a computer or software gliche that is not providing the fuel/air mixture correctly when shifting... Thoughts anyone? Can someone try their TC to see if they have this problem. I first noticed it when driving hard to the point I was shifting fast. Now...every now and then. I'm convinced it is NOT octane levels...
Really what you are explaining, just from muscle car experience would appear to be a timing thing. When you put the car into a heavy load if the timing isn't dead on it can ping. I would check to make sure all the plug wires are tight, also try sticking with one type of fuel, switching fuels could cause that as well.
It's possible the engine has a small piece of metal flash in one of the cylinders that is glowing and causing pinging. I remember a couple of Supras that pinged on anything less than 100 octane fuel in completely stock form. You should not have a pinging problem, and you should not have to run anything higher than 87 octane. If you are at an altitude above 3500 feet, you should be able to run 85 octane without issues. Our FM tC ran just fine in Wyoming and Nebraska on 85 octane.
If you are pinging under part throttle, but not under full load, it is also possible you have a cooling system issue like a faulty radiator cap. Be sure your dealership does a complete cooling system check including the radiator (might it be clogged with bugs?) and the thermostat (maybe it is sticking?).
EDIT - Almost forgot - that dealer that told you to run 93 octane is FOS. Your standard answer when ANY dealership tells you to do something other than what is prescribed in the manual is simple: "Why are you telling me to do something different than what is in the owner's manual? Can't that void my warranty?" Or, "So you are recommending I ignore the owner's manual and follow your instructions, even though Scion does not recommend doing what you are telling me?" Follow that up with "Shouldn't I be able to follow the manufacturer's instructions and have a normal running vehicle?"
You really need to press them on this issue. If there is a pinging problem this early in the engine's life, it will only get worse as carbon builds up in the combustion chamber. /EDIT
Pinging can be caused by localized overheating in the cylinder head as a result of marginal cooling system operation. It is possible the thermostat is sticking, or the radiator is bug clogged and is causing this kind of issue. At WOT, the engine is going very rich to deal with the load, so unless you have a severe shortcoming in the mechanics of the engine, the cooling system is a likely culprit at part throttle. Extra fuel helps cool the cylinder. At part throttle the AFR is being maintained at stoichiometric, so everything has to be working correctly or the engine will ping. There is no extra cooling effect from a rich mixture.
Also, FYI, the 2AZ uses a COP (coil over plug) ignition system, so the only possible loose wires are the low voltage wires going to the primary side of each coil. It's very unlikely they are the problem.
Oh, yeah, another thought - since the engine uses VVTi for EGR, it's possible the VVT is not working exactly right and is causing pinging. A leaky EGR valve can cause part throttle pinging on a conventional setup, but since we have no EGR (VVTi does it all for us), it's possible the VVT isn't quite right.
Thanks lance, i was unawware that overheating caused pinging, i had no idea on the ignition system, this is my first car without a worm gear and a distributor
Pinging sounds like rocks being thrown around inside your engine. It can be heard for a million reasons, i even learned a couple new ones in this thread. Typically pinging is only heard at hard throttle, because that is when you engine is at load and needs to use all its resources.
This shouldn't be confused with a engine knock with is usually found is older cars or worn out engines, which usually go hand in hand. If you have ever hear a car that has a distinct metallic "knock" noise coming from the engine that stay in rythem it is typically caused by a loose rocker arm in the head (you hope).
I hope that helps...
Thank you for the technical feed, Lo Bux. I'm going to take the car to the dealer again. I think your note on the cooling system may be the issue. I never had this problem with the pinging when I bought the car....in January when it was cool. Now the temperature has climbed to 94 degrees with high humidity (Columbia, SC)... and I think the engine is running hot. I noticed the the fans are coming on more frequently...especially when I turn on the A/C...as a matter of fact very shortly thereafter the fans kick in. I'll keep everyone posted. By the way...I've purchased the Scion TC repair manual Vol2. If anyone needs anything from the manual...I'll try to help out.
The repair manual for the SCION Tc is split into two volumes. Vol1 contains the diagnositic details and numbers...Vol2 has the engine and chassis repair/breakdown. You could take the entire care apart if you wanted with this manual.
After I get the spark knock fixed I'm going to try to locate the damn chirp under/in my dash...and the manual will help me with the dismantling...