If it were me even with a high mileage TCH, I would still stick with a low priced top tier station. At least you would still be keeping your engine and injectors clean. Once you fix the problem you would be good to go with a clean engine.

I never heard of a knock sensor causing problems. Then again the newer knock sensors are more sensitive and could cause some new type problems not seen with the old ones.

Just another guess it could be a weak coil over plug that could be intermittent. Perhaps when the trouble occurs the coil may break down reducing the 47,000 volts to the spark plug.

Any coil failure should produce a ECU error. I'm not sure if a slight or intermittent coil problem would produce a error or not or if it's even related to your particular problem.

Found this when reading up on coil over plugs like in our Camry hybrids. Be sure to read the first few lines on this site. I hope my someday next Camry TCH includes that same proposed technology.

http://www.aa1car.com/library/copign.htm

 

Thanks for keeping this going. I really appreciate everyones input. It is nice to have "amunition" when you visit a dealer.

So, I wonder if just unhooking the battery for a little while would reset anything? That is interesting and makes sense to me. Or is that just going to cause a bunch of other problems?

The car runs noticeably better on top tier 93 octane. Night and day difference.

 

Upping the octane shows it's a combustion problem. Combustion is caused from the correct mixture of air/fuel, compression and spark. Other items that can affect combustion is a dirty or weak injector, ignition coil, spark plug or knock sensor. Sometimes deposits usually on top of the piston or valves can also cause these problems.

I find it strange yours seems to happen at the lower speeds. Could be their is more strain on the engine at the lower rpm, than at highway speeds. Does it happen when taking off at full throttle or does the engine tend to hesitate. If it hesitates it could be caused from a dirty gas filter which I have never seen for toyota. I only know about GM cars as they have a filter screen in the tanks pickup to the fuel pumps input. A finer filter is usually located under the car near the gas tank. Again this is on the GM cars I had owned in the past.

Ford uses a good sized metal fuel filter located 'under the car' under the drivers seat area. Ford used to tell me I need to have that $45 filter that don't include labor to be replaced every 15,000 miles. I tell their service department, I drove my '94 Corolla for 185,000 miles and never replaced any gas filters. It's things like this that made me run to buy a Toyota. Still my wife drives a nice 2010 Ranger pickup. We won't be replacing Ford's money making gas filter till it really goes bad. Warnings I guess would be a lean burning engine, sluggish starts and running hotter then normal and tends to die down when trying to accelerate including pinging at any speed.

The top tier phillips 66 station where I buy my gas uses a large gas filter on each of their pumps. I had been their one day when a station maintenance man was replacing them. I believe it's a state law where the gas is tested often for it's octane rating at least once a month at the station. I try to buy gas at the larger stations with multiple pumps. I don't buy gas from the old stations with only a couple of pumps. I prefer buying gas from a station that's not in a low area or near a creek so as not to worry about water getting in the underground tanks.

 

I found another topic with the same issue were discussing as well on this forum:

https://www.greenhybrid.com/discuss/...pinging-13189/

they unfortunately don't have an answer for it either. I had my local mechanic check it out and he couldn't get it to do it, but of course driving home, I heard it twice.

 

Try having your mechanic go up a slight hill running 45 to 50 mph and start a LIGHT accelleration or mantain the same speed with as small a throttle input as possible. If the valves are rattling, they will do it under a load situation similar to this.

 

Ok... I was at Toyota today.

No codes stored, they said it was clean... They did notice some light clunking in the front end. Which I did not notice until they pointed it out (struts, end links or engine mount?).

So, they want me to bring the car back in Monday morning early. It is unfortunate that I cannot leave the car with them. We drive all over the state daily. So, I cannot be without it. I will have to sit and wait again. No biggie since I have Monday off.

I have run 5 tanks of Chevron 93 through it along with the 50th bottle of Techron (I have used so much, I have actually lost track). I switched back to 87 2 tanks ago just to be sure it would be pinging before the dealer visit.

I'll post back Monday afternoon.

 

One concern is that the MSDS for Techron indicates no polyether amine (PEA) in it. PEA is considered to be the most effective ingredient and was originally developed by Chevron. Not sure what is going on. For that reason (and availability) I have used Gumout Regane Complete Fuel System Cleaner, which indicates about 35% PEA on the MSDS.

 

Ok.... Back at dealership yesterday. It has been a blur because I work so much.... Anyway.... No real diagnosis except that they "acknowledge it". It was not as bad? Probably because of my 93 octane over several tanks?

So, they diagnosed my clunking problem in the front end and reset the comptuer. This was yesterday morning.... The noise is gone! No more pinging!! I think GeorgiaHybrid is right on several counts. This proves it in one way. But, still leaves unanswered questions for me.

On another note. I have been driving the car much harder (faster) over the past month. On ramps, etc... I have noticed no drop in mileage with the spirited driving since it is mostly interstate/distance driving. FWIW...

 

Will unhooking the battery reset the computer or will the dealer have to reset the computer?

 

UWA, it should reset if left disconnected for 4 or 5 minutes but I have always used a scanner tool to do this. If it doesn't work, you might need to take it somewhere that has a techstream or an aftermarket equal.

Remember the reset on the master caution light if it comes on.