Ineresting question to ask. For those having problems with some pinging on regular gas, please advise where you live. I am in Florida about 20 feet above sea level. Is anyone having problems with pinging in higher elivations?
I think heat plays a part too. Mine does not ping when weather is < 94 degrees. I put some 93 octane in with my walmart 87 octane, seems to have helped.
I'd just like to add my experience with my '96 120K-mile LC. I've had pinging (sounds like valve knock) under load on and off for years. It seams to be seasonal. Recently the check engine light went off and the problem reappeared. Took it to the Toyota stealer and he said it was fuel related, though recommended EGR/VSV replacement at $450 (Gee...I passed on that). From similar experiences with my 01 Tundra, I found out that here in Oregon, the formulation of gasoline changes in summer and winter. This coincides with the pinging I get. I typically use regular, but just put premium in the LC and the problem lessened significantly. Hence, I believe my pinging is fuel quality related. It is not carbon buildup because it occurs in my V8 Tundra with only 18K miles on it. It seems my tundra has been in for resetting the check engine light every October and June since I got it. I have a friend with a '00 Camry with the same problem.
I'm in High Point, NC which measures approximately 900 feet above sea level. I only notice the pinging when the ambient air temp. gets above 75 degrees.
I think one thing that seperates pinging is when it occurs. Several, like myself, have posted the pinging goes away once the engine has a load. Others post they get a ping with a load. There are probably different mechanisms, or degrees of mechanisms, at work. I'd be willing to guess if I REALLY put a load on the engine, like towing a trailer up a hill on a hot day in Yuma, it would ping. The solution to that would be more octane since I run at 87. My complaint lies with the no-load knocking. That sholdn't be octane dependant, with in reason. The factory manual says "some" pinging is normal, IIRC. But I'm certain not this much.
Interesting stuff. We live on a hill and my 80s don't ping. However, this conversation sparked a memory. Our neighbors a few doors down bought a new Sienna a couple years ago. Within a few months, she called me because it was pinging and the dealer told her it was normal. She asked me to drive it. Turns out for the speed you'd go up our hill, and the gear the Sienna was in, and the light throttle setting, you could in fact make micro adjustments to foot pressure and there was a narrow range it would ping in. The dealer is in town, and the couldn't make it ping. When she put premium in it won't do this.
So, perhaps cylinder environments are now in such a high state of tune to achieve diametrically opposed goals (power vs MPG/emissions) that the knock condition is just a few cylinder deposits away and many of you have them from previous owners. I don't mean to beat a dead horse, but again - consider that it's cylinder deposits and try a cleaner for several successive tanks.
There's a thread on the 3FE list (Yahoo Groups) from last Friday which is a preliminary report on a supposed cure for light-load pinging (in a 3FE). It involves unauthorized surgery to the AFM in order to loosen its spring a few clicks. If I understand the players correctly, the person who did this (to Steve Crase's 62 series) was Robbie from both this list and Christo's shop.
There's a thread on the 3FE list (Yahoo Groups) from last Friday which is a preliminary report on a supposed cure for light-load pinging (in a 3FE). It involves unauthorized surgery to the AFM in order to loosen its spring a few clicks. If I understand the players correctly, the person who did this (to Steve Crase's 62 series) was Robbie from both this list and Christo's shop.
That's how we used to adjust the mix on the 80's bmw M cars. Lean them out for smog and richen them up for driveability. Believe it or not they used the same Bosch type flapper that the non MAF cruisers use. Anyone that has the flapper type AFM can adjust it to either richen up the mix or lean it out. Quick word of caution... MARK EVERYTHING WELL BEFORE MOVING ANYTHING. Inside the AFM is a spring and a big plastic gear. Mark the gear with a paint pen at the tooth that indexes with the spring retainer so you always have a baseline. Beneath the gear is a circular spring that provides resistance to the flapper. Moving the gear just a couple of clicks to loosen the spring will richen it up a percent or 2, tightening the spring will lean it out. Have fun.
I picked up a couple bottles at my local service station. Techron Concentrate at about $9 per bottle. I'll stick it in tomorrow and post the results after the second bottle. I'm not a big additive guy, but I'll give it a try. Thanks for the tip.
Does anyone have any feedback on 95-97 CEL lights flashing when the two pins are shorted to adjust the timing? As I mentioned above, my light comes on fine when I first turn the key on, but I could NOT get it to flash when I shorted the pins (the timing seemed to change, though).
It's a little counter intuitive, but the AFM is not supposed to resist airflow at all, that is the job of the throttle body. The spring in there is very light to begin with. The trick here is to make the computer think it's getting more air than is actually is so it squirts more fuel. For a given throttle position and air flow, the looser spring will allow the flapper valve to open slightly more making the engine THINK it's getting more air than it is, and the injection systems responds by squirting slightly more fuel to compensate for the extra air that's not really there.
Just to add to the list. I have a 97 with 130,000 miles now. Yesterday on the way home driving in the neighborhoood around 20 mph I noticed slight "knocking" that resolved with increased acceleration. Not sure of the difference between the ping and knock - just know I didn't appreciate hearing the sound. Added Seafoam to a tank today. Next I'll do the Techron and Redline. I ususally run 87 octane gas and I'm in S. Texas. Possibly bad gas or the heat as this is the first I noticed in the 3 years of ownership. Nelson
