My 1984 Toyota pickup, 22R engine, pings every time I go uphill in the canyon I live in. Anything over about 1/3rd to 1/2 throttle will give me a lot of pinging. I can normally make it up the canyon in 4th gear at about 1/2-3/4 throttle and 35 mph, but to stop the pinging I go down to 3rd gear and drop the speed a bit.

I recently replaced the vac advance, the retard side was dead...and the timing is set according to the FSM, and total advance is around 30 degrees. The pinging is the same before and after replacing the vacuum advance. I also just cleaned out a plugged accelerator pump nozzle...no difference in pinging even though acceleration is a bit stronger.

Where else can I look...EGR system? Any suggestions?

jc

>>>*Personally, I like the engine to ping lightly at part throttle load if it goes away as more throttle is applied.

That is normally the point of best power/economy.

If the pinging just gets worse and becomes severe, something is wrong.

These engines are high compression and tight quench, so the source could be carbon buildup, a hot spot as a result, something like that.

The tricks are to try a slightly cooler spark plug, assure the EGR passages are open, loosen the valve lash slightly (.001 to .002" often does the job unless it then gets noisy), run a cooler thermostat (180?) or back the baseline timing off by a one or two degrees.

Sometimes spending a day at the drag strip is enough to blow the carbon out and fix the concern....*EB

35 is pushing it for 4th gear. The RPM's are pretty low (under 2000) so I would expect some pinging with a heavy load like climbing a hill. Remember this is a 96hp 4 cylinder engine. Rap er up!

it's very common for that rear vac. diaphragm to go bad over time. almost everyone I talk to about Weber tuning problems has a bad idle advance diaphragm on their distributor.

there is no retard side on the vac. advance; they're both advance. one is idle advance, which runs off of manifold vacuum, and is only active at idle or low to no load conditions on the engine. 2., the front port is normal advance, which runs off of ported vacuum, above the throttle plates in the carb, and is active when the throttle is opened up exposing this port to vacuum.

my own pinging problems, up until this year, were due to timing too far advanced, and I'm not even talking a whole lot here -- only a few degrees. I couldn't run anything less than premium fuel, and even then on the hotter days, it would still ping.

I've since gone from 3-5* back to the stock spec of 0* base timing -- at idle (<900 rpm) with both vacuum hoses disconnected and plugged.

what is your base timing?

I had retarded the timing to 0 degrees (with te1 and e1 bridged) before the pinging finally stopped on my 22re.
Ran it for a while like that and decided to go back to 5dbtdc cause engine was really lacking power. Tried all different kinds of fuel injector cleaners, air intake cleaners, spark plugs, checked the egr system, tweaked the AFM to richen the mixture but alas. So i set all the settings back to stock and now i just run premium in her and that stops the pinging. Does anyone know how reliable the knock sensors are? Im not getting any code from the ecu for it but would it be worth my while changing it out, its an 89 motor with 135k mile on it. If thats not the problem i guess i'll open her up one of these days and clean the carbon buildup off the valves and pistons.

I read an opinion on another Toyota truck forum that the pinging was caused (on this person's truck) by the inner(rearmost) vac advance diaphragm being bad. The pinging went away when the vac advance was replaced. Anyone else had this experience?

Carbon on the pistons will accually glow and be one of the causes for pre-ignition.

Defently dont want to do that. Run the right temp thermostat for your truck.

Try to run a 70%water and 30% coolant mix with some water wetter aded to the system. The higher water ratio will absorb the heat from the engine faster than a 50/50 mix. Sounds crazy, but crazy enough to work.

Your pinging is likly caused by ignition of the gas/air mix in your cylinder before the spark of the spark plug. This causes temperature and pressure peaks that will melt your piston, crack your cylinder head, and drop one of your exhaust valves.

Try running test check to see if your timing is not too far advanced, make sure your compression ratio is not too high, try useing some higher octane gas and see if it helps a little.

I had a sick ping I solved finally last year by going to a 180 degree tstat, new rad, and new water pump. Until I did that nothing helped except for setting the timing to 0 degrees where the truck wouldn't run right anyway.

Btw, the 180 tstat is listed as a stock option at Autozone. After putting that in my temp gauge went back to where it was when the truck was new.