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
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?
