ping and bad MPG

[geezerstiva]

ok, 89 L, 4spd, carbed. it runs great except it pings really bad at a certain place on the throttle, and gets about 35-38 mpg takin it easy. also, before it gets warmed up good, it will start to die when you put the pedal down past half throttle. sounds like its running lean to me, but after a little while (>1 min) it warms up and works fine. any suggestions on any of the problems?
oh i've changed the air filter and that didnt help.

[worfdog]

change the fuel filter also and check the timing on the engine. you may have a partially clogged fuel filter.do the fuel filter first and see if that cures the problem.

[geezerstiva]

would that make it ping like that?
the valves also make a whole lot of noise.

[worfdog]

if you are talking about valve train noise, the valves may need adjusting also.
if a engine is not getting the proper amount of fuel,it will cause a lean condition which could possibly cause a ping. if the valves are not adjusted right valve timing can be off.
the first thing i would check is the fuel filter any way, if it's been a while since it's been changed.

[geezerstiva]

well the guy who had it before me said that it (fuel filter) had been changed fairly recently, i think. how do you check the filter? thanks for the input btw.

[Pu241]

What grade of fuel are you running?
Try a one step upgrade to see if it reduces the issue.
But fuel filter and valve adjustment are good ideas.

[phantorn]

correct me if I'm wrong but a lean mixture runs hotter and could cause hot spot in that cylinder causing pre-ignition(ping)

[worfdog]

they are cheap just replace it.
it's located under the brake booster, down close to the steering rack, on the firewall.

[worfdog]

correct me if I'm wrong but a lean mixture runs hotter and could cause hot spot in that cylinder causing pre-ignition(ping)

thats right ,it will cause all the cylinders to run hot and possibly ping.

[geezerstiva]

oh its up front? i thought it was gonna be some digging under the rear seats or something! well thats a relief! i'll check it out guys. thanks for the quick response!

[Glease]

Have you ever ran out of gas? That will surely clog the filter up prematurely.

[geezerstiva]

nope, never run out of gas. i see what you mean though.

[mechanicaldj]

has anyone even thought of looking at the EGR valve?

which is only on the carb'd models

and also look at the advance/retard mechanism on the distributor.
if its too far advanced, you will have the same problem

[jglutz]

the valves also make a whole lot of noise.

If the the valve noise does not go away with the previous recommendations.....check the oil pressure.

The lean mixture and running hotter, pre-ignition, does not come from hot spots but rather from heat of compression. The air-fuel mixture (to much air, not enough fuel) gets so hot form being compressed, it ignites pre TDC. Years ago, with low octane fuel, very common problem with aspirated cars that would continue to run after the the key was turned off.

[SIBladerunner]

you might have a rod knock with that ping, or you could have ignition timing off with some lean fuel, which could blow a hole in the pistons, make sure to run a compression test to make sure u didnt do that already