Pinging under full throttle

[lindbergh]

I was wondering if some pinging under full throttle is normal or not. I am running regular unleaded, would running mid-grade or premium be better. I guess I could retard the timing, but prefer not to. Thoughts?

[David T]

It should not be pinging on regular. Here are a few things that can cause the pinging:
Bad gas, try another station or brand
Timing not set right
Mechanical or vacuum advance not working correctly
Bad ignition wires causing cross-firing
Worn spark plugs
Combustion chamber deposits from running bad gas.
David Teitelbaum

[DMC3165]

I had the same problem recently and only about 7-8K miles after a tuneup. I started running mid-grade 89 and the problem went away. Ocassionally I would run a bottle of Techron on a full tank and just by coincidence i noticed it didn't ping with the regular and the techron.

Over the summer I decided to give the motor a shot of Sea-Foam through the fuel system. An incredibly messy process out the tail pipes and all over the rear bumper. But since then the car has never run better. 30 years and 60K miles of Carbon and fuel additives build up in the combustion chambers got blown out in 2 weeks. (3615 head's have never been off). But since then the car has never run better! I'd recommend trying it but be extremely careful if you use this stuff whereas it can be harmful to the engine if not used as directed. Good luck.

[lindbergh]

Thanks for the suggestions guys. I'll try a different fuel and go from there. Maybe I will try Shell premium for a tank since it has 5 times the detergents as required. Regular has twice the amount.

[WelmoedJ]

Thanks for the suggestions guys. I'll try a different fuel and go from there. Maybe I will try Shell premium for a tank since it has 5 times the detergents as required. Regular has twice the amount.

Fuels are given names as people more easily remember a name than a number.
The Octane Number however is the right way to determine what fuel type you need to use in your car.

While in the States I noticed several levels of ON available all with the name "Regular", sometimes followed by a number: the R(esearch) O(Octane) N(umber), its official name.
My D didn't like the low US Octanes and once I started using over RON 90, it started behaving like I am used to with my modern car.

Once back in Europe I had other choices.
We only have two flavours: Euro 95 and Euro 98, of which the numbers refer to the RON.
I use Euro 95 and my car s content with it.
Euro 98 is overkill, unless you drive a Turbo vehicle, which most D's aren't.

[DMC1983]

May be running too lean. Check the enrichment microswitch on the throttle spool. If it contacts, trace the fault in the connection

[DMC5180]

I was wondering if some pinging under full throttle is normal or not. I am running regular unleaded, would running mid-grade or premium be better. I guess I could retard the timing, but prefer not to. Thoughts?

You have to mash the pedal to the floor in order to trip the full throttle enrichment switch. Are you sure this is happening? Have someone else mash the pedal while you watch the throttle spool swing around and hit the switch. You can also test to see if the system is working properly by manually pressing the flap switch at idle. The engine rpm should drop slightly as it loads up with extra fuel.

[Ron]

Thanks for the suggestions guys. I'll try a different fuel and go from there. Maybe I will try Shell premium for a tank since it has 5 times the detergents as required. Regular has twice the amount.
I think the first thing you should do is check the timing, base and high RPM...


Ignition Timing:
13° ± 2° B.T.D.C. at 750 ± 50 R.P.M

Spark Advance — Vacuum:
5 in. hg. = 3°
10 in. hg. = 12°
15 in. hg. = 20°

[David T]

Another reason it could be pinging is if you are overheating it. You will also notice a lack of power. If it is just a matter of it pinging under load, like going up a hill or accelerating onto a highway, it is probably bad gas or the timing is off.
David Teitelbaum

[DeLorean]

On a real hot day, especially in city traffic I can get some pinging with regular fuel. 89+ grade seems to correct this.