Hey Everyone

I have a 1987 Iroc z with the 305 tpi and automatic.
I bought it 3 years ago and I still can't stop it from pinging.
I replaced many parts. Plugs (even tried a colder temp plug),wires,cap,rotor,ignition module, egr valve and cleaned the plenum, fuel filter,kn air filter and it still pings under light or full throttle. Even if im creeping on the highway with the throttle if i slowly bring it past 2200-2400rpm i can still hear it pinging. Because of the pinging i usually baby 90% of the time. It has 148,000 miles now but runs really nice and strong. It also pings on ice cold starts too if i give it too much so temperature i dont think is the problem. any help would be appreciated

thanks
brian

mintdb@aol.com

 

did you try replacing the knock sensor

 

I would look into the EGR valve being stuck.

 

I'd say that because you "hear" the knock, the knock sensor is bad, or wiring to it.
But the cause of the knock can be the EGR Valve, worn valve seals allowing oil into the combustion chambers, lean fuel mix or really rich fuel mix, or running hot.
If you replace the knock sensor first, it'll be harder to pinpoint the cause so:

I'd start by checking the EGR valve, you may have to remove runners off one side. Push the valve all the way open and then cap off the vacuum hole. The valve should remain open, if not it's leaking vacuum and is bad. Also make sure it moves freely, not sticking in its seat. If, OK...

Verify ignition timing, reset to factory setting for testing. If it goes away, increase advance 2-degrees at a time until it pings then back it off just 2-degrees.

Then see if it smokes real bad on cold start up, worn valve seals allow oil to leak past. After sitting a long time it will acumulate and puff grayish-blue on start up. Even if you can't see it after warm up, it can suck enough oil on "romps of the throttle" to cause pinging. If bad they can be replaced w/o removing the heads by using an air compressor to hold the valves seated.

Sometimes you can run lean w/o flagging the ECM's "check engine" light. I'v seen O2 sensors sometimes go marginally bad, reading good mix numbers when it's really "lean" or "rich". And replacing them immediately corrected the problem.

Finally, make sure it's not a cooling issue. Running on the boiling point with cheap gas can easily cause pinging. Our cars need "Premium Unleaded" especially when modded. Our compression ratio's of 9.3:1 -to- 9.8:1 can make hot spots in the combustion chamber and ping. We need to run under 210*to be safe. There are chips and low temp fan switches that can turn fans on sooner. You can wire both fans to work at the same time, if you have 2. Run a lower temp thermostat, most run a 180*, I run a 160*(summer) 185*(winter).
This should give some ideas of where to start, good luck..

 

Thanks for the info
I never thought about all those factors
my valve seals are worn I think ill get them done

 

If I already buy premium gas, will octane booster help at all?

 

If you're already using premium gas and its still pings then you have a problem you should be addressing rather than try adding more octane.

 

have you checked the timing?
if you have did you remember to disconnect the connector to put it in base timing