When cruising at 70 in 6th gear and then accelerating, I hear a light pinging. Was wondering if this is normal or should the computer be able to compensate for this, regardless of the load being place on the engine.

 

:rolleyes: This is not normal! What octane fuel are you using?

Could be fuel or electricl related. I notice it seems you have a '99

Spark plug wires and distributor internals are now 4+ years old if they haven't been changed.

Accelerating under load can magnify weaknesses in wires and dist internals.

Fuel can also be part of the problem, try running a good quality cleaner, like Amzoil PI and see if that helps. I also throw in a pt of 91% Isopropyl alcohol (avai;lable from any drug store) to get out any water in the system

:seeya

:steering:

 

Distributor internals? :confused:

 

:D What's your point? :D

:seeya

 

Where did they hide the distributor? :jester

JK, glad we have one less thing to worry with in the ignition system.

Robert :D

 

I have owned three C5's and pinging is normal in hot weather with 91 octane gas.

 

Rubbing (isopropyl) alcohol? Into the gas tank?

 

Pinging is never normal, however having said that, my 98 will sometimes ping. Here in CA, we only have 91 octane gas. GM did set the early C5s to run rich. (don't know if they cranked them back in later years) For me I find that getting caught in traffic, and in warmer weather it pings the first few times I jump on it after cruising for a time, or plogging in traffic.

I attribute it to carbon build up. If your engine is tight, and the LS1s seem to be pretty tight, it takes a lot less build up to kick off the pinging. Just to be sure take her out and do a couple of reasonable acceleration runs (get the gunk out) and then do your cruise thing and see if it still does or gets less.

Ping is the ignition of the fuel sometime prior to TDC. Just some residual carbon due to dirty plugs, worn out wires coupled with, good compression and low octane fuel with just a tad of carbon in a tight engine can cause it.

Sometimes just bad fuel.

Do the blow out the gunk thing, and if it comes back, change the plugs and wires, if it still comes back, try a bottle of octane boost. Careful here do not add a lot stay below the recommended dosage, you want to eliminate the ping, Some additives can foul the plugs and make it worse, not better. Change the brand of gas you are using.

Your timing is set by the computer. Your computer is set up the same for all Corvettes, (providing you have not modified it). Driving conditions cause the computer to change the timing. Humidity, octane, air temp, engine temp, load and a host of other things cause this to be different for every car. It could even be a bad sensor somewhere (I would go looking if the above did not fix it).

Good luck
Jer

 

Thanks for the info BlueDragon. Don't think it's fuel because I have tried several different brands of 93 octane and am using Sunoco 94 now and have same issue. I am going to try decarbonizing procedure first and if that does not help go for replacement of plugs and wires.

 

Depending on your mileage, I agree with BlueDragon that a sensor (O2 sensor) should also be kept in mind. Especially those that are in front of the cats.

Robert

 

Is there any way to test an O2 sensor?

 

I would bet it is carbon buildup. These motors build up carbon quick. The oily gasses flowing into the motor from the PCV are part of the problem.

There are two different dcarb procedures, I would do them both. Start with the sucking it into the intake method and then finish with the spark plug hole method. It is a messy job, but it is the only way to clean that crap out. I would do it about once a year.

 

Going back to your original statement, "accelerating from 70 in 6th".....
Try downshifting to 5th.

 

Not without very specialized equipment. Dealers and or better repair shops have a "Tech 2" scan tool that is used to diagnose many problems. A competent tech can really home in on a problem. Try the de-carb process and a plug replacement first.
Also, if the previous owner (or dealer) washed the engine compartment, water may have gotten underneath the intake manifold and be causing problems with one (or more) of the knock sensors located there. These are the little puppies that send the signal to advance or retard engine timing based on what they "hear" (pinging). The only way to deal with that situation would be replacement on the knock sensor(s).
If the plugs and a good de-carb has no effect, better take it in to be diagnosed. HTH

Robert

BTW, Colorado Chuck makes a good point. In 6th gear, even at 70, you don't have much "grunt". Try downshifting along with the same rate of acceleration and listen for anything.


[Modified by LoneStarFRC, 4:51 PM 11/20/2003]