I'm having a concern w/ my 1988 Corvette. When it reached 200 degrees or higher (not much over 220) it seemed to have considerable ping on acceleration. No engine codes, spark timing is correct. I have all new parts last year including EGR, EGR SOLENOID. It's an L98 w/ no mods. I will give any info you need as requested. Gracious thanks.

 

Are you using Premium grade fuel?

 

Sometimes if you run a lower grade fuel you will be getting a ping out of the motor. If so, use PREMIUM. The ping will go away. Fill up with Premium and see what happens.

 

Check to ensure your knock sensor is connected and functioning. Also check your base timing. I'm running 10 degrees of base timing advance with no issues on regular fuel....and I live in a VERY hot climate. Car can get up to 225 in stop and go traffic with A/C on. On a stock L98, you don't have enough compression to warrant using premium if everything is working correctly.

 

What Frizlefrak said. Knee jerk reaction is your knock sensor or the ESC. All the comments about premium grade gas are also correct but your car should run just fine on regular. YES,you will give up both power and gas mileage but it should run very well.

 

So you are saying the timing may be advanced for performance?

Should the low fuel delivery issue be thrown out there for discussion? I'm experiencing this even with premium. When the hot temps hit, I get a little knock under certain conditions.

 

nobody has anything to add to this?

 

Yes....to a point. And it will take some experimentation to see where your engine is the happiest.

The factory setting is 6 degrees BTDC of base timing. Bumping it up incrementally will generally increase low end torque, but will also increase the engine's propensity to detonate...ie...ping. Raising fuel octane can compensate somewhat for this, but on the L98 the knock sensor will immediately retard timing should it detect detonation. Less advance = less low end response.

So if 10 degrees of base is good, then 20 is even better, right? Wrong. At some point you pass the ideal setting, the law of dimishing returns kicks in, and the engine begins to detonate badly and performance rapidly deteriorates. To prevent damage, the ECM then retards timing....and power falls off. I've found I can get away with 10 degrees and pick up a noticeable difference in low end response with no pinging. At 12 degrees, it pings, the ECM tones things down, and it loses power....even less than it had at 6 degrees. YMMV.

An easy way to test your knock sensor....set a timing light on the engine and note how the timing advances with increases in throttle. Have an assistant smack the block with a rubber mallet near the sensor and watch what the timing light does. The ECM should momentarily retard timing.

One of the reasons that low end response deteriorates in high mileage engines is slop in the timing chain. If your car is still set at the factory base setting of 6 degrees and the chain is sloppy, you may only be actually getting 2 degrees of base timing. Performance will fall off accordingly. I changed the timing chain on my 84 at 143K and it ran like a completely different car.

Bottom line is your car shouldn't detonate on regular fuel. If it does, something is amiss. Timing, carbon buildup, EGR, overheating, knock sensor, poor quality or old fuel.... something. Time to start troubleshooting.

 

It will cost you about $3.00 to run a tank of premium. Try it and see if it stops. Also $3.00 is cheap insurance you are not going to blow holes in you pistons. Just my thinking.

 

 

I had same problem. Cleaned the injectors, MAF sensor and throttle body. No more ping, worth a shot.