L03 305 pingy at part throttle

[Custom Cruiser]

1991 Olds Custom Cruiser(caprice)

Not sure what to do at this point. Timing and fuel pressure good, have replaced every sensor, ESC module, but still getting some pinging on 93 octane starting around 1500 rpm. The engine is a new 305 goodwrench. The old and new motor both exhibited this.

Only thing not stock is it hasn't got a cat on it. Got so clogged up it wouldn't run, so I got rid of it. Also added a heated oxygen sensor so it would warm up quicker in the winter.

Don't really know what to try next. New fuel injectors?
Different chip with richer fuel table in those rpm ranges?

It runs really well, gets 21-22 mpg on the highway. If I could tackle this problem it would be the perfect car.

[Fast355]

1991 Olds Custom Cruiser(caprice)

Not sure what to do at this point. Timing and fuel pressure good, have replaced every sensor, ESC module, but still getting some pinging on 93 octane starting around 1500 rpm. The engine is a new 305 goodwrench. The old and new motor both exhibited this.

Only thing not stock is it hasn't got a cat on it. Got so clogged up it wouldn't run, so I got rid of it. Also added a heated oxygen sensor so it would warm up quicker in the winter.

Don't really know what to try next. New fuel injectors?
Different chip with richer fuel table in those rpm ranges?

It runs really well, gets 21-22 mpg on the highway. If I could tackle this problem it would be the perfect car.

I would try a truck EGR valve. The cars used a positive back pressure and with a low restriction exhaust they will not open at part-throttle.

[In-Tech]

Yes, also most aftermarket egr's come with different restrictors so you can adjust. Otherwise tune or delete the egr in the calibration.

[ScottP]

This thread brings back some good memories for me of my 91 Olds CC. I removed its
tired 305 and swapped in an L29 style Vortec 454.

-Scott

[Custom Cruiser]

Do you have a part number in mind? I only ask because I may have already tried this experiment. I bought a negative backpressure valve to play with and it didn't work very well at all.

The car pinged when the cat was still on it. It only pings once its warmed up. At full throttle it does great.

[Custom Cruiser]

I have never seen EGR with customizable restrictors. Does this mean I could drill out my current egr vac hose orifice and get more travel out of it?

[Custom Cruiser]

Cottonpicker has come through for the win. He advised me to solder my heated oxygen sensor splice that I made and also to check my EGR valve. As it happens my EGR valve pintle adjustment screw was loose in that it was not staked in properly and was able to be unscrewed by hand also he advised me to use a 43 range spark plug and so I did. I disconnected the battery and reconnected it so the computer could relearn and today as I drove to work and back the car did not ping at all. Excelcior!

[Kitch]

Out of interest, could you actually hearing the pinging noise or were you just seeing it in data logs?

[Custom Cruiser]

Quite audible, the warmer the engine, the noisier it got. Put 87 in it once, pinged so bad it finally pulled timing going up a hill.

[Kitch]

Interesting, thanks.