Knock sensor?

[Maxxtraxx K5]

Hey guys my 99 tahoe is pinging, its got the 5.7 in it, most part stock. Got new plugs wires cap rotor all that good stuff about 40k ago. I've recently noticed this is starting to happen more often... I've tried higher octane gas, using Lucas fuel additive, and it makes no difference. There is no light on and it doesnt skip or anything, and I've checked the plug wires and none were loose. Any ideas?

 

[99Yukon_Z71]

First,make sure it is pinging' or pre ignition!! Make sure its not any rattling, or loose exhaust or anything of the like. Using higher octane fuel should have made it quieter. Make sure EGR system is working properly as a damaged EGR valve or poor EGR circulation leads to higher commbustion chamber temps. Make sure all wires are good. If the Check engine light is not on, start by doing a visual inspection. You could have also gotten bad gas?

 

[AtomicHoe094]

Sometimes the SES light on the dash will never come lit, but yet its stored in the computer. I had a few codes in the computer on my grandprix that i never knew about until i hooked it up to a snapon scanner.

 

[Ironman1979]

or it could simply be out of time.. to much advance or retard.. the hold down on the distributor could have came slightly loose causing the dist to turn slightly under hard acceleration
mine did this from Chicago to kc.. didn't know till i did a complete tune up that the bushing in the dist was bad and the rotor was wobbling hitting the contacts

 

[Maxxtraxx K5]

Well I've checked the distributer, plug wires, those were not loose. Haven't checked the egr yet, I've gotta get gas today and will try a higher octane again, the exhaust is all tight and all that, I thought at first it was the belt tensoner, so I put a new belt and tensioner on it, obviously that didnt fix it.. I will go check everything again today. It's goin to the scan tool tomorrow.

 

[Maxxtraxx K5]

Update! Went to start it up this morning and the light is on, I know I've been having o2 codes due to wiring issues, but with the light on does it reset it to base timing? I put 7 gallons of 89 and it was almost empty, from a place with good gas. It's better, once in a while it chirps( sound like the belt but it's not). And it seems to run better, so what now? Lol