Pinging driving uphill

TSTAD9I

MEMBER
CHEVROLET CAMARO

2001 chevy camaro SS, 68K miles, 6 speed. Road trip from FL to TN in 95+ degree heat, 75 mph freeway driving car running perfectly normal, no problems whatsoever.

Last 200 miles or so of the trip, car started pinging badly going up even the slightest inclines. Had to drive the car in 5th gear during any uphill driving at that point to keep the engine from pinging. 6th was only good for flat land driving. However driving through uphill parts of GA earlier in the day (still just as hot weatherwise), no problem driving in 6th gear, no pinging at all. I could even accelerate going uphill as the speed limit increased without any pinging at all. The only difference I remember is I had been filling up with Shell premium for the whole trip except for the last refuel at Chevron in Atlanta after which the uphill pinging started. However i've used Chevron in FL frequently without problems.

Any ideas on what the problem could be? What to have looked at? Car has been previously been tuned to accomodate larger fuel injectors and forced induction on completely stock internals but never got near even zero boost as the pinging occured at anything higher than -10 lbs of manifold pressure reading on the boost gauge at which I would back off on the gas pedal immediately and shift to a lower gear and the pinging would stop. Does the car just need to be retuned for the higher elevation in TN?

Any help would be much appreciated.

regards,

ohNo

4 Replies

CLY

MECHANIC
308 POSTS

I would be tempted to run that fuel out and refill with a highgrade fuel at a shell or marathon before I changed any parts or paid to have it tuned again. I did see some information about a bad knock sensor causing some pinging. But I would try some good gas before I got to carried away.

Cly

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Saturday, August 18th, 2007 AT 5:01 AM

RASMATAZ

MECHANIC
75,992 POSTS

Bad gas don't make it-check the EGR bcuz if its not opening it will detonate. Its job is to lower the combustion chamber temperature to prevent the formation of NOX.

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Saturday, August 18th, 2007 AT 6:59 AM

TSTAD9I

MEMBER
6 POSTS

Thanks so much for the replies guys, much appreciated. The gas was also my first thought, called the guy who tuned my car he also suggested a fresh tank. Got lucky this morning as it was cold out so I burned off the fuel down to a little more than a quarter tank and refilled. Waited for the day to get hot again and ran it up the same highway that I was having trouble with. Same speed, same negative boost readings, 6th gear, outside temp a few degrees cooler. No pinging! I even accelerated while going uphill in 6th, almost back to normal. It pings slightly when I mash the pedal suddenly in the third gear but I still had that 1/4 tank of old gas so hopefully after a couple of more refill cycles it will be completely back to normal. I hope.

No EGR valve on the LS1 engine from 2001 forward. I got lucky, my car was one of the ones that came with an LS6 intake from the factory.

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Saturday, August 18th, 2007 AT 9:02 PM

RASMATAZ

MECHANIC
75,992 POSTS

The engine is it overheating? Could be overadvanced timing, wrong spark plug heat range, A/F mix too lean, low octane fuel, also carbon deposits in the combustion chamber will raise the heat and pressure that will produce spark knock that might be coming from an overheated exhaust valve.

Here's what I know: A pre-ignition is when the mixture fires before the actual ignition occurs. Its the other way around with detonation However pre-ignition can be a contributing factor to spark knock.

My Q is how long is this been happening you probably allready did some damages internally.

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Saturday, August 18th, 2007 AT 11:52 PM