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.
have the same problem?
Friday, August 17th, 2007 AT 9:11 PM