late this summer i was driving up a long mountain grade in 90's heat, air con off, and i guess the car was stayin in 3rd. after goin up this hill for maybe 5 minutes the engine (its a vg) started to make this odd knocking sound, not really a ping but a deep knock. the engine was only at about 23-2500 rpm the whole time, at about 30-35 mph. engine temp gauge read normal. after this noise went on for about 100 yds. i turned off the road and let it sit for about 5 mins. started it back up, fired right up and had no more probs up the hill. never happened before or since. i was wondering if maybe the oil had gone to the back of the pan and this was causing the knocking, or if it was the hot air being ingested in the engine (ive taken the resonator and air tube leading to the airbox off) and that was causing pinging? the engine has always been really solid, its a 90 gxe auto, has anyone else had this prob or knows what the problem might be? im not a big fan of weird engine noises, and i love my max, so any help would be much appreciated, thanks,

scotty

 

I've heard that climbing steep inclines and using low grade gas can cause "knockig" and/or "pinging"...thats what was probably happening does it still make the noise in regular driving??

 

i had 89 octane in it, 87 never goes in. its never made any bad noises at all, no matter what. hasnt made it since either. i guess my tired old max was just letting me know it was sick of dragging my sorry **** up that mountain.

such a quality sig

scotty

 

hmmm...maybe if you are constanty climbing this mountain you need to look into a device that further retards the ignition timing below 15 to compensate for the steep incline and change in altitude, MSD sells a unit for $92 that alows you to retard timing on the fly and prevent knocking or pinging, its just a suggestion if it continues to happen! I dunno, but sounds like this steep incline is causing "pre-ignition"

 

argh, 92. oh well, i may look into it just in case. thanks man

scotty

 

more wild guessing: maybe there were hot spots in the combustion chamber somewhere (causing knocking) because the car had been driven hard for a while, then letting the car sit let it cool just enough to stop the knocking long enough to get over the rest of the hill?

 

could have been, i was driving at a decent pace, i guess there just wasnt enough air flow for good cooling while the engine was under load, even though the water temp seemed ok. ive never driven under the exact same conditions since, and even hard driving in hot weather hasnt made it happen again. so for now i guess hot spots or timing issues were it, but i would lean more toward the hot spots

thanks for the suggestions guys

scotty