OK, now, what could sound like ping? My engine will ping - when under load - at around 1000-1500 rpm's. I have tried cleaning the chambers (pouring water into throttle body), I have tried fuel sytem cleaners, I have tried carb/TB cleaners. I have the timing at 0*, I normally run 89 octane, but I have tried 92 or 93 (I forget what everyone sells around here). With the higher octane, it'll shut the ping up fer a day, maybe 2, then it'll be back! The only thing I can think of is either a bad knock sensor, or some REALLY stubborn carbon build up inside. I have been working on this all winter ('coarse, its my daily driver too ) anyways, if ANYBODY has ANY ideas, please post, I am desprate!

EDIT - Must be under laod, and will ping slightly - if I do a brake stand up to 1500 w/o breaking the tires loose, it'll sound like the engine is getting hit with a wrench. But in normal driving, I'll hear some light tapping (I really cat put it into words). THIS SUCKS!

 

I your EST working? (Easy to check when setting base timing.)

 

It appears to be - set base timing (with EST disconnected) 0* connect EST, and iut jumps up to like 12 or something. The thing is, it sounds exactly like knock - but I whole lot quieter...

 

How about engine mileage? The noise could be a piston skirt slap or wrist pin with excessive clearance. Those noises are similar to a light detonation. Then again, changing to higher octane fuel wouldn't cause those noises to go away temporarily. Just throwing out the possibilities.

Have you removed the spark plugs for inspection? That may give you an indication of a possible lean condition, contrtibuting to detonation.

How about a vacuum gauge reading at hot idle? Deposits on valves can affect the mixture and contribute to detonation or preignition, and can show up as irregularities or "pulses" with a vacuum gauge if severe.

A leaking intake valve can also cause a muffled backfire and irregular operation under load, but again would show up with a vacuum gauge reading.

Any extra information you might have could prove very helpful.

 

If high octane fuel made the problem go away, it's unlikely the problem is mechanical noise caused by excessive wear. Check out the EGR system. If it is malfunctioning (read no egr), the normal ignition timing is effectively too advanced for any set of condtions, resulting in spark knock. Said another way, EGR reduces the octane requirement for a given set of timing calibration.
I couldn't resist in replying so I could say hello to Vader. Boy, did Jefferson get wet yesterday. See me on the trans board,.. fooling around with a 700R4. I apoligize the original poster for throwing in some personal stuff to Vader.
Regards, FJK

 

Yup. I gave up on Jefferson yesterday, and today. Although I could have used a couple of items (heads) I wimped out due to the impending blizzard and floods. Looks like today will be even worse.

Good call on the EGR possibility, but that shouldn't be a big factor while power-braking at a dead stop. Still, if the engine had been running and had hot heads, it could contribute. And we all know that doing that kind of thing with a cold engine and transmission is a BIG no-no, right?

That leaves the other possibility more apparent - is the coolant at high temperatures? Is the cooling system clean, or scaled to the point of poor cooling?

Just more ideas...

 

OK. Here's the deal - yes my EGR dont work to great - but as said, that should affect it more at higher RPM's than low. My fan dont come on till 240*, but if I am sitting, I turn the AC on so the fan will run (this keeps it around maybe 200*).
I do not have a vacuum gauge, but I checked a few plugs yesterday - Now, picture looking at the plug from dead on (looking straight donw at electrodes), the little ridge at the end of the threads (what else would I call it?) was nice and black, but the electrodes were cleanm (they are platnium plugs, for what thats worth). I
tried running some water through (clean out carbon) but that didnt do much but gimme a lot of white smoke... There are about 40,000 miles on the engine, as it was replaced around 90k, and to my understanding with a brand new L03 (now someone please explain to me why buy a L03??).
My car is used for short trips, but at least once veryother day, I'll get fully warmed up (normally twice a day though), and I'll give it a WOT rev or two.
My coolant is prettyt dirty, but if seem to get the job done (I was running at maybe 190 (thermostat) on the freeway yesterday). Basically, I wanna get this engine running a little better before I sell, so I dont really want to spend a lot of money.
Like I said, I have tried everything, and the only thing I can think of, is if the knock sensor is shot, and the ECM advances timing to far or something...