Jglisson

iTrader: (1)

I have a 99 T/A with basic mods (flowmaster, K&N cold air, mild tune - egr/air off, fan speeds, a little touch here and there).

Now that the cool weather has arrived I have a horrible ping under heavy throttle. Sounds pretty bad. I first suspected that I had a bad tank of fuel so I waited out on the tank and re-filled with good premium and it is still pinging. The car has been well maintained. Recent plugs (NGK TR55), injection cleaning, fuel filter.

Fuel pressure at the rail is 52psi with ignition on and 62psi running. I unplugged the MAF and the pinging has been reduced a little bit, but not much. Any ideas?

SSpdDmon

iTrader: (10)

Who tuned it and can you be more descriptive than "a touch here and there?"

moehorsepower

iTrader: (3)

An easy way to find out for certain is put some Fast Gas like 104 and see if it still pings, if it does then it is a tuning problem, if not, then it is something else, carbon build up? ect...

zmonsterjb

iTrader: (16)

pobaly timming related.

Rhino79

iTrader: (7)

I would say since it started in the cooler weather, that the problem may be in the Spark IAT table, tuner may have added some timing in the cooler ranges of the table.

hammertime

iTrader: (1)

Generally speaking, you should be less sensitive to detonation with cooler weather. Have you ever seafoamed your engine? Could be carbon buildup.

Rhino79

iTrader: (7)

Yeah but if the IAT Spark table in the tune is progammed to add 2* of timing at 40*IAT and so on, then you could be seeing a tune related problem.

mrr23

iTrader: (3)

i'm the one that did his tuning, using HPTuners. i'm looking at his high octane table right now.

from 2200-8000 rpms in the .52 - 1.20 g/cyl block, it is all set at 26*

EGR correction table zero'ed out.

IAT Table is all set to zeros as well.

ECT Spark table. i removed the negative timing and set to zero, in the -20-85*C and .16-.44 g/cyl

now, i did just see something odd. the low octane table is all screwed up. for some reason, it is in the 45* range. guess i need to get back with you one day and reupload another file. don't know how i missed that.

it's making me wonder why it's going into the low octane table.

i uploaded the file. if any of you guys see anything else, let me know.

Rhino79

iTrader: (7)

Also check the fuel mixture spark table. Also, if it is showing any MAF codes, it will be running SD and therfore using the low octane table instead of the high. I don't know what other codes could contribute to it, but there may be some.

Frost

iTrader: (45)

It's gonna run some interpolation of the two tables, and the knock learn factor has an influence on which it favors. In this case, if the KLF had it favoring the LO table from persistent knock, and that table was actually higher... I usually just copy the HO table over to the LO and subtract 3 to 4 degrees from the whole thing.

mrr23

iTrader: (3)

usually, i just copy/paste the high into the low. for some stupid reason, i must've hit add and not pay attention to the results. dummy move on my part.