Green Tuner/Pinging issue.

[zstripper2k]

Recently started to delv into tuning and have aquired a high milage (183k) 1999.5 Silverado 1500 LS RCSB 4.8 2wd Auto completely stock. Have done all the regular maintenance items and have recently been chasing a pinging issue. When I swapped out plugs I could not see any indication of excessive oil or water on the plugs or smoking from the tailpipe. It did have a warm start issue which was fixed by replacing the Fuel Pressure Regulator and seems to have taken a little of the pinging away as well. While doing transmission tuning I was data logging and found the truck pinged a lot all over the rev range (87 Octane & Stock Tune). Pinging would reduce with the use of 93 Octane but isn't the way I would like to fix it as this isn't helping me learn tuning. I have done some adjustments on the main spark table with data logging which has reduced most of the pinging but it still exists consistently in the area of the spark table that the engine runs on the highway under a moderate to heavy throttle without upshifting. I am going to replace both upstream O2 sensors tonight and go from there. If that does not fix the issue what would be my next step?

[zstripper2k]

Replaced both upstream o2 sensors and still have the ping. Kind of at a loss here. Seems taking out timing isn't fixing the issue. If im am running rich/lean how do I adjust for fuel in that area since im not WOT tuning?

[MMGT1]

Im going to say, Find yourself a shop that is using "CB30" to flush injectors. It is a Forte product, only injector cleaner Ive ever seen actually work. It must be injected right at the fuel rail. Stuff gets poured into a pressure pot, fuel supply is disconnected, fuel pump disabled and your engine will be run on it until the entire can goes through. Give this stuff a try and see if it helps. Before you run the CB30 through it you can also hit up a GM dealer and ask for the GM Top End Cleaner. You have to pull each spark plug, 2 ounces into each cylinder and the truck needs to sit for a minimum of 4 hours before you fire it up. Both those products do work. I would give that a go and see if it cures it. I bet it will be tons better after you do both...
Once both go through, change the oil right away

[Russ K]

Your fuel trims are very high. Most likely a bad Maf, as it will also lower the dynamic cylinder air, thus increasing the spark advance. Do a WOT scan to redline, the do another with the Maf unplugged. If this solves the lean fueling, then replace the Maf (very common problem on the older vehicles)

Russ Kemp

[zstripper2k]

Your fuel trims are very high. Most likely a bad Maf, as it will also lower the dynamic cylinder air, thus increasing the spark advance. Do a WOT scan to redline, the do another with the Maf unplugged. If this solves the lean fueling, then replace the Maf (very common problem on the older vehicles)

Russ Kemp

I tried doing a MAF cal using one of the configs in the "read here first" section but those configs seemed to not work with my ECU as all the results came to a avg -14 across the whole frequency range regardless of how many times I adjusted it (maybe that is the bad MAF and not the .cfg file). Got to the point where the truck almost wouldn't idle with the adjustments I made so I went back to the stock config. To do that test I cleared the fuel trims and turned off LTFT before running the test.

When logging with the MAF plugged in at WOT on the stock tune there is a little initial pinging but it seemed to not be as bad as the lower rev range. I will try it out with it unplugged and report back.

So are the STFTs supposed to be as close to "0" as possible while accelerating? They do go negative/positive alot which is what im assuming you are talking about? I did notice the LTFT change alot and many times are different on B1 vs B2. Would another stock MAF be my best bet or are there any improved units to go with in the MAF ends up bad?

FYI, the truck did have a K&N filter in the stock airbox so that could be a possible culprit if the maf is bad. I cleaned the MAF with the appropriate cleaner a while back and put a paper filter in.

[Tuffy282000]

You cant do any WOT tunning with narrow band O2's you will fry your engine. either you are very lean, timing wat to advanced or your IAT or ECT is very high. invest in a wideband before any tunning above 4000 rpm. very dangerous area

[blindsquirrel]

2013.