New Datalogs - Running Lean at WOT

[Killer95GT302]

I decided to do some pulls and compare some vdyno graphs tonight since I haven't done so in a while.

I've been running the same custom tuned map for the longest time now, same mods too. It started off as an off-the-shelf map that I tweaked from there. I got the tune dialed in a long while ago and LTFT's have still been staying in an acceptable range, but there's room for improvement.

The tune is targeting 11.8 AFR and 16 lbs of boost. Did 2 pulls tonight, 2nd one I started getting knock. After opening the logs I got a little freaked out and glad I didn't hurt anything. both logs had AFR's in the high 12's!! I figure running this lean is what was causing the knock.

Attached are the logs and respective vdynos, although the 2nd graph is useless. These are both 4th gear pulls. datalog16 is the one with knock, both have lean AFRs.

So question here is what should I start with, vaccum/boost leak? MAF? Injectors? Fuel pressure looks good. I'll be light on the pedal till I figure this one out.

[Killer95GT302]

If anyone cares, I did a boost leak test and things checked out ok there.

I then picked up some MAF cleaner. In removing the MAF sensor from the housing, the screws were kind of loose, but the sensor was still pretty snug in there.

I sprayed the shit out of the MAF sensor and popped it back in and BAM! Back to 11.8 AFRs. Now I need to recalibrate this thing.

[btstarcher]

Shouldn't have to calibrate anything if your AFR looked fine before.

[Killer95GT302]

WOT AFRs look good, but LTFT's slip down to -10 at idle now. I don't know if the dirty MAF screwed things up and if I should drive it for a few miles and see if it self heals.

[btstarcher]

Could be better, but that's acceptable. LTFT will fluctuate some with dirty filter, seasons/temperature, etc. I wouldn't worry about it. There's still plenty of room to move.

[Killer95GT302]

I guess I'll take some new logs and see what I get, I hate recalibrating anyways!

[btstarcher]

I've found that when you constantly watch, they will come full circle. Drive it awhile and see where they settle. Keep in mind that the fuel trims are there for a reason; they allow the ECU to compensate for various conditions. I would worry if they kept moving increasingly positive or negative and pegged out, but otherwise let the ECU do its job. Definitely monitor your WOT AFR though. That's a different story.

[Killer95GT302]

I need to get one of those things that monitors multiple parameters. I got an old access port and torque pro limits my phone usage in the car.

With only one, I choose knock all the time.

[btstarcher]

You don't need to monitor in real-time; just log once a week.

[Agent_Orange]

Originally Posted by btstarcher You don't need to monitor in real-time; just log once a week.

This.

It's pretty much pointless to monitor KR on a real-time PID. By the time you see it, it's already too late to do anything about it.

[Killer95GT302]

I don't know if I'd call it pointless. Sure as far as trying to save your motor from detrimental knock, it may not help. If you get to that point you're probably doing something else wrong.

Under normal circumstances, it may give insight into other things that may be going wrong. Like filling up with a bad tank of gas or running too hot of a plug, or in my case a lean AFR (yes, probably could have been found out by monitoring AFR). Things that would suggest to me "Hey, maybe you should relax on the WOT pulls and take a closer look at things."