1st to 3rd

I installed my PFC today, version 5.08.
Mods: Intake, DP, CB.
The install went smoothly. The a/c even works! I'm a little concerned about the part/off throttle knock readings though.
The knock readings are low (20 range) under boost, but when acclerating slowly (no boost) or coasting/deacclerating they jump up into the 60's with a peak of 74. Is this normal? Could the car be running lean under light throttle or could it be random harmonics the sensor is picking up?

Tim Benton

iTrader: (1)

more than likely its just picking up noise although that tends to be when you left off after a WOT end or heavy load run. Do you have access to a wideband?


Tim

TailHappy

One thing that's helped me while I wait on my datalogit is to go to the 2 sensor monitor mode and set it for RPM and knock. Then put it in graph mode, wind it out, pause it, then look at where the spikes are. As Tim said, mine are usually right when I press in the clutch to shift.

Badog

The knock sensor is a microphone. All knock readings are relative to your car. You will get the highest knock readings during torque peak and where ever esle there could be noise.

Some of you should try to test alittle bit: Take a hammer to a "safe" place on the block and tap it while datalogging or monitoring.

IMHO...your no-load or 20 and loaded of sub-100 seems normal. When you get a 200 in there, or anything near an order of magnitude great than the lowest reading is when you should worry.

BTW...the PFC does not retard based on knock.

Regards,
Tony

twokrx7

iTrader: (1)

Knock is really different from one car to the next, a 140-200 can mean broken apex seals on one car and from what some folks post I guess it means little on other cars.

Drive your car and monitor/datalog many sessions to learn how your car behaves, don't assume other cars will behave the same, and try not to tune to someone else's knock limits.

1st to 3rd

Thanks guys, the advice helped.
I took the car out and monitored the PFC. Everything from holding up grandma's to trying to get arrested. What helped me understand what the car was doing was to monitor the knock behavior on a bumpy road, then drive the exact same way on a smooth road. I'm now confident that the light load/coasting peaks are caused by random harmonics... well, as confident as one can be w/o a wideband. I'll get tuned soon, but am comfortable enough now to bump it down on my list of priorities.