Hey guys -

Started fooling with the Datalogit on my FD some, trying to learn some things and get my feet more wet.

I've noticed when free revving my car it's quite rich - like 12's and 13's. Even holding it at, say, 2000 RPM, no load or anything, and car fully warmed up, it's rich, popping exhaust, etc.

Using the Datalogit to lean it out does nothing - I select a group of cells around the current data point and start leaning it out, nothing. Richening it, nothing.

Using the exact same methods, I can lean and richen my idle no problem whatsoever.

I am NOT using the O2 sensor feedback, no airpump.

I'm trying to determine if it's a PFC problem or some other problem with the car itself. Possibly related, if I'm driving the car and start letting off the gas, the AFR's go pretty rich (like 12's) with the exhaust popping/burbling, then let off a little more and it goes full lean as fuel is cut.

Any good ideas?

Dale

 

For this simple type of testing, use the commander as it is faster and safer then using the DL which requires a pc. That is what the IGL/IGT/INJ screen under SETTINGS is for.

The only time removing fuel does not work is if the injectors are already running at the minimum that the PFC allows. That is why lag is used to lean out 850s at idle. But I think your problem is your lack of experince with the PFC/DL.

 

Could be .

That makes sense that they could be at minimum pulsewidth. I have a Walbro fuel pump rewired, and I might be running more fuel pressure than I should be. That would definitely answer that issue.

I am running stock injectors all around, though.

Thanks, Chuck!

Anyone else seen something similar? It is weird that I can lean out my idle, though - it might be that the RPMs are so low there that there's more injector time available.

Dale

 

If you are runnning more that 38-40 psi base fuel pressure at 0 psi boost/vacuum, then you are forcing more fuel through the injectors.

 

are you holding the throttle completely steady or are you pushing the pedal down? the PFC adds extra fuel as the pedal moves (versus steady at say 1/4, full, or 0 throttle). Those settings are controlled by Accelerate injector (max pulsewidth added vs rpm) and Accel vs TPS 1 (% of max pulsewidth from the other table that is applied vs throttle input) in settings 2

 

Nope, throttle steady - like holding it at 2000 RPM.

I gotta do some more experimenting here and check the fuel pressure.

Dale

 

I am seeing the same thing.

Was checking/setting AFR for emissions, idle tuned to 13:1 OK (no air pump) went to tune @2500rpm & I'm seeing ~11:1.
Adjusted cells around this location (~n5,p3 to n7,p4) & it made no difference to the AFR.
I am also getting a lot of exhaust popping when coming off the throttle suddenly in this region (with AP connected), smoothly coming off doesn't seem to pop/at least not as much. Without AP, no popping, though I haven't tried driving like that yet.

FP is running at 32psi @ idle, adjusted down to 30psi - no effect (both are in spec, so didn't expect anything anyway). No O2 FB

Running (brand new) stock primaries, 1300 secondaries

I notice that the injector fire time is running at ~2.6ms vs ~1.25 to 1.29ms in the map, tidle region values are ~2.7 to 2.8ms logged & ~1.9 to 2ms in the map. Is this a normal offset from the other setting corrections?

I am new to using the DL, so I may be missing something, but the behaviour seems strange.

John

 

I have been working on the same thing. P row 4 is tuned fine and when it drops into P3 at steady speed or slight decel it runs rich 10-11 AFR range like others have stated. I notice between 2,000-3,000 RPM range during normal driving. if it drops into P row 2 it then goes into fuel cut. I am running O2 FB off also. I also have not been able to lean out that area.
Hope we can figure out a solution.

 

have any of ya'll tried adjusting the lag settings?