EFIDynoTuning Forum

I'm really chasing my tail on this one. Been dealing with a lean out and popping/coughing in the intake but the o2 is reading near stoich. Happening under moderate acceleration less than half throttle
I added 10% to the VE table which helped but it did not show up on the O2 reading. Tried setting the hego delay and amplitude from my factory calibration and that did not seem to make any difference. 02 sensor is a brand new Bosch.

I believe I've got a bad/clogged injector getting progressively worse. Checked the plugs #3 was noticeably discolored and the popping in my intake is getting bad past 1/4 throttle. I set my wot threshold to 250 and that helped for a little while but today it started misfiring at cruise. Should I just replace the injector in number #3 or is there a better way to troubleshoot?

popping in the intake is a lean pop.

yeah sounds like youve got a bad injector or your loosing fuel pressure

efloth wrote: ↑2023 Aug 04, 17:59 PXL_20230728_011830931.jpgPXL_20230728_012032926.jpgPXL_20230728_012111931.jpgPXL_20230728_011901348.jpgPXL_20230728_011208793.jpg

Is that a big dog's ported intake?

Yes it is. I swapped the questionable injector. it had a bunch of build up on it whereas the others did not. Still popping between 2-3k rpm. I just cant seem to pinpoint the issue. I can set the ve table rich in those cells and it still pops.

Have you verified your rockers aren't too tight? If its still lean popping in the intake on quick stabs then most likely your cam timing is off.

New plug wires were the silver bullet (facepalm)

The lean pop slowly cropped back up. I tested fuel pressure, and it is dropping when revving up, so I am thinking it is the regulator (original bosch). I degreed the cam 3 times and it was spot on. I have two tanks with separate new pumps so I can't see them both being weak. One is an AEM 340LPH and the other is a HighFlow 340LPH. No fuel is siphoning between tanks so I know the check valves are working.

Should I just pick up the Kirban Adjustable or do you have another recommendation? I have the newer two bolt regulator mount on the rail.

put a fuel pressure gauge on the windshield where you can see it temporarily for testing. Drive around and see if it holds pressure.
edit I didn't read carefully, I see you tested it.

Thanks for that it seems to be regulating fine. It kicks the pressure up correctly when I remove the vacuum line as well. I am playing around with transient fueling since the intake is ported. Strangely, increasing tfcbits from .00005 to .0003 helped drastically. I am reading through lhbh1 and this setting is curious:

TFCBITS = Minimum difference in Equilibrium Intake Surface Fuel to
trigger transient fuel. 1 bit = 0.000015259, therefore to have a
deadband of 5 bits, set TFCBITS = 0.000076295.

NOTE: To see how many bits are contained in the desired fuel puddle,
calculate FN1321 * MTEISF/0.000015259. For example, if FN1321 =
0.0014648, MTEISF = 0.0625, then the number of bits in the puddle is 6.
Thus even a 1 bit change would require an 18% TFCDED to eliminate it.
TFCBITS resolves this issue when puddle values are extremely small.

If I understand correctly, increasing tfcbits it would make it less likely to enable transient fueling. I am confused why that would eliminate a lean pop during acceleration.