24x LT1 411 PCM - Bank 2 Lean Spikes
03-10-2013, 10:48 PM
#1
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24x LT1 411 PCM - Bank 2 Lean Spikes Bank 2 spikes lean while bank 1 stays constant (see attached pic)
I have suspected misfires or vacuum leaks, and have done the following tests to resolve them:
Installed new spark plugs (NGK TR6)
Used an HEI spark tester to test each coil and plug wire
Switched coils from bank to bank
Switched injectors from bank to bank
Used a Noid light to test the Injector harness
Tested for voltage, ground, low reference, and coil control signal at each coil.
Double checked, using a digital volt meter, the PCM continuity for the coils, injectors, and O2 sensors.
Switched in the stock O2 sensors
Performed a compression test on each cylinder
Tested fuel pressure regulator for leaks and for proper pressure at vacuum
Ohmed each spark plug wire
Checked for vaccum leaks / exhaust leaks using brake cleaner and propane
Installed new exhaust clamps at the header collectors, along with exhaust sealer
Also fixed by 58mm TB as per this page:
http://www.hashmarks.com/techtips/throttle_body_mod.htm
At this point, I do not know what else could be causing this issue? Log and tune attached for those of you with HP Tuners.
I have suspected misfires or vacuum leaks, and have done the following tests to resolve them:
Installed new spark plugs (NGK TR6)
Used an HEI spark tester to test each coil and plug wire
Switched coils from bank to bank
Switched injectors from bank to bank
Used a Noid light to test the Injector harness
Tested for voltage, ground, low reference, and coil control signal at each coil.
Double checked, using a digital volt meter, the PCM continuity for the coils, injectors, and O2 sensors.
Switched in the stock O2 sensors
Performed a compression test on each cylinder
Tested fuel pressure regulator for leaks and for proper pressure at vacuum
Ohmed each spark plug wire
Checked for vaccum leaks / exhaust leaks using brake cleaner and propane
Installed new exhaust clamps at the header collectors, along with exhaust sealer
Also fixed by 58mm TB as per this page:
http://www.hashmarks.com/techtips/throttle_body_mod.htm
At this point, I do not know what else could be causing this issue? Log and tune attached for those of you with HP Tuners.
03-12-2013, 11:42 PM
#6
Glancing at the tune, everything looks really good. Looking at the log, some of it still may be related to the aftermarket TB circuit. How bad are the fuel trims when you enable LTFTs and STFTs? An LT1 with a decent cam even does this lightly on the stock PCM. I will say that they lean spikes may not really be all that lean. O2 sensors switch over a very short band (like 14.3-15.0). I would enable STFTs and LTFTs to see what it does. If its less than 5% split, I would think it would be OK.
03-14-2013, 01:49 PM
#7
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I will see if I can get my wideband installed this week to see what the actual air to fuel ratios are. I have my log files at home, but when I turned LTFTs on, they maxed at 25, and the STFTs when another 15% or so. Below is a log of only the STFTs. Will post a log with LTFTs Later.
