One bank 20% leaner
Thread Starter
I need a gauge for that
iTrader: (37)
Joined: Jan 2006
Posts: 10,921
Likes: 3
From: Huntsville, AL
One bank 20% leaner Just got my engine back together after having a head repaired. Only thing that was changed is new gaskets and new headstuds. Engine is a 402 with holley intake and holley fuel rails, 127lb bosch injectors.
Issue im having is bank1 is 15-20% leaner than bank2. I have tried hotter plugs with more gap, triple checked wires, and checked for intake and exhaust leaks. The injectors just got back from being cleaned and tested. Fuel pressure is right where it should be. All exhaust primaries appear to heat up evenly to the touch. Plugs look good, just lean. Fuel crossover is clean and rails are clean. Compression test shows all cylinders are about the same and number is fine. Idle vacuum and speed are fine...
Im out of ideas, anybody got a guess?
Issue im having is bank1 is 15-20% leaner than bank2. I have tried hotter plugs with more gap, triple checked wires, and checked for intake and exhaust leaks. The injectors just got back from being cleaned and tested. Fuel pressure is right where it should be. All exhaust primaries appear to heat up evenly to the touch. Plugs look good, just lean. Fuel crossover is clean and rails are clean. Compression test shows all cylinders are about the same and number is fine. Idle vacuum and speed are fine...
Im out of ideas, anybody got a guess?
Thread Starter
I need a gauge for that
iTrader: (37)
Joined: Jan 2006
Posts: 10,921
Likes: 3
From: Huntsville, AL
No because one is really hard to get to, but my wideband is agreeing that the total mixture is lean. Bank2 shows rich, bank1 lean, wideband lean. So I have no reason to suspect its faulty. They are both brand new as well.
You said the head was repaired, did it blow a head gasket? If so coolant could have killed the 02.
How are you checking for vacuum leaks? The best way is to watch your STFT's and 02's then spray carb cleaner around the intake.
Let us know what you find.
How are you checking for vacuum leaks? The best way is to watch your STFT's and 02's then spray carb cleaner around the intake.
Let us know what you find.
Thread Starter
I need a gauge for that
iTrader: (37)
Joined: Jan 2006
Posts: 10,921
Likes: 3
From: Huntsville, AL
Yes, it melted a section from the edge of a chamber to a coolant passage, but didnt burn all the way to the edge of the head. I had it repaired and surfaced and it looks good as new.
I replaced both o2 sensors after blowing the head because they were both dead.
Checked for leaks by spraying starting fluid around the intake ports and not a single flinch. The ports all look flush to the head and I checked the orings before putting it back on. The top and bottom sections of the intake were never separated.
I replaced both o2 sensors after blowing the head because they were both dead.
Checked for leaks by spraying starting fluid around the intake ports and not a single flinch. The ports all look flush to the head and I checked the orings before putting it back on. The top and bottom sections of the intake were never separated.
Try using carb cleaner instead of starting fluid. Starting fluid is REALLY dangerous to use. The starting fluid might be evaporating/burning too quickly for the 02's to see it.
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Yes, it melted a section from the edge of a chamber to a coolant passage, but didnt burn all the way to the edge of the head. I had it repaired and surfaced and it looks good as new.
I replaced both o2 sensors after blowing the head because they were both dead.
Checked for leaks by spraying starting fluid around the intake ports and not a single flinch. The ports all look flush to the head and I checked the orings before putting it back on. The top and bottom sections of the intake were never separated.
I replaced both o2 sensors after blowing the head because they were both dead.
Checked for leaks by spraying starting fluid around the intake ports and not a single flinch. The ports all look flush to the head and I checked the orings before putting it back on. The top and bottom sections of the intake were never separated.
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Just got my engine back together after having a head repaired. Only thing that was changed is new gaskets and new headstuds. Engine is a 402 with holley intake and holley fuel rails, 127lb bosch injectors.
Issue im having is bank1 is 15-20% leaner than bank2. I have tried hotter plugs with more gap, triple checked wires, and checked for intake and exhaust leaks. The injectors just got back from being cleaned and tested. Fuel pressure is right where it should be. All exhaust primaries appear to heat up evenly to the touch. Plugs look good, just lean. Fuel crossover is clean and rails are clean. Compression test shows all cylinders are about the same and number is fine. Idle vacuum and speed are fine...
Im out of ideas, anybody got a guess?
Issue im having is bank1 is 15-20% leaner than bank2. I have tried hotter plugs with more gap, triple checked wires, and checked for intake and exhaust leaks. The injectors just got back from being cleaned and tested. Fuel pressure is right where it should be. All exhaust primaries appear to heat up evenly to the touch. Plugs look good, just lean. Fuel crossover is clean and rails are clean. Compression test shows all cylinders are about the same and number is fine. Idle vacuum and speed are fine...
Im out of ideas, anybody got a guess?
Thread Starter
I need a gauge for that
iTrader: (37)
Joined: Jan 2006
Posts: 10,921
Likes: 3
From: Huntsville, AL
Both banks are firing and the plugs on the lean side look lean, so I think its a real issue not a faulty sensor.
Both heads were surfaced 0.005 to clean them up.
I plan on taking off the exhaust to see if I can see a leak around the gasket surface.
Both heads were surfaced 0.005 to clean them up.
I plan on taking off the exhaust to see if I can see a leak around the gasket surface.
Thread Starter
I need a gauge for that
iTrader: (37)
Joined: Jan 2006
Posts: 10,921
Likes: 3
From: Huntsville, AL
Yes, this same tune was been in use for a couple months, so its well dialed in. Just in case it is an injector/tune issue, I bought some stock LS1 injectors to try in place of the 127s to see what happens.
Even if the tune was wrong, I would not expect to see such a large difference bank to bank.
Even if the tune was wrong, I would not expect to see such a large difference bank to bank.
Thread Starter
I need a gauge for that
iTrader: (37)
Joined: Jan 2006
Posts: 10,921
Likes: 3
From: Huntsville, AL
Yep all plugs were same color.
I took the exhaust off and there are no signs of leakage on the gasket on either side.
Also took the intake off and both sides were flush the gaskets are all fine and in their slots.
Still looking for that smoking gun :/
I took the exhaust off and there are no signs of leakage on the gasket on either side.
Also took the intake off and both sides were flush the gaskets are all fine and in their slots.
Still looking for that smoking gun :/
Thread Starter
I need a gauge for that
iTrader: (37)
Joined: Jan 2006
Posts: 10,921
Likes: 3
From: Huntsville, AL
I have to take the wastegate off to get to the passenger side, but I think I found my problem.... did a leak down test and cylinder 7 has 54% leakdown and is leaking out of the exhaust valve. Interestingly, cyl 1 has 80%, cyl3 has 87%, and cyl5 has 94%.
Looks like the heads are coming back off....sigh...thanks for the help guys.
Looks like the heads are coming back off....sigh...thanks for the help guys.