Bank 1 always leaner than bank 2 need suggestions
11-28-2005, 09:29 PM
#1
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Bank 1 always leaner than bank 2 need suggestions Ive had a problem for awhile where B1 is always leaner than B2. I have eliminated exhaust leaks, 02 sensors, injectors and vacuum leaks. I am completely stumped and Im about ready to drive this thing off a cliff.
At wot it is easily noticable as the mv are about 60-70mv apart. And under part throttle I can see that b1 will be trimming -1 while b2 is trimming -5, looking at the graph its easy to see that b1 never peaks over b2 etc...
The other vehicles Ive tuned and logs Ive looked at Ive never seen anything like this.
At wot it is easily noticable as the mv are about 60-70mv apart. And under part throttle I can see that b1 will be trimming -1 while b2 is trimming -5, looking at the graph its easy to see that b1 never peaks over b2 etc...
The other vehicles Ive tuned and logs Ive looked at Ive never seen anything like this.
11-29-2005, 12:59 PM
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On my Camaro the rack is side fed, with B1 from
the fuel line and B2 via the crossover pipe with
the pulse damper. So you would expect a degree
of pressure fade in B2, at least at higher flows.
People remove the pulse damper, sometimes.
I don't know how the truck feed is arranged.
If you can see plumbing differences side-side,
and your lean imbalance increases with MAP*RPM
then you might consider going to a custom fuel
rail setup, a Y-block providing identical flow @
pressure to both sides, etc.
Then again, there are probably thermal differences
between sides, exhaust-plumbing-construction and
cooling-airflow-wise that could account for 70mV
worth of O2 sensor difference. You're talking about
0.5mV/degC sensor temp, roughly. Look at the
undercar airflow from the fans, how it's obstructed
(or not) by the low hanging A/C, alternator, starter
etc. and likely uneven side-side.
What is making you chase this? See any bankwise
misfire differences? Does wideband read different
side-side or just the narrowband voltage differs?
the fuel line and B2 via the crossover pipe with
the pulse damper. So you would expect a degree
of pressure fade in B2, at least at higher flows.
People remove the pulse damper, sometimes.
I don't know how the truck feed is arranged.
If you can see plumbing differences side-side,
and your lean imbalance increases with MAP*RPM
then you might consider going to a custom fuel
rail setup, a Y-block providing identical flow @
pressure to both sides, etc.
Then again, there are probably thermal differences
between sides, exhaust-plumbing-construction and
cooling-airflow-wise that could account for 70mV
worth of O2 sensor difference. You're talking about
0.5mV/degC sensor temp, roughly. Look at the
undercar airflow from the fans, how it's obstructed
(or not) by the low hanging A/C, alternator, starter
etc. and likely uneven side-side.
What is making you chase this? See any bankwise
misfire differences? Does wideband read different
side-side or just the narrowband voltage differs?
11-29-2005, 04:23 PM
#4
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Originally Posted by luv2spd
So you've swapped the injectors from bank to bank and the 02s, but bank 1 was still leaner?
I changed all 8 to different injectors that I know flow evenly.
11-29-2005, 04:29 PM
#5
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Originally Posted by jimmyblue
On my Camaro the rack is side fed, with B1 from
the fuel line and B2 via the crossover pipe with
the pulse damper. So you would expect a degree
of pressure fade in B2, at least at higher flows.
People remove the pulse damper, sometimes.
I don't know how the truck feed is arranged.
If you can see plumbing differences side-side,
and your lean imbalance increases with MAP*RPM
then you might consider going to a custom fuel
rail setup, a Y-block providing identical flow @
pressure to both sides, etc.
Then again, there are probably thermal differences
between sides, exhaust-plumbing-construction and
cooling-airflow-wise that could account for 70mV
worth of O2 sensor difference. You're talking about
0.5mV/degC sensor temp, roughly. Look at the
undercar airflow from the fans, how it's obstructed
(or not) by the low hanging A/C, alternator, starter
etc. and likely uneven side-side.
What is making you chase this? See any bankwise
misfire differences? Does wideband read different
side-side or just the narrowband voltage differs?
the fuel line and B2 via the crossover pipe with
the pulse damper. So you would expect a degree
of pressure fade in B2, at least at higher flows.
People remove the pulse damper, sometimes.
I don't know how the truck feed is arranged.
If you can see plumbing differences side-side,
and your lean imbalance increases with MAP*RPM
then you might consider going to a custom fuel
rail setup, a Y-block providing identical flow @
pressure to both sides, etc.
Then again, there are probably thermal differences
between sides, exhaust-plumbing-construction and
cooling-airflow-wise that could account for 70mV
worth of O2 sensor difference. You're talking about
0.5mV/degC sensor temp, roughly. Look at the
undercar airflow from the fans, how it's obstructed
(or not) by the low hanging A/C, alternator, starter
etc. and likely uneven side-side.
What is making you chase this? See any bankwise
misfire differences? Does wideband read different
side-side or just the narrowband voltage differs?
The truck feed is arranged in the same manner, the temp thing isnt something Ive thought of but I dont see how there could be a 35C degree temp difference between the two sides that is huge.
The reason Im traking it down is that when the two sides both read even my fueling is consistent and Ive run my best times then and there is a noticable difference in power.
The only inconsistency between the two sides is that the threads on B2 side I think #7 cylinder where fouwled and I had to force the plug in. Maybe it isnt seated all the way.
Its been a while since I pulled the plugs could it be ignition that causes such a discrepancy?
11-29-2005, 09:59 PM
#6
my bank one will read slightly leaner than bank 2 at idle, part throttle gets better but its still off. wot i dont see the difference you speak of though. plug could play a factor, have you ever had the heads off the car to see how it looks in there? my friend ss will do the same thing on his driver side after the car has been running for a while. the under side of the head looks very shitty. i wonder if it coul dbe from pinging and causing internal damage?
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12-01-2005, 05:28 PM
#8
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My bank 1 was running about 10% leaner than two. I swapped O2's same thing. New wires, plugs, same thing. Reseated, sealed all injectors. Same thing...
I switched all 4 injectors from bank1 to bank2 and the BANK 2 then went 10% lean. In my case the injectors were that problem.
Tommy
I switched all 4 injectors from bank1 to bank2 and the BANK 2 then went 10% lean. In my case the injectors were that problem.
Tommy
12-01-2005, 05:45 PM
#9
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Incomplete combustion could leave residual oxygen
and fool the sensor (whether or not the input stream
was chemically balanced or not). Fouled plug, etc.
Injector imbalance (as well as fuel feed imbalance)
can also skew whole banks, even a single one out of
bed affects the everage seen by the O2 sensors, and
will bend closed-loop trimming. It could as easily be
rich error on the "good" bank, as lean error on the
"bad" one if it's random injector mismatch (roughly
5%, I've seen asserted as bulk product tolerances -
that's 3/4 of a point about stoich (divided by 4 if
you average, but who knows what the other 3 might
be up to?).
and fool the sensor (whether or not the input stream
was chemically balanced or not). Fouled plug, etc.
Injector imbalance (as well as fuel feed imbalance)
can also skew whole banks, even a single one out of
bed affects the everage seen by the O2 sensors, and
will bend closed-loop trimming. It could as easily be
rich error on the "good" bank, as lean error on the
"bad" one if it's random injector mismatch (roughly
5%, I've seen asserted as bulk product tolerances -
that's 3/4 of a point about stoich (divided by 4 if
you average, but who knows what the other 3 might
be up to?).
