[Diy_efi] re: rich/lean and O2
RogeranCarol
rogerancarol at cox.net
Thu Nov 25 19:11:27 GMT 2004
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Thanks for the comeback guys--I don't have a scan tool so I can't say =
what the Block learn or the Integrator #'s are. The ECM won't go into =
closed loop according to the MIL flashes I see while in the Field =
Service mode ( shorting pin A to B on the ALDL connector while the =
engine runs--2 flashes per second are supposed to indicate "open loop" =
and that is what I'm seeing). The ECM is a 16171199 with PROM Broadcast =
code BDWB--the only California certified combo for a K1500 5.7L Chevy =
with an NV4500 manual trans (according to the local SMOG Ref)! You gotta =
love SMOG laws. This ECM has a dedicated O2 sensor ground that connects =
directly to the engine block. I double checked all grounds and =
especially those associated with MAP and O2 sensors. Even removed ECM =
connector pins and inspected for damage/corrosion. All appear good. But =
I didn't check MAP output above idle (idle =3D1.05v). I'll do that =
today. Per my Helm manual, a low MAP voltage (high vacuum) could cause =
the ECM to go into the "Deceleration En-Leanment mode", even though the =
vehicle is not moving--this would cause a significant lean-out of the =
fuel mixture.
I'm thinking fuel pump, even though my pressure readings are steady =
12.5 psi across my test RPM range. What I didn't mention before is that =
since I'm planning on converting to multi port injection, I didn't want =
to install or buy a TBI pump, soooo, I jury rigged my current high =
pressure fuel pump (original engine was a 4.0L Jeep with sequential =
multi port injection) to run at 15psi with the TBI disconnected by =
running a metal return line from the filter output to the original fuel =
return line, then smashing the tube until I got 15psi. Seemed to work, =
except for the cold lean stumble, until I got curious about being in =
Closed Loop. I'm thinking I don't have a grasp of the pressure/volume =
thingy and even though I have good pressure, maybe I don't have =
sufficient volume.
Addition thoughts/comments would be appreciated
Roger
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<DIV><FONT face=3DArial size=3D2>Thanks for the comeback guys--I don't =
have a scan=20
tool so I can't say what the Block learn or the Integrator #'s are. The =
ECM=20
won't go into closed loop according to the MIL flashes I =
see while in=20
the Field Service mode ( shorting pin A to B on the ALDL connector while =
the=20
engine runs--2 flashes per second are supposed to indicate "open loop" =
and that=20
is what I'm seeing). The ECM is a 16171199 with PROM Broadcast code =
BDWB--the=20
only California certified combo for a K1500 5.7L Chevy with an =
NV4500=20
manual trans (according to the local SMOG Ref)! You gotta love SMOG =
laws. This=20
ECM has a dedicated O2 sensor ground that connects directly to the =
engine=20
block. I double checked all grounds and especially those associated with =
MAP and=20
O2 sensors. Even removed ECM connector pins and inspected for =
damage/corrosion.=20
All appear good. But I didn't check MAP output above idle =
(idle=20
=3D1.05v). I'll do that today. Per my Helm manual, a low MAP voltage =
(high vacuum)=20
could cause the ECM to go into the "Deceleration En-Leanment mode", even =
though=20
the vehicle is not moving--this would cause a significant lean-out of =
the fuel=20
mixture.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2> I'm thinking fuel pump, even =
though my=20
pressure readings are steady 12.5 psi across my test RPM range. What I =
didn't=20
mention before is that since I'm planning on converting to multi port =
injection,=20
I didn't want to install or buy a TBI pump, soooo, I jury rigged my =
current=20
high pressure fuel pump (original engine was a 4.0L Jeep with sequential =
multi=20
port injection) to run at 15psi with the TBI disconnected by running a =
metal=20
return line from the filter output to the original fuel return =
line, then=20
smashing the tube until I got 15psi. Seemed to work, except for the cold =
lean=20
stumble, until I got curious about being in Closed Loop. I'm thinking I =
don't=20
have a grasp of the pressure/volume thingy and even though I have good =
pressure,=20
maybe I don't have sufficient volume.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Addition thoughts/comments would be=20
appreciated</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Roger</FONT> </DIV></BODY></HTML>
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