inconsistent injector pulse
11-07-2008, 06:23 PM
#1
inconsistent injector pulse i have a problem with injector pulse floating and dropping under throttle.
the car will not stay running unless i highly manipulate the
pulse width adjustment table {B3701}.
once i get the car to idle, any throttle movement will
make injector pulse drop resulting in an extreme lean out and stalling.
battery, battery cables, and alternator are new and
i have used 2 different PCM`s.
what else besides the PCM has an effect on injector pulse?
i have no DTC`s.
thanks
the car will not stay running unless i highly manipulate the
pulse width adjustment table {B3701}.
once i get the car to idle, any throttle movement will
make injector pulse drop resulting in an extreme lean out and stalling.
battery, battery cables, and alternator are new and
i have used 2 different PCM`s.
what else besides the PCM has an effect on injector pulse?
i have no DTC`s.
thanks
11-07-2008, 11:30 PM
#2
FormerVendor
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could possibly be a coil issue on the injector(s)
Have you tried ohm testing them?
http://www.youtube.com/watch?v=_g8PdrT0MCU
Have you tried ohm testing them?
http://www.youtube.com/watch?v=_g8PdrT0MCU
11-08-2008, 09:35 AM
#4
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The pulse width being pushed by the PCM, wouldn't know about
bad coils or anything like that. Seems to me like if the pulse is
freaking out, you have a problem with either the airflow or the
fuel command "branches" of the fueling.
Can't read your log file, but one thing that will really freak out
fuel (and spark) is an intermittent ECT sensor / connector. If
things are short-term-unstable, begin with shotgunning all the
sensors, and see if anything is jiggy in the same way / time
as the pulse width. Look at the sensors relating to airflow, at
as high a sample rate as you can (fewer PIDs, like <12) and
see whether you have a lot of scatter in your airflow reading
(which will then scatter the fuel calc, only it'll be a bit after
the fact and then maybe it's kicked north just in time for the
airflow to have bounced south again). See a very "lumpy" MAF
signal on my car after cam & big TB, the dynamic airflow is
smoother but if you (say) changed the filtering you might be
able to pass a lot more busy bullshit in through the airflow
calcs to muss up the fuel shot.
Might try locking some things down with bidirectional controls,
like pin the IAC position and spark and see if the injector pulse
still "flickers" the same, etc. if you can hold a steadier RPM.
bad coils or anything like that. Seems to me like if the pulse is
freaking out, you have a problem with either the airflow or the
fuel command "branches" of the fueling.
Can't read your log file, but one thing that will really freak out
fuel (and spark) is an intermittent ECT sensor / connector. If
things are short-term-unstable, begin with shotgunning all the
sensors, and see if anything is jiggy in the same way / time
as the pulse width. Look at the sensors relating to airflow, at
as high a sample rate as you can (fewer PIDs, like <12) and
see whether you have a lot of scatter in your airflow reading
(which will then scatter the fuel calc, only it'll be a bit after
the fact and then maybe it's kicked north just in time for the
airflow to have bounced south again). See a very "lumpy" MAF
signal on my car after cam & big TB, the dynamic airflow is
smoother but if you (say) changed the filtering you might be
able to pass a lot more busy bullshit in through the airflow
calcs to muss up the fuel shot.
Might try locking some things down with bidirectional controls,
like pin the IAC position and spark and see if the injector pulse
still "flickers" the same, etc. if you can hold a steadier RPM.
11-08-2008, 09:57 AM
#5
The pulse width being pushed by the PCM, wouldn't know about
bad coils or anything like that. Seems to me like if the pulse is
freaking out, you have a problem with either the airflow or the
fuel command "branches" of the fueling.
Can't read your log file, but one thing that will really freak out
fuel (and spark) is an intermittent ECT sensor / connector. If
things are short-term-unstable, begin with shotgunning all the
sensors, and see if anything is jiggy in the same way / time
as the pulse width. Look at the sensors relating to airflow, at
as high a sample rate as you can (fewer PIDs, like <12) and
see whether you have a lot of scatter in your airflow reading
(which will then scatter the fuel calc, only it'll be a bit after
the fact and then maybe it's kicked north just in time for the
airflow to have bounced south again). See a very "lumpy" MAF
signal on my car after cam & big TB, the dynamic airflow is
smoother but if you (say) changed the filtering you might be
able to pass a lot more busy bullshit in through the airflow
calcs to muss up the fuel shot.
Might try locking some things down with bidirectional controls,
like pin the IAC position and spark and see if the injector pulse
still "flickers" the same, etc. if you can hold a steadier RPM.
bad coils or anything like that. Seems to me like if the pulse is
freaking out, you have a problem with either the airflow or the
fuel command "branches" of the fueling.
Can't read your log file, but one thing that will really freak out
fuel (and spark) is an intermittent ECT sensor / connector. If
things are short-term-unstable, begin with shotgunning all the
sensors, and see if anything is jiggy in the same way / time
as the pulse width. Look at the sensors relating to airflow, at
as high a sample rate as you can (fewer PIDs, like <12) and
see whether you have a lot of scatter in your airflow reading
(which will then scatter the fuel calc, only it'll be a bit after
the fact and then maybe it's kicked north just in time for the
airflow to have bounced south again). See a very "lumpy" MAF
signal on my car after cam & big TB, the dynamic airflow is
smoother but if you (say) changed the filtering you might be
able to pass a lot more busy bullshit in through the airflow
calcs to muss up the fuel shot.
Might try locking some things down with bidirectional controls,
like pin the IAC position and spark and see if the injector pulse
still "flickers" the same, etc. if you can hold a steadier RPM.
i can only get the car running by manually manipulating the pulse offset
with EFILive and Moates roadrunner.
the injectors are new and the old stockers don`t help.
fuel pressure is perfect.
i have looked for an intermittent circuit/bad ground and found nothing.
spark seems steady and, there is no misfire so i assume the coils are good.
injector pulse drops when RPM/throttle position increases.
