did some datalogging...need some help!
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
did some datalogging...need some help!
Hey guys, just need some quick help here. I finally got my hands on a good scanner and I've been tinkering with it...here's what I've got so far.
IAC at idle is ~144
tps is .50
maf is about 13g/s
My problem is that idle when cold is rough....first start of the morning always dies...have to use the throttle a little to keep it running for the first 15 seconds or so...car runs rich, always.
Now: I need some help with the numbers that I'm seeing. Blms, injectors pulses, etc. I need sense made out of them.
The two alarming things I have picked up are the O2 constantly toggles in and out of closed loop and goes back and forth from lean to rich quite often, and, no spark advance...None! not even at 6500 rpms!
Can someone shed some light? I would have posted in scan and tune, but that section has become pretty dead of late.
Thanks!
IAC at idle is ~144
tps is .50
maf is about 13g/s
My problem is that idle when cold is rough....first start of the morning always dies...have to use the throttle a little to keep it running for the first 15 seconds or so...car runs rich, always.
Now: I need some help with the numbers that I'm seeing. Blms, injectors pulses, etc. I need sense made out of them.
The two alarming things I have picked up are the O2 constantly toggles in and out of closed loop and goes back and forth from lean to rich quite often, and, no spark advance...None! not even at 6500 rpms!
Can someone shed some light? I would have posted in scan and tune, but that section has become pretty dead of late.
Thanks!
Racer
Joined: Oct 2007
Posts: 478
Likes: 1
When you first start the car when cold it is in open loop. It ignores the O2 sensor. When it warms up some it goes into closed loop and reads the O2 sensor.
I think you need to adjust the screw for the throttle blades. Maybe turn it in a 1/4 of a turn and see what happens. Your IAC must be close to wide open at 144 steps. So when the car starts to stall and the computer wants to open the IAC some more there is no more.
It also could be the passages in the IAC circuit are dirty and need cleaning. Just some thoughts.
I think you need to adjust the screw for the throttle blades. Maybe turn it in a 1/4 of a turn and see what happens. Your IAC must be close to wide open at 144 steps. So when the car starts to stall and the computer wants to open the IAC some more there is no more.
It also could be the passages in the IAC circuit are dirty and need cleaning. Just some thoughts.
Thread Starter
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
good thinking there.
I actually believe my lack of spark advance is to blame for the rough running when cold. The IAC is brand new and everything is good and clean in there. Idle is already at 1200 in park and 850 in gear, don't want much higher than that.
I actually believe my lack of spark advance is to blame for the rough running when cold. The IAC is brand new and everything is good and clean in there. Idle is already at 1200 in park and 850 in gear, don't want much higher than that.
Pro
Joined: Dec 2008
Posts: 658
Likes: 0
From: Lubbock for now, headed for Oklahoma
Hey guys, just need some quick help here. I finally got my hands on a good scanner and I've been tinkering with it...here's what I've got so far.
IAC at idle is ~144
tps is .50
maf is about 13g/s
My problem is that idle when cold is rough....first start of the morning always dies...have to use the throttle a little to keep it running for the first 15 seconds or so...car runs rich, always.
Now: I need some help with the numbers that I'm seeing. Blms, injectors pulses, etc. I need sense made out of them.
The two alarming things I have picked up are the O2 constantly toggles in and out of closed loop and goes back and forth from lean to rich quite often, and, no spark advance...None! not even at 6500 rpms!
Can someone shed some light? I would have posted in scan and tune, but that section has become pretty dead of late.
Thanks!
IAC at idle is ~144
tps is .50
maf is about 13g/s
My problem is that idle when cold is rough....first start of the morning always dies...have to use the throttle a little to keep it running for the first 15 seconds or so...car runs rich, always.
Now: I need some help with the numbers that I'm seeing. Blms, injectors pulses, etc. I need sense made out of them.
The two alarming things I have picked up are the O2 constantly toggles in and out of closed loop and goes back and forth from lean to rich quite often, and, no spark advance...None! not even at 6500 rpms!
Can someone shed some light? I would have posted in scan and tune, but that section has become pretty dead of late.
Thanks!
I will guess that the car was warmed to operating temp. and at idle considering the TPS is at .50 volts. That presents some problems with the IAC count at 144. That shows that the Idle motor is wide open and trying to lean the system. The O2 should be "cross counting" it is representative that the ECM has fuel control. It will lengthen and shorten the injector pulse width and IAC to keep the O2 traveling between .200 volts and .800 volts as long as they are up to temp. This is the RICH/LEAN flag change that you are seeing. The mass air flow is high for idle. What is your idle speed? If you can take a capture of the engine at idle and at 2500RPM and post them. If you have to just write everything down JUST as it is shown on the tool.
As for the timing you need to verify that with a timing light and then check your EST connectors.
Hope some of that helps. Get me all the info and we'll be able to see what is going on.
Pro
Joined: Dec 2008
Posts: 658
Likes: 0
From: Lubbock for now, headed for Oklahoma
Is that idle where you set it or is it just happening?
Racer
Joined: Oct 2007
Posts: 478
Likes: 1
There is a procedure for setting up the idle from scratch. I don't have the procedure handy but someone may have it. It involves setting the IAC to zero counts, disconnecting the computer timing and adjusting the throttle blade stop. Things may have gotten out of whack on your car.
Pro
Joined: Dec 2008
Posts: 658
Likes: 0
From: Lubbock for now, headed for Oklahoma
There is a procedure for setting up the idle from scratch. I don't have the procedure handy but someone may have it. It involves setting the IAC to zero counts, disconnecting the computer timing and adjusting the throttle blade stop. Things may have gotten out of whack on your car.
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Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Yep there is a procedure to install the IAC that must be followed for it to be set correctly. Probably in the FSM for his year.The IAC goes from 0-255 counts and should be ~30 at idle(at least it is on my car)
I am use to fuel injected alcohol Sprintcars these computer car stuff I'm just learning.
Pro
Joined: Dec 2008
Posts: 658
Likes: 0
From: Lubbock for now, headed for Oklahoma
IAC - Idle Air Control motor. It is a variable polarity motor(can turn both ways) that is controlled by the computer. It has a small pintle on the end of it that is driven inwards or outwards depending on the direction the motor is turned. This pintle rests inside of a passage that goes around the throttle plates in the throttle body. The computer controls the position of the pintle in the passage to vary the amount of air the engine gets at idle. This in turn controls the engine speed and air fuel mixture(with the fuel injector pulse width).
EST - Is the Electronic Spark Timing. It is the computers method of controlling ignition timing.
FSM - Factory Service Manual
Thanks that helps. 
Melting Slicks
Joined: Apr 2004
Posts: 2,775
Likes: 138
From: cyberspace NY
start reading up on it:
rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean
is what you want. but it should stay in closed loop. try a heated sensor.
rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean-rich-lean
is what you want. but it should stay in closed loop. try a heated sensor.
Pro
Joined: Dec 2008
Posts: 658
Likes: 0
From: Lubbock for now, headed for Oklahoma
I thought it was the ECM's that dropped them out of closed loop at idle? That is to say that it was a time/temp thing and not the loss of o2 cross counts.
I guess this is why I am not programing chips
I guess this is why I am not programing chips
Last edited by BluRay; Dec 28, 2008 at 10:14 AM. Reason: edit