noob warm up O2 question
Thread Starter
Teching In
Joined: Sep 2008
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noob warm up O2 question I have a 3rd gen formula with a lightly modded 98 LS1 swapped into it. I just did my first data log using HPT at idle. I am new to the engine, tuning etc and this is my first attempt. At idle the car runs extremely rich, to the point where when cold I need to peddle it once in a while to keep it running. This gets allot better once the engine closes in on 170 deg F. This is with an idle speed between 1100 cold, 850 warm (in neutral / park).
I am sure the current tune has allot to do with the problems but I am wondering if there is anything wrong with the 02 sensors? I noticed as part of the the warmup there was a phase where the 02 sensors essentialy flatlined around 1 - 4 mv. Is there a portion of the warmup where this is acceptable?
I have attached my tune and log file.
Thank you
I am sure the current tune has allot to do with the problems but I am wondering if there is anything wrong with the 02 sensors? I noticed as part of the the warmup there was a phase where the 02 sensors essentialy flatlined around 1 - 4 mv. Is there a portion of the warmup where this is acceptable?
I have attached my tune and log file.
Thank you
Look at the MAP reading and then look at your open
loop EQ vs ECT vs MAP table. When cold, and at a
moderate to high MAP, you throw down a lot of
commanded enrichment. If there's a cam in the picture
you will probably want to lighten up on that as the
cam effect on idle vacuum (MAP) is driving the
enrichment higher.
There is a compounding effect because a motor that
is running crappy, runs at higher MAP and commands
even more enrichment.
Dunno what "lightly modded" means. So some of this
may be off base. Consider putting some basic info in
the signature.
loop EQ vs ECT vs MAP table. When cold, and at a
moderate to high MAP, you throw down a lot of
commanded enrichment. If there's a cam in the picture
you will probably want to lighten up on that as the
cam effect on idle vacuum (MAP) is driving the
enrichment higher.
There is a compounding effect because a motor that
is running crappy, runs at higher MAP and commands
even more enrichment.
Dunno what "lightly modded" means. So some of this
may be off base. Consider putting some basic info in
the signature.
Thread Starter
Teching In
Joined: Sep 2008
Posts: 3
Likes: 0
my bad...
Stock displacement with ported and polished stock heads
aftermarket cam
BBK SSI intake with 85mm Maf and 85mm throttle body
4" cold air intake
2002 exhaust manifolds, y's into a single 3" exhaust
no cats and only the first set of O2 sensors
Unfortunatly I do not have the specs for the cam.
I did notice that the short term fuel trims were well over 30%. Thank you for the pointer I'll start there.
Stock displacement with ported and polished stock heads
aftermarket cam
BBK SSI intake with 85mm Maf and 85mm throttle body
4" cold air intake
2002 exhaust manifolds, y's into a single 3" exhaust
no cats and only the first set of O2 sensors
Unfortunatly I do not have the specs for the cam.
I did notice that the short term fuel trims were well over 30%. Thank you for the pointer I'll start there.
Thread Starter
Teching In
Joined: Sep 2008
Posts: 3
Likes: 0
Is modifying the primary VE table the best way to lean out the idle?
Based on the open loop EQ vs ECT vs MAP table you recommended I was looking at reducing the values in the table from MAP 30 to 60 and RPM 400 to 1600 by about 5% to start, burn it, log it and see the change. Is this a reasonable approach?
Based on the open loop EQ vs ECT vs MAP table you recommended I was looking at reducing the values in the table from MAP 30 to 60 and RPM 400 to 1600 by about 5% to start, burn it, log it and see the change. Is this a reasonable approach?
I'm not an expert, but you might start with looking at the base running idle airflow for the lower temps. Engine>Idle>Idle Airflow>Base Running Airflow>Idle Airflow. I wouldn't necessarily go directly to the VE tables for an idle issue.
