is there a table for (cold) start-up that affects AFR?
Thread Starter
Joined: Dec 2008
Posts: 1,229
Likes: 24
From: lancaster, pa
is there a table for (cold) start-up that affects AFR? I just installed aem wideband. I currently tune it in OL with maf tuning. The wideband is currently in the passenger side B1S2 location. At idle I got it within +/- 14.9-15.0 but after driving and turning off the car and let it sit for a couple minutes, ie-getting gas or grocery store, when I start the car up again the wideband reads very lean, past 17.0afr but the car doesn’t sound like its starving for fuel though? When I start driving again then at idle its back to the +/- 14.9-15.0? I am tuning using HP tuners and disabled the COT, EGR, Air Pump and the closed loop to off(284*F). Is there a cold start or something that affects the AFR only on startup?
AFR probes must be up to operating temp to read properly. Take a look at the Open Loop Fuel Adder (horrible name, it's actually a fuel divider not adder) table, based on ECT it will adjust the fueling target (usually toward the rich side not lean tho). So if you're seeing lean, I'm going to go with either cold probe/exhaust, or you have a leak that gets plugged as things warm up and metal expands.
Thread Starter
Joined: Dec 2008
Posts: 1,229
Likes: 24
From: lancaster, pa
Hmm well it might just be the aem uego wb itself then. The wideband is a no calibration needed. The car’s basically stock except flowmaster catback and lid-minus tune of course.
Is it okay to adjust the OL fuel adder at all? I was thinking of a vac leak as I was trying to figure out why sometimes my IAC in both park and drive at idle it goes to zero. I played around with the TB adjuster screw and it somewhat helped. What are all of the vac lines on the ls1? I sprayed carb+choke cleaner all around the air pump and theres a thin plastic vac line that’s near the ecm on passenger side but the car didn’t hesitate to stall. If theres a leak on the air pump would that cause a vac leak and cause the IAC to drop to zero? IIRC the air pump hose that’s on the passenger side that goes to the rear from the front of the intake manifold is wrapped in some sort of black tape come to think of it?
Is it okay to adjust the OL fuel adder at all? I was thinking of a vac leak as I was trying to figure out why sometimes my IAC in both park and drive at idle it goes to zero. I played around with the TB adjuster screw and it somewhat helped. What are all of the vac lines on the ls1? I sprayed carb+choke cleaner all around the air pump and theres a thin plastic vac line that’s near the ecm on passenger side but the car didn’t hesitate to stall. If theres a leak on the air pump would that cause a vac leak and cause the IAC to drop to zero? IIRC the air pump hose that’s on the passenger side that goes to the rear from the front of the intake manifold is wrapped in some sort of black tape come to think of it?
Thread Starter
Joined: Dec 2008
Posts: 1,229
Likes: 24
From: lancaster, pa
hmm heat soak. interesting point you brought there. my other DD car, GTP i actually no longer use the IAT to read the incoming temp but have a mod that plugs into the iat and tricks the pcm/ecm to read what the incoming air is so it adds/subtracts timing accordingly. the mod is basically a potentiometer that has a **** that varies in ohms and changes the (temperature) reading. case in point, i forget i am using the iat function on the ls1 haha. i may relocate the iat sensor outside and somewhere it gets constant cooler temp. that should be okay correct? i thought i didnt see a iat spark timing table in hp tuners, unless i missed it somewhere?
If you are MAF tuning then the IAT is pretty much neglected... The table to look at is:
Engine: Fuel: General: Afterstart Enrichment: Initial Adder vs. ECT
The best way to do this is to adjust the table up a few decimal points at your current ECT range until the fueling is inline on startup. Be sure to let your wideband come on for a few seconds to heat up before you crank the car so that the o2 sensor reports accurate readings. If you don't have it connected directly to the battery I've found that using an external separate battery to power the wideband so it stay's energized while cranking so that you get correct fuel readings.
Engine: Fuel: General: Afterstart Enrichment: Initial Adder vs. ECT
The best way to do this is to adjust the table up a few decimal points at your current ECT range until the fueling is inline on startup. Be sure to let your wideband come on for a few seconds to heat up before you crank the car so that the o2 sensor reports accurate readings. If you don't have it connected directly to the battery I've found that using an external separate battery to power the wideband so it stay's energized while cranking so that you get correct fuel readings.
Thread Starter
Joined: Dec 2008
Posts: 1,229
Likes: 24
From: lancaster, pa
the wb is connected to the ign fuse connector thats in the driver kick panel.
currently have the Engine: Fuel: General: Afterstart Enrichment: Initial Adder vs. ECT
zeroed out as thats what is set at the factory starting at 111*f and up. i'll set it at 0.05 for now and see what the afr is. thanks
currently have the Engine: Fuel: General: Afterstart Enrichment: Initial Adder vs. ECT
zeroed out as thats what is set at the factory starting at 111*f and up. i'll set it at 0.05 for now and see what the afr is. thanks
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Launching!
Joined: Jan 2002
Posts: 299
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From: Detroit, Murder City
If you're running a MAF based tune (including stock), the combination of an aftermarket lid and stock programming will cause a mismatch in open loop. The lid changes how the MAF sensor reads enough to warrant calibration changes. I'd start by fixing this on a warmed up engine before you start inventing science to try and explain away something else.
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Joined: Jan 2002
Posts: 299
Likes: 41
From: Detroit, Murder City
You. Have you taken the time to to warm the car up and do an open loop recalibration of the MAF curve based on lambda errors with the fuel trims reset to zero? This should be your first step. You might find that just doing this fixes a number of other potential issues ranging from cold A/F control to Idle control behavior.
