Scaaarrry AFR on startup!

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May 1, 2006 | 08:13 AM

#21

99whitews6

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From: Minnesota

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Originally Posted by RPO_Z06

What did you adjust ?

Even though I dont physically have AIR hardware on the car, I changed the AIR enable temp from 14F to 284F. Then I increased the OLFA and poof, lower AFRs on startup!

May 2, 2006 | 08:02 AM

#22

Hodge

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From: Fort Smith, AR

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Originally Posted by 99whitews6

So I did have issues with the WB sensor but I thought I ironed them out. Car was running fine and starting fine. It was lean(16-17.0:1) on startup prior to this but now I am just confused. I logged Cracker Airflow, Follower Airflow, and Base spark in the histos to try and fix my decel and cruise issue and then input the values(which seemed low) into my tune for the follower and cracker airflow. Went to start up car and after the WB warmed up it said like 19-21.0:1. It definately idled different than before. So after about ten seconds of being confused I gave her a little gas to about 2K rpms and watched the WB go down to about 15.0:1 and then let off and watched it go back to ~19.0:1. What the heck? Do the Cracker airflow and Follower airflow affect AFR that much?

Put a wideband on my Y2K Vette and I am seeing the same thing. At first I thought the wideband sensor wasn't warmed up. Once I had my scanner connected along with the wideband I could see the AFR was VERY lean until the car went into closed loop.

May 2, 2006 | 08:22 AM

#23

99whitews6

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From: Minnesota

Quote:

Originally Posted by Hodge

Have you removed AIR? (not sure if vettes have this or not)

May 3, 2006 | 09:08 PM

#24

Hodge

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From: Fort Smith, AR

Quote:

Originally Posted by 99whitews6

Have you removed AIR? (not sure if vettes have this or not)

You got me thinking... On Vettes, the AIR is on for the first couple of minutes of engine operation (at least that is what my memory says). That would explain the very lean readings. Makes sense because I started the car in speed density mode the other morning and my AFR was a more believable 12.7:1 when cold. Guess I need to deactivite AIR and keep logging. Won't be able to try anything until next week. Going out of town.

May 8, 2006 | 10:13 AM

#25

Hodge

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From: Fort Smith, AR

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Originally Posted by 99whitews6

Have you removed AIR? (not sure if vettes have this or not)

The AIR pump was skewing the readings at startup. I set the enable temp to 150 degC (deactivated) and my AFR is "around" 13:1.

May 8, 2006 | 10:16 AM

#26

99whitews6

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From: Minnesota

Quote:

Originally Posted by Hodge

The AIR pump was skewing the readings at startup. I set the enable temp to 150 degC (deactivated) and my AFR is "around" 13:1.

Good to hear. I found out that I still get high AFR reading on WARM or HOT startups. Cold startups are fine as I see 12.0:1 reading right from startup.

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