Open Loop/Cold Start A/F ????
Open Loop/Cold Start A/F ???? What is the proper A/F ratio for an open loop/cold start be at?
Last week when I tuned my car on the dyno, when I was done tuning, I completly cooled the car down to about 100 degrees. I did this so I could check my open loop/cold start A/F on the dyno's wideband.
When it first started up, my A/F was 12.0-12.7 A/F. I had them put it in gear and drive it and the A/F was about the same. Once the car went into closed loop, the A/F went to 14.3-14.8 A/F.
Are cars suppose to be so rich on cold starts? If so, what is the reason for this?
Last week when I tuned my car on the dyno, when I was done tuning, I completly cooled the car down to about 100 degrees. I did this so I could check my open loop/cold start A/F on the dyno's wideband.
When it first started up, my A/F was 12.0-12.7 A/F. I had them put it in gear and drive it and the A/F was about the same. Once the car went into closed loop, the A/F went to 14.3-14.8 A/F.
Are cars suppose to be so rich on cold starts? If so, what is the reason for this?
TECH Addict
Joined: Mar 2004
Posts: 2,336
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From: Fat Chance Hotel
You want the car to run a little rich when cold because the fuel doesn't atomize efficiently compared to a warm car and runs "shakey." You can lean out the cold a/f to the point at which the car still idles fine.
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To get the ideal a/f ratio for a stock car (yours shouldn't be too different) just divide the open loop a/f multiplier table by 14.7.
You will notice how the a/f gets richer the colder it is out. That should give you a good starting point.
Technical had the right response as to why you want it richer.
You will notice how the a/f gets richer the colder it is out. That should give you a good starting point.
Technical had the right response as to why you want it richer.
Originally Posted by NoGo
To get the ideal a/f ratio for a stock car (yours shouldn't be too different) just divide the open loop a/f multiplier table by 14.7.
Also, I've noticed that sometimes on cold starts I'll get black specks on the driveway from my exhaust pipes, looks and smells like its running rich. Thats another reason I asked the main question above..........
