Data Recorder Shows 300 rpm 'droop' After Car Launches??? - Page 3

Ed Wright · 06-16-2012, 02:36 PM

Acceleration Enrichment is like accelerator pump shot with a carb. Won't happen with a 2 step unless you don't have the pedal all the way down on the 2 step.
If using a 2 step, ignore the wide band O2 data there. It won't settle down until the car has moved. All you can do is add or remove fuel there to see what it needs. I would add fuel first, rather than pulling fuel from a lean condition. It's likely to look lean there, but that data won't be reliable with a 2 step. All you can do is test. I find most cars to be rich there, however. Get it too lean there and you can stick a ring, or worse.

BlueOval Ralph · 06-16-2012, 02:53 PM

One thing to remeber when looking at your data is to be sure all data loggers have same sample rate! Most of the O2 sensors are some what slow in response time and don't operate in very wide bands. I just finished working on a project for one of the major Auto Company's on a engine development program that used 3 different bands of O2 sensors.

Ed Wright · 06-16-2012, 06:34 PM

The humps I was originally getting were to 6100/6150, then pulled down to 5800. If it spun the tires then the humps would be to 6300 or so, then pull down to about 5800.
After fixing the air/fuel there normal dead hooks go to 6100/6150 and stay there a few frames then go up. Now if it spins the hump will still be 6300 or so, then to 6150 or so. Doesn't pull down to 5800 any longer. Shows in my 60's & ETs too. I at first thought I had a 5800 RPM converter. A few passes at a track rental fixed it.

06-16-2012, 02:36 PM	#21
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: Data Recorder Shows 300 rpm 'droop' After Car Launches?? Acceleration Enrichment is like accelerator pump shot with a carb. Won't happen with a 2 step unless you don't have the pedal all the way down on the 2 step. If using a 2 step, ignore the wide band O2 data there. It won't settle down until the car has moved. All you can do is add or remove fuel there to see what it needs. I would add fuel first, rather than pulling fuel from a lean condition. It's likely to look lean there, but that data won't be reliable with a 2 step. All you can do is test. I find most cars to be rich there, however. Get it too lean there and you can stick a ring, or worse. __________________ Ed Wright 4156 SS/JA

06-16-2012, 02:53 PM	#22
BlueOval Ralph Banned Join Date: Feb 2008 Posts: 852 Likes: 0 Liked 0 Times in 0 Posts	Re: Data Recorder Shows 300 rpm 'droop' After Car Launches?? One thing to remeber when looking at your data is to be sure all data loggers have same sample rate! Most of the O2 sensors are some what slow in response time and don't operate in very wide bands. I just finished working on a project for one of the major Auto Company's on a engine development program that used 3 different bands of O2 sensors.

06-16-2012, 06:34 PM	#23
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: Data Recorder Shows 300 rpm 'droop' After Car Launches?? The humps I was originally getting were to 6100/6150, then pulled down to 5800. If it spun the tires then the humps would be to 6300 or so, then pull down to about 5800. After fixing the air/fuel there normal dead hooks go to 6100/6150 and stay there a few frames then go up. Now if it spins the hump will still be 6300 or so, then to 6150 or so. Doesn't pull down to 5800 any longer. Shows in my 60's & ETs too. I at first thought I had a 5800 RPM converter. A few passes at a track rental fixed it. __________________ Ed Wright 4156 SS/JA