AFR goes rich intermittently during cruise
Starting a new thread cause its been a few months and my first one got hijacked. 427w dual quad fitech. Finally got the two synchronized, plugs look good after 30 minute idle, IAC stable around 10. Very rich when cold, but runs well. Trying to tune plugs for cruising. Was lean so I richened up at low cruise. Thing is it seems to drop a full point rich from target during cruise. I think its when load drops, like slight downhill. Any ideas on how to fix this?
https://www.dropbox.com/s/rw993mby0ucgs2s/LOG%2065%20excerpt.xlsx?dl=0
They usually move around that much or more. Let it learn. It will get better.
Thanks Austin. I'm like a nervous parent. Once I get this right I'm going to post a step by step on how to synchronize dual quads. The car came from the builder "fully tuned". After sending the motor back twice from its eating a valve being way over rich, I decided to tune it myself. That's when I found this site. As you pointed out in reply to one of my first posts, the O2 sensor must be beyond the collector, not on a single runner. Also had a bad coolant temperature sensor and needed shielding on tach signal wire. All that before I could start to synchronize the dual throttle bodies. Getting the same color on plugs on fronts (cylinders 1,2,5,6) and backs(cylinders 3,4,7,8) took me a lot of time and plugs. If I can get an efficient way to clean fouled plugs, I'll never need to buy another plug for a few life times. I have enjoyed working on it, and it will all be worth it once I get it right. I'd have been lost with out you and this sight. Thanks again to you and the others who gave advice.
I think I have idle and cruise about tuned. Next will be 3-6.5K.
Glad to hear you are getting good results. I remember your first posts. When someone starts with they had a shop install, I get nervous. I won't install for someone unless they are fully involved. The user needs to have knowledge of the system.
Hey Austin, been traveling for work last couple months. Car runs great, seems to have learned all it can. Still going rich at steady cruise when there's a change of load, even slight down hill. (13.8 goes to low 11's.) Also goes rich letting off the throttle, then leans out after 3-5 seconds. Cruise goes from steady 13.8 to ~10.4 when I lift. If this is a Tip in issue, where's a good place to change it from 0? There's no bogging, and the plugs look good. Is this even a problem or am I worried about nothing? I forgot to get a recent log yesterday, but nothing has changed regarding these issues since the last log. I'll get you a new log when it stops raining (Prolly Tuesday.) Thanks
Let's look at a Log, now that it has had time to learn.
Are 80 lines enough, or should I send more? I think this shows how it goes rich at cruise.
I can't see it. I think you need to share it, so we can see it.
3 dots to the right of the file name in Dropbox, select share, create link, copy to clipboard, paste on website post.
Sorry, I usually get this one right.
https://www.dropbox.com/s/y2ix7jzkhb3w60d/Log%20DB%2082%20Excerpt.xlsx?dl=0
https://www.dropbox.com/s/y2ix7jzkhb3w60d/Log%20DB%2082%20Excerpt.xlsx?dl=0