justavillain
Well-Known Member
So I have had a super regular AFR since I got my last tune all set up in my car. Until last night….I usually Only worry about it mostly when I am hot rodding around or making a pass with my car but I always keep an eye on it just like it‘s oil pressure because if you have it why not. So anyway.
last night I was driving my car home from a wedding (classic car restorer and who helped get my A12 on the road) and the AFR was reading FAT like dumping into the 10‘s at idle. It NEVER has done that it usually idled around 13.2-13.4. But when I put the pedal down it went back to the 12.2-12.4 that I normally get when I do a hard pull. So I wasn’t too worried as I was more rich than lean. car still runs fine, did a hard pull and it stayed in the 12‘s the whole time.
but then out of no where the car went super lean. At idle it flipped and went into the 14’s like around 14.2 14.4. I’d give it a little gas and it would lean to 14.7 and just give it a slight run down the road to like 55-60mph not hard on the throttle it would go to the 13’s not the 12’s this time but then I would lift hard like at the end of a run and it would lean out hard the AFR would go lean to read higher than it could - - - then back in to the 14’s and 13’s. And it did this for miles.
The car still ran fine. The fuel tank was full, good gas ( it had 3/4 of 110 from the last race of the season, then I topped it off with 93 from a super busy station because it was going to be a long run to the wedding and back)
background is we didn’t have time to really do it perfect and stabbed in the AFR only on the left bank I was going to do a left and right AFR so its about 4” back from the header collector on the left side so it’s only reading accurately the left bank. I want to change that there is other things in the works for the car also. The car is called the Fumblebee because every time it starts to run the way it should something goes wrong it doesn’t want to be on the road. This just might be it’s way of messing with me. just last month it kicked the alternator out of The motor. Info on the motor if needed is it’s a 72 block 440 30 over, 6 pack rods, JB Forged molly coated pistons, max wedge ported heads 84CC Cambers, with an M1 intake, Holley 900CFM carb, idk what jets are in it or the power valve, all mechanical no choke, but does have the choke horn, it has the dominator style annulars but idk much more about it. I can get the numbers off it tonight. The Cam is a Huges off the shelf not sure what the specs are I can get that off my build book too if needed. It’s a runner for sure. Nothing hot hot but she gives the modern cars a bit of a show.
so my question is to the powerful internet as I have never really AFR’d a car before, and I haven’t pulled the hood off yet and checked the banks to make sure I’m firing on all 8 cyl. I’ll do that tonight and report back. should I replace all my plugs and keep on? Replace my fuel filter? Replace the O2 sensor? Think it‘s a fluke and run it again and see what it does As the car is KNOWN to cause trouble? Now could it also have been the cool air messing with the car? It was about the mid 40’s last night wen I was driving it home, with a pretty decent humidity level. I have never had to mess around with tuning or running my car this late into the year (never had it running this long as it‘s the fumblebee)
last night I was driving my car home from a wedding (classic car restorer and who helped get my A12 on the road) and the AFR was reading FAT like dumping into the 10‘s at idle. It NEVER has done that it usually idled around 13.2-13.4. But when I put the pedal down it went back to the 12.2-12.4 that I normally get when I do a hard pull. So I wasn’t too worried as I was more rich than lean. car still runs fine, did a hard pull and it stayed in the 12‘s the whole time.
but then out of no where the car went super lean. At idle it flipped and went into the 14’s like around 14.2 14.4. I’d give it a little gas and it would lean to 14.7 and just give it a slight run down the road to like 55-60mph not hard on the throttle it would go to the 13’s not the 12’s this time but then I would lift hard like at the end of a run and it would lean out hard the AFR would go lean to read higher than it could - - - then back in to the 14’s and 13’s. And it did this for miles.
The car still ran fine. The fuel tank was full, good gas ( it had 3/4 of 110 from the last race of the season, then I topped it off with 93 from a super busy station because it was going to be a long run to the wedding and back)
background is we didn’t have time to really do it perfect and stabbed in the AFR only on the left bank I was going to do a left and right AFR so its about 4” back from the header collector on the left side so it’s only reading accurately the left bank. I want to change that there is other things in the works for the car also. The car is called the Fumblebee because every time it starts to run the way it should something goes wrong it doesn’t want to be on the road. This just might be it’s way of messing with me. just last month it kicked the alternator out of The motor. Info on the motor if needed is it’s a 72 block 440 30 over, 6 pack rods, JB Forged molly coated pistons, max wedge ported heads 84CC Cambers, with an M1 intake, Holley 900CFM carb, idk what jets are in it or the power valve, all mechanical no choke, but does have the choke horn, it has the dominator style annulars but idk much more about it. I can get the numbers off it tonight. The Cam is a Huges off the shelf not sure what the specs are I can get that off my build book too if needed. It’s a runner for sure. Nothing hot hot but she gives the modern cars a bit of a show.
so my question is to the powerful internet as I have never really AFR’d a car before, and I haven’t pulled the hood off yet and checked the banks to make sure I’m firing on all 8 cyl. I’ll do that tonight and report back. should I replace all my plugs and keep on? Replace my fuel filter? Replace the O2 sensor? Think it‘s a fluke and run it again and see what it does As the car is KNOWN to cause trouble? Now could it also have been the cool air messing with the car? It was about the mid 40’s last night wen I was driving it home, with a pretty decent humidity level. I have never had to mess around with tuning or running my car this late into the year (never had it running this long as it‘s the fumblebee)
