AF lean between shifts

[Blue89Hatchback]

Is the AF ratio supposed to go lean between shifts and when you let off on the throttle? Iv'e datalogged my AF and it goes over 20/1 between shifts and also backfires in the exhaust. This is not a mod motor but a 5.0. Need some help with this please. Thanks.

 

[stangbear427]

If you let off the throttle under load and use the compression of the engine to slow down, it will go lean- very lean. And that's fine. However, I don't see why it would between shifts. That may be a sign that something is wrong somewhere, but I wouldn't know what. I just haven't observed it on mine, and it doesn't sound right. Back to the top...

 

[powershift351]

what injectors do you have, and what fuel pressure are you running? where is your timing set to? What are your plugs gapped at?

 

[powershift351]

shouldnt be leaning out with that massive 255 pump, must be something past the afpr

 

[Blue89Hatchback]

Im running 38ib injectors, 46ibs FP base, 20 degrees total timing, and an S-trim with stock pullies.

 

[stangbear427]

Unless I misunderstand your post, you are overworking those injectors. Step up to 42# ones at least if you're running that much pressure.

 

[Demented4.6]

what computer are you running?? 5-spd computers change timing when clutch is pushed in, maybe lean it out as well .