Doing some data logs tonight and noticed my WOT AFR were getting lean.

So I drove to the gas station (20 minutes of highway driving, so I wasn't that low on fuel) fill up the tank and voila. My AFR are richer....

Any input?

 

Yea this is common. The aftermarket pumps struggle when your low on gas and can cause the motor to go lean. Be careful and fill up

 

Actually it was probably closer to 1/2 a tank. Is that common?

 

Fuel pressure may be dropping, look into getting a FPR?

 

Sounds like the pump was starving

 

What pump do you have?

 

AEM pump.

I actually noticed it again the other day. Tank was almost full.....


I was just cruising around doing part throttle logs and after about an hour the AFR's would go VERY lean when slightly accelerating.

Almost like the pump was "tired" and needed a second before it would get going......


Any ideas?

Thanks!

 

do you have 02 feedback and if so how far can it skew the fuel map I have seen fluctuations like that from 02 feedback but I run aem v1

 

Any other suggestions? Or maybe some guidance on what to check?

 

I have been experiencing a similar issue...my AFR goes way lean at partial throttle...to the point that the car started to bog down or stumble. It was not the fuel pump, it was not the injectors, it was not the alternator...but it may have been the coils... will let you know as I find out.