I have headers, test pipes and catback. When I coast/shift etc. my a/f ratio will spike to 20 and instantly come down to 12-13 once I step on the gas. I have searched and a few post have said this is normal and not a problem. I am just checking to make sure that lean under these conditions especially a/f of 20 is ok.

Thanks for any help
Doc

 

Ummm well considering when you let out of the throttle you loose most of the fuel untill your rpms fall to idle.. it will peg the sensor untill your ideling again then will go back to ~14.7

 

So definitively its ok for car to spike like this as long as it returns back to 11.5 to 13.5 under load?

 

It will do that bone stock, same as all other cars

 

No load, goes to vacuum, less air, no need for fuel, no worries.

 

Well technically if hes N/A he will always be in vaccum.

 

Well at wot my vac gauge reads 0 so it's at equilibrium with the atmospheric pressure or 14.7 psi. So it's technically never a complete vacuum.

 

its called decel fuel cut.

 

Thanx

 

Yes it's normal. /lockthread