alhanooti

i did valve adjustment yesterday, I set my intake to 0.008 and exhaust to 0.010. i noticed that my AFR is leaner when the car is cold (16.2-17.1) until the engine is worm than decreases little richer than normal (13.1-13.5). my fuel pump had some high pitch sound but i don't hear it anymore. my idle is almost the same, it's just when the engine is cold the AFR is leaner than before. so i'm wondering if valve adjustment caused it to change or my fuel pump ? what should i check ?

sohc_mshue

It can affect the afr.

boostedf22c

I most definitely can and almost always will.

joes sled 2000

The map sensor readings change when the valves are adjusted hence the change in afr .

sohc_mshue

No the afr is changing because the cylinders are filling with a different amount of air.

joes sled 2000

Yes and when the cylinders take in more air the map readings increase .

alhanooti

do i need to get tune again or is there anyway to fix it ?

joes sled 2000

If you have a wideband in the car just make sure it stays nice and rich under full load . I dont think it should be off by much .

sohc_mshue

Volumetric Efficiency is changing. There is a different amount of air entering the cylinders at a certain load/rpm point compared to before. (i.e. there is more/less air entering the cylinders at 5000 rpm and 5psi manifold pressure than before at that rpm and load). Map readings are constantly changing.

joes sled 2000

I really dont want to hijack this thread . If a cylinder takes in more air than it did before , the map readings will be different than before . Regardless of rpm . Its really not rocket science . I do understand what you are saying . The op has not stated if he is even running forced induction even though this is the forced induction forum .