polo g40 air fuel ratio ?

[Oli b]

just got a innovate mtx-l wideband afr gauge just wandering what afr reading would determine if the mapping is right for my engine
my current spec is
standard g40 engine and head
stage4 jabba charger (peaking at 1 bar 15000 miles since last rebuild)
65mm pulley
jabba chip in ecu
gt inlet
dewedged tb
i know 14.7-1 is ideal but should they be rich like around 12-13 on full chat
cheers all

[AlexG40]

I think mine used to go to 11 on full throttle and right off the other way on the over run. Part throttle pretty close to 14

[Andy]

Should cycle either side of 14.7:1 at idle and low load. On cold start you'll find it's circa 10:1, and anywhere between 12.5:1 and 10.5:1 on full throttle/full boost. You'll get full-scale lean (might be 16:1 or >20:1 depending on gauge) when you snap the throttle shut.

[Alexiskayak_7]

Should cycle either side of 14.7:1 at idle and low load. On cold start you'll find it's circa 10:1, and anywhere between 12.5:1 and 10.5:1 on full throttle/full boost. You'll get full-scale lean (might be 16:1 or >20:1 depending on gauge) when you snap the throttle shut.

On cold start what's the afr at idle and at 2500rpm with partial throttle?

[Andy]

Depends on MAP value, coolant temp, air temp etc. etc.

[Oli b]

Should cycle either side of 14.7:1 at idle and low load. On cold start you'll find it's circa 10:1, and anywhere between 12.5:1 and 10.5:1 on full throttle/full boost. You'll get full-scale lean (might be 16:1 or >20:1 depending on gauge) when you snap the throttle shut.

mine cycles around 14.7 at idle and sits around 14.5 driving slowley off boost  and on full boost hits 11 but creeps upto 12 near the redline,  goes max lean when on over run when its up to running temp cold starts is initaly 9.5-10

[Andy]

Sounds about right to me - though on cars with stock cast pistons I tend to have them richen up nearer the redline to keep things a bit cooler.