AFR not right ?
 

I have a MY00 PPP running a full Decat. I use an Autometer AFR Gauge and just wanted to check the following.

When the car is up to temperature and I use light throttle etc the LED's on the AFR swing back and forth. Now if I put my foot down slightly more certainlt not going for it or anything but I say raise the boost pressure to about 4-5psi it continues to swing back and forth......If I then floor it the LED's swing around to 'Rich' which is what I expect. My concern is however that when I use lightish throttle but do get positive boost pressure it still swings back and forth ? I thought that it would swing around to 'rich' ? What I have also noticed is that this happens when the revs are below 3500 rpm - if I put my foot down with the car over 3500rpm with slight throttle or full throttle - only holding say 4psi or anything upto 16psi - then I get a 'rich' reading.

Sorry for the essay - but is this normal or do I have a problem ?

Anyone ??

that is normal operation.. it is still using closed loop (reading the AFR from the lambda sensor) and swinging the fueling arouns stoich.. it cuts to open loop and uses set fueling when the boost goes able a certain level etc..

Get a knocklink if you haven't already, you can then be confident it is not knocking or do something about it if it is.

Thanks for the reassurances JGM - I thought this was the case but just wanted to be sure :)

K/L is on my Xmas list ;)

no problem.

Either WOT or boost above 0.5 bar will send it into closed loop (full rich)

MB

Nice one Mark thanks for that - thats exacty it, anything over 0.5 bar and the AFR shows a 'rich' mixture.....and the more i push the throttle the more 'rich' it goes ;)

Thanks again for your reassurances