Indication of an issue, possible vac leak?

[BMWManiac]

My car idles perfectly and I get 18-20 vac, whenever I drive at a constant rate drives perfect and around 14-16 vac, but.....if I let off the gas completely, the car does what it is supposed to do and goes "LEAN" on the sideband. The point of concern for me is that as soon as I tap the throttle, the wideband shows rich to less than 12 and sometimes into the 10s for an instant before returning to the usual 14-15 AFR when cruising...is this normal, or indication of a possible vac leak?

Other reason I suspect a vac leak is whenever I start up the car after sitting overnight or longer, the car runs lean and just bogs down and wants to die if I press the accelerator until I ease into it for a couple minutes....thoughts?

[gerry_miranda]

Wideband observations on my car....
Idle 14.6
cruise 14.6
WOT 12
Shut the throttle ...too lean to record
Intial opening of throttle ... rich

I belive this is normal operations.

[marc1119]

My car idles perfectly and I get 18-20 vac, whenever I drive at a constant rate drives perfect and around 14-16 vac, but.....if I let off the gas completely, the car does what it is supposed to do and goes "LEAN" on the sideband. The point of concern for me is that as soon as I tap the throttle, the wideband shows rich to less than 12 and sometimes into the 10s for an instant before returning to the usual 14-15 AFR when cruising...is this normal, or indication of a possible vac leak?

Other reason I suspect a vac leak is whenever I start up the car after sitting overnight or longer, the car runs lean and just bogs down and wants to die if I press the accelerator until I ease into it for a couple minutes....thoughts?


sounds normal to me too..

[BMWManiac]

Good.....that is what I was trying to confirm! It just seemed that initial use of the accelerator after letting off it, there was always a noticeable "hiccup" getting back on as the wideband read "rich"

[BadBoostedBmwM3]

Mine does the same so... i hope its okay.