Manifold change

[v8slrtorana]

Intro.
304, crane 284 cam Active single plain manifold, 808 12P, tune copied over from modified factory tune.
Motor ran ok, i always new the manifold was incorrect so i brought a AFR gauge to start tuning.
Generally AFR's was around 13.5 on cruise and light throttle. Didn't bother me with the planned next change.
THEN
I fitted a torque power dual plain.
Now my AFR's are 18.9 cruise and 22 on light throttle.

Can the manifold cause such drastic change, or have i got a vacuum leak ?
With Tuner pro running, motor was idling in the 100kpa field.

Cheers

[immortality]

Where are you getting your map reference from?

[v8slrtorana]

tunerpro RT
Map vacuum line is connected to the Edelbrock 3878 vacuum port

[HQ355]

What AFR gauge are you using ? Have you got a wideband ? That would be better to tune with, that is really lean, I'd be careful

[Dylan]

Yes it could. I tuned a 304 with small cam and active intake. The VE was less than stock. And flow figures on the net say the same thing. I spoke to a guy from active on the phone once and he said they cast the ports smaller than stock so guys can match port them.

More air flow would result in a leaner mixture.

[Dylan]

As for the vac reading thats not right that motor once tuned should idle around 50 60 kpa.
Still got the active hat on this intake?

[v8slrtorana]

Using Innovate MTX-L. I even made sure i re-calibrated it after the manifold change because of so much difference
No, never had the active hat.
Was using the same Edelbrock 4 barrel on both manifolds.

[Dylan]

The different AFR's don't surprise me but the vacuum reading does. Somethings wrong for sure. Remove the hose from the throttle body and suck on it while logging and look for a reading to prove the sensor and wiring. Then if that's ok look at the ports you are using to get the signal from if that even changed ports? Blocked hose? 0 actual vacuum is 100kpa.

Does it read as expected while driving?

[v8slrtorana]

Does log this help ?

[Dylan]

Idling at 50kpa on my screen? 12 V112 1 bar ADX I used.