Different NA intake plenums in different models?

Troubleshooting
1

Hello all my name is: Dylan
I have a: 1991 NA Auto AWD GTO

It has the following: Hey guys bit of a weird one here. My VICS unit was damaged beyond repair and the nylon gear had been ground away due to incorrect installation. My car is a 91 automatic GTO AWD. I purchased a second hand intake off another guy on a forum, off basically the same model (NA Auto awd GTO) and the intake is different. The VICS unit is significantly smaller, the rotation of the VICS is about 30 degrees where my original one had approx 90 degree rotation, and the nylon gear is non removable. Any ideas? I’m getting backfires and detonation - probably due to the fact the ECU is anticipating different airflow due to the greater degree of movement the old intake had?
Also the intake to the engine looks bigger on my old one, but that may be a optical illusion.

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Old plenum

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New plenum

Cheers

2

Did you double check to see if you have reconnected all the hoses to their proper locations? I’ve checked and rechecked every time I’ve taken mine off and still sometimes overlooked one.

3

A long shot but might be worth disconnecting the battery to reset all the fuel settings etc. Might help the car adjust to using the new airflow with this intake.