Maybe you can guide me here. I installed a Blackwing several weeks ago with and upgraded Air Bridge. A little prior background as well. The previous owner had a halltech tric or trap on there and there is now the cut out where it went through. When the previous owner sold it he put back on the stock. When I removed the stock I found that it had previously been modified. I installed the blackwing over this hole. Also the previous owner put Z06 style screens around the fog lamps.

The only problem I noticed off the bat was my fuel consumption went way up. At the same time several forum members mentioned that a upgraded air bridge was not really necessary unless I was doing more perfomance mods to the engine, which I am not. So I returned the air bridge and put the stock back on but with a new tappered silicone coupler instead of the stock accordian. Now when I drive, fuel consumption is normal but when cruising let say at 70 and then coasting to about 55, as soon as I hit the 55 mph range to about the 45 or so, the car shakes or hesitates. (engine braking).

I did a idle relearn: Disconnected the battery for 15 min., started it with everything off and let it idle for 5 minutes then a another couple of minutes with the AC on. Didn't help. I have another idle relearn procedure that is different which I am going to try.

The only other recommendation was that it might be a vaccum leak. I will check the connections this weekend.

Another member from another forum suggested that I had to cover the hole that was made from the installation of the halltech because of the hot engine air and cold air mixing throwing the PCM off. Was there any kid of whole their originally on the stock setup?

Any thoughts on the matter?

Thanks!

Chris

Chris,
It is true that those overpriced airbridges cause ill engine functioning but so also does that smooth couplier.
They also give zero gains since the cylinder volume is small and increasing flow outside the engine does not make cylinder volume any larger.

GM is not stupid and their coupler is designed to work correctly with the PCM's adaptive strategy and to reduce air movement sound.

I make a cold airbox called the Icebox, it was deisgned to tottaly enclose the Blackwing and only allow the colder airflow coming from a hole behind it via shroud.

In your case what happens is when your driving the engine gets better colder airflow and adjusts the AFR but then when butterfly of throttlebody closes the pressure changes and now engine gets the hotter engine bay air which causes the PCM to adjust again thus this causes PCM to ramp back and forth from a richer to leaner state

So you either have to block off that hole and live with the hotter airmass which does not make as much HP or install a box like the Icebox and only allow the colder outside air into filter.

ANY leak, even the slighest from aircleaner to TB will cause weird effects for its unmetered and the adaptive strategy was never designed for that condition.

Consider my 1999 C5 is about 500 HP at flywheel and I still use stock MAF, airbridge, coupler and TB and none of those are causing a limit of airflow even when I went 217 MPH.

My Blackwing is now 5 years old and still functions as well as day it was put in with cleaning it about once a year and BTW the new C6 Z06, GM is using now a Donaldson filter.