Let there be boost (control)

When it came into my hands, the GSX had an analog boost gauge and a brass manual boost controller. The car was tuned to deliver about 14lbs of boost and it did so well and consistently, but this was a little old school for me.

Enter, the AEM Tru-BoostX controller. This little number is a combo digital boost gauge and controller and included a shiny new boost control solenoid. The box showed up and with the help of a friend we got right to installing it. I yanked out the old gauge and chose to reuse the vacuum line that was already feeding it rather than running my own and I fed its harness down the same path as the existing AFR gauge harness.

The install was dead simple, largely thanks to the existing vacuum line and gauge pod from the previous owner. I’m less thankful though for his wiring job… I went to find the power source for the gauge and discovered its ends shoved under some key-on fuse under the dash… not great… but it works. This is definitely something I’m coming back to later. I spliced the power used for the AFR into the boost gauge and fed its harness through the firewall to hook up the solenoid.

Mounting the solenoid was easy as well. We selected a spot just behind the passenger side headlight where we drilled a pair of holes and bolted it in place. (After painting inside the fresh holes and putting a padded backing on the solenoid) The existing vacuum lines here were less impressive and so they were replaced with some fresh ones which we tied into place. With that, I hooked the battery up and clicked the key to ACC and the system fired right up.

Install done! But now to tune it…

Unfortunately this will have to wait, as just after the installation, a discovery was made. The car fired right up with the controller turned off, but as one of us reached to move something under the hood, the idle dropped and the car struggled to keep running. I got out and with the car idling, began tapping and prodding around under the hood. Each time I’d touch something around the MAF sensor, the idle would nearly die and then it would surge back. What was going on?

After a little more prodding, we found that the idle would fall whenever the intake or its harness was moved around. Following the harness back, it was immediately clear that the home made adapter connecting the later generation MAF to the earlier generation car was the culprit. It appears as though, rather than cutting the wires in the middle and soldering them together, a previous owner saw fit to dremel off the end of the old connector and solder wires from the MAF harness directly to the exposed internal contacts. Several of these solder joints were corroded and some were hanging on by a single strand. One was broken, and moving the connector around would disrupt the airflow signal to the ECU.

A new adapter is on the way while this one awaits the trash can, but tuning the boost controller will have to wait.