Does anyone have the adjustment procedures (OEM or one that works) for the ASR servo and accelerator cables? I installed a Holley 58mm T.B. on my 97 Z28 w/ ASR, however, the T.B. butterflies are only opening about 65 degrees (70%) with the accelerator pedal pressed all the way down. I’m sure the T.B. butterflies and TPS should be at 90 degrees (at, or near the T.B. mechanical end-stop) at WOT and the problem is an adjustment issue with the ASR system.

 

I figured-out the ASR cable adjustment and thought I would post it. This is how it works. The throttle cable (between the TB & ASR servo) has an adjustment device on the cable outer sheath. The TB range of motion (more or less) is changed by this adjuster. To achieve more range of motion and increase the butterfly opening, you extend the adjuster (outer sheath is longer). Conversely, to decrease the TB range of motion you shorten the adjuster (outer sheath is shorter and pushed in on the adjuster).

To release the adjuster, remove (unsnap) the plastic lock clip on the adjuster, and the tension on the throttle cable becomes lose. Pull both halves of the outer sheath (each side of the adjuster) extending the sheath until the cable to the TB becomes snug. Leave a very small amount of slack in the cable to ensure the TB butterflies are not pulled open at idle. Re-insert the plastic lock clip and ensure it completely locks the adjuster (snaps all the way down).

Have someone slowly depress the accelerator pedal while checking the TB range of motion. The TB should reach its end-stop (WOT) exactly when the accelerator pedal is all the way on the floor. If the TB butterflies are still not completely open with the accelerator on the floor, unlock and extend the adjuster a small amount and recheck. If the TB hits its end-stop before the accelerator pedal is on the floor, or it is causing a fast idle (butterflies pulled open at idle), slightly shorten the adjuster to provide some slack in the cable. After I was finished with the adjustment, I placed a tie-wrap (plastic zip-lock) over the lock clip to ensure it doesn’t release (additional insurance).

The ASR servo alignment should not be an issue with this cable adjustment. Let me know if this works for you. Also, I had been running mid/high 12s @ 107 mph with my stock 48mm TB. I’m can’t wait to see what the Holley 58mm will do now.

Kooks w/ y-pipe (no cats), LT4 Hot Cam, 1.6 RRs, 3.73s, 2600 TCI stall, Aeromotive fuel regulator, aluminum CNC LCAs w/ relocation brackets, aluminum drive shaft, under-drive pulleys.