88 TC 5 Speed Low Boost (IHI turbo)

I've got a 5 speed 88 TC that's only getting 9-10 PSI with the premium switch on

pulls 19-20 vacuum at idle

I have an aftermarket Autometer boost gauge that shows vacuum and boost up to 30 PSI

Haven't found any vacuum leaks, has a new air filter if that matters

where should I look next?

BCS or fuel switch relay may have failed or you may have a wiring issue.

Do yourself a favor and pitch the stock boost control system and get a Gillis manual boost controller which will let you set max boost to anything you want. Plus you will get max boost in all gears and boost will come in quicker.

BCS or fuel switch relay may have failed or you may have a wiring issue.

Do yourself a favor and pitch the stock boost control system and get a Gillis manual boost controller which will let you set max boost to anything you want. Plus you will get max boost in all gears and boost will come in quicker.

^^^^ +++++

I’ve done that and I’ll never go back to the BCS.

Slowbird, I had a similar issue with my 88 TC after checking multiple things I found that the wastegate actuator road was seized up on the flapper on the turbo. It looked like it was somehow welded to the pivot and I had to pry it off and then sand it down and re-install. As it wouldn't pivot and close, it was only building low boost, if you have a vacuum tester, something like a mightyvac you can hook it up to the wastegate and put some air pressure on it to check movement. just something else to check out