Bought 87 GTA does not have stock exhaust and I also had to swap in an engine. I thought I got a stock L98. Everyones telling me it cant be.

It really sounds good and I know if I lowered the idle down below the 850 or so that it idles at it would have a tremendously lopey idle. Its about half way there already.

One day I unhooked the MAF (trying to troubleshoot another issue) and this thing had a wicked idle. It idled down I guess while the puter was trying to adjust to the missing MAF. After about 2 minutes it made its adjustment and it went to the normal idle.

So how can that be done?

 

idle set screw, punch out the cover on it and turn it counter clockwise, you may get it lower than 850, but not by much.....

 

Will any changes need to be made to the IAC settings or TPS. The Haynes manual says I need to disconnect stuff check voltages, ground the ALDL, and reconnect stuff.

Will I mess something up if I remove this plate and adjust idle withoout doing these other things?

 

Short answer, yes. The computer has no way of knowing the actual position of the IAC other than the position it's supposed to start at. If you adjust the idle screw while the IAC is not at a known position, the computer tries to compensate. if you do it the correct way i believe it "learns" the new state and wont try to compensate.

Anyways, it's not hard to do it the correct way. Think of it like trying to adjust the timing while the computer is trying to adjust it at the same time. That's why you disconnect it.

 

Whats the best tool to use to punch out the cover? I tried a few punches and then a flat head and nothing made it budge, am I being to soft on it?

 

yea you are. It's kinda thicker than aluminum foil, but thinner than a tin can. Not by much though.

 

I used a stout scratch awl. puncture the edge and then pry it out. Alternative, a puncture dead center will allow a series of larger drills to enlarge enough to get a torx screw driver into hole to reset TSS.