91 TBI intake vacuum hookup??!

[Hubnut]

Can someone tell me where this intake port is supposed to go to? PO left if off. If I block it off, truck misfires a bunch and has poor power, poor shifting. If I leave it open, it runs great with plenty of power. I'm assuming an unfiltered intake is a bad thing.

 

[randy88k5]

I recognize it. I can't remember off the top of my head where it goes. I'll check when I get home tonite.

 

[Hubnut]

thanks!

 

[GalDemSuga]

Can someone tell me where this intake port is supposed to go to? PO left if off. If I block it off, truck misfires a bunch and has poor power, poor shifting. If I leave it open, it runs great with plenty of power. I'm assuming an unfiltered intake is a bad thing.

There is a line coming off of the fire wall that connects to that.

 

[Thunder]

That port should have a vac line running to the Vacuum reservoir. The heater controls and cruise control use that line. As far as i know no engine/trans controls use that port. What is the line that comes off of it hooked up to?

 

[Hubnut]

The vacuum line from the intake (shown in photo) splits and runs to a hard skinny line on the firewall, and to a round plastic thingy on the driver's firewall (reservoir?). When the line is closed off, it runs rough. When I allow it to suck air, it runs fine. I will try the experiment again. Maybe it was a fortuitous relationship and not causal.

One more question. If the injectors are going bad. Would they give symptoms like an electrical problem? I occassionally get skips, especially when accelerating hard like the rotor button missed a few cylinders. Sometimes it's real bad. Ive changed the IAC, Ignition module, rotor and cap, and coil. I'm confused and ready to trash the freakin thing it's so frustrating!!