What is this part?

[Aaron285]

91 4.0 Is it the vacuum res.? If not what’s it called And where Is the plug located on the harness?

 

[RobbieD]

That's the cruise control servo. I'm not sure, on what plug that you're asking about.

 

[Aaron285]

It has a line that runs to vacuum block on manifold and other into cab thru firewall. the plug is on the side, between part and fender.
Only info online says its EGR Exhaust Vacuum Canister Reservoir Tank.

 

[Aaron285]

Also. I’m not sure why but my truck does t have or use any of these parts.

 

[alwaysFlOoReD]

Its part of the cruise control. The six pin plug should come out if the firewall below and slightly left of the big main white electrical connector.

You can see the hole in the firewall in this pic. I don't have my interior harness installed at the moment so can't confirm this is where the plug wiring would go to, its just my best guess.

 

[Aaron285]

I don't think I have this plug my harness. I'm having an issue with my truck loosing power while driving over 3000 RPM in 2nd gear and once shift into 3rd big power loss. Drives but feels like its only running on 3 cylinders. Just trying to go over all electrical/ connections to figure out the issue. Truck was fully rebuilt. Frame off, motor fully rebuilt with 422 cam, 80% new parts. Motor and harness are off a 91 4.0 2wd auto, ECU was changed and is re-manufactured for 91 4.0 4x4 Manuel. Truck frame, transfer case are 89', manual trans from 2001 R1 HD, dash, cab is 91/92 ranger.
Any ideas?

 

[91stranger]

Do you have any O2 sensors on your exhaust? Could just be a bad O2 sensor causing the power loss, or a bad catalytic converter if you have one.

 

[Aaron285]

Do you have any O2 sensors on your exhaust? Could just be a bad O2 sensor causing the power loss, or a bad catalytic converter if you have one.

Brand new headers and entire exhaust back is brand new and a brand new O2 sensor.