Plenum Torque specs
 

I've had the plenum off of my 95 Jimmy a couple of times now. Once was to change the CPI and the other was to make changing the distributor cap/rotor easier. I'm curious, if there are any, what are the factory specs for torquing down the plenum? I don't know if mine's over torqued or under torqued or if it even matters. I had one mechanic tell me not to worry about it, but with my chronic OCD, I do worry about it.

EDIT: I've actually had the plenum off 3 times. The third time was to change the gasket that I pretty much destroyed the first 2 times I removed it.

Tighten the bolts to 10 N·m (88 lb in). I know on my 1997 which has a different manifild, they have 2 passes. 1st pass at 44 in-lbf and second pass at 88 in-lbf. Remember these are in - lbf., so it is not a large amount of torque.

The sequence starts with the 1st bolt to the left of the throttle body and proceeds clockwise ending with the 10th bolt on the right side of the throttle body (Looking from the front of the vehicle).

Actually the 10th bolt is in line with the throttle body, it's the 9th that is just to the right of the throttle body. I was not sure how to paste in teh picture.

From Chilton's
Removal & Installation

The CMFI assembly is mounted to the lower intake manifold. The upper intake manifold assembly must be removed for access. The CMFI assembly includes a fuel meter body, gasket seal, fuel pressure regulator, fuel injector and six poppet nozzles with fuel tubes. Should a failure occur in any components of the CMFI unit, the entire assembly must be replaced.

1. Remove the plastic cover and properly relieve the fuel system pressure.
2. Disconnect the negative battery cable, then remove the air cleaner and air inlet duct.
3. Unplug the wiring harness from the necessary upper intake components including:
   • Throttle Position (TP) sensor
   • Idle Air Control (IAC) motor
   • Manifold Absolute Pressure (MAP) sensor
   • Intake Manifold Tuning Valve (IMTV)
4. Disconnect the throttle linkage from the upper intake manifold, then remove the ignition coil.
5. Disconnect the PCV hose at the rear of the upper intake manifold, then tag and unplug the vacuum hoses from both the front and rear of the upper intake.
6. Remove the upper intake manifold bolts and studs, making sure to note or mark the location of all studs to assure proper installation. Remove the upper intake manifold from the engine.

http://www.chiltonlibrary.com/conten...s/85385059.gif Exploded view of the upper and lower intake manifolds and the CMFI system components
Click to Enlarge

1. Unplug the injector wiring harness connector at the CMFI assembly.
2. Remove and discard the fuel fitting clip.
3. Disconnect the fuel inlet and return tube and fitting assembly. Discard the old O-rings.
4. Squeeze the poppet nozzle locktabs together while lifting each nozzle out of the casting socket. Once all six nozzles are released, carefully lift the CMFI assembly out of the casting.

To install:

1. Align the CMFI assembly grommet with the casting grommet slots and push downward until it is seated in the bottom guide hole.

CAUTION To reduce the risk of fire and personal injury, be ABSOLUTELY SURE that the poppet nozzles are firmly seated and locked into their casting sockets. An unlocked poppet nozzle could work loose from its socket resulting in a dangerous fuel leak.

1. Carefully insert the poppet nozzles into the casting sockets. Make sure they are FIRMLY SEATED and locked into the casting sockets.
2. Position new O-ring seals (lightly coated with clean engine oil), then connect the fuel inlet and return tube and fitting assembly.
3. Install a new fuel fitting clip.
4. Temporarily connect the negative battery cable, then pressurize the fuel system by cycling the ignition switch ON for 2 seconds, then OFF for 10 seconds and repeating, as necessary. Once the fuel system is pressurized, check for leaks.
5. Disconnect the negative battery cable.

http://www.chiltonlibrary.com/conten...s/85385060.gif Upper intake manifold torque sequence
Click to Enlarge

1. Position a new upper intake manifold gasket on the engine, making sure the green sealing lines are facing upward.
2. Install the upper intake manifold being careful not to pinch the fuel injector wires between the manifolds.
3. Install the manifold retainers, making sure the studs are properly positioned, then tighten them using the proper sequence to specifications. Refer to Section 3 of this manual for the manifold specification.
4. Connect the PCV hose to the rear of the upper intake manifold and the vacuum hoses to both the front and rear of the manifold assembly.
5. Connect the throttle linkage to the upper intake, then install the ignition coil.
6. Attach the necessary wiring to the upper intake components including the TP sensor, IAC motor, MAP sensor and the IMTV.
7. Install the plastic cover, the air cleaner and air inlet duct.
8. Connect the negative battery cable.

Attached are the Specs for a 95


Here are the numbers for a Vin W 4.3l Upper Intake Manifold 124 in/lbs or 14 Nm.

[IMG]file:///C:/Users/Owner/AppData/Local/Temp/moz-screenshot-19.jpg[/IMG]

Thanks for the replys, especially the one with the pics. Now, do you know where I can find a cheap but reliable torque wrench?

Best bet is Harbor Freight Tools.

http://search.harborfreight.com/cpis...ench&Submit=Go

If you have a store near you, they also have an online version for their stores at
www.harborfreightusa.com.

You can sign up for their emails which routinely provide 20% off coupons on nonsale items.

Yeah, I do have a store by me. I'll have to check that out and sign up for their email thing. The only thing is, they have some pretty cheap stuff. I've bought some stuff there that I wouldn't recommend to anyone. I've bought some stuff there that's been awesome too. It's kind of hit or miss. I will give it a try though.

wow, this is good to know. especially that i have to check my spider in my 95 S10. has anyone ever bought a remanufactured spider injector from rockauto before? is so how was the quality? did it run good after? im considering buying it from them and was wondering any info or experiences from others who have bought it from them. let me know
thanks

I got mine from Rockauto. I got the cheapest new one, I believe. I got it for $250 ish? I think. It was almost a year ago now so I don't really remember. I've also been driving around with an over torqued plenum for that long too :(

Well I torqued the plenum back to where it was supposed to be, and it didn't change anything. It was definitely over-torqued. 124 in-lbs is pretty much right where you start to feel resistance when you're hand tightening the bolts.

I guess it was worth a try; too bad it didn't fix anything though.

THanks!
 

Just want to thank posters for pics and info... I replaced Fuel pressure regulator and surging stopped, motor runs great! The previous owner had spent 10 years chasing the problem of shuddering (I changed rear u- joint) / surging and shaking - cause of missfire was gas spewing out of regulator n causing fouled plugs on passenger side