My Mods

These mods were done on a 1996 LT4. Your C4 may be different but most things should be similar.



Holley 52mm TB
Holley AFPR

Pics of my Holley 52mm TB and my Holley Adj Fuel Pressure Regulator. Both went relatively smooth. Hooking the fuel line backup to the AFPR took a little work. Because of the locations now the fuel lines are right up against each other.

On the TB I wanted to continue to use my Grand Sport TB cover, however, the holes don't line up exactly and I had to elongate most of the holes on the stock TB cover. Also, the top vacuum connector comes out of the TB parallel whereas the stock one came out on a down angle. So, hooking the vacuum line to it was a little work.

























TB Bypass

I have noticed that after driving the TB is alot cooler. Both radiator hoses going into the TB are 3/8 inch. Some might have a 5/8 inch hose. The right side hose is a short elbow hose at the bottom of the TB. It's also the most difficult one to get to because of the other vacuum lines and wires.



This is the other hose on the left side of the TB at the bottom. Very easy to get to. You'll need various needle nose pliers, regular pliers, and channel lock pliers to remove the various spring clamps on the hoses. You may also need a razor blade to cut the hoses off of the connectors.



(blue circle) Here's a view inside of the TB, still debating whether to put out $40 for an air charger. As you can see this area is not very air flow friendly. Most opinions are that they are not very affective unless your running at very high RPM's.



OK, ready to reconnect the hose. Getting to the elbow hose is a chore. Notice all of the disconnected vacuum hoses and wire connectors that I moved out of the way to make it easier to get to the hose. The two hose clamps on the elbow were some work also. The elbow hose I had to cutoff, not much space there to wiggle the hose off. Notice how close the connectors are for the elbow hose. Don't forget to put some rags down to catch any fluid drip. I actually had very little drippage.



I bought one of those TB Bypass kits and didn't use it. Wasted $18. The connector in the kit didn't seem to fit the hose right anyways. It was too loose. I did use one of the screw clamps. I trashed the elbow hose. I used the existing hose that was connected to the other side of the TB. I trimmed off about 6 inches so that it would bend and lay alright and then connected it to where the elbow used to be attached. I also attached bypass caps to the now unused TB connectors. Looks better. Got them at my local auto parts store. They are "HELP!" brand manufactured by Motormite, 3/8 inch bypass caps part number 02256, 2 in a pack.

Now ready to reconnect all of the other tubes and wires. This would probably take about 1 to 2 hours to do. I took a little longer as now some things were easier to get to I did some cleaning and polishing.



IAT Sensor Relocation

Bought the relocator kit for about $35. Includes the wiring harness extension as well as a new IAT sensor. This should take about 30 minutes. Drill a 7/8 inch hole in the filter housing. Most are plastic housings, mine was a little more involved because it is made of metal. Install the rubber grommet. Insert the new IAT sensor.



Connect the wiring harness extension and you're done. The length of the wiring harness was just right.
Special Note - While I had the SLP system off to drill the hole I also used my Dremel to cut 3 holes in the radiator shroud. I thought that I would give this a try to see if it would bring in a bit more fresh cool air. I think it helped. Directly underneath each filter in the shroud I cut a 1 inch wide hole by the length of the filters about 4 inches long.





Dust Shields

Bought the black neopreme dust covers for about $28. Attached with the 8 existing 10mm bolts in the wheel well. Thread the wheel motion sensor through the hole. Wrap the flap around the shock and tuck the top part underneath the hood gasket. And you're done. About a 30 minute job. (notice my new MSD 8.5mm plug wires)





Mass Air Flow mod

This modification I noticed a difference right off. It seemed to idle better. It seems a little more responsive when I accelerate. And at WOT my exhaust has a nice deep rumble. This picture is right off the engine and before disassembly.



Looking from the air intake towards the TB. Notice the air flow restrictive screen.



Looking from the TB towards the air filter. In the circle is the IAT sensor protruding into the airway.



Side view. In the circle is the old IAT sensor, now unused and replaced with the one that came in the relocator kit. SPECIAL NOTE - The 2 clamps on either side of the MAF are crimp clamps and cannot be reused and need to be cutoff using some wire cutter pliers. ALSO, your local Chevy dealer cannot order you any of these clamps. They don't carry them. They are only available in MAF rebuild kits. They suggested that I go to a local hardware store and get some simple screw clamps. I'm going to use some 14" black wire ties.



Disassembled. This is the MAF. Screen side up, the side that faces the air filter. Notice the 2 unusable and cut clamps on the left.



Disassembled.



This is the MAF disassembled. Use a #25 torx to remove the 4 screws.



This is the center section of the MAF. Notice the 3 thin sensor wires. Damage these and you're out $300 to $400 to replace the MAF.



This is the section that has the screen attached. Notice the retaining ring that holds the screen in. Not easy to remove.



Here's the screen removed with the retaining wire shown on the right. You'll notice that I damaged the screen while trying to pry the retaining ring out. That's OK, I don't plan to reinstall the screen anyway. The screen is 1/4 inch thick. The holes are honeycombed. You'll notice some dirt and debri on the screen. My stock air intake did not have a tight seal between the filter and the plastic base. Some unfiltered air was leaking in.



The MAF cleaned, polished, and reassembled.



Some will use a hacksaw and cut the center fin out and file smooth. I decided not to do this at this time. I'm just happy to get the screen out. I don't think these fins are that restrictive plus they do act as a support for the sensor wire assembly.



Here's the all of the pieces cleaned and polished, ready for reassembly. In the blue circle is my old IAT sensor. I cut the wire connector and sensor cage off. I'm going to use the middle section as a plug for the sensor hole in the plenum.



In the blue circle is the center part of the old IAT sensor. I used some JB Weld to fill in the hole where the sensor wire was.



My homemade plug is installed and is now flush with the plenum inside and out.



Reassembled. Notice the 14 inch black tie wraps used in place of the original crimp clamps.



Now a less restrictive flow. Just wish I could do something about the "accordian" plenum. I did find a company that has some "smooth" flow replacements in a choice of colors. But both plenums would have cost about $300. WAAAAAY too much.





Done