Mod Guide: Removing the computer from your 4th gen
Removing the computer from your 4th gen
One of the most frequently asked questions deals with the stock computer system on the Monte Carlo SS/Sc. The computer system is often removed, and many like to know how this is done.
Disclaimer: Please note, performing this operation will render your car emissions illegal, and will not be able to pass visual emissions inspection, and most likely, tailpipe emissions inspection as well. This write up also assumes you are capable of installing a carburetor and distributor, timing, and tuning the motor. Also, the owner, administration, staff, membership nor anyone else affiliated with www.montecarloss.com assume no legal liability implied or otherwise for the content in this guide. Use at your own risk! Furthermore, there is no affiliation with the products and companies mentioned in the links below. There are other products available, but those were simply the most convenient links to site at the time of composition
Many Monte Carlo owners have issues when they change the carburetor or the distributor. The problem is that both of these items are computer controlled, removing one of them for a non computer controlled unit will make the car run very poorly. The computer controlled Quadra-Jet has both a Throttle Position Sensor (TPS) and a Mixture Control Solenoid (MCS). These are directly linked to the computer, as in input and output, respectively. The TPS just tells the computer how much throttle is applied, and the MCS either richens or leans out the mixture, based on the input of the O2 sensor, among other components. In the event that the computer controlled Distributor is removed for a traditional vacuum advance counterpart, but the Quad is not, you will run into a serious issue: The computer will set the MCS to full rich, so gas mileage and drivability will suffer. Should you replace the Quad with a non CC replacement, you will have poor drivability, as the computer is no longer getting input from the TPS sensor, and the distributor will not advance timing.
To remedy these issues, both a non CC carburetor and a traditional vacuum advance distributor need to be used. If you are to use the stock intake manifold, you must get a spread bore carburetor, or an adapter. This would be an excellent point to upgrade your intake manifold, and you can get a dual spread bore/square bore design intake manifold, and run whatever carburetor you want.
The computer is located in the passenger side kick panel. You will need to remove the metal floor “Body by Fisher” panel on that side, and then remove the kick panel. Removing the computer should be self explanatory, get it out of the kick panel, and disconnect it from the wiring harness. There are two halves of the wiring harness, and you will need to remove the computer/engine harness. You will need to remove the passenger side wheel well to get to the hole in the firewall where the harness goes through. There is a bolt and bracket holding the grommet in that encases the harness, remove this, and pull grommet/harness through. Now trace this back to the motor, and disconnect anything it connects to. All the items it does connect to may be removed (but use common sense, the transmission can’t be removed). This harness is not at all connected to the harness that runs the gauges and A/C, etc., so all other functions will be fine, and it will remove easily. Now just reinstall everything you took out, making sure to replace the grommet, though no wires will br going through it, so water does not find its way into the vehicle.
At this point, everything should be installed and running, (assuming you have the correct throttle brackets and etc.). You should be able to time the motor, have her running, but do not drive it, as there are two more things that need to be addressed. You need to adapt your TV cable to your non CC carburetor. Assuming you have a Holley or Edelbrock, you can use this product to attach your TV cable (for your 200-4R, if you have an 85+) up to your new carburetor. This is imperative for the life your transmission, so make sure it is done.
B&M TV Cable Adapters
TCI TV Cable Adapters
Holley TV cable Stud
Holley TV/Throttle Bracket
Finally, you need a lockup kit, to lockup your torque converter at highway speed. This saves gas and helps the transmission run cooler. Note- often people just run a toggle switch (like keeping the part of the harness that goes to the trans and having pins A and F od the ALDL connector on either side of the switch), but I recommend a lockup kit, because the toggle switch is easy to foget about disengaging after a long trip, which will result in trans damage.
B&M Lockup kit
TCI Lockup Kit
Painless Lockup Kit -Note, the Painless Harness is for a 700-R4, it will work, but you are unable to use the pan gasket, and the TCC solenoid
Superior Lockup Kit -You are looking for "The High gear lock-up package #K013 by Superior". This is a very simple kit, and works great, but you will need to use the plug off the harness that goes to the transmission, as it does not come with one.
Original thread from MCSS.com
Comp removal
Disclaimer: Please note, performing this operation will render your car emissions illegal, and will not be able to pass visual emissions inspection, and most likely, tailpipe emissions inspection as well. This write up also assumes you are capable of installing a carburetor and distributor, timing, and tuning the motor. Also, the owner, administration, staff, membership nor anyone else affiliated with www.montecarloss.com assume no legal liability implied or otherwise for the content in this guide. Use at your own risk! Furthermore, there is no affiliation with the products and companies mentioned in the links below. There are other products available, but those were simply the most convenient links to site at the time of composition
Many Monte Carlo owners have issues when they change the carburetor or the distributor. The problem is that both of these items are computer controlled, removing one of them for a non computer controlled unit will make the car run very poorly. The computer controlled Quadra-Jet has both a Throttle Position Sensor (TPS) and a Mixture Control Solenoid (MCS). These are directly linked to the computer, as in input and output, respectively. The TPS just tells the computer how much throttle is applied, and the MCS either richens or leans out the mixture, based on the input of the O2 sensor, among other components. In the event that the computer controlled Distributor is removed for a traditional vacuum advance counterpart, but the Quad is not, you will run into a serious issue: The computer will set the MCS to full rich, so gas mileage and drivability will suffer. Should you replace the Quad with a non CC replacement, you will have poor drivability, as the computer is no longer getting input from the TPS sensor, and the distributor will not advance timing.
To remedy these issues, both a non CC carburetor and a traditional vacuum advance distributor need to be used. If you are to use the stock intake manifold, you must get a spread bore carburetor, or an adapter. This would be an excellent point to upgrade your intake manifold, and you can get a dual spread bore/square bore design intake manifold, and run whatever carburetor you want.
The computer is located in the passenger side kick panel. You will need to remove the metal floor “Body by Fisher” panel on that side, and then remove the kick panel. Removing the computer should be self explanatory, get it out of the kick panel, and disconnect it from the wiring harness. There are two halves of the wiring harness, and you will need to remove the computer/engine harness. You will need to remove the passenger side wheel well to get to the hole in the firewall where the harness goes through. There is a bolt and bracket holding the grommet in that encases the harness, remove this, and pull grommet/harness through. Now trace this back to the motor, and disconnect anything it connects to. All the items it does connect to may be removed (but use common sense, the transmission can’t be removed). This harness is not at all connected to the harness that runs the gauges and A/C, etc., so all other functions will be fine, and it will remove easily. Now just reinstall everything you took out, making sure to replace the grommet, though no wires will br going through it, so water does not find its way into the vehicle.
At this point, everything should be installed and running, (assuming you have the correct throttle brackets and etc.). You should be able to time the motor, have her running, but do not drive it, as there are two more things that need to be addressed. You need to adapt your TV cable to your non CC carburetor. Assuming you have a Holley or Edelbrock, you can use this product to attach your TV cable (for your 200-4R, if you have an 85+) up to your new carburetor. This is imperative for the life your transmission, so make sure it is done.
B&M TV Cable Adapters
TCI TV Cable Adapters
Holley TV cable Stud
Holley TV/Throttle Bracket
Finally, you need a lockup kit, to lockup your torque converter at highway speed. This saves gas and helps the transmission run cooler. Note- often people just run a toggle switch (like keeping the part of the harness that goes to the trans and having pins A and F od the ALDL connector on either side of the switch), but I recommend a lockup kit, because the toggle switch is easy to foget about disengaging after a long trip, which will result in trans damage.
B&M Lockup kit
TCI Lockup Kit
Painless Lockup Kit -Note, the Painless Harness is for a 700-R4, it will work, but you are unable to use the pan gasket, and the TCC solenoid
Superior Lockup Kit -You are looking for "The High gear lock-up package #K013 by Superior". This is a very simple kit, and works great, but you will need to use the plug off the harness that goes to the transmission, as it does not come with one.
Original thread from MCSS.com
Comp removal
Last edited by Budsjlm; Sep 11, 2010 at 02:03 PM.
Joined: Nov 2005
Posts: 79
Removing the computer offers no gains in power - just cleans up the engine bay if that's what you're after. Note that fuel mileage will take a bit of a hit without the CCC system.
All info in the first post is quoted directly from a sticky on www.montecarloss.com :
http://www.montecarloss.com/communit...007#Post245007
The non-SS's from 81-86 were SC's (Sport Coupe) and from mid-86-88 they were called LS's (Luxury Sport).
All info in the first post is quoted directly from a sticky on www.montecarloss.com :
http://www.montecarloss.com/communit...007#Post245007
The non-SS's from 81-86 were SC's (Sport Coupe) and from mid-86-88 they were called LS's (Luxury Sport).
Joined: Jan 2010
Posts: 259
From: charleston, south carolina
i ripped mine off and voila more engine space, then i went ahead and removed everything that was A/C related from compressor to blower fan; then emissions. my next step is to swap out the clutch fan with an electric fan and also remove all the belts
I just left my computer alone. I have almost everything disconnected. I have no lights that are on in dash that shine. I did set the timing up and run it with good octane gas. I bought a GM crate motor (early 80s) and it was a tit for tat swap. I think the most problem I had was putting the headers on and finding a way to mount the ac bracket but then I saw a long bolt in my junk drawer and it had a welded nut on one end..Hard to describe but I’m sure there is a tech name for that. It was perfect length and works like a charm. I have not cut any wires just in case the outside remotely, slim almost nil chance I might part with it.
Last edited by Alive85; May 14, 2014 at 11:05 AM.
