Subject – Removing Computer

One of the most frequently asked questions deals with the stock computer system on the Monte Carlo SS. 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.

For other information not contained in this guide, see The Engine Tech Section of the site. There's tons of info there.

I have opened this topic for corrections or additions. Please post them, but no questions. Limit questions to other topics, as they will be promptly deleted here. Thank you.

Mike

I would like to add that you don't need to buy a lock-up kit if you don't mind operating the TCC solenoid manually. Do a search in the Drivetrain forum for "You don't need to buy a lock-up kit" and I explain it all. Anyone can also e-mail me I have pictures and I developed single line AutoCAD drawings of how the system is wired.

Where do you tap in to power for the new distributor???

The power and the tach wire should still be there. They are part of a different harness. The only thing you remove from the distributer is the 4? prong plug that controls the timing. The other wires. coil and tach, should still be there after you take out the computer harness

HTH

Rob

The lock up vacuum switch from a 81 and up 3 speed auto will work on a 200R4 or 700R with no computer.

I have just done this and all you need is a wiring harness from a 81 and up non SS car. Its not as hard as it sounds.

That won't work for US members - they have had the CCC system and computers since 1981. Canadian emissions laws/requirements varied greatly back then, as did the same car on each side of the border in this respect.

Can I unhook the computer componets, but yet stil leave them in the vehicle?

Tranny Question:
We are in the process of replacing the engine and removing the computer. We have a question regarding the tranny. We have disconnected the computer from it and were wondering if we can drive it as is, while we wait on the lockup kit. Will it just act normal without locking up. We need to drive it a short distance
Another question, do we remove every wire from the computer on the engine bay side? Or, do we remove everything including the compuuter and just leave the inside cables sit there.

hello,I have a 1986 SS with 700r4 with no motor. the motor i have came out of a 1973 corvette has performer intake and a holly 750 double pumper and the dipstick comes out the block on the drivers side which will get in the way of the exh. manifold. the original 305 motor has dipstick out of pan on passenger side. wondering what all i need to do to put this motor in? and should i remove the computor. looking for the cheapest but right way to go! thanks......scott

check out this link. itll tell you everything you need to know


web page

dumb question. i have a 200R4 from an 86LS in my 88LS with no comp hooked up and it shifts fine. i use a Holley carb with a shiftercable, do i need a lock up to prevent damage or am i ok? does it have its own internal vacumn or do i need to run a line to it? sry. i know jack about tranny's

thank you for the directions on removing the comp n comp harness.

ok. can you send me all the pics n instructions. i didn't think it was but my TCC is still hooked up. will a 30 amp switch and a 30 amp inlise fuse be strong enough? i have them laying around.

my e-mail's xxhardcorechevyxx@yahoo.com also. how do i hook it up so it tells me if i forget to kick the switch off when i come off the highway?

why would anyone want to take out the computer, i kept the computer and got jetchips to make me a remapped brand new chip, (the chips in the montes cannot be reprogrammed) and used a computer controlled rochester Q-jet, the chip retards the timing at criuse or idle sppeds and i get over 20mpg on the highway from a 406sbc with over 400hp and it advances the timing under full throttle, it knows this from the trottle position sensor on the q-jet and the bosch wide band sensor in the edelbrock TES headers which ups the horespower by around 30 at full throttle, keep the computer, it can be your friend if you know how!!
We interupted the wire going to control the air pump so i can switch it off when i need more power and programmed the chip to lock up the converter at low rpms becuase of the torquey motor and installed a ratchet shifter so as i can override it when i want to race, the computer can give you a balance between street and strip and the best of both worlds.

well said viper killer, that sounds very similar to what i plan on doing when i upgrade my motor. Definatally keeping the computer and getting a custom mapped chip.

this has got to be the most informitive post of all time from both ends wild to mild my hat is off to all

I'd have to agree with that,but it only fills my head with more questions and leaves me wondering which is the best way to go.I do like what "viper killer" said...A remapped chip sounds a lot cheaper than buying a carb,intake and distributor and going through the set up of it all.I guess it a personal preference thing?!?!
-Blackened.

What about on an 87? The wiring is different than an 86. Can anything connected to the computer harness really bne removed?

yes.

hey, for me your links dont work, its going to the jegs webpage main page. help!

It was made over 2 years ago...

They are links to items jegs has.

Good read guys. Thanks

i done away with my comp with a used distributer and a 650 helloy carb and it ran twice as good

I have a question please. my brother has a 87ss, he had the comp. removed. he has a holley carb and a non- cc dist. on it now. but his tranny is wineing on accel. without shifting till he gets up to about 35mph. he has a over drive switch in it for his od gear to use for the highway. what could be causing this wineing shift? tia.....Bill