DrBrown54

I have an 87 LT qjet. So it's kind of a transition car from the sounds of it with 2 fuel pumps, with a carb, but still run on the computer. I would really like to just remove the computer controlled nonsense, keep the AC, and ditch all the extra emission stuff. I have not tore into the dash to even look for the ECU yet, but I assume it controls hvac and powers all the engine sensors (O2s, egr, iat etc). This isn't really an EFI to Carb swap, so those write ups really aren't a 1:1. Hopefully someone else has done this because I'm not good at being a guinea pig lol.

If it matters, I'm thinking of building a single turbo setup and blow through carb. Nothing too crazy but looking to get 400ish whp out of the 305. It's a reman engine with low miles. If anyone has any input I'm all ears!

FRMULA88

The ecm is on the passenger side, in the dashboard.

Try getting the shop manual first and reading it, especially the wiring diagrams so you know what needs to stay and what can be removed.

Seems silly that you want a turbo but don't even know the basics about your car yet.

Do you have any idea what it will take to install a turbo?? there is no "kit" for this car that I am aware of.
you will have to fabricate: headers, intake / intercooler piping mount a intercooler, oil line for turbo, blow off valve, waste gate etc ,etc, . So unless you can fabricate. weld, etc.. you will be paying someone else to do all the work.

Hate to say but a complete turbo kit will cost more than your car is worth, (AT LEAST 7000 $ TO DO IT RIGHT) are you in a position to spend that kind of money?


Learn how to walk first... then run. You will thank yourself in the long run for taking the time.

DrBrown54

The reason for my post is geared towards the carb/computer. The 87 was a transition setup that had both mechanical and electric fuel pumps, and some sort of PCM control. The question is WHAT control does it have. Haynes manuals do not explain whether the PCM controls ign timing, references crank/cam positions, intake temp sensors, coolant temps etc. OBD1 and OBD2 cars clearly use all of the above. The question is more about what does this 87 ECU require to not freak out.

I understand you probably assumed I'm the typical newb but I've fabricated turbo systems for other cars completely from scratch and did my own tuning via MegaSquirt. I have no reservations about turbo systems at all... except for blow thru carbs; that's a new animal! I appreciate your input, but my questions are not geared towards turbo at this time, just the EFI/Carb setup.

FRMULA88

Check the wiring diagram for the 1987 carb model... it will show the schematic for the ECM. (ie what is connected to it) Perhaps your Haynes manual does not have the electrical schematics... If that is the case try finding a Chilton's at the library... or use the search engine on this site since guys have posted wiring diagrams in the past..

Common sense tells me the emissions regs were same for the late 80s.. so a anything controlled by the ECM on a 1987 or 88 or 89 TBI or TPI car should be similar for CARB...

IN fact the only thing the ECM cannot do with the CARB is adjust the mixture... which is why they went to EFI...

it should still have: 7 pin distributor (to control timing) air inlet temp sensor , O2 sensor, MAP sensor, throttle position sensor, coolant temp sensor, etc.

Take inventory of the sensors present in the engine bay and on the engine, this help. A seasoned car crafter such as yourself should be able to ID them.

rockstarr4

So here is my experience with my 84, I removed all emissions related devices except for the PVC valve, plus installed a Performer manifold and Holley Street Avenger carb. My 305 ran much better, but was still rather weak. I finally realized that I should have also replaced the distributor since without all the sensors functioning the original CC distributor would have no advance curve. Once I had mechanical and vacuum advance with the new distributor, the car runs extremely well (for a 305).

I experienced no ill effects on any other system. The ECM is still installed, I just cut all the original emission sensor and control cables back at the firewall and wrapped them to tidy things up. Eventually, I’ll pull the wires and ECM out to reduce the clutter even more. One note, though, I do not have AC.