Swap from TBI to Carb what to do with wires
 

In the near future I plan on installing the carbed 383 that I am building into my 88 Formula. My previous Firebird, when the owner did a swap to a 350 he left the fuel injector wiring in and only used the wires that he needed to. This looked very sloppy. I would rather take the whole computer, harness, relays and all out. The thing is what would I need to do to wire the new motor and get my guages to work? Ive never looked to see if the computer sends a signal to the guages or if the guages are directly connected to the engine. Same thing goes for the ingnition although I have no problem installing a pushbutton start. I know other people have done this before so what have you all done???? Are people making their own harnesses or finding them from old carbed thirdgens? Oh and I am not worried about passing inspections.
Thanks for any advice.
Dennis

Re: Swap from TBI to Carb what to do with wires
 

There are a couple vendors that advertise right on this site that do harness conversions.

1. Hook up all the wires you need and get the car running.

2. Remove the passenger side plastic fender liner and disconnect the ECM harness connector from the kick panel pass-through.

3. Pull the harness out from the engine compartment side. Unbolt sensors that are attached to the harness so they can be removed with the harness. Separate out any wires that you are using from the harness, and take the harness out.

Re: Swap from TBI to Carb what to do with wires
 

five7kid, you confused me on the last step, I have no problem hooking up the wires needed to get the engine running... But, what if those wires are powered through the ECM, then when i unhook the ECM the car wouldnt run... so seperating them would be more difficult then just untangling them, This is the problem i was running into last time when i was trying to clean up the engine bay was that the wires went to the ECM so i couldnt take the whole harness out...

cdartz, care to link me to it ive been looking, thanks

The wires that are needed to run a carb'd engine don't go through the ECM. Some of them might be bundled in the ECM harness, even though they eventually go to a different place.

Re: Swap from TBI to Carb what to do with wires
 

Ahh, thank you very much, what about things like the coolant temp guage and oil pressure sensor and such for the guage cluster... as well as the tach, do those things run through the ecm?

Nope.

Re: Swap from TBI to Carb what to do with wires
 

I'm getting ready to do a carbed 350 in my 86 IROC and I've been getting the 305TPI ready for pull. I'm removing the TPI components now and I'm finding miles of vacuum lines attached to it. Am I correct that I'm not going to need most of these? Are there any that I need to keep that I wouldn't be able to make out of vacuum hose later on?

Thanks

Re: Swap from TBI to Carb what to do with wires
 

in neck deep in a motor swap right not, i have the engine bay totally gutted and i have removed all the wiring that is not necessary. the only wires that come out of the passenger side harness that you need for a non emissions engine are for the speedo sender, if you have an electric one and the lockup for the trans, thats it. the harness on the driverside needed to be left completely alone, but im doing a carb to carb so yours may be different. then there is the harness for the heater. if you have a brain fart like i did years ago when i did my first swap, you can remove all but the orange wire in that harness and the heat will still work (a/c delete), but only 1 speed, high. then there is a orange that goes form the battery to the computer which can go, i think "fingers crossed" and that pretty much it.

Re: Swap from TBI to Carb what to do with wires
 

Yeah there are actually two main harness connectors (at least on my car). The computer wire harness (which goes into the pass. fender area) and then a block that connects to the firewall, left of the brake booster. The block left of the brake booster is what has your gauges, lights, and igntion components. As for vacuum lines, the only one you need (other than the ones on the engine, like a vac. distributor advance) is the brake booster, which will connect to the back of your carb manifold in most cases. If you want HVAC controls, there is a pair of vacuum lines that comes out of the firewall near the heater core coolant passages. However, one goes to the coolant diverter.

One thing I forgot to mention; there is another set of wires that is bundled in to the wire harness on the pass side, but does not go into the computer. If you have this on your car, you may need to follow that to find out if you need it or not.

Re: Swap from TBI to Carb what to do with wires
 

Ok, i'm going through the exact same thing.....I'm running a 406 with a 4L60.....the wires that go to the trans were in the wiring harmess for the ECM, I was told in another post that that i no longer need that and I could take it out.....is this true??

Re: Swap from TBI to Carb what to do with wires
 

Those are the trans torque converter lock-up wires AFAIK. Your torque converter will no longer lock up on the highway (it'll hit your fuel econ.) but you can buy a kit that locks it up by vacuum. Check out summit for it.