Fuel Injection Conversion Question Re: Computers

So I am starting to see the "light at the end of the tunnel" on my current project. I have set an arbitrary date of June 18 (my 40th birthday) to have this thing running and take it for a spin. Of course, life happens and money that was planned for the swap has been diverted to other causes.

My question is, if I take the stock computer I have, without any re-programming whatsoever, will the engine fire? It IS NOT the computer that was originally installed in the donor vehicle with the engine, but came out of the same year/model/engine as what I have. I know I will throw tons of trouble codes for the emissions systems I have not hooked up (EGR, Canister Vent, O2 sensor behind the catalytic converter, etc). Just want to know if I can start the engine enough to drive it around the block a few times and get the computer re-flashed at a later date.

 

ECU from same year/model/engine should work fine. Do you have an upstream O2 sensor?

Rather than buy an EPROM and reflash, can't you make a dummy circuit for each of the missing pieces, and let the ECU think they are there? If it were me, I would just run the devices. No real downside to performance if you don't modify the engine.

 

It will likely fire on that ECM. What model is the 4.3? Is it throttle body or multi port? Throttle body ones are pretty simple from what I hear, but I don't think the MP ones are rocket science anymore either.

 

No room for a charcoal canister under the hood, EGR is not compatible with my headers I used, so I know I will have to re-flash the ECM eventually. My 4.3 is a '99, so it is the multi-port injection.I do have upstream O2 sensors installed in each header collector. I guess I can give it a try, whats the worst that can happen?

 

Charcoal canister can go back under the rear corner. I thought the Chevy TBI/MPI EGR valve was simply an electrically operated EGR valve (maybe not in this case?), mounted in the crossover passage of the intake manifold. As long as your headers don't block the crossover, it should work. The ECU expects the EGR to be present, and the exhaust gas dilutes the charge, lowering combustion temperatures. Should run, but the mixture the table calls for will be too high in O2.

 

The valve opens and closes to allow exhaust gas into the mixture as needed. The engine was set up for the gas to come off a port in the factory exhaust manifold and piped into a 2nd port on the intake manifold, with the valve in a 3rd opening to regulate. I would have to add/weld a mount into the header to source the exhaust. Many companies make EGR delete block off plates, and as long as you re-program the ECM, it operates fne without it.

 

If the donor vehicle had a vehicle anti theft system (VATS), it may not start or stay running if it does start. Look at lt1 swap.com. It has a ton of info.

 

I put an LT1 motor in an older truck. I bought software and programmer and re-flashed. You can turn all those items off that your not using, VATS, ect.. It was a lot of work to figure it all out. I don't think it will fire if vats still active. There should be guys locally that can re-flash. Just take the computer over to them and they can do it fast! There are some geeks out there that can hook you up. Try Craig's list search and Google for computer re flash services locally. Once it's flashed your good to go, as long as fuel pressure set correctly and O2 sensors are good, along with mass airflow sensor. Don't get frustrated, keep at it.