Ok the specifics are I am using the painless perfect managment software and putting a 5.9 into my 65 coronet.
It won't start and just backfires thorough the exhaust.
A couple of times it sounds like it will try to catch, but never fully engages.

This is not supported by painless. They gave up on the program last year. I bought the harness and computer from them so I could get my car running.

It is a modded jeep 4.0 harness from my understanding.


I am using a NGK afx wide band sensor and controler, with a host of other GM sensors based on painless's computer program.

Generic questions.
Does the o2 sensor have to be working on start up?
That is while I am cranking to start the car?
Just wondering if other programs/ systems require it?

I wired it to the fuse box and of course it powers off during cranking.

Anyone have problems with power between start and run?
I noticed the computer reset when I let go of the key. I might have to do something about that, but was wondering again, how others solved this, or if it was taken care of by software.

Finally, when tuning, anyone have some base lines for a stock 360?
Timing, injectors, fuel amount stuff like that?

It is possible that the problem you are having is related to voltage. When I converted my Cuda to EFI, the system would not start because there was no place on the Cuda that got 12 volts while the engine was being cranked. I ran the wires that requires 12 volts directly to the battery terminal as an experiment and everything started. You should always have at least 12 volts there. Most computer systems and ignition systems require a certain amount of cranking voltage to start the engine.

I don't know if this is your problem, but it is worth a try.

not likely.
I have rewired the entire charging system. I have 12 volts to the computer without a doubt.
plus both systems, the o2 sensor and computer both note low voltage in the display if that happens.


thanks for the idea though.

btt for the mornining crew.

Does the o2 sensor have to be working on start up?
NO.
That is while I am cranking to start the car?
NO.
Just wondering if other programs/ systems require it?
NO.

ultimately you need to make sure power to the computer is hot during both cranking and in the run position of the key. may have to pic a different wire on the ignition switch.

also if your cranking, what are you using for a crank pick up? do you have a crank trigger? a distributor? do you need two inputs? one for crank timing and one for dist timing?

whats the pulsewidth at cranking? are your plugs wet? whats your timing set to? do you have mecahincal advance in the dist or just the computer controlled advance.

So I have been thinking about that. I may have to rig up a switch for power while cranking.

What I did was take the lines from both sides of the ballast and tied them together.
So I would have power while cranking and in run.
But that moment when I let off the key seems to be showing as a computer "reset" when I am attached via laptop.

That is, when I program the computer via laptop, in the bottom corner it shows connected. It tells me to key off and on to save the new programming.
The icon changes when you do that, and it does the same when I release the key.

Pickup is some shutter wheel thing they added to the distributer.
All timing is controled by the computer. Pretty much an empty distributer except the pickup.
So that is why I am not sure if I have to be dead on tdc for the distributer or not. But that may be a software vs just efi in general thing.

backfires through the carb, check the basics, is the dizzy 180 degrees out?

What about doing the second wire to the starter solenoid?

I managed to talk to someone from painless. o2 sensor isn't used till water temp is 150.
so there is that.

I am getting backfires through Exhaust, not intake.

I will have to verify timing again. He said it was just as important for this application as a regular carb car. I just got it close didn't verify tdc. I thought it wouldn't matter based on the computer control. But no big deal.

Power, not sure that will help wiring to starter solinoid.
The problem is I need something that only powers with key on, but maintains power when the key moves. Don't know of anything that does that.
When I release the key, power interupts enough that the computer sees the power loss as the key turning off and back on again.

Any idea how big a capacitor? What the cost might be?

Is there another key on circuit I could be using that doesn't drop in start?

If you tie the dark blue and the green together from the column (wire to the balast and wire to the coil), you should have 12v through cranking.

I have it set that way right now.
I will have to reset my timing first and see if it will run after that. Or at least catch and die when I let go of the key.

If it stays running, then I have nothing to fix.

Thanks for all the help. I won't get to work on it till the weekend.

Just to update anyone that cares. I was 180 out.
It fired up and blew white smoke everywhere, but it runs.

Turned it around and drove it up and down the driveway.

Runs like crap, but it runs.