And how is your ground grid?  Do you have pins 40 and 60 solidly grounded to the engine?  Is the engine solidly bonded to the firewall and frame rails (chassis)?  Are you sure this thing ran for the PO?  What cam do you have and what PCM?  You do know that the mass air engines had a different firing order than the "standard" 5.0 with speed density EFI.  You can run the standard (289 firing order) on a mass air system by changing the secondary leads on the dizzy but you MUST leave the injector FO as set up for the HO. 

More as I think of it.

BB

Okay...sounds like you've certainly done your homework.  Thanks for the info.  Now...if you had timed it to the exh stroke the dizzy would be 180 degrees out if I'm thinking correctly and it shouldn't run at all.  And reading #1 with the timing light would not show the degreed part of the damper if it did run a little. 
Tell me about the harness.  As I have said, these things will forgive a lot if the components are good and wired correctly.  Did it come from the PO?  Was it a MASS AIR harness to begin with?  You verified continuity but have you verified the pin-out at each connector?  This is a really good place to make mistakes...don't ask how I know.  And the only place I have  found to get good pin-out info for the various connectors is from Probst's book.  May be some info on line for each sensor but Probst's book has it all and you can easily see if you have, literally, gotten your wires crossed.  I'll be happy to shoot copies of the appropriate diagrams if it will help.

All of the codes you see except 31 should be eliminated by the addition of some 75 ohm (need to verify that value) resistors between each of the circuits to ground.  That will make the PCB think it's operating a vacuum solenoid when it tries to enable each feature.

What about the PCM?  Did it come with the rest of the stuff?  Did you see and hear it run?  These things have a habit of developing a leaky capacitor which can cause a lot of trouble...just ask Glens 1965 5.0.  It's something that can be fixed but you need to know if it's happened and that means you need to open the PCM case...I'd save this as the last resort but keep it in mind. 
I honestly think you have harness trouble.  And if I were there, the first thing I would check is the Key On, Engine Off voltage on the orange wire at the TPS.  If you crossed the ground (black) wire with the #46 (signal return) you would have 5 volts at the orange wire instead of .62  to .68 (idle value). Did the idle go south after you replace the TPS?  It will run with a failed TPS...your nearly broken ground wire...but the new one would look like full throttle at all times if the wires are crossed.

My advice:  Re-check the spark plug order at the dizzy to be sure #1 is at the designated #1 position and that it's timed correctly.

If you had any connectors off or replaced, verify the pin-out for each sensor connector. 

If you don't know if the PO had connectors off but think he might have...verify the pin-out.

Your ground bonding sounds good but you still didn't say where you laid down the PCM grounds or if you were careful to be sure all grounds were made to freshly cleaned (with 80 grit sandpaper) bare metal.

DON'T GIVE UP...IT'S JUST A MACHINE AND IT DOESN'T KNOW THAT YOU DON'T KNOW ANYTHING ABOUT IT.

BB
 

Last edited by Bullet Bob (4/10/2016 7:42 AM)

Well good news, some idiot (me) installed the upper to lower intake gasket upside down while removing the egr.
Noticed and thought it was weird when reinstalling that the two middle bolt holes didn't line up. Turned around but had no effect. Realized over night that had I flipped it the stagger would have lined up.
Also may not have had PCv line fully on the intake. I had a clamp on it, but apparently I missed the hose with the clamp. It looked like it was on but it certainly wasn't clamped.
Fired right up with mad and everything plugged in. Crossing my fingers for a better test drive

It might start with the distributor 180 degrees out.  Usually you'll get a pretty serious backfire when this is the case, and it will stall out.  I would definitely verify this, just pull the #1 plug and put your thumb over the hole.  Roll it over by hand until you feel pressure against your thumb indicating you are on the compression stoke, roll it to TDC (or 10 degrees BTDC), and time from there.

Are you using the correct firing order?  Its really determined by your cam, but a 5.0 should use the old school 351 firing order.  I hooked up a 351 with the old 289/302 order once, and it ran that way, though not well.  If its the 5.0 firing order make sure its right, and check the firing order which should be printed on the cam card that came with the cam.  If the cam's ground on the old school firing order that's what you have to run. 

Are you sure your injectors are all plugged in right?  If you flip flop the harness bank to bank you'll get it fueling at the wrong time, which could also cause backfiring.  Its probably starting because it gets a shot of fuel, runs on that fuel, and then dies because something's wrong and preventing it from continuing to run as it should.  You can pull an intake manifold vacuum line and spray a little starting fluid into the port and see if it stays running.  If it does you may well have a fueling issue.  Have you checked rail pressure?  Hoe old are the injectors?  Did they sit for an extended period before you tried to fire it up?  Often they will varnish up or succumb to ethanol contamination from periods of prolonged inactivity.  Two bad injectors in the order of the firing order will stop an engine from staying running.  If they're just gummed up you can send them out and get them sonic cleaned.  If the issue isn't spark its almost certainly fuel. 

Just throwing out some stuff I've had problems with before on Ford and GM EFI both. 
 

soonerfan wrote:

Thanks for the responses guys.

Looks like this problem was entirely vacuum related and caused by myself.
Doesn't surprise me, because I thought I could hear a vacuum issue, I just had trouble locating it until after I slept on it.

Test drove yesterday and the engine seems to be running great.  When I drive the car, it bucks really badly when I start to accelerate under light throttle.  Not sure what to investigate at this point.  Originally I thought maybe the engine was cutting out on me, but maybe it's really a drive train issue, since the engine never dies and never sounds like it's dying.
I did a 5 spd conversion with this swap, so I now have a clutch, T5, and shortened the drive shaft to fit.

Bucking under light/part throttle can be caused by being lean. What size injectors are you running? What is your base fuel pressure, and like BB mentioned set your TPS voltage as well.
 

Yes, I asked the injector question because many folks do not realize the relationship between aftermarket MAFs and injector size. **Or** the other way around some folks make the assumption that a Cobra MAF and 24lb injectors are all that is needed for a swap from 19s.

MS wrote:

Don't be afraid to turn that idle screw that everybody tells you to never mess with.

That's true but with a caviat or two.  MS saved my Bash trip last year when the dan'g thing wouldn't idle once I got down where there was air.  He told me to open the butterfly a bit and absent any better ideas...I did.  And it idled just fine.  Did a little research when I got home and it seems this is a standard problem with a bit more heads and cam.  But...it also raises the TPS voltage above the legal limit of about .68v...mine is presently about .9v.  This will cause the engine to run rich.  So, you can file the slots in the TPS and maybe adjust it back or you can buy or make a spacer that has a built-in adjustable by-pass to go between the TB and the IAB.

BB

Last edited by Bullet Bob (4/11/2016 3:39 PM)

Previous thread questions:
--Checked the TPS.  It was within range based upon everything I've read online, between .6 and 1.0.
--Injectors - Look like 24lb to me.  Bluish color, though I haven't pulled one to get the part #.
--Air filter - K&N conical filter.  Having read that these can be susceptible to air turbulance, I tried rotating 90 degrees and also tried covering with a cardboard box with one side open to the fender side. - No benefit in doing this.
--Computer is A9L.
--Fuel pressure shows 38-40 lbs when in the garage before and after the drive.

So here is a new description of my issue, based upon my last two test drives.

Car starts right up, idles, then drives fine for the first several miles.  1, 2, 3, 4 gear all drive fine.  Light or heavy throttle acceleration no issues, coasting in gear no issues, cruising no issues, idle at light no issues..
Once the engine gets fully up to temp (it's showing a little past the middle on my original '66 temp guage), the car starts cutting out and jerking, at idle, light throttle or heavy throttle.

TFI has been removed and tested at O'Reilly and reported to be fine.
Sprayed water on spark plugs w/ no impact.  No arcing seen w/ lights off in garage.

Thoughts on where to go from here?
Less frustrated today, but still tired of only being able to drive about 2 - 4 miles.

Dizzy is original as far as I know. TFI is an Accel, so I assume that has been replaced at some point by the engine's PO. No clue on miles, but I was leaning toward replacing the dizzy next unless some had a different suggestion.

Sooner,
Staying on the distrib topic, google: Profile Ignition Pickup Circuit failure.....commonly known as PIP.
Many posts on this topic but open up the ones from sbftech.com and read what's been discussed.  Several addition hotlinks attached to the posts there describing symptoms, testing and replacing the PIP. 

Lotz of other posts to read on this topic......may just be the what's causing your hair loss with this swap...
 

I have a 5.0 EFI distributor I will be happy to donate to the project if you will pay shipping.

AND, a garage point, of course.

Raymond_B wrote:

Yeah the MAF injector mis-match was what I was worried about. If you truly have a Cobra MAF and injectors the MAF transfer function more than the injector size is probably the source of your woes. I think I have a set of 19lb injectors you can borrow (I would like them back, but no hurry). Sadly I do not have a stock Fox MAF, but I bet you could find one easily. Can you take a picture of the MAF? Especially the top of the black portion where the part # is?

I DO have a stock HO MAF that I have loaned to others...and you're welcome to try it along with those 19lb injectors.   Just send your addy along with your first born...on second thought I have enough troubles so forget the first born and just send the addy.  Raymond if it's easier for you orSoonerfan, or if those injectors haven't run for a while I can include a set that should be clean and clear with the MAF.  They do have a tendency to freeze up if left setting with gas in them for a long time...don't ax how I know.  I think I flushed these with acetone before putting them away but I can test them before shipping.

BB
 

Last edited by Bullet Bob (4/22/2016 2:17 PM)