Boss 302 5.0 tough to start, very lean.

Currently working on a 2013 Boss 302 that we bought missing a few parts. I've installed everything(minus the cooling fan) back to stock including Boss 302 intake, stock air box, stock maf, stock injectors, etc. The problem I'm having is the car will rarely start. It will take 3-4 tries til it stumbles and runs for a few seconds, then it dies. If I feather the gas pedal once it is running it will struggle to stay running, but will. At about 3,000 RPM it will smooth out sometimes, other times it will just die again. If I do get it to smooth out, it will fall back and idle perfect for about 10 seconds, then will die again. Once it does run, there are no codes or lights. Also, the factory wideband gauge is pegged at 20+ when it does get running, also checked this with the SCT doing a datalog. It does seem like its choking out, as in not enough fuel.

Things I've tried:
-Different MAF
-Unplugged MAF
-Preloaded SCT tune for stock parts and 87 octane, reloaded several times
-unplugged evap
-Checked fuel for freshness, made sure it is actually getting fuel to rail
-New battery, plus a jump box
-Checked for vacuum leaks, couldn't find any
-Checked throttle body for proper movement

History on the car is it had a paxton on it at one point, which was removed before I got it. I'm not sure which tune is on the car, but I've tried an SCT preloaded tune and it runs the same on both tunes. Also has a Vortech Boost a pump, which I've removed(ran the same with and without it).

I'm lost. Only thing I can think of is bad PCM at this point. Any tips, suggestions or things to look for?

This is probably going to sound stupid, but fuel filter? Could have sat and clogged, and fuel pump could be bad. Sounds like not enough fuel. So I would start with those.

Fuel filter is not replaceable, it's part of the fuel pump on the Coyotes.

Any chance you have another bad crank sensor?

Unlikely it's a bad pcm if you can load tunes and communicate with it.

Have you verified the engine's mechanical condition? Comp check, leakdown?

How about going over it for vac leaks again, post maf? They are super hard to detect on this car because the computer is so good at working around things. If you datalog (when it runs) and see massive low rpm fuel trim correction, that's a bingo, as it were.....

007GTCS said:

This is probably going to sound stupid, but fuel filter? Could have sat and clogged, and fuel pump could be bad. Sounds like not enough fuel. So I would start with those.

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Gabe said:

Fuel filter is not replaceable, it's part of the fuel pump on the Coyotes.

Any chance you have another bad crank sensor?

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I have not checked the crank sensor, it does attempt to crank and does start, just very rough when it does.

5lho said:

Unlikely it's a bad pcm if you can load tunes and communicate with it.

Have you verified the engine's mechanical condition? Comp check, leakdown?

How about going over it for vac leaks again, post maf? They are super hard to detect on this car because the computer is so good at working around things. If you datalog (when it runs) and see massive low rpm fuel trim correction, that's a bingo, as it were.....

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I have not done a compression or leak down test, but the way the engine dropped down and held idle for 10 seconds or so leads me to believe the engine is sound. It sounded perfect for those few seconds. I'll log it again and see what I can find.

Are you using the stock o2 to read afr? I would try a standalone sensor. Also, have you checked what injectors are in it? Wouldn't surprised me to find a random mismatched set of injectors on a repo car that had parts stripped.

cbass said:

Are you using the stock o2 to read afr? I would try a standalone sensor. Also, have you checked what injectors are in it? Wouldn't surprised me to find a random mismatched set of injectors on a repo car that had parts stripped.

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Yes using the stock o2 sensors. I bought a set of take off injectors from a member here. I really doubt injectors are the problem.

I managed to get it to stay cranked for about a minute today. I made a video of it which I will post tonight.

Have you checked the fuel pressure yet? The bap could have fried the fuel pump.

Here is the video I made. The rattle/banging sound is popping from the exhaust, not the engine. You can see the wideband in the center at full lean. At one point at around 3k rpm it smoothed out and the air fuel dropped to normal, you can also see it idling smooth for a few seconds before I tap the throttle again.
https://www.youtube.com/watch?v=bgJ90bD8Zeg&feature=youtu.be

jewc75 said:

Have you checked the fuel pressure yet? The bap could have fried the fuel pump.

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I have not. What would be the best way to check fuel pressure? Trouble is getting it to stay running without someone mashing the gas. I did unhook the fuel line and turned it over, which it did keep a steady stream of fuel coming out.

Have you tried new o2's yet?

jewc75 said:

Have you tried new o2's yet?

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I have not. Forgot to mention, first attempt to start it today and the check engine light did stay on. Code was p1639- Vehicle ID Block Corrupted, Not Programmed. At this point I flashed it "back to stock" and the above video.

just some thoughts from a novice that maybe will spark an idea from someone who knows what the fuck they are talking about:

idle air control valve dirty?
Is there something going on with the exhaust tripping the knock sensors?

^^^ These cars don't have IAC valves.

07TGGT said:

^^^ These cars don't have IAC valves.

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Good riddance. Throttle by wire enables this I assume.

Where do you find these pieces of junk? It seems every car you come on here talking about is a three year old car needing a new engine, or bits and pieces put together or...this issue.

I'm still sticking with the massive vac leak, maybe in the manifold or flange itself, if there's nothing obvious in the piping, given it's showing spectacularly lean. A datalog would show this, if possible, because it would show heavy fuel correction at low rpm that tapers off. How much idle vac in the engine showing it's pulling? Should be close to 20" and steady.

I guess failed O2s are a possibility but they usually fail and default to full rich, not lean.

5lho said:

Where do you find these pieces of junk? It seems every car you come on here talking about is a three year old car needing a new engine, or bits and pieces put together or...this issue.

I'm still sticking with the massive vac leak, maybe in the manifold or flange itself, if there's nothing obvious in the piping, given it's showing spectacularly lean. A datalog would show this, if possible, because it would show heavy fuel correction at low rpm that tapers off. How much idle vac in the engine showing it's pulling? Should be close to 20" and steady.

I guess failed O2s are a possibility but they usually fail and default to full rich, not lean.

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From what I gather by his posts--he finds these at auctions. Probably reposessions.

5lho said:

Where do you find these pieces of junk? It seems every car you come on here talking about is a three year old car needing a new engine, or bits and pieces put together or...this issue.

I'm still sticking with the massive vac leak, maybe in the manifold or flange itself, if there's nothing obvious in the piping, given it's showing spectacularly lean. A datalog would show this, if possible, because it would show heavy fuel correction at low rpm that tapers off. How much idle vac in the engine showing it's pulling? Should be close to 20" and steady.

I guess failed O2s are a possibility but they usually fail and default to full rich, not lean.

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Find them at auction, fix them up(restore) and resell them. Buy them cheap, fix them up nice and put them back out there. I actually enjoy doing it, getting paid to do it is a plus.

I've looked inside and out for a leak, plus the entire manifold is brand new from ford racing with all new gaskets. I'll have to do a little more checking today.

Strengthrehab said:

From what I gather by his posts--he finds these at auctions. Probably reposessions.

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I think I know of what car it is, or at least I saw it online a few weeks ago. By the pictures I saw of the engine, it was stripped down to just the long block, no intake. I believe it was an auction unit. Looked a little rough.

EDIT: kinda tree'd.

was the car flashed back to the as built stock boss file?

if not then its most likely the tune is still setup for the Paxton and will run lean. because of the maf.

loading the canned sct files just modifies whats on the ecm,It doesn't overwrite.

I would start with a as built file or get a custom tune