347 problems

[1987Mutt_stang]

Okay i am now going nuts!!! 347 just started, ran fine for 2 days, and now backfires and losses power when off idle. Changed intake(found a crack), found a kink in fuel line(fixed it), new fuel filter, and a new pump. Still having issues. Timing is at 36 degrees.(is that right?) It is fuel injected with 30# injectors. Fuel pressure 37lbs at idle. Any ideas? I have beat myself against the wall on this for 4 or 5 days now. Any help is greatly appreciated. Thank you.
PS First post hope its enough info. New to forums.

 

[Grn92LX]

whats the entire set up? Sounds like a vacuum leak to me somewhere. is that 37psi with the vacuum off or at idle with the vacuum on?

 

[1987Mutt_stang]

347 stroker stock block, eagle 4340 crank, eagle H-beam rods, Mahle pistons(8.6:1 comp.) gt40p heads(ported and bowled), Comp cams .544/.560 on 114 centerline, edelbrock rpm 2 intake, FRPP 30# injectors, Abaco 85mm mass air, anderson 3.5in power pipe(mass air in fender), Accufab 70mm throttle body(egr delete),255 walbro pump...........i think thats it and yes with vacuum hooked up to regulator(thats what i forgot) which is an aeromotive reg. thank you.

 

[1987Mutt_stang]

Also i dont have much for vacuum lines i deleted the vacuum tree. Just brake booster, pcv, and regulator.

 

[84Ttop]

Still sounds like a vac. leak. Just because you don't have a lot of vac lines, doesn't mean they're not leaking. Your intake could also be leaking. Will the car stay at idle by itself?

 

[1987Mutt_stang]

Brand new intake and vac lines. Just did them 2 days ago but I will double check though. Yes it will idle by itself.......which it would not do before the new intake.

 

[84Ttop]

what is your timing set at? base and full advanced? remembered to pull the spout connector when setting the timing?

 

[1987Mutt_stang]

36 which is where the engine builder told me to set it.(may be wrong with fuel injection) With the spout pulled.

 

[84Ttop]

is that 36 at idle or full advanced. is the car being controlled w/ some sort of tuning device?

 

[Grn92LX]

you may have set the timing improperly. Pull the spout and set it to 14-16* then put the spout back in.

 

[1987Mutt_stang]

thank you i had already tried it at 20 better but still popped a lil but now i will put it at 16 thank you very much

 

[1987Mutt_stang]

and it was 36 at idle i thought it was high but that is where the engine builder said to put it and that is also where the line is on the damper

 

[84Ttop]

i think the engine builder meant 36 at full advance, which usally equals 14 degrees base or so.

 

[1987Mutt_stang]

So I put it at 16 took it for a short drive ran the greatest it has ran yet.........for about 10 mins then it started acting like it was running out of gas the problem got progressivly worse the longer it ran barely made it back around my neighborhood loop, turn it off start it up ran good for 30 seconds and started it again. Have to go out for a few hours now will look back later...
thank you guys it is getting better.... i hope.

 

[1987Mutt_stang]

well i thought someone may have had information on this "new problem". I am going to keep looking though if any one has info please help. Thank you

 

[1987Mutt_stang]

Does any one have any ideas why it acts like it is running out of gas when it gets to operating temp? New pump new filter new regulator everything on it is new as far as engine and fuel system goes is there anything i am missing?

 

[RatStang]

Nothing more than a stab in the dark here but aside from tracking down vacuum leaks, I'd also be taking a hard look at your fuel regulator.

For the purpose of troubleshooting, see if you can find an OEM non-adjustable regulator to slave in there just to elimnate it as a cause.


After that, you symptoms sound like they are tune related. Start it up, it runs fine... Warm it up and it turns to crap. I have a sneaking suspicion that your MAF and fuel injectors are not agreeing with your EEC. It sounds as if it's attempting to go into closed loop and pooping all over itself.

How were your EEC, injectors and MAF matched?

Is your EEC stock and unmodified or chipped?
Is your MAF supposed to be calibrated for 30# injectors? ...and if so, is it calibrated for 30# injectors and EXACTLY the EEC model you're using? (if it's cal'd for an A9L and 30s then a Cobra EEC will not work etc.)

If all of that is correct (as much as you can tell), then I'd send the MAF in for flow testing to ensure it's setup the way it needs to be for your computer and injector size.

 

[1987Mutt_stang]

I have an Abaco 85mm digital mass air with a 30# tune on it.a9l reman computer. no tune on the computer. I hope it is not the regulator it is new. I appreciate the ideas. I will go check out the reg and look for vacuum leaks. And maybe retune the mass air. Thank you.

 

[liljoe07]

Run the codes from the Computer with the engine at operating temp.

 

[RatStang]

Does your MAF use sample tubes?

If so: Ensure the correct tube is installed (of course) and also try "re-clocking" the MAF.

I'm not familiar with Abaco so thought to ask.