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EFI Questions

77broncodriver

Full Member
Joined
Nov 21, 2009
Messages
344
Hey guys, Ive been posting a lot of questions lately, sorry about that but I have fixed a lot of things but still the efi isnt running good. No matter what I do, i have all new sensors and everything on a new crate engine.

But now im thinking, this engine has the aluminum heads and a cam in it, will it ever run with stock injectors and a stock tune?

will i need to go with 24lb injectors and a tune?

Thanks, Evan
 
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77broncodriver

77broncodriver

Full Member
Joined
Nov 21, 2009
Messages
344
its the e303, here is all the specs of the motor.

http://fordracingparts123.com/index.php?main_page=product_info&cPath=34_97&products_id=529

it doesnt idle smooth and always smells like gas and almost drives like it has a miss, just not smooth and it seems like it should have way more power.

i have a rjm harness, explorer upper and lower, mustang throttle body, reman maf, new act, mustang computer, a9p?, im assuming stock injectors.. they are yellow.
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,344
E cam is not that aggressive, it should run fine. Sounds like an A/F problem. Run a KOER test and see what codes pop up. Yellow or orange injectors? What are the specifics on the MAF?
 

dclack

Sr. Member
Joined
Feb 16, 2012
Messages
402
Here's some info from Old Fuel Injection:

"Camshafts

Camshafts are an important selection with EFI, pick the wrong cam and your computer be unhappy. Contrary to popular belief, a bigger cam will not necessarily make more power; in fact it can sometimes cost you performance. Stock cams actually have a very efficient profile and shouldn’t be your first engine upgrade. Larger cams might make a little more power but will generally shift the power band of an engine upwards. If your vehicle has stock heads, intake, or both, installing a larger cam is a waste of time and money. On the other hand, if you’ve got a good matched set of high flow cylinder heads and intake, a cam change can be worth the effort.

Large cams that change the engines manifold vacuum will confuse a Speed Density EFI system which will improperly calculate engine load. Large cams that cause a surging or pulsing of air at idle will confuse a Mass Air Flow EFI system, making idle quality suffer. If you still feel the need keep the lobe separation of the cam at or above 114 degrees. Be cautious with lift over 0.5�; any more might create an interference if the timing chain brakes.

A cam swap might need larger fuel injectors! The computer is programmed with the stock cam profile, so it knows how much time it can hold an injector open. If your cam opens & closes the valves faster; small injectors might not have enough time to deliver all the fuel. A larger injector will deliver fuel faster. Changing the cam and injectors will benefit from EFI programming of some type."
 
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77broncodriver

77broncodriver

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Nov 21, 2009
Messages
344
I ran the codes and nothing more that egr things come up, i think they are yellow.
its a reman stock unit
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,344
Since the specific MAF can have a huge affect on the A/F ratio and running qualities you need to get some info from it.
 

Ourobos

Bronco Guru
Joined
Jan 7, 2008
Messages
1,225
Loc.
Big Island Hawaii
19 # injectors should be able to hold that power, worst case bump the fuel pressure up to 45 psi or so.

EGR always helps drivability, any reason you deleted it? It's just a valve, EVP sensor, and a couple vacuum hoses.

And in your application, that cam might light it better being advanced a bit to move the power band down in the rpm range.
 
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77broncodriver

77broncodriver

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Nov 21, 2009
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344
here is all the info i have on the maf

photo.jpg


and for the egr, I got it with it all blocked off so i just left it
 

Viperwolf1

Contributor
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Aug 23, 2007
Messages
24,344
'91 mustang MAF. Should be good for an A9P ECM. You might try cleaning the sensor wires with some spray cleaner. Even dirt and dust on the wires will make it run poorly. And there usually will be no code generated.

Another area to look is fuel pressure. There are no pressure sensors so no codes.
 

ilovemaui

Bronco Guru
Joined
Jul 10, 2010
Messages
1,651
Loc.
Pacific Moist West
It sounds like air to fuel ratio. You should be able to get it running smoothly with 19 lb injectors and stock maf. My 408 runs quite smoothly with 19 lb injectors and 70 mm maf off the stock A9P settings, but it's never going to reach full potential without upgrading. If you're running a 55 mm maf you may consider bumping up a 70 mm and it should still run smoothly with the stock ecu settings. You might not be getting enough air. On your cold air setup you should avoid bends right before or atfer the MAF. The ECU is expecting laminar air flow. You should also check your idle with the idle control valve disconnected. It should idle with the valve disconnected. Do a search on resetting the base idle. A permanent fuel pressure gauge and adjustable regulator are also a good things to have.

I've just installed a third wideband O2 sensor to monitor the exact A/F ratio along with a quarterhorse tuner in the ecu. Optimum is 14.7% (14.08% with E10). I have a set of 42 lb injectors and Lightning 90 mm LMAF I plan to install as I educate myself on tuning. The injectors are over kill but the system can be tuned handle them just fine. The more you modify the more likely you're going to exceed the stock tune. I've been playing with different tune settings as a trial error in my learning curve. Little things can make a big difference. Tuning is a little intimidating to me, but I can't leave anything well enough alone.
 
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77broncodriver

77broncodriver

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Nov 21, 2009
Messages
344
which wires are you talking about? the actual connector or the wire mesh inside of the housing? i dont recall this one having that mesh on it
 

Viperwolf1

Contributor
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Joined
Aug 23, 2007
Messages
24,344
which wires are you talking about? the actual connector or the wire mesh inside of the housing? i dont recall this one having that mesh on it

Neither. These are the actual sensor wires, deep inside the 1/2" hole. Do not touch them with anything solid or you will break them and the sensor will be trash.
 
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77broncodriver

77broncodriver

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Nov 21, 2009
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344
I am 99% sure I got all the vacuum leaks out, that was a prior problem, but it's worth a shot to spray around again
 
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77broncodriver

77broncodriver

Full Member
Joined
Nov 21, 2009
Messages
344
I did the ground test and everything's good

And I have 40 psi when idling then 32 when giving it some gas
 

chuzie

Contributor
Bronco Guru
Joined
Jul 21, 2006
Messages
2,756
Where are your o2 sensors mounted?

Sent from my Droid using Tapatalk 2
 
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