View Full Version : EFI running lean


BrianS
02/20/2006, 07:09 PM
I have a 68 mustang gtcs witch I just finish installing my EFI for a 86-93 mustang. Im using my 68 302 long block with an EFI intake with all new senors and a new main harnes from motorspot SVO and new ecu from motorspot.

The car fires right up but wont hold a idle. I can put my hand infront of the intake to restrick the air flow and it will hold an idle and run right, as soon as I remove my hand it will run like shit and will stall out. there is no check engine light on. I disconect any senor and the light comes on so I know it is working.

I am lost and need help with my problem and no I cant take the car to a shop.

rvrtrash
02/20/2006, 07:29 PM
To bad you can't take it to a shop, 'cause that's what I'd recommend. Since you can't, start by taking a vacumn reading and looking for a vac. leak. Check your fuel pressure to make sure it's correct. EFI runs a lot higher fuel pressure than carb's. Are the injectors firing in the correct order for the older firing order? After that, you'll need an analyzer so you can see what the sensors are reporting. Just because the check engine light doesn't come on doesn't mean all the sensors are accurate. Hope this gets you started in the right direction.
Steve

BrianS
02/20/2006, 08:32 PM
yes I know my firing is right and i have plenty of fuel and it shows no vac leak... you see Steve, I need someone that know pasted those steps. but thanks for your input. if you have anything else to and please let me know.

Mosesatm
02/20/2006, 09:35 PM
you see Steve, I need someone that know pasted those steps.

What does this say?

joedls
02/20/2006, 09:41 PM
What does this say?

I think he meant to say, "you see Steve, I need someone that knows past those steps."

Mosesatm
02/20/2006, 09:52 PM
Probably not going to find too many people like that here. Steve is one of our best, if not THE best.

joedls
02/20/2006, 10:02 PM
Probably not going to find too many people like that here. Steve is one of our best, if not THE best.

Probably doesn't need anyone anyway. According to his signature line, he's done it all.

BrianS
02/20/2006, 10:55 PM
all Im asking if someone mybe knows what to do in the problem that im having, to help me narrow the diagnoising time. If anyone has any suggestion please let
me know, and lets not get off the subject im not putting anyone down.
I have taken Steve's advice before.

joedls
02/20/2006, 11:03 PM
all Im asking if someone mybe knows what to do in the problem that im having, to help me narrow the diagnoising time. If anyone has any suggestion please let
me know, and lets not get off the subject im not putting anyone down.
I have taken Steve's advice before.

I apologize if I misunderstood your prior post. It did seem to me that you were insulting Steve's advice. I'm glad that's not the case. I hope someone can help you figure out your problem. I know I can't.

jk89cat
02/20/2006, 11:19 PM
well heres a good question, are you using the 5.0 ho firing order with the stock 68 cam? with using the 86-93 mustang, requires the ho and 351 cam. the so tbird /cougar /crown /grandmarquis, would be sutible to use for the stock cam if thats what your doing otherwise, you may not have the intake sealed enough for the intake to pull a proper seal , you could also have a bad iac . i will be doing a ho style swap when i get my galaxie done, i want to make a efi/overdrive 67 / 68 gtcs clone / restomod

BrianS
02/20/2006, 11:20 PM
Thanks for understanding.
My best bet is to just step back for a week or too and not think about this EFI
problem and go back with a clear mine.

BrianS
02/20/2006, 11:30 PM
my firing order on the EFI is the same as the 302 becuase of the main harness
you can get the one that fires the 351 order...... the part # at the end are difernt.

rvrtrash
02/21/2006, 01:56 AM
I just logged back in. Thanks for the compliments guys.:embarass: I don't know what else to say.
Steve

jk89cat
02/21/2006, 10:19 AM
hmm, i think thats your problem, if the pcm you have is out of a mustang , or tuned for one, and your usign the std 302 firing order, that is , its not the same firing order. i really think this is what going on, you have a ho computer and have the engine set up for a std output 302 , in which the cam , pcm, firing order and upper intake are diiferent

BrianS
02/21/2006, 06:35 PM
when I was working today, my coworker/buddy told me to pinch the return line to the gas tank to see if my fuelregulator is working. He told me I may need a ajustable fuelregulator to increase the fuel in the line.

So I thought 45-60 on my fuel is in spec, but 60-80 is the right presser to run the EFI. So I pinched the return line and started the car
IT RUNS, IT HOLDS AN IDLE, IT RUNS GREAT!!!!!!
So I now know what to do install an ajustable fuel regulator..

jk89cat
02/21/2006, 09:36 PM
ok, thats a different way of diagnosing it, what kind of fuel pump you running? should be around 190 lph you could just have a bad fuel pressure regulator too

rvrtrash
02/22/2006, 12:49 AM
[QUOTE=BrianS]He told me I may need a ajustable fuelregulator to increase the fuel in the line.
QUOTE]

Gee- a fuel pressure problem. I wish I'd thought of that.:wink: I'm glad your buddy at work could help you out.

Steve