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Old 08-01-2014, 08:43 AM   #51
JBeachstang11
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Quote:
Originally Posted by 90nSSMD View Post
Here's a website with tons of diagrams/info:

http://veryuseful.com/mustang/tech/

Might come in handy if you're looking to trace down the harness for a problem.
Thank you sir!
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1990 GT 5spd

311ci Edel 6025 2.02 heads, Comp XE274HR, Comp 1.6 RR, Tubular GT40 upper, ported lower, 24# Inj, 70mm BBK TB/EGR, ProM75mm MAF A9P ECM, BBK Shortys, Hpipe etc..,

Eibach sport springs and sloppy shocks/struts..
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Old 08-01-2014, 02:03 PM   #52
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Checked continuity from MAF wiring back to harness and doesn't appear to be any breaks at all.

Going by this test to check the resistance

http://www.myo-p.com/Ford-EEC/Main%20Frame.html

Instead of 10k ohms or better across the #50 MAF sig and #9 MAF rtn wires I was getting (on the 20k setting) 2.01

Also between the #50 MAF sig and ECU Grnd I was only getting 3.01 instead of 10k or more (on the 20k setting)

Results of this according to that test say faulty control unit. Also verified my Injector info and changed the breakpoint to 1.9182 from the 3+ that is was effectively richening it to no avail.

Same crap idle and stall or surge if I hold the gas down just a tad.
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1990 GT 5spd

311ci Edel 6025 2.02 heads, Comp XE274HR, Comp 1.6 RR, Tubular GT40 upper, ported lower, 24# Inj, 70mm BBK TB/EGR, ProM75mm MAF A9P ECM, BBK Shortys, Hpipe etc..,

Eibach sport springs and sloppy shocks/struts..
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Old 08-01-2014, 03:54 PM   #53
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Not sure what's going here but I've known the ECU was an A9P in my 5spd car but what I just noticed was the harness plug going into the ECU say A9P on it as well...

It's had a few owners, my tag is painted over on the drivers side and running down my vin only gives me basics, no trans info.

Does that section of the harness change with different ECU's?
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1990 GT 5spd

311ci Edel 6025 2.02 heads, Comp XE274HR, Comp 1.6 RR, Tubular GT40 upper, ported lower, 24# Inj, 70mm BBK TB/EGR, ProM75mm MAF A9P ECM, BBK Shortys, Hpipe etc..,

Eibach sport springs and sloppy shocks/struts..
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Old 08-07-2014, 02:26 PM   #54
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Really have no idea at this point. New computer, new 02 sensors (old ones were coming apart), idle reset, even capped vacuum at pipe off intake, away from vac tree and still does it. Voltage good at 02 sensor heaters. No idea

Only thing that remains a constant here is unplugging the MAF sensor and it will idle, but it is a new sensor and the curve is entered in the computer..
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1990 GT 5spd

311ci Edel 6025 2.02 heads, Comp XE274HR, Comp 1.6 RR, Tubular GT40 upper, ported lower, 24# Inj, 70mm BBK TB/EGR, ProM75mm MAF A9P ECM, BBK Shortys, Hpipe etc..,

Eibach sport springs and sloppy shocks/struts..

Last edited by JBeachstang11; 08-07-2014 at 03:04 PM.
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Old 08-08-2014, 10:57 AM   #55
88 orangepeel notch
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You've got me stumped, you've done everything that I would have tried. I only read the last 2 pages of this thread to get caught up, were there any codes stored on the way old ECM before you swapped them?

Also, I've seen a bad ground do some really weird things on these cars,
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306 with all bolt ons, letter cam, ported E7's, T5 swap, full exhaust, 3:55's, 2" drop, and the worst paint you'll ever see or feel.
Dyno'd 300/316, 2745lbs-track scale
Best ET………12.4@108, 1.66 60ft on 8" ET Drags.
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Old 08-08-2014, 05:13 PM   #56
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Quote:
Originally Posted by 88 orangepeel notch View Post
You've got me stumped, you've done everything that I would have tried. I only read the last 2 pages of this thread to get caught up, were there any codes stored on the way old ECM before you swapped them?

Also, I've seen a bad ground do some really weird things on these cars,
I now it's been a mess.

Only öld comp" codes before I swapped were
Pulled codes eng off Key on and got..

15 rom test fail or power interrupt to memory
85 ecessive fuel pressure or flow, canister purge circuit

91 (not sure since eng was off?) Oxygen sensor problem, fuel pressure out of specified range or injectors out of balance

96 Fuel pump circuit

Now the codes I pull off the new computer, eng off key on are
15
31
85
84
96
""
-1-

31
96
""
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1990 GT 5spd

311ci Edel 6025 2.02 heads, Comp XE274HR, Comp 1.6 RR, Tubular GT40 upper, ported lower, 24# Inj, 70mm BBK TB/EGR, ProM75mm MAF A9P ECM, BBK Shortys, Hpipe etc..,

Eibach sport springs and sloppy shocks/struts..
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Old 09-03-2014, 05:09 PM   #57
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Finally got my build sheet from Ford. Turns out from what I can gather this car was an automatic car and at some point somebody swapped in the manual trans.

Now it has a manual computer and I know there is a wiring issue on pin 30 between the two with the neutral safety switch but I'm not sure how that would cause an idle issue.

Still stumped as the idle problem is almost the same as it was before I rebuilt the engine so it must be a wiring harness issue or a TB issue or maybe my vac tree is cracked but something has carried over, even though most of the sensors are new with the fresh engine build.

Still digging.

BTW Moates recommended I start with the "Cobra" strategy to begine with as it is already setup for the TB, Inj, and MAF mapping. but now the car smokes sometimes like its getting too much fuel..
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1990 GT 5spd

311ci Edel 6025 2.02 heads, Comp XE274HR, Comp 1.6 RR, Tubular GT40 upper, ported lower, 24# Inj, 70mm BBK TB/EGR, ProM75mm MAF A9P ECM, BBK Shortys, Hpipe etc..,

Eibach sport springs and sloppy shocks/struts..
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Old 09-04-2014, 07:19 AM   #58
88 orangepeel notch
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Wish I could be more help, but your thinking on a vacuum leak is where I'd start. Good luck

Have you checked fuel pressure?
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306 with all bolt ons, letter cam, ported E7's, T5 swap, full exhaust, 3:55's, 2" drop, and the worst paint you'll ever see or feel.
Dyno'd 300/316, 2745lbs-track scale
Best ET………12.4@108, 1.66 60ft on 8" ET Drags.
24 mpg (combined)
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Old 09-04-2014, 10:29 AM   #59
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Quote:
Originally Posted by 88 orangepeel notch View Post
Wish I could be more help, but your thinking on a vacuum leak is where I'd start. Good luck

Have you checked fuel pressure?
Well I appreciate all the help and tips you've given so far orangepeel.

I haven't checked the fuel pressure yet, good point. It does have a new stock type regulator and PO swapped in 190lph pump but like you said best idea is to eliminate variables.
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1990 GT 5spd

311ci Edel 6025 2.02 heads, Comp XE274HR, Comp 1.6 RR, Tubular GT40 upper, ported lower, 24# Inj, 70mm BBK TB/EGR, ProM75mm MAF A9P ECM, BBK Shortys, Hpipe etc..,

Eibach sport springs and sloppy shocks/struts..
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Old 09-04-2014, 10:29 AM
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