Any resources for DIY EEC-IV repair?

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Any resources for DIY EEC-IV repair?

Unread postby NIKwoaC » Mon Sep 23, 2019 7:52 am

I have a bad A9L that causes the whole no-start/fuel pump runs continuously thing, but I am fairly confident the capacitors on the board are ok. Are there any other common faults that would cause this? I see a million how-tos for the cap replacement, but I'm having a hard time finding anything beyond that to diagnose and repair the board. Are my only options to either pay someone else to fix it or just scrap and replace with a new one?
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Vehicle Information: 1986 Mustang GT
Stock rebuilt 5L shortblock with Twisted Wedge 205 heads, Trick Flow R intake (long runner), 90mm TB, custom cam. ~ 9.8:1 CR, 42 lb injectors, 97mm Abaco MAF, Astro built "Cobra spec" T5, shorties with full 2.5" exhaust, Half ass self tuned with BE/EA and a Quarterhorse on an A9L with an A9L2-based tune. 336.3 HP @ 6050 RPM, 323.9 ft-lb @ 4700 RPM

Re: Any resources for DIY EEC-IV repair?

Unread postby decipha » Mon Sep 23, 2019 1:39 pm

Most likely either the eeprom or the processor is fried from disconnecting the j3 while powered up.

i do not know of any resources.
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91 4r70w - Skarlett
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Re: Any resources for DIY EEC-IV repair?

Unread postby NIKwoaC » Mon Sep 23, 2019 2:33 pm

decipha wrote:Most likely either the eeprom or the processor is fried from disconnecting the j3 while powered up.

i do not know of any resources.


Hmmm, yea I don't think it's that either. The QH hadn't been removed from this unit for 6 years, and the failure happened when the car was just sitting in the garage. Was running fine one day, then dead the next.
NIKwoaC
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Posts: 23
Joined: Tue Aug 04, 2015 6:58 pm
Name: Nik
Vehicle Information: 1986 Mustang GT
Stock rebuilt 5L shortblock with Twisted Wedge 205 heads, Trick Flow R intake (long runner), 90mm TB, custom cam. ~ 9.8:1 CR, 42 lb injectors, 97mm Abaco MAF, Astro built "Cobra spec" T5, shorties with full 2.5" exhaust, Half ass self tuned with BE/EA and a Quarterhorse on an A9L with an A9L2-based tune. 336.3 HP @ 6050 RPM, 323.9 ft-lb @ 4700 RPM

Re: Any resources for DIY EEC-IV repair?

Unread postby decipha » Mon Sep 23, 2019 4:26 pm

if the qh was on it then the qh battery died

pull the qh off and see if it primes the pump a sec and shuts it off
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90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce
07 GMC 2500HD 6L - Veranafer

Re: Any resources for DIY EEC-IV repair?

Unread postby NIKwoaC » Tue Sep 24, 2019 6:43 am

Tested the QH battery, it shows 2.8V, and the car acts the same with it removed from the A9L.

The reason I say that I doubt it's the caps is because this A9L is already a reman and they've all been replaced with higher voltage rated caps, and they still look brand new.

As always decipha, I appreciate the help!
NIKwoaC
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Posts: 23
Joined: Tue Aug 04, 2015 6:58 pm
Name: Nik
Vehicle Information: 1986 Mustang GT
Stock rebuilt 5L shortblock with Twisted Wedge 205 heads, Trick Flow R intake (long runner), 90mm TB, custom cam. ~ 9.8:1 CR, 42 lb injectors, 97mm Abaco MAF, Astro built "Cobra spec" T5, shorties with full 2.5" exhaust, Half ass self tuned with BE/EA and a Quarterhorse on an A9L with an A9L2-based tune. 336.3 HP @ 6050 RPM, 323.9 ft-lb @ 4700 RPM

Re: Any resources for DIY EEC-IV repair?

Unread postby decipha » Tue Sep 24, 2019 8:34 am

thata odd indeed ive never seen an ecu fail by just sitting

if i had to guess i would think something came loose in there

it would be prob be easier to just upgrade to a cbaza ecu, the 94-95 mustang auto ecus sell for cheap and are still plentiful
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decipha
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90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce
07 GMC 2500HD 6L - Veranafer

Re: Any resources for DIY EEC-IV repair?

Unread postby NIKwoaC » Tue Sep 24, 2019 8:50 am

Are there any benefits to that beyond controlling an auto trans?
NIKwoaC
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Posts: 23
Joined: Tue Aug 04, 2015 6:58 pm
Name: Nik
Vehicle Information: 1986 Mustang GT
Stock rebuilt 5L shortblock with Twisted Wedge 205 heads, Trick Flow R intake (long runner), 90mm TB, custom cam. ~ 9.8:1 CR, 42 lb injectors, 97mm Abaco MAF, Astro built "Cobra spec" T5, shorties with full 2.5" exhaust, Half ass self tuned with BE/EA and a Quarterhorse on an A9L with an A9L2-based tune. 336.3 HP @ 6050 RPM, 323.9 ft-lb @ 4700 RPM

Re: Any resources for DIY EEC-IV repair?

Unread postby decipha » Tue Sep 24, 2019 11:07 am

its readily available and an upgrade to the fox ecu
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decipha
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Posts: 17845
Joined: Mon Jul 15, 2013 5:29 pm
Location: New Orleans, LA
Name: Michael Ponthieux
Vehicle Information: Supercoupin' x10
90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce
07 GMC 2500HD 6L - Veranafer

Re: Any resources for DIY EEC-IV repair?

Unread postby dleach1407 » Tue Sep 24, 2019 12:58 pm

does it have to be a v8 ecu? I may end up doing an auto swap and ill use a 4r70w since i know we can use it with CBAZA
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Vehicle Information: 1995 Mustang T5 CBAZA/T4M2 Moates QH BE or TpRT
331 10.2:1 compression, TFS 11r 190 56cc heads
HPX MAF 3.25 OD tube with SaxonPC air straightener
F303 Cam, 1.6 Miller Mid-Lift rockers
T5 with an XTD clutch that somehow holds my power
80lb Dekas, Stock lines and rails 340LPH in tank
Minor upgraded T5 with counter gear stiffening plate
76mm On3 turbo, HP hotside, Custom coldside
560WHP and 606TQ 8lbs tapering to 6 91 octane
27degrees total timing.
Vehicle 2 Information: 1957 Ford F100
Mustang II front suspension -done
C-notched rear frame - done
Luxury ECU using RZASA - have
Fuel injected explorer 302 - have
4r70W -have

Lots of stuff planned including air bags and twin 55mm turbos.

Re: Any resources for DIY EEC-IV repair?

Unread postby decipha » Tue Sep 24, 2019 3:59 pm

yes

all cbaza ecu's are v8s no such thing as a v6 cbaza ecu
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decipha
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Posts: 17845
Joined: Mon Jul 15, 2013 5:29 pm
Location: New Orleans, LA
Name: Michael Ponthieux
Vehicle Information: Supercoupin' x10
90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce
07 GMC 2500HD 6L - Veranafer

Re: Any resources for DIY EEC-IV repair?

Unread postby dleach1407 » Tue Sep 24, 2019 6:14 pm

U4P0 and W4H0 are the only codes I know of for autos. Are there more?
dleach1407
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Posts: 204
Joined: Fri Sep 07, 2018 10:13 pm
Vehicle Information: 1995 Mustang T5 CBAZA/T4M2 Moates QH BE or TpRT
331 10.2:1 compression, TFS 11r 190 56cc heads
HPX MAF 3.25 OD tube with SaxonPC air straightener
F303 Cam, 1.6 Miller Mid-Lift rockers
T5 with an XTD clutch that somehow holds my power
80lb Dekas, Stock lines and rails 340LPH in tank
Minor upgraded T5 with counter gear stiffening plate
76mm On3 turbo, HP hotside, Custom coldside
560WHP and 606TQ 8lbs tapering to 6 91 octane
27degrees total timing.
Vehicle 2 Information: 1957 Ford F100
Mustang II front suspension -done
C-notched rear frame - done
Luxury ECU using RZASA - have
Fuel injected explorer 302 - have
4r70W -have

Lots of stuff planned including air bags and twin 55mm turbos.

Re: Any resources for DIY EEC-IV repair?

Unread postby decipha » Wed Sep 25, 2019 7:27 am

2 more

FCL0
S4M1

and

A4A1
User avatar
decipha
Tooner
 
Posts: 17845
Joined: Mon Jul 15, 2013 5:29 pm
Location: New Orleans, LA
Name: Michael Ponthieux
Vehicle Information: Supercoupin' x10
90 (4x 5spds) - Dante, Ruby, Daja, Ava
91 4r70w - Skarlett
92 (2x) 5spd & auto - Bianqa, Andrea
93 auto - Danika
94 5spd Rionda
95 auto Aisha
Vehicle 2 Information: Others:
00 Lincoln LS - Luanda
98 Camaro SS - Bounquisha
02 Harley F-150 - Sasasha
03 Marauder - DyShyKy
00 Explorer 5L - Bernyce
07 GMC 2500HD 6L - Veranafer

Re: Any resources for DIY EEC-IV repair?

Unread postby NIKwoaC » Sat Sep 28, 2019 7:19 am

Small update.

I had a spare A9L on hand from a junkyard car, it had a broken pin and a fried sigrtn trace. I've never tried my hand at circuit board repair, but I was able to correct both issues and got the car running again with it. Turns out, the alternator was bad, which was causing power surges/flickering at idle. Can a bad alternator kill a computer? At this point I still don't know what caused the first one to die, but the bad alt seems suspect to me.
NIKwoaC
General Poster
 
Posts: 23
Joined: Tue Aug 04, 2015 6:58 pm
Name: Nik
Vehicle Information: 1986 Mustang GT
Stock rebuilt 5L shortblock with Twisted Wedge 205 heads, Trick Flow R intake (long runner), 90mm TB, custom cam. ~ 9.8:1 CR, 42 lb injectors, 97mm Abaco MAF, Astro built "Cobra spec" T5, shorties with full 2.5" exhaust, Half ass self tuned with BE/EA and a Quarterhorse on an A9L with an A9L2-based tune. 336.3 HP @ 6050 RPM, 323.9 ft-lb @ 4700 RPM

Re: Any resources for DIY EEC-IV repair?

Unread postby dleach1407 » Sat Sep 28, 2019 12:22 pm

Circuit board trace repair isnt too hard assuming you have good places you can solder jumpers. Good job on fixing it. If the alternator is surging above 16v it could cause it but I still feel its pretty unlikely. If the voltage is all over the place though that can place extreme loads on certain parts like capacitors. Capacitors are essentially power stabilizers. The lower the voltage the more amperage each component inside the ecu will pull to perform the same functions so its possible something overheated and failed due to the voltage.
dleach1407
Power Poster
 
Posts: 204
Joined: Fri Sep 07, 2018 10:13 pm
Vehicle Information: 1995 Mustang T5 CBAZA/T4M2 Moates QH BE or TpRT
331 10.2:1 compression, TFS 11r 190 56cc heads
HPX MAF 3.25 OD tube with SaxonPC air straightener
F303 Cam, 1.6 Miller Mid-Lift rockers
T5 with an XTD clutch that somehow holds my power
80lb Dekas, Stock lines and rails 340LPH in tank
Minor upgraded T5 with counter gear stiffening plate
76mm On3 turbo, HP hotside, Custom coldside
560WHP and 606TQ 8lbs tapering to 6 91 octane
27degrees total timing.
Vehicle 2 Information: 1957 Ford F100
Mustang II front suspension -done
C-notched rear frame - done
Luxury ECU using RZASA - have
Fuel injected explorer 302 - have
4r70W -have

Lots of stuff planned including air bags and twin 55mm turbos.


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