Engine Strange drivability issues and can only pull koeo codes

Blown88GT

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Nov 13, 1999
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UPDATE!!!! I was finally able to pull koer codes!!! I pulled my eec back apart and one of the e-caps I replaced I must have got the board too hot with the soldering iron and burnt a trace off the board that connects the e-cap to I think the processor.i could see a open spot in the trace and verified with my fluke meter it was open. So I soldered A wire in its place. Now I wonder if I messed up more than just that because on some of the e-caps 1 leg only has one trace going to it while the 2nd leg will have up to 4 traces going to it (checked by shining a flashlight from underneath to look through the board)??? The one I fixed though allowed me to finally dump koer codes although I don’t think they mean anything in my case as I believe they are all related to my missing emissions equipment. So here are my codes koeo= 31,81,82,85,84 CM= 31 koer= 94,44,31 and passed cyl bal test with a 9 four times. So my conclusion is I did more harm than good replacing the e-caps or they leaked so bad they messed up the board. Since none of my codes point to any bad sensors or anything that would cause my drivability problems. Does everyone agree? Have any input? What’s the cheapest/best route to get a new or refurbished A9L?
So would anyone else agree since
I'm pretty sure it's only a 2 layer PWB (Printed Wiring Board), component side & solder side. There are no internal ground planes or voltage planes. 4 traces going to the negative leg would make sense since there is no internal ground plane. Be glad it's a 2-layer board, because you can literally run ECW's (Engineering Change Wires) in place of every trace. It'll be okay. If you have a Fluke meter, you should also have a good solder station. I recently had to replace my 30 year old one with a new Weller WE 1010NA.

There are almost no A9L's or any EEC-IV's available, since 30 year old electronics are considered salvage & melted down for the rare metals, i.e. gold, silver, copper, etc.
 
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jrichker

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I'm pretty sure it's only a 2 layer PWB (Printed Wiring Board), component side & solder side. There are no internal ground planes or voltage planes. 4 traces going to the negative leg would make sense since there is no internal ground plane. Be glad it's a 2-layer board, because you can literally run ECW's (Engineering Change Wires) in place of every trace. It'll be okay. If you have a Fluke meter, you should also have a good solder station. I recently had to replace my 30 year old one with a new Weller WE 1010NA.

There are almost no A9L's or any EEC-IV's available, since 30 year old electronics are considered salvage & melted down for the rare metals, i.e. gold, silver, copper, etc.
Hold the PC board up to the light; if you can see light through the board where there are no components, it is a 2 layer board.

Most of the computer boards that I worked on in the late 80's were multilayer, with a minimum of topside, bottom side, with power and ground in between. Six and 8 layer boards were not uncommon in computer manufacture during those years. The large ground plane created by the ground layer of the PC board helped to reduce stray signal noise. The next layer being the +5 DC made the PC board act as a large surface flat capacitor to help reduce localized current spikes.
 

Foxy420

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Aug 6, 2019
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One side of the electrolytic cap is ground (negative or - sign). The other side goes to the circuit it serves.
Yea I know that and I installed them correctly. Believe me I was very OCD about getting it right. I’m just thinking that since I can’t see the traces coming off the side of one cap that should have at least 4traces I either got it too hot and melted them traces or the e-caps leaked so bad it ate away the traces or when i was scraping away the protective coating I ruined the traces. Since repairing the one obviously melted trace got it to flash koer codes this is the direction I’m leaning now. Especially since no codes point to anything related to my isssues. Only codes are for the emissions stuff that’s all been deleted. So now I’m looking to buy a replacement A9L if you know of any? I found an A9P locally but unsure if I want to go that way I’ve heard of idle problems and less aggressive timing curve. Anyone have any input on running the A9P with a 5speed?
 

Foxy420

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Aug 6, 2019
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I'm pretty sure it's only a 2 layer PWB (Printed Wiring Board), component side & solder side. There are no internal ground planes or voltage planes. 4 traces going to the negative leg would make sense since there is no internal ground plane. Be glad it's a 2-layer board, because you can literally run ECW's (Engineering Change Wires) in place of every trace. It'll be okay. If you have a Fluke meter, you should also have a good solder station. I recently had to replace my 30 year old one with a new Weller WE 1010NA.

There are almost no A9L's or any EEC-IV's available, since 30 year old electronics are considered salvage & melted down for the rare metals, i.e. gold, silver, copper, etc.
Yea I’m gonna take it to work tomorrow where we have a really nice solder station with solder suckers and everything else needed hopefully I can fix it as funds are low due to back to school shopping
 

Foxy420

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Aug 6, 2019
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Anyone see my pic above of the 2 wire black connector that I believe to bee for the eec power ground?? Anyone ever seen that connector before??? All the info I’ve found says it should be a 1 pin connector with just the black/green wire. Mine has 2 pins with a black/green and black/yellow. Kind of stumped as to where the black/yellow wire goes or what it’s for??
 

Foxy420

New Member
Aug 6, 2019
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38
NW O-H-I-O
Anyone see my pic above of the 2 wire black connector that I believe to bee for the eec power ground?? Anyone ever seen that connector before??? All the info I’ve found says it should be a 1 pin connector with just the black/green wire. Mine has 2 pins with a black/green and black/yellow. Kind of stumped as to where the black/yellow wire goes or what it’s for??
 

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jrichker

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If there is only 1 connector pin inside the plastic shell, that is the computer power ground. Use a multimeter or DVM to check continuity t between the single connector contact and computer pins 40 & 60. You should see less than 1 Ω.
See my post #13 in this thread for more information and pictures of the battery negative ground wiring.

Computer wiring harness connector, wire side
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Computer wiring harness connector, computer side
88243.gif
 
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