Computer Issue I think 93L

9

93blackbeauty

Chris Clayton
Hey guys not sure if this is the right section but this is what Ive got. Bought a 93 Lightning two weeks ago as a non runner. The dealer couldn't figure it out and the shop they sent it too knew nothing about OBD-1 (They were convinced it was the ECM but would take three days to get one and I just couldn't wait that long. It would start idle for a few minutes but if you touched the gas or put it in gear it would stall. So I towed it back to Atlanta from just outside Myrtle Beach. (price was too good to pass up). So dropped it at the shop I have most of my diagnostic work done here local and had it looked at by a tech who claims to have had two of these Gen 1's. He said he found a loose ground and they truck ran all day for him no problems. So I went and picked it up. Been driving it for a few days even drove it to work one day 40 miles all interstate no issues started every time ran really good. Till this morning went and got new tires then ran a few errands and came home and washed it. Immediately wouldn't start after. Finally got it to catch but it ran really rough smelled like fuel and had really erratic idle. Will run about 2-3 minutes then idle dips so low it just stalls. Truck is completely stock as far as I can tell with the exception of the ECM I pulled it out when I first got it home and its labeled as a 94 good ECM so pretty sure its been replaced in the past. I had two codes today which is the first time it has set any code 26 and code 654. Not sure what that indicates as 26 is a MAF code which I'm 100% sure this truck is speed density and 654 pulled up as a trans not in park code. Any info is appreciated. I can get the ECM but its non refundable so id hate to buy it and that not be it. Any definitive way to test one?

Also not sure if it maters but this ECM only works if you install it in the slot rotated 180 degrees from the stock position. Not sure if its somehow grounded in the tray or if this is another symptom. It also will not run period if you take the PCM out of the tray. (I was testing to ensure it wasn't a harness short). I have toyed with the idea of a mass air conversion but not sure if its worth it at this point. Really just need her to run. Bought it as a winter daily since my mustang is way to much on winter roads.

Codes:
26, 654

Hope this isn't too wordy but wanted to give as much detail as possible.
 
93blackbeauty said:
Also not sure if it maters but this ECM only works if you install it in the slot rotated 180 degrees from the stock position. Not sure if its somehow grounded in the tray or if this is another symptom. It also will not run period if you take the PCM out of the tray.
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Say Whatttttt?

What is the catch code of the EEC?
 
Ill have to take a pic to show what I mean haha. Its backwards from all the diagrams I have seen. Maybe a dumb question but what is a catch code? Its the wierdest thing. Im getting pretty confident it is a PCM issue but just want to be sure. The engine has been running perfect for the last two weeks since I got it home so I really doubt its mechanical. Im at work at the moment so I will have to do the checks when I get home.
 
Oh now I gotcha all my training is OBD-2 stuff. I have no problems whipping the laptop out for the stang but this truck has me stumped lol. Ill grab that when I get home Im pretty sure its C3 something.
 
If the issue started after you washed it - I'd look for water intrusion in the pcm connector
 
It should run no problem with the EEC just hanging there connected to the 60pin connector. When you are saying it is giving a mass air code that's what makes me want to check your catch code 1st
 
Thats what I was thinking but since its done it before I wonder if I have a cowling leak dripping down on it. I had to scrub it pretty good to get it clean. Is there anyway to seal these things off if it is a leak?
 
93blackbeauty said:
Thats what I was thinking but since its done it before I wonder if I have a cowling leak dripping down on it. I had to scrub it pretty good to get it clean. Is there anyway to seal these things off if it is a leak?
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What did you scrub? The tray? The 60 pin connector or the PCM? I'd also make sure the center bolt that helps hold the 60 pin to the PCM is tight. Does it the PCM have a chip? Maybe take a few pics and post.
 
Haha no the cowling above the computer it's the only thing I can think of that caused it. The truck was super nasty.

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Jamie V said:
It should run no problem with the EEC just hanging there connected to the 60pin connector. When you are saying it is giving a mass air code that's what makes me want to check your catch code 1st
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OK the computer is a C3P2 and the door pillar sticker says C3P1. The top of the computer has 94 Lightning good origional written on it. It came from a man called Arthur Todd not sure if he's active here but he's big into lightnings or so I'm told. I pulled the computer apart and found an exploded capacitor looks like by mounting it the wrong way it allowed it to make contact by gravity so it worked intermittently. Now it did have evidence of water on the case but I didn't see any on or around the board. What can I do to shield the new one from any water?

Jamie V said:
It should run no problem with the EEC just hanging there connected to the 60pin connector. When you are saying it is giving a mass air code that's what makes me want to check your catch code 1st
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93blackbeauty said:
OK the computer is a C3P2 and the door pillar sticker says C3P1. The top of the computer has 94 Lightning good origional written on it. It came from a man called Arthur Todd not sure if he's active here but he's big into lightnings or so I'm told. I pulled the computer apart and found an exploded capacitor looks like by mounting it the wrong way it allowed it to make contact by gravity so it worked intermittently. Now it did have evidence of water on the case but I didn't see any on or around the board. What can I do to shield the new one from any water?




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I have a good 93 L computer if you need one. First I would re solder the component and seel if it works. You need to get everything very clean. Use an acid brush cut off all but about a 1/4 of the hairs to stiffin it up and clean the pad and lead with rubbing alcohol. Put some flux on there and then with a properly cleaned solder tip you should not need to add much solder just enough to make a bridge and reflow the loose lead. when finished clean again with alcohol to remove flux and spray some conformal coating on your repair and your done. 5 min job and may not need another computer. Now if the cap is bulging or burnt looking then replace it which might entail removing the board and a lot more time but probably only a couple dollar component. If other damage was done to IC's then may not fix but worth a try if you have the time.
 
Jabo04 said:
I have a good 93 L computer if you need one. First I would re solder the component and seel if it works. You need to get everything very clean. Use an acid brush cut off all but about a 1/4 of the hairs to stiffin it up and clean the pad and lead with rubbing alcohol. Put some flux on there and then with a properly cleaned solder tip you should not need to add much solder just enough to make a bridge and reflow the loose lead. when finished clean again with alcohol to remove flux and spray some conformal coating on your repair and your done. 5 min job and may not need another computer. Now if the cap is bulging or burnt looking then replace it which might entail removing the board and a lot more time but probably only a couple dollar component. If other damage was done to IC's then may not fix but worth a try if you have the time.
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Yeah I may run to radio shack is there a listing on specs for these capacitors somewhere? At least to get it running everywhere I called said minimum of three days turnaround time on one. Also can you use silicone on the two halves of the case to protect from water or will that effect cooling? I just don't want to toast another. This doesn't look like short damage but I did find water on the case from where I wasjed the truck.

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Pull your cowl off and reach down there and you will find a seam. That's more than likely where the water comes from. I'm sure somewhere on the forum someone has talked about the steps they've went through to cure the leaks that occur in the cab and dash area. I tore my entire interior apart so it was easy to find every leak. Even the dash...

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Now is a good time to install Struckby's protection harness.


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IVSVS said:
Now is a good time to install Struckby's protection harness.


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How do I get hould of one? I'm going to try to get the capacitors tomorrow on my day off and see if I can fix my current one.

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IVSVS said:
Ed has them advertised in the classifieds


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Perfect got in touch with him thanks for the info.

Also on another note only other issue I have with this truck is a slight ticking from one cylinder. Is the lash adjustable on these trucks? I can hear it with the stethoscope on the header flange and it kind resonates in the upper intake I can put my hand on it and quiet it a bit. Just wondering if this is bad lifter or adjustment or if it's a bearing on the way out. Noise is not really noticeable anywhere but idle.

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OK anyone have diagnostic codes list for these trucks? I replaced the capacitors on the PCM and it will start everytime now even with the PCM just kinda sitting there but after a few minutes of running it starts running rough surging idle and will finally stall but it will start right back up and go immediately into the bucking and surging. Also I tried to move it around the driveway and it pretty much slams int drive and reverse. Not really sure where else to look. It sets codes 26 and 654. I can't really find a reference to those anywhere. Does anyone have a codes list or a direction to start looking?

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