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Turbo Tbird
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Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by Turbo Tbird » Mon Jul 18, 2022 8:25 pm

I've had a Quarterhorse in my 93 Tbird SC for about three years now (the later version with removable 2032 battery.) Recently my car would not start, no fuel pump and cooling fan runs constantly. The first thing I tried was hooking my laptop up to the QH. I use TunerPro RT and it detected the QH as usual and allowed me to verify, download, and upload the current tune I've been using. Nevertheless I removed the computer and replaced the battery in the QH just in case, but no luck there either. Then I tried the computer *without* the QH (key on only, since obviously it wouldn't run right with the stock tune) and still nothing.

To make a long story short, amongst many other troubleshooting steps I've tried putting in a different known working computer, but unfortunately in my haste to try it I neglected to test it WITHOUT the QH first. Can a faulty QH potentially brick one of these computers or is that literally impossible? Because I'm at wits' end right now...

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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by jsa » Tue Jul 19, 2022 5:59 am

It is known that removing or installing a QH while ignition power is on can cause issues.

I imagine an intermittent crap connection between a QH and the J3 port could cause the same issue.
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cgrey8
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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by cgrey8 » Tue Jul 19, 2022 6:15 am

The other possibility is that the EECs are just old. Open the cover and look for leaking capacitors. They often leave residue on the circuitboard when they are leaking from the bottom. Here's what to look for:
Image

Also look for bulging caps. When bulging, they are bad. Note, they can also leak from the tops as seen here:
Image

When the capacitors go bad, they can usually be replaced and all is well.

If you attempt to replace the cap yourself, then I highly recommend you take pictures of the capacitor you are about to remove from multiple angles. Use these pictures to make sure you get the replacement put back in with the polarity correct (look for the band going down the length of the label). Installing caps backwards will damage them and possibly other components on the board.

Replacement caps (and soldering equipment for that matter) can be purchased online. If you find bad caps, I would certainly try replacing them before scrapping the EECs.
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Turbo Tbird
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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by Turbo Tbird » Tue Jul 19, 2022 9:23 am

jsa wrote: Tue Jul 19, 2022 5:59 am It is known that removing or installing a QH while ignition power is on can cause issues.

I imagine an intermittent crap connection between a QH and the J3 port could cause the same issue.
Can a intermittent/crap connection kill the computer though? i.e. make it completely unusable even without the QH plugged into it?

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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by Turbo Tbird » Tue Jul 19, 2022 9:26 am

cgrey8 wrote: Tue Jul 19, 2022 6:15 am The other possibility is that the EECs are just old. Open the cover and look for leaking capacitors. They often leave residue on the circuitboard when they are leaking from the bottom. Here's what to look for:

Also look for bulging caps. When bulging, they are bad. Note, they can also leak from the tops as seen here:

When the capacitors go bad, they can usually be replaced and all is well.

If you attempt to replace the cap yourself, then I highly recommend you take pictures of the capacitor you are about to remove from multiple angles. Use these pictures to make sure you get the replacement put back in with the polarity correct (look for the band going down the length of the label). Installing caps backwards will damage them and possibly other components on the board.

Replacement caps (and soldering equipment for that matter) can be purchased online. If you find bad caps, I would certainly try replacing them before scrapping the EECs.
Thanks! I did a visual inspection to the best of my abilities/knowledge, but I couldn't find any caps that were leaking or bulged or any other signs of failure, but I suppose it could still be one (or more) caps that look like the one pictured that is only slightly bulged. I ordered a "reman" computer from Autozone, which I assume is just a factory Ford PCB with caps replaced and cleaned up/tested. Hopefully that fixes it, otherwise I am going to be completely dumbfounded.

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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by Paulie » Tue Jul 19, 2022 11:26 am

Have you checked to make sure you have power and ground to the computer?
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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by cgrey8 » Tue Jul 19, 2022 11:51 am

As for the QH bricking an EEC, I've only ever heard of this happening during installation/removal of a chip on and off the J3 port with the ignition ON. I've never heard of a single intermittent connection doing it.

I always just assumed that the real cause of doing this is how people often wiggle the chips back and forth until the chip releases. Since this rotates the chip connectors at an angle relative to the edge-connector, this can cause the contacts of one connection to bridge over and simultaneously touch a neighboring contact. If multiple connections do this at once and the EEC is powered, I could see how it'd be possible to fry RAM/ROM/Processor components that weren't designed to tolerate more than 5v.

I've always wondered would there be any damage removing a J3 chip if the chip were kept perfectly parallel to the EEC circuit board while the EEC is powered. I don't know and I've never been so curious I felt the need to risk an EEC to find out.
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Turbo Tbird
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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by Turbo Tbird » Tue Jul 19, 2022 11:59 am

cgrey8 wrote: Tue Jul 19, 2022 11:51 am As for the QH bricking an EEC, I've only ever heard of this happening during installation/removal of a chip on and off the J3 port with the ignition ON. I've never heard of a single intermittent connection doing it.

I always just assumed that the real cause of doing this is how people often wiggle the chips back and forth until the chip releases. Since this rotates the chip connectors at an angle relative to the edge-connector, this can cause the contacts of one connection to bridge over and simultaneously touch a neighboring contact. If multiple connections do this at once and the EEC is powered, I could see how it'd be possible to fry RAM/ROM/Processor components that weren't designed to tolerate more than 5v.

I've always wondered would there be any damage removing a J3 chip if the chip were kept perfectly parallel to the EEC circuit board while the EEC is powered. I don't know and I've never been so curious I felt the need to risk an EEC to find out.
welp, i just tried the reman'd computer from Autozone (no QH plugged in) and still no dice. so right now i am just completely at a loss for what to do or check next...

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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by cgrey8 » Tue Jul 19, 2022 12:01 pm

That's actually good news.
This means you may still have good EECs. But it does mean you will need to look elsewhere for the failures. Start by verifying voltage on the pins that are supposed to have voltage on the big EEC plug.
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Turbo Tbird
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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by Turbo Tbird » Tue Jul 19, 2022 12:21 pm

cgrey8 wrote: Tue Jul 19, 2022 12:01 pm That's actually good news.
This means you may still have good EECs. But it does mean you will need to look elsewhere for the failures. Start by verifying voltage on the pins that are supposed to have voltage on the big EEC plug.
that's the really confusing part - all 3 pins listed in the EVTM for 12v are getting healthy 12v. all 3 grounds are getting ground. it makes no sense whatsoever. thanks for the assist btw!

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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by cgrey8 » Tue Jul 19, 2022 12:37 pm

The next things to check are going to be things the engine needs to run. Here's my thinking:
  • Injectors are fed 12v and they are activated by sinking to ground through the EEC. So make sure they have 12v when the ignition is ON
  • Check if the EEC is sinking them to ground when cranking the engine via test-light or analog meter if you have one
  • Check for fuel pressure
  • If unsure whether you have fuel, spray starter fluid on the air filter. If the engine cranks, then dies as the starter fluid supply dries out, then you have a confirmed fuel delivery problem, not an EEC problem. If the engine still doesn't do anything, then move onto ignition.
  • Check the coil/plugs for a SOLID spark. Weak coils may give you a spark in open air, but the spark is usually very weak. When the air is compressed, the coil may not have the strength to jump the gap. A healthy spark should be easily heard as well as seen. With vehicles that have a dedicated ignition module (e.g. gray/black TFIs, EDIS 4/6/8, etc), you should still have spark even if the EEC is failing. Now for EECs where the control of ignition coils is internal to the EEC, that may not be the case.
...Always Somethin'

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Turbo Tbird
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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by Turbo Tbird » Tue Jul 19, 2022 1:02 pm

cgrey8 wrote: Tue Jul 19, 2022 12:37 pm The next things to check are going to be things the engine needs to run. Here's my thinking:
  • Injectors are fed 12v and they are activated by sinking to ground through the EEC. So make sure they have 12v when the ignition is ON
  • Check if the EEC is sinking them to ground when cranking the engine via test-light or analog meter if you have one
  • Check for fuel pressure
  • If unsure whether you have fuel, spray starter fluid on the air filter. If the engine cranks, then dies as the starter fluid supply dries out, then you have a confirmed fuel delivery problem, not an EEC problem. If the engine still doesn't do anything, then move onto ignition.
  • Check the coil/plugs for a SOLID spark. Weak coils may give you a spark in open air, but the spark is usually very weak. When the air is compressed, the coil may not have the strength to jump the gap. A healthy spark should be easily heard as well as seen. With vehicles that have a dedicated ignition module (e.g. gray/black TFIs, EDIS 4/6/8, etc), you should still have spark even if the EEC is failing. Now for EECs where the control of ignition coils is internal to the EEC, that may not be the case.
thanks for taking the time - here's the thing though, the fans kick on immediately, there's no check engine light, and no codes can be pulled, all of which points directly to the ecu. the fuel pump doesn't prime with the key, but it does run when jumped at the eec test port. basically every single clue points to the ecu yet it clearly isn't the ecu...

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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by cgrey8 » Tue Jul 19, 2022 1:05 pm

I would agree, not having a priming pump (which usually its the fuel pump that's stuck on when the EEC is dead), stuck on fan, and the inability to pull codes does point to something with the EEC.
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Re: Can a Quarterhorse potentially brick the computer in my 93 Thunderbird?

Post by AuroraGirl » Thu Jul 28, 2022 10:45 am

is the fuel intertia thing tripped?

the fans on and the codes thing sounds like a hardware fault thing (forgot the name) with minimum functionality and just defaults to fans on for not overheating and would have little reason to communicate with the outside world since its not doing 'Ok'

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