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Discussion Starter #1
I can't get a useable Data Log because the whole thing is a bunch of spikes. ('95 4.6 DOHC)
The RPM line looks like a row of Empire State buildings- same for the
STFTs and a few other parameters too.
Thought I had it traced down to the Data Link Connector wiring, but the whole mess seems
intermittent. I'll get a few seconds of good data, then it's spike city.
PCM is new, I have a new back-up PCM- spikes just the same.
CAM and crank sensors- new.
DLC wires. Batt. voltage on yellow wire good. Black wire and Blk/yellow ground good.
Don't know how to test the twisted tan/orange and PK/LB or the purple wire.
I have the electrical trouble shooting manual, but here is something weird-
for those that have the trouble shooting manual, check out page 24-10.
My pinout is upside down from the book! Is yours?
I mean the connector works -- we have used scanners and such in the past.
I also have one of those BlueDrivers things -it works. I guess the devices figures what wires to use somehow.
Anyway, I need to get a good clean Log to send to my tuner.
Any ideas of what is going on ?
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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I've seen this a few times - the usual suggestion is to clear KAM on the PCM. I see it infrequently myself but it hasn't been so severe that I've had issues refining the tune with the data I've gathered.

What device are you using to collect the data?
 

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Discussion Starter #3
Wow, theterminator93, fast response there and thanks.
I'm using SCT X4 and Livelink Gen 2.
I've never cleared the KAM- I'll try that tomorrow morn. after the neighbors wake up.
Thank you again
 

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Discussion Starter #4
I cleared the KAM and I still have many many spikes.
If it weren't for the data log and my tuner, I wouldn't know about the spikes
because the instrument panel's Tach is dead steady.
I would know though that something is wrong cause i'm pretty rich.
Back to chasing the ghost one wire at a time.
And thank you for the suggestion theterminator93. It was worth a shot.
 

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I'd suspect a ground wire is barely connected somewhere; check all the ground bus connectors for green powder.

That's a sign of copper rusting.
 

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Discussion Starter #6
Thanks Grog6, i'm using the manual now to find all grounds.
 

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Something I always do is disconnect every connector in the lineof stuff I'm working on, look into the face of it for water, crud, or discoloration, add some dielectric grease, and plug it back together securely, making sure it's tight.
That actually fixes a lot of stuff.


You can try to check the grounds with a meter; you'd connect the - lead to the battery negative terminal, then check the grounds one at a time with the other lead.

Voltage drops that move around when you flex the wires and connections are one indicator.

Any voltage on a ground wire can be traced toward it's source at the battery and see if the voltage gets added in one particular connection.
 

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Discussion Starter #8
Thanks again Grog6, I've check every connector that the Data Link Connector's six wires go- except
connector C284. I can't find it.
Book says " behind LH side of I/P on G200 ground bus. (ground bus like you said)
Anybody know what it looks like?
According to the book c284 goes to g203, and I know where that is-- near the PCM.
I may be reading it wrong, but it looks like an indicator, lamp, lighter, airbag monitor-BK/O, the DLC and a junction block-GY/R all go to c284 and g200.
Why can't i find it? Exhaustion? I have 5 ohms through that wire to c284 while all others are .3 to .5
 

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That's probably your problem.
5 ohms is a LOT for something that included the cig lighter circuit, and that's probably why it's bad, being overheated.

The EVTM for my 96 says it's under the radio and or ashtray area of the dash, near G200, more to the right hand side. Right is left from inside the car, iirc.

IDK if a 95 is the same, but I'd look there.
 

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Discussion Starter #10
Good idea-- I'm gonna pull my console and trace the cig lighter ground to what should be c284 or
a least G200. Thanks.
 

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Discussion Starter #11
Fixed it!
Never found C284 or G200. I don't think they exist in a three dimensional 1995 Thunderbird universe.
But I did completely uninstall LiveLink Gen 2, went to SCT web site and re downloaded LiveLink,
and just like that, my spikes were gone.
Thank you to all that showed an interest in this enigma.
 
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