5ktq electrical problems update (not fixed)

Cody Forbes cody at craincorporated.com
Tue Sep 23 10:15:58 EDT 2003

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I'm still having electrical issues on the new '87 5ktq. The problem is that=
 when ever the voltage gets to 12.8v I get a missfire, and 12.6v basically =
shuts off the motor unless I hold it full throttle. Normal voltage is in th=
e 13.5 area. Problem is completely ignition related for sure. The voltage u=
sually goes down to that range with the headlights and/or with the rad fan =
on. No, I can't just take the fan out and not use the headlights, :-).

I have replaced the voltage regulator (yeterday, Eric's suggestion), and la=
st night I found corrosion on the main engine ground, so I cleaned all of t=
he connections there and cleaned the chassis where it bolts up and even use=
d a new bolt. Didn't make a slight differeance. Then I went to the alternat=
or. I took both wires off and cleaned them, then started the car up and it =
was fine. I could use the headlights, even the highbeams, so I went for a 2=
0 minute drive. It would still miss just slightly with the rad fan AND the =
highbeams on, but thats about it. So I went back to the shop to get my tuni=
ng computer because I was way rich on the EFI (on purpose). Went to go for =
another drive with the tuner and it was back to the same thing as before. I=
 assumed there had to be something loose near the alternator, so I went to =
the starter and cleaned all the wires and contacts. I didn't have the chanc=
e to test it after cleaning the starter wires, but does this at least sound=
 like I'm the right track? I did order a new ignition switch too, figured i=
t couldn't help. I should be able to test it later today and install the ig=
nition switch. I'll let you know what happens.

My issure though is that ok with all of the charging system good I shouldn'=
t ever go below 13v which would cure it, but shouldn't the ignition work fi=
ne well below 13v? Even if cleaning all the contacts get the charging volta=
ge up to 14v it will fix my immediate problem, but I will still have weak i=
gnition and loose power. I don't have the 2nd volume of the Bentley which i=
s electrical stuff, so I don't have any wiring diagrams. I do get full batt=
ery voltage @ the coil.

-Cody Forbes
Black Forest Racing
2x '86 5ktq
'87 5ktq
'88 80 4cyl


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