Jim, I got all my information from the following site:
Again, I used this information on my FI setup and it worked perfect. If you
are getting incorrect voltage readings, I would suspect something is wrong
[mailto:email@example.com]On Behalf Of Jim Altman
Sent: Monday, November 19, 2001 2:38 PM
To: TR8 List (E-mail); Triumph List (E-mail); Rover V8 List (E-mail)
Subject: 1980 TR8 EFI Throttle pot query
As some of you have followed (and others have not, cause I am sending this
to more lists than it started on) I have been trying to find the right
setting for the throttle pot when at idle (or at rest). One can reference
this discussion either to a voltage with the ignition on or to a resistance
with the TPS disconnected. Someone mentioned a resistance of 900 ohms (red
to green), another mentioned 325 mv (red to green) with the ignition on. I
can't get mine to set anywhere near that low, lowest 3890 mv (3.89 volts).
I'd like to try and figure out what's right. I was in a place earlier today
that has gobs of service bulletins and training materials from the old days.
There was one dealing injection, but the front page which indicated the
application was gone. It mighta been a Jaguar sheet instead of the Rover/TR
setup. It indicated a resistance of 450 ohms at idle and 4500 ohms at full
throttle (red to green). Digging around the parts bins I was able to find 1
SD1 plenum with a TPS attached, it sat at 1150 ohms at idle.
What I'd like to instigate is a mass measurement. If you have a 3.5 liter
SD1 or TR8 please disconnect the TPS at the plug a couple inches up the pig
tail at rest (idle) and at full throttle and send them to me. I will compile
the results and see if there is a pattern suggesting an original set up.
Mine was set way low (about 50 ohms at idle). I moved it up to 900 ohms and
my gas mileage zoomed up. It had been about 15 mpg, it jumped to 23 on the
Thus, I'd like to figure out what right. I'll be happy to post the results
back to the lists.
BTW, one of the guys at the shop has an old Epitest unit. I am going to
borrow it and play. That ought to be interesting. He said (he used to work
in a Triumph dealer) they never used it cause it was junk. I'll see how its
setting compares to what my CO meter sez is good and report back on that
Thanks for the help.
Jim Altman firstname.lastname@example.org Illigitimi non Carborundum
http://www.altlaw.com/metro/jaltman.html 69-TR6 76-TR7 80-TR8 W4UCK
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