I made it through the weekend, and yes, it is still doing the 1500rpm
65 second runup during startup. However, several times it started
normally. The weather has been dryer here the past 3 days, so maybe
that is a factor, I don't know.
To Tom Adkins and Lugnut (if you'd care to answer):
1. Do you think it could be a bad EEC?
2. Could it be a short somewhere?
3. Is it possible it's linked somehow to humidity change, ie some
sensor sticking (TPS?).
I might throw another part at it.
Look at the power steering pressure line between the P/S pump and
the gear box, see if there is an electrical switch ported into
the pressure line. If so, disconnect it and see if the symptoms
Offhand, If you're going to toss a part at it, I'd say TPS, Throttle Position
Sensor. You're getting to a point where you will have to have it checked out,
person, by someone qualified to do a diagnosis.
The TPS is a "wear item" that can cause all kinds of strange symptoms as it
It's ~$25 and will either solve your problem, or it won't. If it does not, it's
to bend over and see your local dealer (or qualified Indy Shop).
I agree with Tom. I think the only part I would just throw
at it at this point is the TPS. Fairly cheap and easy to
change. They can get flaky and fail w/o setting a code. I
have seen them hold 30-35 mph after the throttle was
released and not set a code. You may want to pin the wires
on it after you replace it to be sure the voltage at idle is
correct. IIRC, it should be around 0.5 VDC. Around 1.0vdc,
the ECM starts the off idle sequences to advance timing,
increase fuel and other chores. The ECM's are pretty
reliable and not prone to failure. More often than not,
ECM's that are replaced do not correct whatever the problem
might be. IMHO, the Ford STAR tester is more capable than
any other tool on the market on Ford products. A
knowledgeable teck should be able to find the problem with
it. Most of the dealership in my part of the world will
apply the diagnostic fee toward the repair. At this point,
I think it is probably worth your time and money to get this
done. There are cases where a temporary breakout box has to
be installed to find the problem.
You may also want to follow up on 'cuda's suggestion because
the ECM does increase idle to compensate for steering
pressure. A stuck switch can do this and the check is
quick. This should also show up on a complete diagnostic.
Should be on the bottom of the throttle body. You will need
to dismount the throttle body from the intake to get at it.
The water hoses should have enough flex to avoid
disconnecting them. You will probably have to disconnect
the EGR valve assembly. The TPS is held on by a couple of
Phillips head screws. They are usually pretty tight. If
the TPS has never been replaced at 150K, it is probably due.
They do wear because they move just like an old radio tuner
every time the throttle is moved. The TPS is simply an old
fashioned potentiometer that slides a contact over a coil of
wire to change resistance.
See my post on the manifold. If you do one of these, yopu
may as well do both. Gaskets, TPS and supplies are probably
less than $50 to do both at the same time and you will be
finagling several of the same parts to do either repair.
BTW, while you are working in that area, you will see an
idle adjust screw on the top of the throttle body. Unless
you know exactly what and how you are doing whatever, resist
all temptation to touch it or change it. It is set using
some very specific parameters and will have no effect on
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.