1972 145E idles way too high

A very tricky car to work on, as this model is almost nonexistent! It
idles so high, I don't want to put it into gear. The idle adjuster is all
the way down. A mechanic told me I may need a temperature sensor, which
may not be available. Any ideas anyone?

 

Something is sure out of whack. I used to have a 1970 145 here in the US,
and I didn't really have any problems with the carburetor. (Don't get me
started on the distributor and points, though!) It had a manual choke, too,
which doesn't fit in with the temperature sensor recommendation.

The central question is whether the throttle plate is open, causing the high
idle, or if the air is coming in someplace else and the carburetor is just
tweaked to keep it from stalling. My guess is that the throttle is actually
partly open, possibly because the throttle linkage is misadjusted. IIRC
there was a turnbuckle affair in the linkage on mine - it may need to be
loosened. On yours, not mine ;-)

Finally, how long has it been like this, and did it get this way suddenly or
did the idle just creep upward?

Mike

 

The bowl under SU's have a poppet valve in the throttle plate. If you
heat the solder fixing the valve stem and spring assemblt to the plate
you can screw the poppet down flush with the throttle plate surface.
Clean, flux and sweat the valve permanently closed and the idle can be
reset.

Bob

 

On the side of the head, below the thermostat, in front of the manifolds
is a valve which allows air to bypass the throttle when the engine is
cold. Pinch one of the 2 hoses going to it, and see if the idle slows
down. If it does, pull off the top hose, you should see an odd shaped
hole with a metal cylinder that slides across to block it from below.
If it's not completely closed when the engine is hot, it'll be your
problem.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

 

145E= Model series 1. 4 cylinders. 5 doors. E - electronic fuel injection.
Leave the carburettor guessing. Think: Fuel Injection.

//Erik

 

Group,

The 145E was outfitted with the Bosch D-Jetronic Electronic Fuel Injected
fuel system. No carbs. No manual choke cable on the dash. No fuel bowls.

Franko, is this still using the D-Jet, or has it been converted to carbs
(SU, or Weber, or other)? Believe it or not, the conversion from carb to
EFI or from EFI to carb is pretty straightforward, and somewhat common,
depending on one's fuel system religion.

If still using original D-Jet, are you sure that the closed down idle screw
is letting the throttle plate close completely? Gunk may have seeped into
the throttle body from intake and oil, preventing closure. Has throttle
switch (on side of throttle body) been cursed at or otherwise tapped/abused
recently? If yes, go back to square one on proper throttle switch
adjustment. Haynes manual on the 122/1800 is probably adequate, though you
may need the Volvo 1800E Supplement publication for the D-Jet, if not found
in the Haynes 120 or the Haynes 140.

The cold sensor valve, very close to the thermostat housing, should not have
more than 500 rpm impact on your idle speed, I would not think. I think
warm engine idle is around 1200, cold engine is around 1700. I'm working on
memory alone, mostly in need of modern RAM upgrade. Anyway, this valve is
probably a piece of ancient over-engineering, mattering little if it works
or not. However, if the vacuum hoses to and from this valve are decayed,
then these could affect idle.

Main common culprits on D-Jet are decayed vacuum hoses and fuel delivery
hoses and seals, allowing unmetered oxygen intake to mess with your mind.
You should always use fresh rubbers.

 

IPD had all the temp sensors for my '72 145E w/B20F engine; they seem
to be fairly common Bosch parts. There are three--one for the intake
air, one at the thermostat, and one at the right rear corner of the
head. The first two are used by the FI system, the last is for the
dash temp gauge.

If the wire breaks on the one at the thermostat, the engine stops.

Generally, high idle is an indication of a vacuum leak; check all
hoses; also check the timing.

IPD is http://www.ipdusa.com

A detailed description of the D-Jetronic system and settings is at
http://www.icbm.org/erkson/ttt/engine/fuel_injection/d-jet.html
which includes instructions on setting the TPS.

As far as I know, the only impossible-to-find part is the MPC sensor;
on the right fender, looks like a fat ignition coil with a tube to
the intake manifold. Those are no longer made.


Gary