Idle problems with a 245

Got a 1990 245. starts fine, but if I dont keeps the revs up, as soon as it
drops below 1k it stops. Changed the fuel pump relay with a known working
one (940 and 240 FPR's are the same!), made no effect. Throttle possition
sensor clicks when I move the throttle, so machanicaly thats ok.
Checked the codes, were 1-4-4 and 2-1-4. cleared them, restarted the engine
(several times, including driving up and down the drive, keeping the revs
up), then checked the codes again, and there clear, shows 1-1-1, but car
stil wont idle.
Does anyone have any ideas. How do you check TPS and AMM are ok???

TIA
2 Volvo's Grizly (one sick one)
Giant mutant cockroaches will be using it as their lowrider after the atomic
bomb gets us and all the american cars.

 

AMM is simple to check.

While the engine is running, disconnect it. If the engine idle changes,
that's one sign. The other sign of a failed AMM is if you quickly do a
mini-throttle while the AMM is disconnected, it usually comes close to, or
will stall.

Have you checked your flame trap, and throttle body for dirt? How about your
air filter in the airbox?
I'd be checking for low air flow first in these situations.

Rob
Kitchener, ON, Canada

 

Wed, 9 Jul 2003 14:19:35 -0400, suggested:
: AMM is simple to check.
:
: While the engine is running, disconnect it. If the engine idle changes,
: that's one sign. The other sign of a failed AMM is if you quickly do a
: mini-throttle while the AMM is disconnected, it usually comes close to, or
: will stall.

I don't think I understand. Wouldn't the behavior with the AMM
disconnected be the same whether it had failed or not?

 

Make sure your base idle is correct. You can ground the CIS (constant idle
system) so you can set the idle. There's a connector near the firewall
connected to a blue/white wire. Ground the wire and the CIS system will be
overridden so you can set the idle.

Check your injector seals for vacuum leaks. When cold (and/or hot) spray
carb spray on each injector; if the idle changes your seals are leaking. The
seals can leak when the car is cold but seal up when the car gets hot. If
the idle problem goes away when the car is warmed up I would suspect vacuum
leaks from somewhere.

Check the car for vacuum leaks. The vacuum at idle should be between 16 and
22hg. If the vacuum is low (10-14) at idle the car will stall easily.

Make sure the ignition timing is set correctly.

Make sure the CO is set correctly. A too lean setting will cause stalling.
As a test, disconnect your O2 Sensor and see if the idle problem goes away.
If it does then your car is probably running too lean. Sometimes the O2
system will pull the CO too low when connected.


Brick_0


Changed the fuel pump relay with a known working

 

Thu, 10 Jul 2003 16:52:16 GMT, suggested:
: if I read the messages in the thread correctly, the car was running OK, you
: had the air filter changed, and shortly thereafter it began to have the
: problem? If so, I'd first think that the connector to the AMM might have
: been knocked askew during the filter change, and finally worked itself loose
: enough to cause the bad running. With the engine off, try removing and
: reconnecting the connector to the AMM several times, leave it connected, and
: see how the engine runs. I do this periodically on mine, whenever it
: develops a rough idle or lacks power on acceleration, and it seems to fix it
: each time!

That sounds like the contacts are oxidizing. You might try shooting a good
contact cleaner on the pins for the connector next time you do this and
see if it holds up longer.

 

been there, done that, didn't help much, but didn't hurt either! Used
PROGOLD, a contact treatment that I've been using on other
electronic/computer connectors for years, generally very good.... Since I
only have to "work the connector" a couple times a year, that's an
easy/cheap fix.....

 

AMM connections going bad? Seriously?
My thought at that point is the wiring harness is going bad.

I also had a problem with starting / rough idle in damp weather. The
electronic advance component that enters the distributor at the front of the
distributor had a broken mounting point, resulting in water getting thrown
into the distributor by the fan.

If idle was OK then all of a sudden not, the AMM connector not being seated
is one thing, but I've also heard from other folks where cracks in the air
intake tubing resulted in poor idle / engine performance.

Too me it sounds like an air / vacuum leak occurred. OH WAIT! I had rough
idle also start once when the rocker cover bolts became loose (long story on
that one). I tightened them down and it smoothed out, but I don't suspect
that's what's happening here.

The flame trap is located dead center underneath the intake manifold in the
middle of a Y splitter tube that enters the engine head/block. Hard to see
from a-top, but you can feel it with your hands.

Rob

 

Actually, the base idle can get screwed up if the throttle linkage is worn
or broken.
I had a problem where the spring clip was pretty worn from maintenance
disconnection and it had free play, which resulted in unstable idle.
Normally the idle switch should trigger the ECU to set up the idle speed,
but occasionally my 'idle' ran high.

Throttle body dirt is another source of bad idling, but this case sounded
rather sudden, which leads me back to vacuum/air or electrical connection.