Dodge Shadow, idles badly when cold

My O.L. has an '89 dodge shadow, 2.5L non-turbo, auto tranny and it has
started to idle very badly when started 1st thing in the morning, on a cold
or warm morning. It sounds like it's "loading up", but there is no black
smoke coming from the tailpipe. When you step on the gas it smoothes right
out, and runs fine down the road. Also, if you let it idle long enough to
warm up, eventually it will idle normally, it's only when the engine is
COLD, (not been run for many hours), that it idles rough. I wonder if there
isn't a bad sensor somewhere that controls the idle mixture and makes it run
that way when cold.
Within the last 10K miles we replaced the spark plugs, distributor cap and
rotor, plug wires, and coil, (for a different problem, and also to tune it
up. Turns out it was a cracked coil and the car would barely start when it
was wet outside). Anyway, I feel I can pretty much rule out an ignition
problem because of this.
Has anyone had this happen, or read about a fix?

Thanks,
Snydley

 

Does the check engine light work? Are there any fault codes stored in the
engine controller?

 

<<I wonder if there
isn't a bad sensor somewhere that controls the idle mixture and makes
it run
that way when cold.>>

Check the temperature sensor located on either the side or top of
the thermostat housing. It tells the computer when the vehicle is hot
or cold. It acts like an automatic choke for the fuel system. When
the engine is COLD it should be telling the computer to give the
engine extra fuel till it warms up. It might not be working correctly
and causing the engine to run too lean when cold. When it warms up,
it is ok. Not seeing the car, this is only a guess. They are not too
expensive if you think that is what it is.
GOOD LUCK

 

Thanks for the help. I changed that yesterday thinking that might have
something to do with it, but not knowing. I changed that one, and the sensor
that screws into the head in the front. The temp. guage stopped working
awhile ago, and not knowing which one of those 2 sensors controlled the temp
guage I replaced them both.

Thanks,
Snydley

 

The codes I get are:
33 - air conditioner clutch relay, (there's no air cond. in this car)
34 - open or shorted condition detected in the speed control vacuum or vent
solenoid circuits. (not sure of this one)
55 - end of message code

I don't know what 34 is, but I'll have to check that one out.
One thing though, when the car started idling badly I took the air cleaner
off to check the filter. It was stuffed with Maple tree seed "wings" that
my O.L. must have run over and got sucked up into the air cleaner. I got my
shop vac and vacuumed them out. I figured if I missed anything it would have
gotten sucked down into a cylinder, burned and that would be that. Now I'm
wondering if something didn't get wedged in somewhere enough to change the
fuel mixture when cold. I'm afraid I'm going to have take the throttle body
and manifold apart and thoroughly clean them. I don't know what else to do.
So far I've replaced the air filter, and replaced the coolant temp. and
temp. gauge sensors, checked all of the vacuum lines,(ok), and find nothing
wrong. It's something that isn't generating a fault code, yet is making the
engine idle so badly it will hardly run when cold. I hate to take it to a
shop, it's an '89, yet only has 39K miles on it, I hate to put a lot of
money into it, but it's in great shape and has been a strong runner until
now.

Thanks,
Snydley

 

33 is normal in cars with no A/C

Does the car have cruise control? If not, this code is normal. If it does,
this could point to a potential cause of the rough idling.

That is possible. The air cleaner on these cars is not particularly well
designed -- there are crevices and crannies where crud can collect, and
the air filter element itself is undersized for the job.

Before that, remove, disassemble and service the air cleaner assembly.
Replacing the air filter itself is barely just one part of the job. See my
post here:

http://groups.google.com/groups?q=&rnum=1

Don't be such a cheapskate. If it's only got 39K on it, what does it
matter that it's an '89? Fix it! Why do you "hate to put a lot of money
into it"? If a simple inspection and/or replacement of wear parts in the
air cleaner and crankcase vent system doesn't do it, I guess you have
three choices: Sell/junk it because you "don't want to spend money",
continue to randomly throw parts at it that you guess might be the problem
but really aren't, or get it in for proper diagnosis that will probably
show the problem to be easily and inexpensively repairable.

DS

 

No, the car has no cruise control. I guess the computer codes are ok then.

I put a new element in the air cleaner. I was thinking maybe something got
sucked into the throttle body, or manifold somewhere and causes the car to
idle badly when cold. I don't have any black smoke coming out of the
tailpipe so I'm assuming it's running too lean not rich.
My next move is to remove the throttle body, and thoroughly clean it. I'm
wondering if the AIS motor is somehow stuck open, creating too lean a
mixture when cold, and then when the engine is warm the mixture is ok. I
don't really understand how all of this works. When I was in High School in
the '70's, and took mechanics in BOCES, a type of trade school, cars were
carbureated. If there was a problem with the mixture when the engine was
cold adjusting the choke would usually fix it. I haven't "kept up" with cars
since fuel injection and computer control became the norm and I am somewhat
lost here.

http://groups.google.com/groups?q=&rnum=1

I'll go through the proceedure. I believe that replacing the air filter
would be enough to straighten out too rich a mixture, if that was the case,
which I don't believe is.

I guess I didn't make myself clear, or you misunderstood me. What I meant by
"I hate to put a lot of
money into it" is that I hate to have to take it to a dealer and pay their
price. That's why I'm on here. I'm trying to get some tips and fix it
myself. I also don't want to "randomly throw parts at it", which I haven't
done yet. "Push comes shove", if I have to I'll take it to a local repair
shop and have them fix it.

Thanks,
Snydley

 

Yes, you mentioned that, and that is why I went to the effort to explain
why that's not a complete job of servicing the air cleaner assembly.

When you remove and disassemble the air cleaner, pay special attention to
the hot air "stove pipe". If it is disconnected, crushed or obstructed,
the car won't run right when cold.

Very doubtful -- it doesn't work this way.

Assuming usually costs more money than diagnosis.

Feel free, but it's not likely to get you anywhere -- this throttle body
is self-cleaning by design, and does not get crudded up the way the 3.0
throttle body does.

Doesn't work this way. The AIS motor controls idle *speed*, not idle
*mixture*.

The point of giving you the procedure for completely servicing the air
cleaner and crankcase vent system was to indicate to you that simply
replacing the air filter is NOT enough to address all the possible causes
of an incorrect mixture when cold.

Thought you said you had begun replacing various sensors.

DS

 

HI!
I had a problem like what you have. The fix was to torgue the bolts of the
throttle body to spec.. When engine is cold you have air leak at the base of
the throttle body and as the engine warms up everthing expands and the leak
stops. Good Luck!

 

Hi
Try torguing throttle body bolt to spec. ; air leak at base of throttle
body when cold.

 

Hi Delbe,
Can I say, YOU'RE A GENIUS!!!!!!!
That took care of the problem!! I torqued it down to 175 in-lbs, (only
turned the bolts 1/16 of a turn or so). I started it up and it purrs like a
kitten!!! Gosh, it just goes to show you sometimes when we think it's the
most complex of problems it turns out to be something so simple!!

Thanks so much!!,
Snydley

 

My 88 Aries 2.5L had the same problem. Went to 3 different shops.

They replaced between them:

MAP sensor
Cam Sensor
Engine Control Computer
Distance Speed Sensor
Oxygen Sensor
AIS motor
All the vacuum hoses

After having no repair help for more than 3 days, I replaced the injector in
the TBI myself and that solved it. However, you will not get any codes for a
mechanically worn out injector.

Dan

 

Hi Dan,
After thinking the problem was solved, I went to start the car Wed. morning
and the same problem arose. I replaced the throttle body to manifold gasket
and that seemed to solve it. I let it sit for 5 hrs. started it up and it
was idling like crap again. I'm so confused now. When I re-torqued the T.B.
and then changed the gasket it ran great until it thoroughly cooled down. I
may try the injector next.

Thanks,
Snydley

 

Re-torque the T.B. when it's *COLD*.

 

It WAS cold. Here's how it went:

I let the car sit all night. I drove my Saturn to work in the morning. I
stopped at an auto parts on the way home and got the gasket. I went home and
installed it, (removed the T.B., cleaned both surfaces, reinstalled it using
Locktite on the screws, partially torquing in a criss-cross pattern 4 times
until finally torquing to 175 in.-lbs. At this point it hadn't been started
in over 24 hrs ). It started up and it idled great, (thought the problem
was solved). I shut it off, went back in the house. Returned about 5 hrs.
later to check it, started it up and it was idling badly again.
I'm so confused! Any ideas?

Thanks,
Snydley