1996 Chrysler Concorde

1996 Chysler Concorde
3.5l
Friends daughter is coming home from
school this weekend, and wants help with her car.
Check engine light is on...

Runs great at any driving speed, but at idle - in park or
neutral, it runs extremely rough.

Car has 60k miles, and is MINT!

I am having thoughts or:
02 sensor
fuel filter
spark plug
air filter

but unsure what to have on hand when she gets here---

IDEAS?

email me:

 

Possibly just clean the throttle body. Loose gas cap could have made the
light go on. Disconnect battery and see if it resets and stays off.
Otherwise take it somewhere that will read the codes for you.

 

I was going to suggest cleaning the TB too. I did my '99 a couple of
weeks ago, and it straightened out a rough idle. Haven't run enough
tanks thru to be sure, but it appears the mileage has gone up a couple
of mpg too.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Just to be clear, there are TWO Throttle Bodies on the '96 3.5L. Make sure
you clean both thoroughly and then do a power reset by removing the battery
cable for a minute or two when you are done. You also don't say when the
vehicle was last tuned. At it's age, regardless of mileage (my '96 Vision
TSI has about 70K and I have replaced the plugs twice and the wires about
two years ago ), the spark plug wires should also be replaced assuming they
have not been to date. I agree on replacing the air filter, fuel filter,
and the PCV (not on your list) as well.

Lastly, as preventive maintenance, the transmission pan should have been
dropped/cleaned, the magnet removed/cleaned, filter replaced and then
refilled with ATF+4 at least twice by now. I only mention this in case you
want to suggest this to the owner keep it running well Chrysler
transmissions of that vintage are noted for having problems if they are not
properly maintained. Make sure they drop the pan and replace the filter and
don't just do a power back flush (which supposedly gets all the fluid, but
leaves the dirty filter, used clutch material, and debris in the pan.

Good luck. I suspect the rough idle is from dirty TBs and possibly a
plugged air filter. Assuming much of this maintenance is due anyway, I'd go
ahead and do it first to see if it solves the problem. If not, then take
the advice and get the error code read. It could be an O2 sensor or the EGR
as well.

Bob

 

By the way, if you get a bang under the AT console when parking or turning,
it is probably the rear AT mount and not engine mounts.

 

Could be a vacuum leak. Places to look first are the power brake booster
(disconnect and plug the vacuum line to see if it smooths out the idle),
PCV valve, and if it comes to it all the smaller vacuum lines.

Also could be a bad EGR valve (this would actually be my first guess).

 

One thing everybody here has missed, and is common with the 3.5L. The
intake manifold gasket develops a leak, (around cyl 5 IIRC) which causes
loss of vacuum, rough idle and sets the CEL. The ingition
ON-OFF-ON-OFF-ON sequence will most likely reveal error code 43.

 

Yep..... forgot that one because most people are driving 2nd generation LH
these days.

 

Thank you all very much:
I plan to scan the codes:
then
change the air filter
clean the intake(s)
replace the fuel filter
change the air filter
change the PCV valve
and then 02 sensors

 

Good point- I tend to forget that one because my wife's car never did
that in 215,000 miles. I did replace the lower intake gaskets at
210,000, but it was because they were weeping coolant, not causing a
vacuum leak. They were JUST about to start leaking at #4 port, though.
#5 wasn't far behind.

 

Thank you all!
--
Car came in with a p0301 code- mis-fire in cyl #1;
and plug is burnt...-- reset codes,
replaced plug, cleaned intakes with seafoam,
and treated engine and fuel with Seafoam also;
running now, with no codes, and idles smoothly;

 

ok,
changed fuel filter, plug #1, air filter, checked all fluids, engine still
idles rough, touch the accel. and she smooths right out. Spraying a little
starting fluid around the front of the intake manifold changes the idle
speed instantly. have cod p301 #1 cylinder misfire again-
intake gasket?

 

ok,
changed fuel filter, plug #1, air filter, checked all fluids, engine still
idles rough, touch the accel. and she smooths right out. Spraying a little
starting fluid around the front of the intake manifold changes the idle
speed instantly. have cod p301 #1 cylinder misfire again-
intake gasket?

 

both upper and lower intake gaskets are
leaking -- both brittle and hard.
ordered the thermo gasket, the egr tube gaskets, the fuel rail gaskets,
plugs, and wires; since we are here.... hardest part is getting the old
gasket off....