Concorde missing on hills

Gents,
I have a problem with my 2003 Concorde Ltd. It has very low mileage
(only 16000km - I work all the time and never go anywhere!) and has been
serviced regularly. Problem is when I do try to go somewhere - as soon
as I go up a hill the engine starts to miss on a cylinder and runs
rough. The engine light will blink and then at the top of the hill
settles down and glows steadily. Next hill it will blink for a while and
the engine will miss again, then it glows steadily once more. It has
been in to the dealer three times with this, and each time they change a
gummed-up spark plug and say the computer says there's nothing else
wrong. I'm putting premium gas in it; they attribute it to bad gas.
I'm no mechanic, but it seems the mixture is not adjusting for the
workload of a hill, and this gums the plugs. The light behaviour fits in
with the emissions being worse as it misses on the hill, and then
smooths out on level ground again, no? I have heard of a gas cap problem
affecting the engine warning light - would that behave this way? Any
other ideas I can suggest to the geniuses at the dealers?

ChrisC.

 

Chris, first of all use the gas that is recommended for that engine, if you
are not supposed to use high octane dont!! It will cause drivabilty
problems.
You are experiencing a secondary ign problem,find out if the plug is
fouling due to oil consumption
on the spark plug or possible a bad coil causing low voltage to the plug.
You can always get a second opinion from another shop also. you yourself
can swap the coils out on the cyl, if number 3 is fouling, swap the coils
with cyl 4 to see if the problem goes to that cyl, if it does, replace the
coil

Glenn Beasley
Chrysler Tech

 

I had a car with a similar problem. Turned out to be a defective
catalatic converter. When the car went uphill, the contents shifted
back, limiting the flow of exhaust. The backpressure sometimes slowed
the car to a crawl

I don't know what it takes to loosen up the exhaust somewhere before
the converter on your car( mine required loosening 3 bolts), but if
access is easy, the testing would be simple. Open it up enough to
relieve pressure, then drive noisily up a hill. My situation was
rather rare, but I too had tried everything else. As a minimum, you
may want to look under the car for obvious physical damage to the
exhaust system.

They might also consider defective wiring to the fuel pump, or
something clogging the fuel lines, filter or tank.

To me, your situation seems more mechanical than electronic.

I slept in a Holliday Inn last night.

=============================

Problem is when I do try to go somewhere - as soon

 

Call me a skeptic, but I think missing on hills is always a high-tension
ignition problem. I'm quite surprised that the OP'd dealer didn't changed
the plug wires, although I realize you'll probably say "Oh, yeah, they did,
but I forgot to say so."

The easy diagnosis is a plug wire. But, if not, it still could be a coil or
a plug getting fouled. What causes that phenomenon is that when you lug up a
hill in overdrive, the cylinder pressure is as high as it ever goes. That
makes dense gas in the cylinder, and more electrical resistance to the
spark. So, when your car starts to only miss under certain conditions, those
are always the conditions. That's the worst condition for ignition.

 

He's more likely to say "It doesn't have plug wires - this engine is
coil-over-plug". But you're right about coil or plug possibly
causing that.

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

 

He's more likely to say "A 2003 Concorde doesn't HAVE plug wires, it
uses coil-on-plug ignition."

That said, I agree with you. It may be a dead coil or internally cracked
insulation on that particular coil, which is effectively the same as a
bad plug wire.

Or the engine's sucking oil on that cylinder and repeatedly fouling the
plug- I'd be especially concerned about that if it's a 2.7L.

 

OK...this should be a fairly easy problem for a competent diagnostician
to nail. Key word being "competent". I am guessing (but it is *only* a
guess) the problem lies with the secondary side of the ignition system,
which on your car means the spark plugs, the plug "wires" (actually
boots with internal conductors, connecting the one-per-cylinder coil to
its spark plug), and the coils themselves.

A very common cause of persistent misfire is as follows:

Misfire occurs due to secondary voltage leak down spark plug insulator
to ground. First component replaced is spark plugs, but plug boots have
also been affected, so affected plug boots continue to allow voltage
leakage. Misfire persists, so spark plug boots are replaced, but plugs
are left alone since they were just replaced. But, faulty plug boots
caused leakage path on plug insulators. Back and forth and back and
forth. Often a persistent misfire of this nature will go away when
plugs AND wires are replaced at the same time.

Again, though, this assumes the problem originates in the ignition
system. It's possible there is a fuel system problem-anything from a
flaky injector to a problem with the engine management system that
drives the injectors, and several other possible issues as well. That's
why my guess is only a guess. You need the services of a good
diagnostician.

Horsepucky. There's obviously something wrong. It is lamentably hard to
find competent and motivated diagnosticians at Chrysler dealers. Very
easy to find lazy and ignorant ones, though. (Some of them post
barely-coherent non-answers here!). If they're not taking the vehicle
for uphill drives with the diagnostic computer ("scanner") hooked up
and recording the datastream from the vehicle's own computer, then
they're not doing their job. Perhaps you should shop for a good tech at
a location other than a stealership, er, dealership.

As far as "gummed up" spark plugs...this covers a lot of territory. The
correct term is "fouled" spark plugs, and there are lots of different
ways spark plugs can foul, and different causes for each different kind
of fouling.

How come? It's not "better". Using higher-test fuel than is recommended
probably isn't causing your symptom, but it's also not doing you any
good. Just a waste of money. Look in your owner's manual and follow the
fuel recommendations found therein.

Possible, but not terribly likely. Bad gas does not selectively affect
individual cylinders.

The Check Engine light does not monitor emissions *per se*. It monitors
engine systems and parameters that *affect* emissions, but it's not an
excessive-emissions indicator light as such.

No, not at all.

See above. If your car is out of warranty, there's NO reason to take it
to the dealership-and every reason not to.


DS

 

Damn, Steve. Read both of our first sentences. That's scary!!

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

 

Bill Putney wrote:

I did, after I sent my reply. Yes, it scared me... but it should
probably scare YOU more... ;-)