Concorde missing on hills

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.

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

Any

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.

Unlikely.

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')

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