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what causes my 1998 plymouth neon to run good when it is cold but when it warms up it starts running rough?

it could be a o2 sensor, is

it could be a o2 sensor, is there a check engin light on?
when did it start running poorly?

it started all of a sudden,

it started all of a sudden, changed oxygen sensors, that was not it it's still doing it, would the crankshaft sensor have anything to do with it?

no, more so a cam sensor, but

no, more so a cam sensor, but frist is there a engin light on?

sometime it will come on and

sometime it will come on and sometimes it won't

well that should be

well that should be checked.
you can have it scanned for free at most parts stores, ie= autozone, advanced auto and pepboys.
if you get lucky and the guy knows a bit about the readings he's looking at have him right down the fuel trims and the codes and then let us know what they are, it'll help alot.
if it comes up with a o2 sensor code, donn't just have it replaced yet, let us know the fuel trims and we'll have you check what ever effects the trims frist.
do this and let us know, we'll try and save you some money.

we had it put on diagnostics,

we had it put on diagnostics, it said it was the camshaft sensor and crankshaft sensor. we put a new camshaft sensor on it before and it still came up as camshaft sensor. the camshaft sensor on it now is cracked on one side where one of the bolts are, it was tightened too much and cracked, could this be the problem?

that code is very common with

that code is very common with chrysler cars, and it could be either sensor that sets it.
if the sensor is cracked it will need to be replaced, it has to be flat on the head to read the can magnet on the cam, so replace it.
with out a scope to read the signals from each sensor, it's a guess as to witch one set code.
i'd say replace both sensors and be done with it, they aren't that much money and any guessing will be over.
make sure you check the connectors for any signs of corrosion that could also give you a problem.

Does the engine run

Does the engine run hot.
Could be cause by a blown head gasket. Check for compression gases in the cooling system. can either have shop to do it or buy a kit from the autoparts store and do it yourself (very simple), takes about 5 mins.

no it doesn't run hot

no it doesn't run hot

i'd say get the sensors

i'd say get the sensors replaced and see if it fixed it, the broken cam sensor should be replaced no matter what.
start with the problem you know is there.

replaced cam sensor still

replaced cam sensor still doing it, i'm about to give up

like i said that code can be

like i said that code can be caused by either of the 2 sensors, that's why i replace them both when i donn't have a scope or if it's a intermitten problem, and i'm a chrysler master tech at the dealer, and come backs are a no no.
do you have a scan tool?

Just because a code is set

Just because a code is set doesn’t always mean a sensor has failed. Many individuals (pro mechanics) included make that same mistake. They “ASSUME” that because a code is set that a sensor must be bad.

“ASSUMING IS THE MOTHER OF ALL EVILS” in the business of auto repair. A part in a vehicle, any part, or any sensor, should never be changed, until it is “CHECKED AND FOUND TO BE DEFECTIVE”.

You should know that a wiring or circuit issue could be setting your codes. The “PCM” doesn’t know the difference between a failed sensor, a wiring issue, a circuit issue, or a connection issue. The “PCM” simply sees the error, set’s the code, and turns on the “MIL”.

SOMETHING AS SIMPLE AS:

A broken wire.
Poor wire connection.
Dirt or corrosion on a wire connecter.

Could be why the codes are still set. Have you ruled out "CIRCUIT" issues with the "CAM and CRANK" sensors?

You should also do another scan and post the actual error codes numbers. Example: P1391

where do we need to look for

where do we need to look for broken wires, poor wire connections and dirt or corrosion on a wire connector?

if you like i can send you

if you like i can send you all the diag. info and wiring diagrams to test out the cam and crank circuits, that way we can folow along with you while you go thru the tests.
just need a email ad. to send them to, also let me know the code numbers that are setting.
do you have a scan tool or a volt/ohm meter?
let me know, mws919

check for a spark at the

check for a spark at the spark plug wires when the engine cuts off. If spark is not present, then the ignition system is at fault.

Also check fuel pressure before and after the engine cuts off. If pressure drops and then engine cuts off then fuel system is at fault (fuel pump or clogged filter).

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