340 code. changed cps. now car still throws code and sometimes wont start PLEASE HELP

[whitemustang89]

ok as title says my wife is driving the car today starts to run rough and dies. i show up, limp the car to autocrap and have them scan to see why the ses light is on. they say cps so i change it in the parking lot and have them clear the code. runs fine......for 5 minutes. light comes back on. no acting up just light. have it cleared again and same thing........ please help ive had to take custody of my little sisters and this car is the only way i have to get them to school and back right now. why is it throwing same code? what else could be problem? is this a common problem? heres some stats about the car. THANK YOU!!!!

99 gt
auto
165,000
well maintenanced
no mods just a k&n

 

[wmburns]

P0340 CMP Circuit Malfunction

I am assuming the DTC code is P0340. Unless I am missing something, this is a failure of the camshaft position sensor (CMP).

This could be a failure of the sensor or the wiring from the sensor.

Check the connector. Look of loose/bent/pushed pins or burnt/chaffed wires. Has any recent work been done?

Since the sensor has already been replaced. Wiring faults should be suspected. Note, it is possible this is a bad PCM. IMO, why too soon to suspect a bad PCM.

>>
P0340 - Camshaft Position (CMP) Sensor Circuit Malfunction

The test fails when the PCM can no longer detect the signal from the CMP sensor.

CMP circuit open
CMP circuit short to GND
CMP circuit short to PWR
SIG RTN open (VR sensor)
CMP GND open (Hall effect sensor)
CMP misinstalled (Hall effect sensor)
Damaged CMP sensor shielding
Damaged CMP sensor
Damaged PCM

Harness routing, harness alterations, improper shielding, or electrical interference from other improperly functioning systems may have intermittent impact on the CMP signal.

 

[whitemustang89]

yes it is the p0340 code. i plan on taking a really close look at it tomorrow when i am a little more focused and while the motor is not 200 degrees. lol. but thank you for that info. i will definately look at the wiring and trace it back but have a few other ? if it is the connector what/how do you think best fix would be? and how do i fully tell if its the pcm? is that common because i dont believe i can afford one of those any time soon.

 

[mr-mike]

check the alternator out put & battery if you have a bad battery it can cause some of the problems you have described

 

[wmburns]

check the alternator out put & battery if you have a bad battery it can cause some of the problems you have described

good point. Just to be sure, have the alternator checked for excessive AC ripple.

Regarding your question about how to tell if it is the PCM. Gennerally, once everything else has been ruled out, the PCM is what is left. Basically, if the sensor is good, the wire path to PCM is good, the connectors are good, and the electrical system is good, that's when you begin to think "bad PCM".

 

[whitemustang89]

thats what i thought. crap i hope its not that. i could be my batter though it is pretty old. i just hate to start throwing parts at something. wait.... let me rephrase i LOVE throwing parts at my car till it fixes it just as long as my bank account doesnt have a bottom. lol. what kind of excessive ripple am a looking for here? i have replaced the alternator twice on this car once just because the diode problem and it was throwing a ses light. thanks again guys!

 

[wmburns]

what kind of excessive ripple am a looking for here? i have replaced the alternator twice on this car once just because the diode problem and it was throwing a ses light. thanks again guys!

IMO, you are making this harder than it needs to be.

Take it to your local autoparts store. Ask to have your alternator tested for proper output and AC ripple. Cost=nothing. Piece of mind=priceless.

Consider that there maybe something else wrong with the car if it is eating alternators. Bad grounds, stupid big sound system, or very high power lights come quickly to mind.