[KennethRichard]

Hey everyone.

I have a 1997 V6 3.8L and about 2 weeks ago i got a check engine light, knowing the previous owners never gave the car any TLC i did a quick tune up, new spark plugs, new cables and a new fuel filter. code never went away so i went out and bought a OBD II scanner.

got a P0340 code.

I replaced the sensor right away, cleared the code, and got it right back. in the process since everything is so old and brittle i snapped the Coolant Temperature Sensor right inhalf, so i was now getting a code for that, rather then the CPS. replaced that but the P0340 came right back.

I came onto here and saw alot of people have been saying its their alternators that are going bad, they replace them and the code goes away. Took the alternator out, went to 2 differnt auto zones, had it scanned, passed both times, put the alternator back in had them test the volts, they said i was good, about 13.4ish volts, and said it was reading my diods are good
maybe it could still be this, but i dont want to drop $200 on a new alternator and that not be my problem.

meanwhile, my air conditioning goes haywire along with this, while idoling, you turn on the a/c. and the car starts to seize, the a/c motor kicks on quick then shuts off. then goes right on and then off, over and over. Figured, maybe my battery is going since its seems old, maybe its bad electrical and not pumping enough, and sending the CPS to go haywire also.

$105 dollars later on a new battery, still getting the code

so, im at a lose here, is it my alternator? maybe like how i said everything seems so brittle maybe i have some bad wires? i dont knowww.

someone help me out here please!

and sorry this is so long...

[tinkerbell_too]

I had the same code....replaced the sensor, but still got the code...had my alternator tested and it tested fine. Kept throwing the code, so I decided to replace the alternator...never got the code again

Code p0340, sensor replaced, check engine light still off, but backfiring...help!!

[KennethRichard]

hmm, yeah, i saw your post, it was the first one i saw about the alternator, so it gave me hope, maybe ill just suck it up and get a new one, thankss

[tinkerbell_too]

Originally Posted by KennethRichard hmm, yeah, i saw your post, it was the first one i saw about the alternator, so it gave me hope, maybe ill just suck it up and get a new one, thankss

No problem - if you do change it, post again and let me know if it worked Good luck!

[KennethRichard]

So my sister's boyfriend is a mechanic and is bringing me a new Alternator today, so im going to cross my fingers and hope for the best. and ill deff let you know if it works

[tinkerbell_too]

Originally Posted by KennethRichard So my sister's boyfriend is a mechanic and is bringing me a new Alternator today, so im going to cross my fingers and hope for the best. and ill deff let you know if it works

Awesome. Good luck!

[KennethRichard]

So yeah, threw the new alternator on in like 15 minutes, i was so excited to finally have my car back to normal.

not even down my block, already had the misfire/backfiring. then not even a 1/4 mile, already had P0340 pending, and then within 5 miles, check engine back on.

ughh, i cant win with this car. Looks like its back to square one for me.

thanks for all the help though!

maybe ill just pull out the syncronizer, and get a new one maybe

[tinkerbell_too]

Hopefully you still have the new alternator on because you should try this...
First, did you clear the code by unplugging your battery for about 20 minutes? Second, it's possible that the old alternator already messed up your sensor again, so you might want to replace it again. Is the alternator he brought you a reman or brand new? If it's a reman, I wonder if they replace the diodes inside or just test the alternators to be sure they're fine? The bad diode inside of them is what causes the electrical feedback that destroys the sensor, but the alternators test fine. That's why I didn't go by an Autozone or Advance rebuilt unit. So, those are just my thoughts..good luck.

[yellowstang6r]

Could be crank or cam position sensors, which did you replace? And ^^^^^^ good question

[KennethRichard]

ive replaced the cam, im prob going to replace the crank next

[KennethRichard]

Originally Posted by tinkerbell_too Hopefully you still have the new alternator on because you should try this... First, did you clear the code by unplugging your battery for about 20 minutes? Second, it's possible that the old alternator already messed up your sensor again, so you might want to replace it again. Is the alternator he brought you a reman or brand new? If it's a reman, I wonder if they replace the diodes inside or just test the alternators to be sure they're fine? The bad diode inside of them is what causes the electrical feedback that destroys the sensor, but the alternators test fine. That's why I didn't go by an Autozone or Advance rebuilt unit. So, those are just my thoughts..good luck.

i was talking to him about that, he was saying that they just completely guy everything and put all new stuff in, new diodes, new coils, brushes, springs, everything

[tinkerbell_too]

Hmm. Do you still have the new alternator in? If so, I would replace the sensors, unhook your battery for a bit to clear the code and cross your fingers . Also, I know your sister's boyfriend says that they replace the diodes, etc...but I still wonder.... but that's just my 2 cents. Please let us know what you end up doing and what happens. Nothing worse than someone searching for an answer, coming across a thread that describes their exact problem, but then there's no follow up to say what the problem was . Again, good luck .

[KennethRichard]

so update.

Changed my camshaft position sensor (again) and changed my Crankshaft position sensor.

at first i was still getting some misfireing but after about 10-12 miles it went away. but i did get P0340 pending on my scanner again.

cleared it, re-drove around normaly, doing no WOT at all =\

code has yet to come back after about 30miles.

so in the end what i think it is, my timeing belt my need to be replaced, my father said he had the same problem with his mustang when he was my age.

so as long as i dont drive my muscle car like a muscle car, i should be fine =\

[236Mustang]

well that sux

[MineralGray02K]

Do you have any updates on this?

I read tinkerbell's thread and a bunch of other threads about people having this issue. I am getting the 0340 code too and replaced the FRPS and cam position sensor, but the light came back on. My car is not misfiring or anything though, but I ordered a PA Performance alternator tonight from AM, this one here actually PA Performance Mustang Alternator - 130 Amp (99-04 GT) at AmericanMuscle.com - Free Shipping!

I'm going to clear the code with my XCal and install this as soon as it comes and hope the light doenst come back on.

[tinkerbell_too]

Originally Posted by MineralGray02K Do you have any updates on this? I read tinkerbell's thread and a bunch of other threads about people having this issue. I am getting the 0340 code too and replaced the FRPS and cam position sensor, but the light came back on. My car is not misfiring or anything though, but I ordered a PA Performance alternator tonight from AM, this one here actually PA Performance Mustang Alternator - 130 Amp (99-04 GT) at AmericanMuscle.com - Free Shipping! I'm going to clear the code with my XCal and install this as soon as it comes and hope the light doenst come back on.

Good luck. Hopefully it will turn out to be your alternator, too. Please update us. Thanks and good luck

[KennethRichard]

Sorry mineral for not getting back sooner.

but after about a year, finally some update...........got my code to go away. (i started to lose hope and drag my feet)

[IMG]


I ended up finally replacing my camshaft position synchronizer. when comparing it to my new one, you could tell that there was just some hairline wear and tare. Guess such a small amounts makes such a huge difference!

It was so easy to replace too, took like 15 minutes to get the new part in. (that doesnt include the hour of taking everything that in the way out, and then replacing it.)

while i was in there i threw some new spark plugs in, since they got pretty shot. and it was easier to turn over the engine to TDC with them out.

hope this helps anyone!