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Discussion Starter #1
I have an 04 mustang gt with a 02 engine. I've had a check engine light since i put the motor in, P0340 cam position sensor bank 1. I swapped the motor 6 months ago, never had a problem until recently. Car is now occasionally missing, idling rough and occasionally knocking.

I replaced the cam position sensor with a used one i had lying in the garage...going to buy a new one from ford tomorrow....did not fix the problem.

After i reset the ECU, the car runs like it should. The moment i turn the car off and then back on again, the check engine light comes on and all the problems come back.

I've heard of the alternator causing issues, as well as the cam position sensor. Originally i was thinking wiring, but now really dont think so since the problem does go away.

Now the big question...if the alternator is causing a problem, would it actually cause the car to run rough???

Any help would be apprecitated.
 

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Unless your battery is going low it wont cause issues. Check if the connection is clean, and replace... its a cheap sensor. Do you have a tuner? Clear the codes, then do battery reset.

No idea about alternator... How is your voltage? Here is a list of things it can be when you get code from another site...

  • 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
http://www.paladinmicro.com/PalMFrame00.htm?wks=obd&dtc=P1130
 

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Discussion Starter #4
thanks for the input

I've replaced the cam position sensor and crank position sensor...they were both cheap sensors so i figured id try them. Still have the code and car is running like crap.

I'm down to either PCM or wiring...highly doubt its wiring since it isnt always a problem and problem is getting worse.

I read up on the alternator causing it to throw the code, but it looks like thats an issue on the 05 and up. They are having a problem with the voltage regulator diode.
 

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Discussion Starter #5
Oh and one more reason to point towards the PCM...the car used to be supercharged...the first time i had it tuned, it was tuned by a shady shop that fried the PCM. Supposedly they replaced it...I'm starting to think they just got it to work enough to make the car run. I've had this problem ever since it was in their shop over a year ago.

Can a tune shop shut of the Service Engine Soon light through their custom tuned chip?
 

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I have an 04 mustang gt with a 02 engine. I've had a check engine light since i put the motor in, P0340 cam position sensor bank 1. I swapped the motor 6 months ago, never had a problem until recently. Car is now occasionally missing, idling rough and occasionally knocking.

I replaced the cam position sensor with a used one i had lying in the garage...going to buy a new one from ford tomorrow....did not fix the problem.

After i reset the ECU, the car runs like it should. The moment i turn the car off and then back on again, the check engine light comes on and all the problems come back.

I've heard of the alternator causing issues, as well as the cam position sensor. Originally i was thinking wiring, but now really dont think so since the problem does go away.

Now the big question...if the alternator is causing a problem, would it actually cause the car to run rough???

Any help would be apprecitated.
i had the same problem , it was the baterry ,,it was over charging the system and it had a bad cell and was blowing out the diods in the alt ,, i just changed the bat and the alt and it was all good mill whent out and all was fine
 

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Can a tune shop shut of the Service Engine Soon light through their custom tuned chip?
They sure can. Typically ECU failure is VERY rare. Datalogging is the key to solving problems like this.
 

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Discussion Starter #8
superbeef when you had the problem, where you experiencing any problems or just a service engine soon? Also, what year is your car?

Jgorm, the first tune shop supposedly fried the ECU. I'm really wondering if they just hid the problem. I don't have their chip installed anymore. I wish i could do data logging, but dont have the tool. I do have the pinout, so im gonna check the voltages and resistance tomorrow.
 

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superbeef when you had the problem, where you experiencing any problems or just a service engine soon? Also, what year is your car?

Jgorm, the first tune shop supposedly fried the ECU. I'm really wondering if they just hid the problem. I don't have their chip installed anymore. I wish i could do data logging, but dont have the tool. I do have the pinout, so im gonna check the voltages and resistance tomorrow.
no the car was running crazy like the timming was way off and some times it would not start rite or shut rite back off after starting ,,if the electrical system is not get the propper power or to mutch power it can create all kinds of problems that are not realy there and of course i was getting all kinds of codes one of witch was the cps..
 

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Discussion Starter #10
Superbeef, I'm an electronics tech so i know all about voltages causing funny problems. When you had the problem did you have code P1639 Manfacurer Contrl Auxiliary Input Auxiliary Outputs.
 

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you have 1639? that is... if you have that code it is probably the tuner that screwed it up.

This diagnostic trouble code (DTC) indicates that the vehicle ID (VID) block is not programed or the information within is corrupt.
  • New PCM
  • Incorrect PCM
  • Incorrect VID configuration
 

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Superbeef, I'm an electronics tech so i know all about voltages causing funny problems. When you had the problem did you have code P1639 Manfacurer Contrl Auxiliary Input Auxiliary Outputs.
well i got a bunch of codes but i dont think that was one ,,but the one for the cps i got was for a line brake or bad wire, oh and my car is an 02 gt
 

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Discussion Starter #13
you have 1639? that is... if you have that code it is probably the tuner that screwed it up.

This diagnostic trouble code (DTC) indicates that the vehicle ID (VID) block is not programed or the information within is corrupt.
  • New PCM
  • Incorrect PCM
  • Incorrect VID configuration
Ryan thanks for the help. I think you've help me before with my problems...one of these days ill have a working mustang.

Ok so here is a real quick history on the car. Tune shop blew the computer, supposedly replaced it. Had numerous other problems with that shop. Car used to be supercharged, but i blew the engine back in june. So i put a motor out of a 02 mustang in the car. The only thing i have done to the computer was remove the chip the tune shop put in it...did not replace it with anything.

I had advanced auto run a code scan on the car. This is how it looks...

DTC (Codes)
P1639
Manfacurer Contrl. thats how its spelled
Auxiliary inputs
Auxiliary outputs

DTC Pending (Codes)
P0340
Camshaft Postion
Sensor A - Bank 1
Circuit Malfunction

P1639
Manfacurer Contrl.
Auxiliary inputs
Auxiliary outputs
 

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no problem... your computer is probably messed up, if you replaced the cps and still getting code. And that 1639 code points to a big computer issue, either with tune or with the ecu itself. Although its rare that it is a hardware failure on the ecu, so i would talk to someone with more knowledge than me. Possibly have a dealership run a diagnostic on it. I just did that for my car and it was a bit under 150. But it gave me a direction on what needs to be done.
 

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Discussion Starter #15
Looks like i'll be ordering a new PCM from ford. When i get it, do they have to transfer the data from my old comp to the new one or is it something i can just take home and pop in?
 

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You have to have them re program it... i just went through this (well currently) and they forgot to tell me that when i bought it at the dealership. But i might not have to use it after all...
 

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Discussion Starter #17
I kinda figured you'd say that. So its around $400 for it then of course they are gonna charge you to re-program it, right?
 

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yeah. It was 540 or so at the dealership, but a 100 dollar core charge when you return the old one. And they said it would be around 80-160 to put it in (like hour or two depending) Pull the trim for them and it will help.
 

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Discussion Starter #19
i'd be pissed if they charged time to get to my PCM...that takes about 30 seconds to get to. All the parts guy quoted me was 340-400 depending on VIN...i knew there was gonna be more to it. I have a ford engineer looking at my problem right now.
 
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