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Peter Bagley
Peter Bagley, Toyota mastertech
Category: Mazda
Satisfied Customers: 775
Experience:  master tech at Toyota dealer
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03 Mazda6 2.3 Won't start, P0340 Car was running really

Customer Question

03 Mazda6 2.3 Won't start, P0340Car was running really rough and no power.
1. Replaced plugs & wires - Drove car, idle better but power now good.
Ran it up to about 4500rpm on the road then slowed to turn around. After the turn the engine died and hasn't started since.When I try to start, It tries to hit once, then just cranks without starting. I can hear the fuel pump cycle. I also added a couple of gallons of gas just to make sure.1. Checked the cam sensor resistance - 475ohms
2. Tried a replacement cam sensor (just for grins)
3. Sparks once per cyl then nothing
4. Checked for voltage continuity from the cam position sensor. Terminal A and PCM (ECU) terminal 85 CMP sensor terminal B and PCM terminal 86
5. Checked cam timing (cam alignment tool)
6. checked Crank sensor resistance - 475 ohms
7. Checked Crank timing - perfect
8. Checked Crank sensor alignment - perfect
9. Rechecked Cam timing - Still perfect
10. Checked for fuel flow on the rail - okAny Ideas?
JA: Is the power loss consistent, or does it fluctuate?
Customer: It won't start
JA: Are you fixing your Mazda6 yourself? What have you tried so far?
Customer: Please read what I originally sent
JA: Anything else you want the mechanic to know before I connect you?
Customer: no
Submitted: 8 months ago.
Category: Mazda
Expert:  Peter Bagley replied 8 months ago.

Hello and welcome to just answer, my name is ***** ***** master tech here to help. I cannot see your vehicle so I rely on your input to my questions so I can better help you. I read your question and what you tried so far. Looks like you have tried just about every thing pertaining to that code but one basic.

Expert:  Peter Bagley replied 8 months ago.

Possible causes- Faulty Camshaft Position Sensor- Camshaft Position Sensor harness is open or shorted- Camshaft Position Sensor circuit poor electrical connection- Faulty starter motor- Starting system circuit- Dead (Weak) battery

Expert:  Peter Bagley replied 8 months ago.

Have you done a battery load test and starter draw test? this is important as these newer vehicles require a higher reserve voltage to run things or the ECU will randomly spit out anything. So that said , do you know what the reserve voltage you have while cranking?

Customer: replied 8 months ago.
Battery is fully charged and holding above 11v when cranking. I believe the threshold voltage for the ECU is 9.6v
Expert:  Peter Bagley replied 8 months ago.

Thanx for that info, and yes your correct as to the reserve voltage needed.Reading all your notes ans checks you did I would try a new Ecu as all the checks are good that you did.