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Pete
Pete, Car Enthusiast
Category: UK Car
Satisfied Customers: 27918
Experience:  Over 17 years experience diagnosing and repairing automobiles.
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Car wont start - no spark. replaced crank sensor, cam

Customer Question

hi
JA: Hi. What is your issue regarding?
Customer: car wont start - no spark. replaced crank sensor, cam sensor, maf, intake temp, sparks, coil pack. when i plug my laptop in (scanxl pro software) ALL of the sensor values are going crazy, for example, rpm goes from 34,000 to 2000, when the car is off! bad ground, +ve wire touching another wire???
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Mazda. The Mazda Mechanic I'm going to connect you with knows all the tricks and shortcuts. Are you hoping to fix this yourself?
Customer: yea
JA: Great! What have you tried so far?
Customer: car wont start - no spark. replaced crank sensor, cam sensor, maf, intake temp, sparks, coil pack. when i plug my laptop in (scanxl pro software) ALL of the sensor values are going crazy, for example, rpm goes from 34,000 to 2000, when the car is off! bad ground, +ve wire touching another wire???
JA: Is there anything else the Mazda Mechanic should be aware of about your Mazda?
Customer: no
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mazda Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: UK Car
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know.

Inspect the wiring running to the engine computer to see if any issues are found with the wiring.If no wiring is found at fault one common component I have seen cause this issue here especially with the erratic readings from the sensors is a fault with the computer itself needing replaced.I have had to replace this computer several times before in the past to correct this fault here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Hi Pete, thanks for replying. I've got the car running now, sensor readings are still all over the place, BUT, the problem lies with the crank position sensor - give it a tap and the car stumbles, pull on the wire and the car stumbles. So I will replace the crank sensor and go from there. The ecu sensor readings may be a red herring - the car drives well WHEN IT RUNS, fans kick in etc, good acceleration, she's pretty quick. Perhaps my scan tool and software are partly/all to blame for the dodgy graphs.Thanks,Tom
Expert:  Pete replied 1 year ago.

The scan tool may be causing this here with the readings or a short in the sensor causing erratic readings.

Make sure the connection and terminals are a tight fit in the connector to the crank sensor and make sure the wiring isnt shorted together at all causing this here.If this is all checked and found to be o.k. then the sensor needs replaced.

Let me know if you need anything else and feel free to rate my help here.

Thanks Pete