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Hello, I have a 2007 Mazda CX-7, 107,000 miles. I've been messing with it for a few months now. I have replaced the Crankshaft Sensor, Camshaft Sensor, Plugs, and took the throttle body off and cleaned it.
It will crank up and idle but when you put it under load, it dies. Putting it in drive dies immediately, in reverser it will take a few seconds... when you turn the wheel the power steering load kills it (I have to put the wheel straight to start it back up).
I did notice that when it is idle, I do not get a reading from the 02 sensor 1. It is always at 0.00 on my scanner. It's a scanner that has an app on my phone.
If you are getting 0 v at idle but the O2 sensor gives a voltage ouput if you can raise the RPM and hold it for a few seconds it suggest a fault in the sensor heater circuit.
I would also check for a blocked cat the quick and dirty (and very loud) way to test for this is unscrew the upstream O2 to give the exaust somewhere to go. Trouble is you have already fired the parts shotgun.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Last edit: 4 years 8 months ago by Andy.MacFadyen.
With the dying at idle/turning you will need to test power steering pressure switch and circuitry. Also do the key on engine off and key on engine running tests with scanner what codes pop up from those tests?
Hardtopdr2 wrote: With the dying at idle/turning you will need to test power steering pressure switch and circuitry. Also do the key on engine off and key on engine running tests with scanner what codes pop up from those tests?
The only code I ever received was the PO335 for the crankshaft sensor. The TSC light is on. I will see if I can test the pressure switch and circuitry for the power steering but it doesn't seem to matter about which load hits the engine, it dies. Just putting in gear without touching the steering kills it too.
Does it die instantly when put into drive wheels straight? Almost sounds like the wiring harness is being pulled from the engine movement.. I’d try pulling on the wiring harness around the crank sensor. But you could also monitor 5 volt ref to if you wanted
Matt T wrote: Can you rev up the engine with the gas pedal?
Yes. You can let it idle... You can rev it up to however many RPM's you want. It will go up and down and up and down with your gas pedal. It's just when you put any load on it. It will die.
Cheryl wrote: Does it die instantly when put into drive wheels straight? Almost sounds like the wiring harness is being pulled from the engine movement.. I’d try pulling on the wiring harness around the crank sensor. But you could also monitor 5 volt ref to if you wanted
When you turn the wheel you can hear a strain then it dies. When you put it in reverse it will run for a second or two and then die.... in Drive it dies immediately. Before I put the new crankshaft sensor on, I'd have to wait til the next day to start it. Now with the new one, it cranks right back up but if I have the wheel turned, it will not. I have to straighten it back up to get it to crank back up then it cranks right back.
Andy.MacFadyen wrote: If you are getting 0 v at idle but the O2 sensor gives a voltage ouput if you can raise the RPM and hold it for a few seconds it suggest a fault in the sensor heater circuit.
I would also check for a blocked cat the quick and dirty (and very loud) way to test for this is unscrew the upstream O2 to give the exaust somewhere to go. Trouble is you have already fired the parts shotgun.
I took the up stream out... No change in how the car acts. Still died under loads, steering wheel, reverse and drive.
Cheryl wrote: Is it stalling like it’s running out of fuel? Or does it just shut off like the ignition is being turned off
I think I would say more like the ignition is turning off as it doesn't start to sputter or anything like that. It seems to also idle for about 10 minutes and then it will turn off as well. I can crank it right back up when it does that too. Just now noticed that happens.
Fuel pressure / flow would be my main suspect. When was the filter last replaced ?
You might have static pressure that can fall off a cliff as soon as flow is needed. Graph the pressure against rpm and see if the FP drops out first
Other thought would be that the drive train is locking up, effectively stalling the engine.
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