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Discussion Starter · #1 · (Edited)
p0340 code two days after replacement of cmp sensor

1998 3.0 ohv with 125k miles

just purchased this car. after a couple of days, it threw a code, which turned out to be p0340-camshaft sensor (or wiring). i have checked the wiring for both the ground and signal wire, as well as the shielding ground back to the firewall mounting point. all three wires have perfect continuity from the connector to the ecu plug or firewall ground point. so i replaced the sensor, and since the synchronizer was not chirping and the sensor's pickup hadn't fallen inside and mashed it up, i didn't replace the synchronizer.

two days later the code came back. the car runs fine, but gets around 13mpg (i don't have a heavy foot).

anyone have any suggestions?

thanks
 

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Out of curiosity, where did you get the sensor from? I know that certain parts stores, like O'Reilly's, autozone etc. sell pretty bad parts. I was working on a friends maxima that had a bad Mass Air sensor and the first THREE that I got from O'Reilly's were defective and showed voltage readings that were out of range and didn't correct the problem. Thankfully, I had access to alldata and could look up the voltage specs (1.0-2.0v). When the sensors were showing 12v, the car would accelerate and dumped fuel like crazy.

Only use Motorcraft parts for sensors.
 

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Discussion Starter · #3 ·
sensor was a genuine motorcraft (ford) part. even said ford on the top-center of it i believe.

is it possible the previous owner changed the synchronizer, and didn't align it correctly? though i would've thought it would throw the code instantly, not after 2 days of driving.
 

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Discussion Starter · #5 ·
if there was a problem with the synchronizer, i doubt the code would take 2 days to return. i don't buy it, and especially not for $200 i won't replace it just to "test" a theory. the shaft is tight, no damage to the metal tab, sensor wasn't broken and sitting inside. this is what i'm trying to avoid, a mechanic just spending my money for guesses on what is wrong.
 

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Out of curiosity DJ Rosa, is your vehicle flex fuel? I'm trying to find a picture of the cam synchronizer, is it that part that the sensor bolts to? If so is there a reluctor ring in there? (A ring with teeth, not the one at the bottom of the shaft) If there is, try sanding the high spots, sometimes that makes it send a better signal.
 

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BlackOmega, yes, the cmp sensor bolts to the sync. Sync is in the old distributor location. Some parts houses have it listed as the crank angle sensor or synchronizer.
 

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BlackOmega, yes, the cmp sensor bolts to the sync. Sync is in the old distributor location. Some parts houses have it listed as the crank angle sensor or synchronizer.

Ok, I thought that was the part, I just wasn't sure.

At any rate, under the sensor, is there a reluctor ring that may or may not resemble this:



I know on some of the older distributors, and even on some ABS sensors, cleaning that reluctor ring from any rust and or contaminants sent a "cleaner" signal. The magnet in the sensor could sense the voltage oscillation easier.
 

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Discussion Starter · #11 ·
Any reddish rust under the cap on top of the sync?
no reddish dust. it was suprisingly clean. suprisingly clean, possibly the previous owner was there recently? why?


Ok, I thought that was the part, I just wasn't sure.

At any rate, under the sensor, is there a reluctor ring that may or may not resemble this:

nah, looks nothing like that. that looks more like a trigger wheel for a crank sensor to me.
 

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CMP has only 1 tooth, not several as in the pic above.
 

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Discussion Starter · #16 ·
nah, i would prefer not to attempt it. i have already fixed issues with the car, such as the automatic door lock not working which proved to be some marretts that came lose in the door. so if this shade-tree mechanic changed the synchronizer, and messed up aligning it, i will rip it all apart, and re-align it later. i was just hoping there would be some other cause that i could fix that would be easier.
 

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nah, i would prefer not to attempt it. i have already fixed issues with the car, such as the automatic door lock not working which proved to be some marretts that came lose in the door. so if this shade-tree mechanic changed the synchronizer, and messed up aligning it, i will rip it all apart, and re-align it later. i was just hoping there would be some other cause that i could fix that would be easier.
It only should take about 25 minutes if you've pulled it once already. They're not really hard to remove. I was expecting way worse when I did mine.
 
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