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Old 06-08-2015, 10:53 PM
nmyron nmyron is offline
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2006 Sentra
 
Join Date: Jun 2015
Posts: 1
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So, I just joined this site simply to reply to this thread. My buddy has an 06 Sentra 1.8 with an auto trans. He's had hard start problems for a while, multi-second crank times, and sometimes multiple cranks. And very recently began missing something awful.

I read this thread, and checked out a couple YouTube videos. And then began silently cursing to myself about the misery I would soon be enduring to diagnose what would from the outside seem to be a nightmare.

But then I started thinking, I've not seen anyone post results after CLEANING OFF the Crankshaft Position Sensor. So grabbed some Carb cleaner (check the label and ensure it says "safe for O2 sensors", if its safe for them its safe for any, I've used carb cleaner to clean the rear axle speed sensor on my old Durango too), popped the sensor out, sprayed down liberally, allowed to dry then reinstalled.

Wham, bam, thank ya mam. Car turns over quickly, and no misfire.

Please note that I think part of the problem is the design of the sensor housing. The top of the sensor has a grooved surface, and I believe oil is resting in the valleys and gels when sitting. I'd bet if you pulled diagnostics on that sensor you'd see mild fluctuations in readings from post-start until warmed up (crankcase temp rises, oil heats, fresh oil gets tossed at the sensor and readings are less disturbed). These sensors basically detect changes in electromagnetic fields, and are designed to pick up 'markings' on either the cam or cam-gear (some engines have a cam sensor and crank sensor, in those systems the two values are correlated) thereby determining what cylinder needs fired. After a couple oil changes, and 6k or so miles, no matter how nice your engine is, it has metal particulates in it. Facts of life. Piston rings wear, bearings wear, and the results are tiny grains of metal floating in your oil. And that metal-laden oil resting in those valleys on top of that sensor? I bet that therin lies the rub...

Newer parts (I like O'Reilly, but whatever floats your boat) like these I would bet have better results, simply because they all are smooth (aluminum, maybe, so non-magnetic) metal cylindrical housings.

MasterPro Ignition 2-96239 - Sensor | O'Reilly Auto Parts

Now this isn't gonna fix the fuel pump issue. I can buy that some of these hard starts are being caused by vaporlock due to fuel drain-back out of the rail. But if you've done the pump service... Before you just start throwing money at the problem, clean the part first. If after a few days it starts back up, replace with something like the above part from vendor of your choice. If you notice that after a couple oil changes it starts creeping back... Maybe just take that as part of your new oil change routine and every 3k miles you pop that bad boy out and spray it down.

Last edited by nmyron; 06-08-2015 at 11:02 PM. Reason: Proofreading is a P.I.A. huh??
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