'94 q45 crank position sensor

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Jman47
Posts: 9
Joined: Tue Nov 21, 2017 11:44 am
Car: 1994 Infiniti Q45

Post

Hello,

My q45 recently started having issues running rough after some driving, then shutting off completely. I dont have any diagnostic equipment so I took it to a shop and they were able to pull codes from it. The vehicle needs a crankshaft position sensor. The problem is they told me that the crankshaft position sensor has been discontinued. Ive tried looking around a bit and havent found one so If anyone here knows if I can find one somewhere please let me know. Thanks!


Jman47
Posts: 9
Joined: Tue Nov 21, 2017 11:44 am
Car: 1994 Infiniti Q45

Post

Just a quick clarification- despite what the shop said they told me when I picked up the car it gave them a code 11- which is the camshaft sensor. They said they couldnt find the oem part but looking it up it seems there are remanufactured ones. I will replacr that and hopefully tge issue does not persist.

3Q Jay
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Car: 94 Q45a
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I was going to suggest it was maybe the CAMshaft sensor. This is aka the "distributor" even though that is not technically precise.
Your profile says you have a '94. Depending on your build date, you may have the part with one connector and one harness, or just the part with one connector (no additional harness on the part).
23731-67u00 should be the OE part number for the "early" version with the sub sensor harness.

Jman47
Posts: 9
Joined: Tue Nov 21, 2017 11:44 am
Car: 1994 Infiniti Q45

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Yes Jay it confused me as well, the guy at the shop insisted it was a CRANK sensor (even after pointing the sensor out to me) and I didnt bother arguing just took the car and left. The sensor has just a connector with no harness, so that would be the late model. It is held on by 2 bolts and is easy enough to get to. Apparently the OEM sensor was made by Hitachi but is no longer available. I purchased a reman from AutoZone for $218 and it should arrive tomorrow. Just one question, does it need to be 'clocked' a certain way like a traditional distributor would? I can definitly see the resemblance, but cant seem to find any literature on replacing it other than 'code 11, check cam sensor harness and connector and if good, replace sensor'.

3Q Jay
Posts: 2545
Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
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01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

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it's an easy swap. be careful to align the "key" on the engine side of the new sensor (it won't easily go in all the way if it's clocked, but you could break something if not careful).
yes, this will absolutely affect your timing.

Jman47
Posts: 9
Joined: Tue Nov 21, 2017 11:44 am
Car: 1994 Infiniti Q45

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Ok so an update. Last night I tried unplugging the old sensor and plugging it back in, and the car from that point on cranked but did not start. Today I replaced the sensor and am having the same problem- crank but no start. The sensor is in flush and screwed in and plugged in. Its a remanufactured duralast brand from AutoZone. I had the battery unplugged the whole time I was replacing it. I'm not sure if I overlooked anything or if there is anything else I can do.

3Q Jay
Posts: 2545
Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
97 Q45t (sold)
01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

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What did you do to keep the timing set?
I'm also inclined to think the MAF harness may have been bumped during connector and or part R&R. very easy to do-- that (3-pin MAF) connector is VERY fickle.

Jman47
Posts: 9
Joined: Tue Nov 21, 2017 11:44 am
Car: 1994 Infiniti Q45

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I didnt do much else besides take out the old sensor and put the new one in. I had to move the 'key' around a bit on the new one to get it to go in all the way. Once it was in and flush I plugged it in. As far as the MAF sensor, I unplugged it and removed the intake box with the air filter so I had more room. I did plug it back in correctly with the metal bracket in place before I tried starting the car. Im guessing that perhaps the timing on the new sensor is not correct, but I didnt see any way on the sensor to make sure that it is before I put it in. I can pull it out again if there is a timing procedure I need to do for the vehicle, if anyone has a link or any literature on it I can take it from there.

3Q Jay
Posts: 2545
Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
97 Q45t (sold)
01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

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Do you have the FSM?
See EF&EC 32 for the description on how to measure and set timing..
But that procedure assumes the car is running.
I'll get you a picture in a bit from my '94 that will show you the relationship when properly timed. that will hopefully get you close enough to get it running, then you can properly set the base timing via FSM procedure.
Don't throw away the old sensor yet.
I'd also try wiggling (gently) the MAF connector while trying to start it, if it still doesn't start after you get the base timing close.

Jman47
Posts: 9
Joined: Tue Nov 21, 2017 11:44 am
Car: 1994 Infiniti Q45

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Yes thank you. I do have the FSM downloaded from this website and will look into it. Any pictures you have would be very helpful as well. Thank you very much!

3Q Jay
Posts: 2545
Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
97 Q45t (sold)
01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

Post

Image

Where the red circle is. there is a sharp ridge on the body of the sensor, it should clock about where the valley is on the camshaft cap. That should get you close enough to start it if everything else is good.

Here's another shot from my '95
Image

Jman47
Posts: 9
Joined: Tue Nov 21, 2017 11:44 am
Car: 1994 Infiniti Q45

Post

Image

I'm not sure if this picture will show up (I took it on my phone) or not but if it does it shows how I have my sensor setup. I tried to get it where you described as best I could. Still crank no start.

3Q Jay
Posts: 2545
Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
97 Q45t (sold)
01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

Post

No picture.
Good troubleshooting protocol says make a list of everything that is known to be different or impacted since the last time it was running.
Then make a list of everything near by the surgery site that could have been disturbed.
then methodically go thru and examine each item on the list.
don't change more than one variable at a time.
keep at it until you find it.
If you have an ECU interface tool, it would be very helpful to know what voltage the ECU is seeing from the MAF (down to the millivolt), both with Key on engine off, and then while cranking.
Pure speculation on my part (but based on my personal experience after dorking with the Cam sensor.....it's the MAF).


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