# Camshaft sensor wires 2.0 mr20de



## Nissan0301 (11 mo ago)

Car runs fine without the sensor plugged in but when it's plugged in it will not start, it turns over catches and dies immediately.

how far do I have the cut back the wires to check? All the way through the wiring harness or just the wires that come off the harness and into the camshaft sensor?


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## VStar650CL (Nov 12, 2020)

That sounds like a bad sensor and not a wiring issue. When a CMP or CKP malfunctions but doesn't go "flatline," it will cause no-starts because the ECM is confused about when to fire the plugs and injectors. Disconnecting the bad sensor flatlines it and allows the ECM to run using the remaining good crank or cam sensor without being confused.


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## Nissan0301 (11 mo ago)

I have recently purchased 3, 2 aftermarket and 1 oem camshaft sensor and they all have done the same thing though (there's no way all 3 were bad out of the box, could there be?). And I did recently just install a new oem crank sensor. It's really becoming a money Pitt. Could the reluctor ring just be so full of crap it's confusing the sensor while its trying to do its job?

or more so, could the ring be damaged? The car seems to run fine without any weird sounds so I assume pieces of metals aren't flying aroundin there.


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## VStar650CL (Nov 12, 2020)

Nissan0301 said:


> or more so, could the ring be damaged? The car seems to run fine without any weird sounds so I assume pieces of metals aren't flying around in there.


The cam reluctor on an MR is machined into the end of the camshaft, so you'd be in big trouble if that was the problem. It is possible you have some magnetic crud built up on the reluctor teeth (or on the tip of the sensor) that's preventing proper triggering, but that's easy to check for and clean up by removing the sensor and bumping or hand-turning the engine. The most likely answer is just a sensor that's getting weak.


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## Nissan0301 (11 mo ago)

But I've tried 3 different sensors and they all acted the same, even oem camshaft one from Nissan. So if the ring isn't dirty i dont know what to do next. I don't really want to buy another new oem CMP when I just got the Nissan one..


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## VStar650CL (Nov 12, 2020)

Could be an issue in the wiring, then. I can look up the colors and tell you how to test it, but I'll need MY info.


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## Nissan0301 (11 mo ago)

there not in order but is the correct way? On the first picture when it says to check voltage am I grounding anywhere or somewhere specific? I'll do the testing but when I put the sea-foam into the crankcase I noticed it seemed to want to start a little easier, possibly it was cleaning the Ring? Lol who knows I'm at loss now.


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## VStar650CL (Nov 12, 2020)

You'll need some safety pins for back-probing the connectors, the way the ESM tells you to check it is incomplete. They also don't mention anything about pin-fit, and that's something you can also check with an 0.025" diameter safety pin. You may end up needing that since the sensor is probably falsing and not dead, but start with any old pins and we'll see if you need a specific one. 
1) Check voltage between G/Y and BR with the sensor disconnected and the key on. You should see right around 5V. If not, check from G/Y to the battery ground. If you get 5V from the battery ground, but 0V when using the the BR wire, then BR is broken. If both grounds give you a 0V reading then G/Y is broken.
2) Check voltage on R with the sensor disconnected. You should also see 5V there, but the voltage is coming through a pullup resistor in the ECM and not from the 5V supply (AVCC). If you see 0V then either R is broken or there's a problem in the ECM.
3) If steps 1~2 check out, back-probe G/Y and BR with the sensor plugged in but removed from the valve cover. Repeat step 1 but using the back-probes, keeping the sensor away from metal. If G/Y reads much lower then you have resistance in the G/Y wire. If BR reads much above 0V then you have resistance in the BR wire. If R reads lower then it's a bad sensor, new or not. Resistance on G/Y or BR can be in the wire _or_ at the ECM connector pins, so that's where pin-fits come in.
See what you find, and if 1~3 don't reveal anything, I'll show you how to remove the backshell from the ECM connector so you can check there.


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## Nissan0301 (11 mo ago)

Alright, man thank you so much I'll be getting to working on it shortly!


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## Nissan0301 (11 mo ago)

First 2 steps I got right around 5v. I'm confused on the second part.

I have the pins in the GY and BR and the key ON, I touching the GY one with the BR or the ground?
And what about the BR one, am I using that pin in that one and touching the ground?

Sorry I need to work on my wiring diagnostic skills


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## VStar650CL (Nov 12, 2020)

You're back-probing both wires with the sensor connected, so the sensor is drawing operating current the way it would with the engine running. Voltage doesn't always tell you anything unless current is flowing. Here's what a "back-probe" means:








You're sliding the safety pin in between the rubber and the wire to make contact with the pin without removing the connector. When you repeat steps 1~2, you'll be touching the safety pins instead of the connector pin. I.e., for the first part, you'll touch the safety pin on G/Y with the red meter probe and the safety pin on BR with the black meter probe. Since current is flowing with the sensor connected, if the readings are different from what you measured when disconnected, it means there's resistance in the circuit. That's known as a "voltage drop" test.


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## Nissan0301 (11 mo ago)

ah alright I understand that, Thank you. I will get that done asap and let you know, is there a specific reading that's good or bad? Less than 5v?


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## VStar650CL (Nov 12, 2020)

The G/Y and BR should read the same connected or disconnected, if they differ by more than about 30 millivolts (0.03V) then there's a resistance issue. The Red wire may be a bit lower depending how much the sensor leaks, but it shouldn't be lower by a lot with the sensor away from metal. The way that works, the sensor has an internal transistor that "overpowers" the pullup resistor in the ECM whenever it sees metal pass by, pulling the signal line to ground. Unfortunately the sensors are very precise and also directional, otherwise you could check them just by waving a metal tool in the vicinity of the tip. That doesn't usually work with the type of Hall sensors Nissan uses.


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## Nissan0301 (11 mo ago)

I will do the testing today. Just FYI i'm not a big fan of wiring, it's confuses me. Replacing parts and test other misc parts is easy for me but having to do in depth is like a run a round for me.

I just watched a video with a guy doing a 3 connector cam sensor test, he plugged it in outside of the car and and back probed the GROUND and signal wire and started cranking the car, is this correct?









I really appreciate your time doing this and explaining everything, not just laughing. I was never taught to do much wiring so I'm learning right now lol.

There is another thing that confuses me. Even if it has issues starting cold If say I do get it up to normal temp and drive around I can shut it off and it will restart perfectly, with the same connector plug into the sensor?


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## VStar650CL (Nov 12, 2020)

That test will tell you if the sensor is working, but not whether it's working well or half-a$$. To answer your second question, it isn't uncommon for Hall sensors of any type to be temperature-sensitive. I've seen ones that worked cold and no-started warm, and others that worked warm but no-started cold. Sometimes the mechanical clearances warm/cold contribute to that, since all Halls are very sensitive to the gap between the sensor and the teeth. And of course everyone has heard some nightmare story about wiring that's broken internally and only loses contact when hot or cold, and that can truly be a nightmare. If you think temperature is a factor, one way to find out is the test in the video performed both cold and warm. The sensor output voltage should show little or no change.


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## Nissan0301 (11 mo ago)

Edit: I did the accelerator pedal release and the throetlttlw body set by doing key on and off for multiple seconds following the video.
So I was just out messing around with it. It cranks and catches and dies, but then I can try again and it almost dies and I catch it with the gas pedal feathering it and it revs up to 2-3k and the settles down normal. Should I do the Throtfls body relearn and accelerator pedal procedure for sh*ts and giggles?
But once it does get running it sounds perfect, runs great sounds good, throttle response is good. Could the electronic TB be out of whack maybe needing a relearn?

Oh man, I really hope there's no broken wire hidden in the harness 

Is it possible to clean the reluctor ring with like a Qtip or something?

i have one more oem Nissan CMP on the way, and I pray that fixes it because I'm not liking this car very much right now lol!

Thank you so much for trying to help me, and I'm sorry if I'm frustrating you with this. I'm an extremely big dummy when it comes to wires and testing


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## VStar650CL (Nov 12, 2020)

Nissan0301 said:


> So I was just out messing around with it. It cranks and catches and dies, but then I can try again and it almost dies and I catch it with the gas pedal feathering it and it revs up to 2-3k and the settles down normal. Should I do the Throtfls body relearn and accelerator pedal procedure for sh*ts and giggles?


And an IAVL, yes. IAVL will be the important one, that's what calibrates the MAF and synchronizes the MAF with the TPS. It certainly can't hurt.


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## Nissan0301 (11 mo ago)

Yup, I just did both of those. The car is at operating temp now. When it cools down I'll go out and try to start it. And I do have another oem CMP on the way as well I'll install when I get it. I know it's a broken record but I can't thank you enough for giving me tips.

I'll post back if it's still doing the issues later.


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## Nissan0301 (11 mo ago)

I did the IAVL and no luck. Still same thing.

how do I disconnect the ecm harness connector? It says to check continuity between terminal 2 (on the sensor itself?) and ECM terminal 63.

-continuity should exist it says.

then check terminal 3 to ECM terminal 65 and same thing.

-continuity should exist. If it doesn't that means there's a break somewhere in the wire right?

I'm confused what it means by checking harness for short to ground and short to power. If all checks out it says to:
Check and remove any debris from signal plate( reluctor ring). How would I do that without having to rip the whole cylinder head off I don't have a place to really work on it, beside my apartment parking lot and they're already giving me the bug eye for doing what I'm doing.


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## VStar650CL (Nov 12, 2020)

A fishing magnet through the sensor hole works fine for capturing metal debris on the reluctor. Anything that isn't metal isn't a worry.

Checking for shorts to ground or power involves taking both ends of the wire loose and ohming to battery+ and battery-. With both ends loose, if the reading isn't infinity (or at least megohms) then there's an insulation failure inside the harness. Where wires run in a bundle like the 3 conductors on your cam sensor, it's also a good idea to ohm each of the wires to one another.

Here's how you get the connector at the ECM loose and remove the backshell. These pics are of a TCM connector, but the ones on your ECM will be the same sort:


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## Nissan0301 (11 mo ago)

So can I set the multimeter for continuity with the sound and touch from camshaft connector to R pin 3 phase wire to the ECM pin 65 To verify there’s no break? Lol once this is all said and done I’m going to read up on a bunch of electrical stuff for learning, this is embarrassing For me.


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## VStar650CL (Nov 12, 2020)

Yep, exactly. I'd keep any eye on the reading and not just use the beeper. Sensor wires should read below 1 ohm, if the reading is higher it's usually a hint that the wire has or is developing a break.


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## Nissan0301 (11 mo ago)

if say there is a break in one of the wires to the ECM, can I just run A new wire directly from cam sensor connector to ecm with a new pin? I’d rather not have to dig through the wiring harness, I’m just trying to get this up and running for a little longer, the previous owner just destroyed (as in no maintenance ever) it And I’m trying to fix all the problems I can daily it for a little while longer.


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## VStar650CL (Nov 12, 2020)

Ohms is good for checking for insulation failures, but the best way to verify continuity is actually with differential voltage and not ohms. Back-probe both ends of the wire and put the red probe on one end and black on the other with the key on, engine running if possible. If the wire is in good shape then you'll see a few millivolts at most between the ends. More than that means there's resistance in the wire which is causing a different voltage at one end than the other. The advantage to doing it that way is you can "wiggle test" any wire that gives you suspicious readings while the engine is running, and often locate the break that's causing the issue. 

You should probably do a pin-fit check too, while you have the ECM connector loose. Find a size of safety pin that drags a little when inserted into the female cavities (don't use any real force, any pin large enough to need force can actually damage the pins). Then check all 3 of the pins for the sensor and make sure they all drag. Pin-fit issues are usually caused by the tiny leaf-spring inside the female connector breaking off or fatiguing, so a bad pin won't give you much or any resistance compared to the pins next door.


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## Nissan0301 (11 mo ago)

Ok I will try to do this when I get off work! Might fail because I'm a dummy with electrical but damn it I'm going to try!

thanks, I'll probably respond later with some dumb question, so be on the look out! Haha


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## Nissan0301 (11 mo ago)

How do I know which connector on the ECM has the camshaft sensor wire? I didn’t see any numbers correlating to the sensor, liken pin 63, 63 etc. Have I told you how much I hate wiring? lol…

and at this point, I’m getting zero codes… if I get any I’ll report back.

edit: when the car is starting it looks to the cam sensor, crank sensor, maf and coolant temp sensor right?

also when it did start with the sensor unplugged I let it fully warm up. Had plugged the sensor in andshut it down. It restarted without any any issues at all.....for whatever reason it does not like cold starts

could the electronic TB be involved with the start up?
Or the accelerator pedal sensor? I’m super frustrated about this


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## VStar650CL (Nov 12, 2020)

The TPS or APP are unlikely to be involved in a startup problem. The ECM also looks at the IAT (Intake Air Temp) during startup, otherwise I think that list is correct.

The ECM should have color dots on the studs that engage the connector levers, and the connectors themselves will have colored front shells. One will be black, one brown, one gray. If you look at the layout of F25 on the wiring diagram, you'll see a little "BR" underneath the connector ID. That's the Brown connector.


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## Nissan0301 (11 mo ago)

Alright so the cam sensor wires will be in that connector? (I replaced the maf which is combined with the IAT). I'm going to swap my old OEM maf in today.


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## VStar650CL (Nov 12, 2020)

Nissan0301 said:


> Alright so the cam sensor wires will be in that connector?


Yep, just like the diagram. The diagram shows a "Harness Side" view (where the wires enter), so when back-probing that's the view you'll use. Looking at the face ("Terminal Side") to use the ohmmeter or do pin-fit checks, it will be mirrored. You can use the location of the larger terminals 73~80 to get the connector oriented properly vis the diagram.


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## Nissan0301 (11 mo ago)

I think I have an issue with the fuel pump causing these problems. I can only hear it prime sometimes when I turn the key on, not every single time. The times I can hear it, it wants to start up and run but dies quickly. It's a old fuel pump with many miles, I think I'm going to try and replace it for the heck of it. If it solves the problem, hey that's great.


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## VStar650CL (Nov 12, 2020)

It's normal for the pump to "blip" on for a few seconds and then quit when you turn the key on without starting the car. That's a priming mechanism to make sure the rail is full for starting, but keeps the pump from running unnecessarily with the engine stopped. But it still should do that every time the key is cycled. If it doesn't then you may have a weak pump.


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## Nissan0301 (11 mo ago)

I was listening to it, when it starts and surges the pump sounds like it's not being able to provide the power needed. And i can only hear it "prime" 1 out of like 5 key turns. I'll turn key and then off, try again and nothing, same for couple more times and then I hear it and it seems like it wants to start


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## VStar650CL (Nov 12, 2020)

That certainly could be a weak pump which has trouble spinning up when there's already a head of pressure.


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## Nissan0301 (11 mo ago)

I hve a pump arriving tomorrow, what's the easy way to remove the lock ring on the pump top? I don't have a Special tool for it, do you know which one works I could buy?


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## VStar650CL (Nov 12, 2020)

I've never done one on a Nissan by hand, at the shop we use a Nissan special spanner tool and an air impact. In the bad old days we used a brass chisel and a heavy hand sledge, but make sure it's a _brass_ chisel and not steel (no sparks).

This spanner on Amazon looks pretty sturdy for $24, and I guess if you have Prime you can get it quickly:








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## Nissan0301 (11 mo ago)

Great. Thank you! I'll let you know how it goes.


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## Nissan0301 (11 mo ago)

Changed new fuel pump same thing, but when I unplug the cam sensor it starts normally sometimes and now it's definitely leading toward wiring. Is there any relays or extra fuel fuses I can check?

can I just run 3 new wires from camshaft plug to the ecu?


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## VStar650CL (Nov 12, 2020)

Nissan0301 said:


> can I just run 3 new wires from camshaft plug to the ecu?


Yes, provided the problem isn't bad pin-fit at the ECU. It will be foolish to plumb new wiring without checking that.


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## Nissan0301 (11 mo ago)

So just unplug the ECU and check the pins like the pictures above?


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## VStar650CL (Nov 12, 2020)

Like I said earlier, a safety pin the right size will work fine. Get an assortment box from Dollar General or Walmart, start small and work up until you reach a diameter that drags slightly. The factory pins are 0.025" nominal, so if you have a caliper, find one that's close to that. The drag you feel will be the leaf springs inside the female terminals. If they're all healthy then they should all drag about the same. Check both ends, the bad fit could be in the sensor connection too.

There's one other thing you should probably try before condemning the wiring. Take the screw loose on the sensor, turn the sensor 90 degrees and try to start it. If the problem goes away then you might be getting wrong parts for some reason. Have you been shopping using the Nissan part number from Nissan EPC, or by make-model-year? The latter is almost always a mistake.


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## Nissan0301 (11 mo ago)

I will try your ideas thanks. I've been looking around for OEM camshaft sensor and can't seem to find it? Mainly make mod year

I'm now getting a P0183 code for the fuel temp sensor, it's literally brand new... lol this car is such a headache. Are these just defective parts? The fuel pump I got on rockauto.

Edit: there's a 2012 Sentra in the junk yard and I think I'll see if it has an OEM camshaft sensor, possibly the fuel temp sensor for the fuel pump or just the entire thing if it's oem.


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## Nissan0301 (11 mo ago)

VStar650CL said:


> Like I said earlier, a safety pin the right size will work fine. Get an assortment box from Dollar General or Walmart, start small and work up until you reach a diameter that drags slightly. The factory pins are 0.025" nominal, so if you have a caliper, find one that's close to that. The drag you feel will be the leaf springs inside the female terminals. If they're all healthy then they should all drag about the same. Check both ends, the bad fit could be in the sensor connection too.
> 
> There's one other thing you should probably try before condemning the wiring. Take the screw loose on the sensor, turn the sensor 90 degrees and try to start it. If the problem goes away then you might be getting wrong parts for some reason. Have you been shopping using the Nissan part number from Nissan EPC, or by make-model-year? The latter is almost always a mistake.


I did just that and it started like normal... I am going to go recheck it later after it's cooled down completely but it worked this morning also. What is the correct part number OEM? I've tried 3 camshaft sensors now already.


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## VStar650CL (Nov 12, 2020)

Go to NissanPartsDeal.com and plug in your VIN. They're a consortium of Nissan dealers marketing on the internet, so their dbase and drawings are identical to Nissan EPC. The p/n you get from them will be exactly what your ride was built with.


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## Nissan0301 (11 mo ago)

Alright I'll do that. A question though why did the sensor work when turned at an angle? I started the car after waiting a day and the sensor still angled it started like normal?

looks like this is the one so I'll go ahead and get it.


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## Nissan0301 (11 mo ago)

Ops didn't mean to double post.


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## VStar650CL (Nov 12, 2020)

Nissan0301 said:


> Alright I'll do that. A question though why did the sensor work when turned at an angle? I started the car after waiting a day and the sensor still angled it started like normal?


Any Hall Effect sensor is magnetically active, and all magnetic fields have a polarity. Most Hall sensor IC's are constructed to work best in a certain polarity orientation, with or across the field, and south or north. That doesn't mean the sensor won't function in a different orientation, it just won't work as well as it should. Many aftermarket manufacturers cut corners by making their IC's work in orientations that they really weren't designed for but still work "good enough" in most instances. That's most of the reason some people have grief with aftermarket Halls but others work fine and have no issues. You can't exactly x-ray the sensor and identify the silicon to see if it's set up ideally for the design of your reluctor wheel.


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## Nissan0301 (11 mo ago)

The OEM camshaft sensor from Nissan is on the way, should be here Tuesday or Wednesday. I'm hoping it finally resolves this.

Side note: the cam sensor (aftermarket) in the car currently is still angled and it's started normally every day I've taken it so far which has been about 3 days. Thanks for this tip since this is my DD.


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## Nissan0301 (11 mo ago)

Got the oem camshaft sensor, installed it in normal orientation and started the car it did the same surging and died.

I then angled the oem sensor and it started completely normal. I'm not sure what else to do. I think I'm just going to leave it as is, the sensor is secure in place and doesn't move but I'm done chasing this issue.


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## VStar650CL (Nov 12, 2020)

That's bizarre. Are we sure your engine hasn't jumped time by one or two teeth? That usually won't prevent them from running, but it can cause hard or no starts.

Use a dab of Permatex Ultra Gray underneath the flange if you want to just leave it, that stuff is nasty once it sets up (we all call it "Gray Death" if that tells you anything). Just a tiny dab should keep it in place, but not so much that you can't pry it loose again if you need to.


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## Nissan0301 (11 mo ago)

The jumped timing could be a possibility but it's not something I've looked into yet. Is that a pain to check on this car? Wouldn't it idle weird if it was off 1-2 teeth? As it's warming up it idles fine with no noticeable symptoms and since I've started this journey on trying to solve this issue the car hasn't made any strange mechanical sounds when starting it. Is it common for these to jump teeth? I mean it does have 187k on it..

edit: I just looked up the repair manual for the timing chain and that's an extensive project, especially since this is my daily and I don't have another vehicle at the moment. I wish it was a timing belt so the timing case didn't have to be sealed.

much thanks for all your time and input on this headache though!


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## VStar650CL (Nov 12, 2020)

Checking it is easy but takes a streaming scanner capable of reading the cam timing. The cam angle should be 0 degrees at idle (sometimes they bounce at 1 or -1). If it reads anything higher than 1 then it's jumped. On Nissans each tooth is generally about 3 degrees, so you'll usually see a jump in approximate increments of 3.


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## Nissan0301 (11 mo ago)

Can you give any suggestions on a scanner that can do that?

I was looking at this. It says it live data and graphs but I'm not sure if one of those is cam angle data.


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