Intermittent Hard Starting & Engine Stutter

[tpjockey]

My 2008 M45x with 89k miles is exhibiting an intermittent hard starting and occasional mild engine stutter problem. Both cam sensors and the crank sensor have been replaced without improvement. The Check Engine light is on and most times you really can't tell there is any problem. I can do around-town driving for a couple of days and notice nothing. Occasionally, upon starting the engine cranks for a few seconds before starting or the starting system just times out after 5 seconds or so and I have to try again. The starting problem seems to be more prevalent following longer drives. When driving at constant speed, the tach needle will occasionally flutter with a very slight sensation of the engine stumbling. When this happens (with the Check Engine light already on usually) several other warning lights come on. These other warning lights typically go away after the car has been stopped and restarted. The Check Engine light has gone away a couple of times but mostly is always on. When braking to a mild stop for a stoplight, there is a slight feel of the throttle giving the engine some gas at times and then the transmission disengages and everything seems normal. The car has never left me stranded with this problem over the past month but I have had a couple of times where the starter timed out like 4 times before I was able to get the engine started.

Really hoping somebody has some insights into what my problem might be. Thanks.

[EdBwoy]

What are the primary codes you've been seeing when the check engine light is on?
How new is the battery and what is the condition of the battery terminals?

Also, part of this sounds like a funky alternator. What are these other warning lights that come one with the engine fluttering? Is the battery light one of them?

[tpjockey]

Thanks for getting back on this. I don't know the codes myself. Tomorrow I plan to go to my local independent auto repair business to have them get the codes. Originally, they said that the codes made the cam sensors suspect. (I have had a lot of good dealings with this auto repair business over the years, so am inclined to trust them.) As to warning lights, I recall I get a "SLIP" light, but not so sure about a "Battery" light so that might be one of them. I will check the battery itself and connections myself tomorrow and also have the auto repair business check it out also. I have only owned this car for about 4 months/3k miles but all was good for the first 1500 miles or so. Again, thanks for getting back to me on this problem. I will follow up.

[Larz]

You mentioned cam sensors. That or maybe O2 sensors may cause this as well. I'm sure after the codes are read, you will have an idea what is needed. Let us all know how this ends.

[fabM45]

I've experienced engine stutter, flickering lights, and hard starts with my 2003 M45. I had the brake and battery lights come on at the same time after the car was up to operating temp (means low charge). Turns out it was the faulty non-OEM spec alternator from O'reillys. Replaced it with an Autozone alternator and the stuttering went away. The CEL code should tell you exactly what is wrong, so I would get that checked first before buying any more parts.

[tpjockey]

Brought the car to the local mechanic to get the codes checked. Codes faulted right cam function. Mechanic says that cam timing on this car is controlled by the cam positioner sensors (I may not have the exact terminology correct here) which use engine oil as the motive force for positioning the cams. Mechanic says good news is that the cam positioning sensors themselves (which he had already replaced) were not showing a fault code. Tried to pick up on the discussion between the boss and the mechanic that ensued. Heard something about possible sticking in the cam positioning mechanism and something about this design as being similar to a Honda V-TEC engine. The car has been starting and running fine although I've not really driven it much since the sensors were replaced. I will be bring it back to the mechanic next week for them to investigate further.

[Costee]

What are the exact codes? Again you said you've had to change the two cam sensors and the crank sensor. But the M45 has only one cam with the crank sensor. The other related sensors are two VCT sensors.

[tpjockey]

While I heard the mechanic say the code he saw, I don't remember what he said. It was some alpha-numeric thing, like maybe 3 letters/numbers. Since I paid $122 each for two cam sensors and about $50 for the crank sensor, I am hoping there really are two individual sensors for the two banks of overhead cams. Perhaps reinforcing that was the initial report from the mechanic that the (I think is was) right side cam sensor showed up as a culprit. They recommended replacing both the left and right side sensors and remarked to me that these sensors are a common failure point for both the M35 and M45 models. The mechanics statement that today's code had to do with the right cam sensor also supports the two cam sensor argument. Of course, I am only going on what the local auto repair business is telling me but I have the advantage of living in a small enough community that anybody who does not operate their business with honesty and integrity gets found out fairly quickly and this auto repair place has been in business for probably going on 20 years or so and they get lots of business, mostly a combination of German makes and Jaguars though.

[tpjockey]

BTW, what are VCT sensors? Perhaps that is what was replaced.

[dougie1022]

Hello all, I'm new to this game of Asian cars but I finally let go of the American muscle Chevys etc and now I have a 2003 M45.
I recently dealt with "service engine soon" light and "VDC" and codes for cam sensor..
Car stalling, not starting, starting a half hour later being able to drive then stalling again..headaches..
This happened for a week and I changed the 2 cam sensors and the crank, ran diagnosis and finally found out that there is another sensor....it's called the "cam phase sensor"
Located on the drivers side under the cam sensor...it costed about $60
And my car seems all good now..I hope this helps anyone that's been having similar issues

[tpjockey]

Wow. cam sensors, crank sensors, cam phase sensors ! ! ! This s*** used to be a lot simpler! But, then again, the reliability of those older, more simply designed engines was pretty much for s***. So, trade-off: generally higher reliability for newer designs but with a s*** load of mostly reliable sensors that, when things go south, gum up the works. Yaay progress ? ! ? !

[Costee]

BTW, what are VCT sensors? Perhaps that is what was replaced.

See topic607101.html
On a confusing note, you might see the VTC as either cam or crank sensor. What matters is the part number.

[tpjockey]

The latest - Have driven the car now for several days following replacement of two cam sensors (@$122 each) and a crank sensor (@$60). Basically, no change. When the car is cold, all is fine. Starts and runs normal. Following a more extended drive and with ambient temperatures being in the 80's, things revert back to multiple warning lights coming on and hard starting - as in multiple start attempts before the engine fires up properly. Basically, the Service Engine Soon light has always been on since shortly after picking the car up from its last repair. Occasionally other warning lights, specifically, "VDC OFF", "SLIP" and the Auto Lane Departure Correction icon all show up in yellow (as in "off"). Per a prior questioner, I can now say that the battery light has not been one of the lights that has come on. These other warning lights often go back off not long after they come on. Perhaps only after the engine has been turned off and then back on later. Also, the coolant temperature gauge isn't showing anything other than a normal coolant temperature, as in slightly higher under higher ambient air temps and slightly lower under lower ambient air temps. I will have the car back in the shop on Tuesday and will follow up on my continuing saga . . . .

[EdBwoy]

Thanks for the updates. With more information, we'll surely get somewhere.

The automotive shop that you're going to might as well be diagnosing the car well enough but you have an anomaly of a car. On the other hand, with no offense meant to your guys, the cynical side of me says that a shop that mostly works on Jags and Benzes might be used to open checkbooks.

Infinitis are typically not that expensive to keep on the road. Next time you go in, politely ask for a diagnostic report. Tell us the exact codes and symptoms they find and there's a good chance we'll get rid of your cluster lights for much cheaper. Or get the codes read for free at autozone - last time I was there they offered a printout with the codes.

[tpjockey]

More data - Drove to Boone, NC over the weekend. Gassed up with the engine warm and ambient temp about 75 F. Expected multiple engine start attempts but presumed no more than 5-6 based on past experience. After probably 12 start attempts, still no-go. Also, in prior hard starting episodes, the sound of the engine cranking was accompanied by muffled mild detonation sounds (at least that is what I assumed was making that sound). Sounded kinda like what mildly slapping the side of a RubberMaid trash can with an open palm would sound like. But in this case, it was solely the sound of the engine cranking. Started spacing out my start attempts in 10 minute intervals. Finally after about 45 minutes, the engine started up.

So, a couple of things: Engine temp or under-the-hood temp certainly seems to be a factor. When cold, the engine has never exhibited the slightest hesitation to fire right up. Also, the elevation for Boone is around 3100 feet. The elevation in my home town is around 450 feet. So maybe the somewhat thinner air in Boone aggravated my problem?

Something that has never changed is that once running, the engine has never stalled or even given the slightest indication that it might stall. All the power is there all the time when the engine is running.

It'll go back to the shop on Tuesday. I will ask for a print out of the codes and also for the codes that caused them to suspect and replace the cam & crank sensors and include in my next update.

[tpjockey]

I just looked back through the posts and see that I had not answered all the questions asked. My bad. After all, you all are kindly giving of your time to help me out here. My apologies.

The battery: It's an Infiniti dealership battery. It says it's an 84 month battery but I don't see where the month and year parts of the battery's label were marked. I checked the CarFax that I have for this car and don't see anything about a battery replacement. Clearly, It cannot be the original battery, right? Per CarFax, this car was last serviced by an Infiniti dealership in Feb 2015 where (at a recorded 76,458 miles a "3,750 mile service was performed" ? ? ? Typo I guess. Prior to that it saw the same Infiniti dealership in Nov 2013 where only "Vehicle serviced" shows up. Have to go back to Dec 2010 for the next record of an Infiniti dealership servicing.

Meanwhile the battery post connections look clean and good and, with all those starting attempts in Boone, NC, there wasn't the slightest indication that the battery showed any reduction in power.

[tpjockey]

For all who have responded to my posting, many thanks. To date, here's what I know - the OBD code that has repeatedly come up I am told is P0340. My local mechanic says that this code implicates the cam sensors (one or both I'm not sure) as the problem. However, the two cam sensors and the crank sensor were originally replaced with after-market parts without any change in engine behavior. The local mechanics then replaced all three after-market sensors with OEM Nissan parts, again without any change in engine behavior. With the code P0340 again coming up, and the sensors having been replaced twice now, my local mechanic is at a loss to diagnose the cause of my problem.

In order to reach out to a broad an audience as I can for help with determining just why my M45 engine is behaving as it is, I am starting a new post focused on the OBD code P0340. I have titled this new posting as "Need Help with OBD Code P0340: Cam and Crank Sensors Replaced But Engine Problem Persists". If you have any thoughts on where the problem with my engine might lie, please either respond to this posting or the new one.

Again, many thanks for taking your time to consider my problem and offer help.

[Costee]

The culprit is the sensor identified as #3 in EDBwoy's I referred to earlier. It seems you have changed the VTC and crankshaft sensors. Install the crankshaft sensor in #3 and seen what happens. Problem solved. Use OEM.

[tpjockey]

Thanks. That's great info.

BTW, I started a new thread for this same issue entitled:

P0340 Code: Cam & Crank Sensors Replaced - Did not Fix Problem

I did this because when I went to add to the old thread, the website said not enough time had passed since my last posting to add a new one. ? ? ? Odd.

[tpjockey]

The final chapter, (I hope).

So, after my local mechanic replaced "two cam sensors and the crank sensor" twice - first with aftermarket parts and then with OEM Nissan parts, I still had the problem described. So I then went to the Infiniti dearlership in Columbia, SC, d!ck Smith Infiniti. There, they replaced the "crank position sensor", part # 23731-4M50B 23731M, located on the front of the engine on the driver's side below where the "cam" sensors are. (That is the sensor that prior respondents had pointed to, to their credit and I thanks them.) My problem appears to be solved. I went back to my local mechanic to acquaint him with what the Infiniti dealership had done. And here is where things get very interesting. My local mechanic looked up the Nissan OEM part number for the "crank" sensor he had replaced and it was an EXACT match to the one the dealer had replaced! But my local mechanic said the crank sensor he replaced was on the BACKSIDE of the engine, not the front. While I was there, my local mechanic called the local Infiniti dealership, in this case in Augusta, GA, and inquired into why their prior guidance had not identified the sensor on the front of the engine as the "crank" sensor. From what I took from listening in on this call, the M45, at least for the 2008 model, has TWO identical sensors, with IDENTICAL part numbers, associated with this engine, one on the backside of the engine and one on the front side. I can't say for sure but, I'd give this a 95% chance of being correct.

To his credit, my local mechanic told me there was "no charge" associated for the additional work he had done. Still, I had paid for the replacement of two "cam sensors" and one "crank sensor" at aftermarket prices. There were no further charges for replacing these three parts again with OEM NIssan parts. So, I guess, all in all, I have confidence that my problem was solved and maybe also have some new parts on my car that, technically, were never really needed. But, hey, life has its twists and turns. I'm not pissed at my local mechanic. He did his best with honest intent and then did okay by me regarding his charges for his work. I hope this information proves useful to the next M45 owner with a "P0340" error code.

Good luck and thanks again to all who responded to my posting.

[The00Dustin]

I'm sorry you had a rough time, but Costee posted a link to a thread on May 12th that looks to me like it has all of this information with pictures:

BTW, what are VCT sensors? Perhaps that is what was replaced.

See topic607101.html
On a confusing note, you might see the VTC as either cam or crank sensor. What matters is the part number.

I know some things were changed for the 08 model, so did you take that information to your mechanic and find something different?

[paulypotz]

Did you ever try just simple fuel injector cleaner? Long shot but I have intermittent starts and couldn't find the cause. Figured might have something to do with injectors. So far so good, issues are no longer.