I have a 2005 6MT coupe. 4 days ago it took about 3-4 seconds to start, and this is the norm now. The starter sounds like it's working ok, it seems to just struggle to turn over. There is no check engine light. I still took it to Autozone and had them run the OBDII... no codes. I also had them run a starter, alternator, and battery test... it all came back good. I replaced both camshaft sensors today. The problem seems to have gotten worse. I've tried searching our forums, it has gotten me this far. Any ideas of what it could be? Any help is appreciated. **I'm currently trying to reset the ECU by disconnecting the negative terminal to the battery, pumping the brake and waiting 2 hours to reconnect the battery**

 

I haven't experience this personally, but I've heard anything other than OEM engine sensors do not play well with these engines.

How old is the battery? I had an intermittent no-start scenario not too long ago, 8yo battery tested fine and I had full voltage everywhere that mattered, but some forum users smarter than I suspect one of the cells in the battery was failing and I wasn't getting full voltage while cranking. I never tested the theory and just bought a battery, and I haven't had an issue since (and it's been firing stronger than ever).

 

I've read mixed reviews on aftermarket and OEM here, figured I'd give aftermarket a try to save a few bucks. I bought a new battery about 8 months ago. I'm gonna run up and buy a crankshaft sensor as well. It has 185k miles on it. I've put about 90k of those miles on it, and I've never changed those sensors.

 

You'll be playing a game of cat and mouse by buying aftermarket sensors and you'll usually end up as the mouse. I don't know what research you've done but the majority of the forum understands that aftermarket sensors are NOT recommended, it's OEM or bust. Take this advice seriously, Nissan/Infiniti vehicles don't play nice with aftermarket across the brands.

 

I understand this. However, I'm still going to use aftermarket sensors as I've tested them and I know they're functioning properly. Treat this as if I'm using OEM, and help me to look for something I may have missed.

 

You say you understand, but I don't think you understand. MANY people before you have reported issues with aftermarket sensors that went away when they switched to OEM.

You may have missed... all of the evidence telling you the aftermarket sensors are not going to work.

Otherwise, maybe your timing chain skipped a tooth?

 

I've watched videos for 350z, G35 sedan/coupe on youtube, and also visited 350z forums for about 14 hours so far only to see that Non-OEM has worked for more than those who have complained Non-OEM malfunctions. I bought mine from Autozone, tested them and they are within specs of OEM. The fact that nothing has changed tells me I'm missing something and that my old OEM sensors that I replaced were not the culprit.

I just called up to Infiniti, gave them my VIN number and they have told me that my engine has 4 camshaft position sensors. I was under the impression that the VQ35DE only had two camshaft position sensors. Is this different for AT's and MT's? $690 for all four camshaft sensors and $130 for the crankshaft.

Edit: I'm guessing it's the REV-UP has four camshaft position sensors.

 

Correct revup has 4 sensors. Cost $178 a pair, would need 2 pairs. Found them on Amazon

I replaced all 4 a little over a year and a half ago with Denso ones from rock auto. One died after 11 months and another died last week. Should've just gotten OEM the first time around.

 

I appreciate the link. I've installed all the Autozone ones. When I press the accelerator all the way down...it feels faster than it ever has before for a second, then it starts to stutter. I'm gonna bite the bullet and go OEM to see if it fixes.

Did you experience the same problems when your sensors started to malfunction?

 

Ok... here's an update. I've installed OEM throttle body, OEM camshaft position sensor x4, OEM crankshaft sensor. I've performed an ECU reset, accelerator pedal release learning, throttle closed position learning, and idle air volume learning. Nothing has changed except now I have ABS, SLIP, and VDC lights illuminated. The vehicle still takes about 3-5 seconds to start and the throttle hesitates and gets sluggish around 3000 - 4000 rpms. Still no CEL.

Note:
I've also installed Whiteline bushings for: front upper control arm, front lower control arm, compression rods (radius rods), and differential. Changed out differential fluid. Installed a new PVC valve and cleaned the MAF sensor. Anyone have any good guesses or next step... I throwing parts at the car at this point hoping for a fix.

 

Take it to the dealer let them do diagnostic?

 

 

Did you clean the MAF sensor with electronics cleaner? I've read using std brake clean or similar can leave residue that will damage the sensor. I've never experience this myself, but I used electronics cleaner when I cleaned mine.

 

You really need to have a scanner hooked up and check for "pending" codes while the car is acting funny. If you dropped $600+ on new OEM sensor, then you should be able to spring for a cheap Bluetooth OBDII dongle and $10 for the NDSII app on your phone. My car would "stutter" then seem like it was missing torque, that's when I noticed the "pending" sensor codes, but no check engine light. They would clear up the next time I started the car, then come back later. While the code is pending, I was able to monitor that the intake cams were no longer being advanced like they should, hence my lack of torque. My starter also finally gave out, and I noticed in the FSM that the starter was one of several causes of the code I was getting. *facepalm*

The ABS, SLIP, and VDC lights could be something as simple as not plugging in a sensor correctly when you did all of that suspension work.

I got bored and looked at the FSM Symptom Matrix Chart under both "Hard/No Start" and "Hesitation/Surging/Flat Spot" to see if there was something in common for both of those. The FSM lists components to check, and gives them an order (like check this first, that seconds, etc).

#1 for both of these is the battery and generator circuit.

Going down the list of #1 and 2 overlap, other things to check "first" are:
Fuel pump circuit
Fuel injector
Electric throttle control actuator
Ignition Circuit
MAF circuit
Engine coolant temp circuit
O2 sensor 1 circuit

Again, that list is only things that have a 1 or 2 on both symptoms. So for example, crankshaft sensor is a #2 for slow/no start, but isn't even checked for hesitation issues.

Depending on how old your battery is, I'd just replace it and also have your alternator checked.

 

@g56sp
I cleaned the MAF sensor with a cleaner specifically formulated for cleaning MAF sensors.

@LoSt180
I'm a college student with frustration forcing me into running through credit cards to fix this. I bought one of those OBDII a while back and it didn't work Bluetooth... I have an iPhone and recently heard BT ones don't work with iPhones. I'll look for a WiFi one and give it a shot... the BT one drained my battery when I had it.

I'll check the the two sensors on the Diff and the speed sensors on the hubs of the front in the morning.

Fuel pump circuit - Haven't Checked/ will look at the FSM
Fuel injector - Haven't Checked/ will look at the FSM
Electric throttle control actuator - cleaned old TB, no change/ installed new TB, no change
Ignition Circuit - Haven't Checked/ will look at the FSM
MAF circuit - Cleaned MAF sensor with cleaner, no change
Engine coolant temp circuit - Haven't Checked/ will look at the FSM
O2 sensor 1 circuit - Haven't Checked/ will look at the FSM

You're the man and a person that makes this site awesome. Hopefully I can share my solution with others once this is fixed. I really appreciate you taking the time to look through the FSM for me. Classes start tomorrow at noon, I'll try some tonight and in the morning to tackle the items you listed and report back. I'm not gonna purchase any more parts. If I can't identify the problem by inspection or evaluating a simple circuit with a multimeter... I'm gonna pull the trigger on the $128 Nissan diagnostic. It's amazing how many post are on this site and 350z sites for this exact problem with no solution.