I'm back and made improvements, but have more questions

[98_Q45]

So since the last time I've been on the board and shared my loss of hope...I've still decided to keep the Q, reach deep inside and make some improvements. Since then, I've made 2 major discoveries. I had to vacuum leaks, the main one coming from the intake manifold gasket and another for some thing adjacent to the EGR valve. I also replaced all 8 injectors and fuel pressure regulator. The engine runs Soooo much smoother, no more erratic idle or stalling and backfiring. Also tweaked the N idle speed to just at factory spec of 650 rpm (couldn't see numbers, just went by the tach and how it sounds happier on cold starts).

Also painted my calipers (rears went bad, figured I'd rust proof the fronts this time)...I want this as my repaint body color instead of the pearl tan factory color. My car was always a gold color, but THIS is a gold colour i was looking for lol.

However: 2 things I still can't figure out: engine still cranks and won't start readily once warmed up, unless done within 5 minutes. It used to be 30 minutes. Now it's not even 15 minutes. It'll crank fine first thing in morning, but not on hot start. Flooring pedal helps it turn over, but still lags. I hoped it was injectors/ pressure regulator. Injectors only got rid of the fuel smell coming into the cabin. When it finally does start, the RPMs drop to almost 0, before catching to normal idle. I know throttle body dirty can cause that, but I've tried that already.

I'm thinking nothing else is left except the fuel pump. Did the filter already. No avail. But before changing the fuel pump, how can I rule it out? Codes show evap purge P1447 (found a plastic tube behind charcoal canister in the rear (California model) that was gummed shut with some kind of hardened black substance, removed it) oxygen sensor code (fixed some torn wiring, and did crankshaft sensor while I was at it) And bank 2 P0174 too lean. Maybe those were stored codes from bad injectors and vacuum leak, but the starting issue still persists.

I want to take it to my mechanic for diagnosis, but nobody is getting this s*** right. I don't want them tinkering around and pulling spark plugs when it's not necessary because I already did that too...and it didn't help. So if fuel pump, anyone done it? Drop tank? Where's the access door?

2nd question: can't figure why the airbag light won't stop blinking. Had it turned off last year by Infiniti themselves. Came back on couple months ago

[Ludeaem]

If you ever find out the long crank after warm issue be sure to make a post. As I've mentioned in a previous post I have the same issue but the remedy is just to turn the key to ACC and wait until the 'brake' light comes on in the dash and it starts as it should.

My advice, just do that unless you want to dump hundreds, if not thousands of $ into this 20+ year old car. Some things you just have to deal with and be glad its road worthy. You won't win every battle. Deep breath man

[98_Q45]

If you ever find out the long crank after warm issue be sure to make a post. As I've mentioned in a previous post I have the same issue but the remedy is just to turn the key to ACC and wait until the 'brake' light comes on in the dash and it starts as it should.

My advice, just do that unless you want to dump hundreds, if not thousands of $ into this 20+ year old car. Some things you just have to deal with and be glad its road worthy. You won't win every battle. Deep breath man

Thanks bud..however I have tried that, no avail. Even turning the key on and off to “prime it” hasn’t helped either. I hear the fuel pump slightly when turning the key though. It doesn’t look as easy of a job as I imagined, so I’m hoping that if I go that route, that’s the fix. Can’t be much harder than removing the 8 injectors lol.

Unfortunately I can’t deal with how’s it doing, because every stop at the store or elsewhere turns into steady cranking. I don’t want to burn out my starter for a 2nd time either, as that’s always a $500 repair I want to avoid

[VStar650CL]

Don't know if you've ever put a crank sensor in it, but that's the most likely culprit for a long crank with no codes. When those sensors get magnetically-weak, they become bouncy or flatline at low RPM (cranking) but normalize as soon as the engine fires and the extra RPM increases reluctance. That problem will tend to worsen when the sensor is warm, especially when the sensor sits on a "cooking" engine with no airflow for about 30 minutes. The ECM will hold off firing when it sees an erratic crank signal, but after about 5 seconds it will say the heck with it and start on the cams alone. Because the crank signal recovers immediately when it fires, you get no codes.

As for the airbag, once the ACU throws a code, it will remember it forever even if the code goes "past". ACU codes don't clear after a certain number of cycles with no error like engine or transmission codes. So you need to get the codes read and find out what it saw. On a vehicle that old, there's a good chance you'll find driver airbag "open" codes. They may be "past", but clearing them won't help because it won't be the airbag that's at fault. It will be your aged spiral cable causing the issue, and if so, they'll keep recurring till you replace the spiral.

[98_Q45]

Don't know if you've ever put a crank sensor in it, but that's the most likely culprit for a long crank with no codes. When those sensors get magnetically-weak, they become bouncy or flatline at low RPM (cranking) but normalize as soon as the engine fires and the extra RPM increases reluctance. That problem will tend to worsen when the sensor is warm, especially when the sensor sits on a "cooking" engine with no airflow for about 30 minutes. The ECM will hold off firing when it sees an erratic crank signal, but after about 5 seconds it will say the heck with it and start on the cams alone. Because the crank signal recovers immediately when it fires, you get no codes.

As for the airbag, once the ACU throws a code, it will remember it forever even if the code goes "past". ACU codes don't clear after a certain number of cycles with no error like engine or transmission codes. So you need to get the codes read and find out what it saw. On a vehicle that old, there's a good chance you'll find driver airbag "open" codes. They may be "past", but clearing them won't help because it won't be the airbag that's at fault. It will be your aged spiral cable causing the issue, and if so, they'll keep recurring till you replace the spiral.

Yeah i mentioned earlier i replaced the crankshaft sensor (one under the engine not far from the passengers side oxygen sensor) on my last oil change, it didn't fix it. Now if you refer to camshaft sensor on the front near the air intake, i didn't do that. And that is an expensive part.

It's frustrating as hell because before... it would cure it when i changed the oil and filter, then it would help when i added seafoam to the oil, and also changed pcv valves (did it twice to rule out defective ones since they're only $4). All would help for a 1,000 or 2 miles, and come back after a long road trip (the Q has been my road trip car since I brought it 3 years ago).

Also, this just started happening a year ago. It's just gotten more progressive over the months. Non of the above tricks are working anymore. Based on what you're saying, do you think it could be camshaft sensor instead?

[VStar650CL]

Possibly, yes. Check the quality of your grounds, too. As little as 50 millivolts (0.05V) can make Hall sensors misread and fail. Use a voltage drop test to check dynamically, both from the negative-post to the block and negative post to the sensor ground pins (backprobe the connectors). To run the test, put your VOM on the lowest voltage scale and start the engine, and put the common probe on the negative post (not the lug, the post). Put the red probe anyplace on the block. Anything above 0.05V and your ground cable is corroded someplace. Then measure to the backprobes in the sensors, if they're much higher than the reading at the block then the individual sensor grounds are crappy.

[98_Q45]

Possibly, yes. Check the quality of your grounds, too. As little as 50 millivolts (0.05V) can make Hall sensors misread and fail. Use a voltage drop test to check dynamically, both from the negative-post to the block and negative post to the sensor ground pins (backprobe the connectors). To run the test, put your VOM on the lowest voltage scale and start the engine, and put the common probe on the negative post (not the lug, the post). Put the red probe anyplace on the block. Anything above 0.05V and your ground cable is corroded someplace. Then measure to the backprobes in the sensors, if they're much higher than the reading at the block then the individual sensor grounds are crappy.

You lost me here...I don’t really have those type of testers. When you say bad ground, you refer to the sensor or the engine as a whole?

Going back to the airbag, I did replace the spiral cable couple years ago from used eBay. But when it went bad previously, all the steering button and horn functions stopped working. Right now they all work, but I have noticed some occasional automatic movement from the steering wheel. Few months ago, I had to Re-tighten the steering wheel bolt as it was loose, which involved removing the airbag, but the light didn’t come on until a couple weeks or so after that.

[VStar650CL]

You lost me here...I don’t really have those type of testers. When you say bad ground, you refer to the sensor or the engine as a whole?

Both, and all you need is a common voltmeter, nothing fancy. $8 from Harbor Freight will work fine.

How good a ground any device needs depends on how much current it draws. That's why checking grounds dynamically, with the engine running, tells you much more than an ohmmeter. Coils, for instance, draw a lot, and the ones Nissan uses with built-in transistors react very badly to "soft" grounds, it makes them heat up. This is what the famous "warty" coils come from, as well as the myth that coils fail in groups. They don't. When groups fail, it's invariably from crummy grounds.

The negative battery post is the "ultimate source" for all grounds on the car, so that's what you're measuring relative to. Ohm's Law says the more resistance you have between a device and the negative post, the higher the voltage you'll read between the device and the post. So the reading between the block and the post tells you the relative health of all the connections in between, automatically accounting for however much current your particular engine consumes. Even a tiny amount of resistance in your main ground cable can cause an unhealthy "soft" ground. 50mV is usually considered to be the healthy limit; applying Ohm's Law to an engine that consumes 10 amps, we get 0.05V / 10A = 0.005 ohms. Five thousandths of an ohm, that's all it takes to give your ECM a headache. That's also why an ohmmeter won't tell you anything meaningful, unless it's a very good meter.

The same principle applies to the thinner wires and connections that carry ground to the sensors, so checking them is important when looking at sensor issues. We had a Murano in the shop some years back that had "eaten" the original crank sensor and two replacements in the space of 18 months. The ground finally got checked when the owner started screaming, and we found 63mV between the connector and the block. The small wire connecting the sensor to the block had gone south and was blowing up the output transistors in the sensors. That sensor was only drawing about 12 milliamps, so a measly 5 ohms in the small wire was all it took to blow it. The car was out of warranty, so we spliced a shorter wire direct to the transmission housing. It never had another problem. Lesson learned.

[98_Q45]

You lost me here...I don’t really have those type of testers. When you say bad ground, you refer to the sensor or the engine as a whole?

Both, and all you need is a common voltmeter, nothing fancy. $8 from Harbor Freight will work fine.

How good a ground any device needs depends on how much current it draws. That's why checking grounds dynamically, with the engine running, tells you much more than an ohmmeter. Coils, for instance, draw a lot, and the ones Nissan uses with built-in transistors react very badly to "soft" grounds, it makes them heat up. This is what the famous "warty" coils come from, as well as the myth that coils fail in groups. They don't. When groups fail, it's invariably from crummy grounds.

The negative battery post is the "ultimate source" for all grounds on the car, so that's what you're measuring relative to. Ohm's Law says the more resistance you have between a device and the negative post, the higher the voltage you'll read between the device and the post. So the reading between the block and the post tells you the relative health of all the connections in between, automatically accounting for however much current your particular engine consumes. Even a tiny amount of resistance in your main ground cable can cause an unhealthy "soft" ground. 50mV is usually considered to be the healthy limit; applying Ohm's Law to an engine that consumes 10 amps, we get 0.05V / 10A = 0.005 ohms. Five thousandths of an ohm, that's all it takes to give your ECM a headache. That's also why an ohmmeter won't tell you anything meaningful, unless it's a very good meter.

The same principle applies to the thinner wires and connections that carry ground to the sensors, so checking them is important when looking at sensor issues. We had a Murano in the shop some years back that had "eaten" the original crank sensor and two replacements in the space of 18 months. The ground finally got checked when the owner started screaming, and we found 63mV between the connector and the block. The small wire connecting the sensor to the block had gone south and was blowing up the output transistors in the sensors. That sensor was only drawing about 12 milliamps, so a measly 5 ohms in the small wire was all it took to blow it. The car was out of warranty, so we spliced a shorter wire direct to the transmission housing. It never had another problem. Lesson learned.

Wow, that’s still pretty technical for me lol. I’m just not versed on electric stuff. Most of my diagnosis have been straightforward stuff, and I’ve not needed those things. But what you’re saying is certainly pointing me in the right direction. At this point, I don’t think it’s the fuel pump after all. Like I say, I replaced the crankshaft sensor... but didn’t help.

I’ve also replaced both coolant temp switches, didn’t help either. I know it’s stupid to throw parts at it, but there’s just so much information out there that says, “this part going bad will cause hard starting” and I change it, but doesn’t help. I’ve also spent time going to mechanics to diagnose stuff, and they’ve gotten it wrong too (not this particular issue though)....

I think it also goes to show how hardy 90s Maxima and Infiniti’s are. A lot of stuff just doesn’t go bad. Even the fuel pressure regulator which I was positive was the issue... didn’t seem to have a problem with fuel in the vacuum lines. So obviously there’s got to be something obvious that I’m not catching. I’m going to pull the camshaft sensor and it’s wiring, and take a look.

[Macnalty]

Great explanation on grounding and how to test for ground, it's worth your time learning this, it is simple and easy to do, your future self will thank you for taking the time to figure this out.

[98_Q45]

Great explanation on grounding and how to test for ground, it's worth your time learning this, it is simple and easy to do, your future self will thank you for taking the time to figure this out.

It is, but only if one knows what part to test on.

[Macnalty]

I agree it seems daunting now, the light will come on for you soon we all go through a learning curve like you are experiencing now, the trick is to stick with it. I think everyone would agree you are already doing things that are much more complicated.

[98_Q45]

I agree it seems daunting now, the light will come on for you soon we all go through a learning curve like you are experiencing now, the trick is to stick with it. I think everyone would agree you are already doing things that are much more complicated.

Yeah, I think I may have to consult one of my mechanics on this one. But that’s going to involve setting an appointment, and spending MORE money. s*** that I already f*** did last week: $136 labor at one place for power steering pump, and $180 for all rear brakes+calipers at another. I just wish the s*** would just work lol. I’ve been maintaining it meticulously, obviously just wear and tear and previous ownership demons lol.

But It’s just too many variables, and I’ve already exhausted my guesses. Now I think it may be the coils or a coil going bad based on research. But I’d have to get someone to test for spark. At this point, it’s got to be either the camshaft sensor, fuel pump (perhaps not holding fuel pressure when hot), or the ignition coils (replaced the boots and plugs already).

I’m glad I fixed the idle and vacuum leaks along with the fuel vapors in the engine. But this starting issue has been plaguing me for over a year on and off...and now it’s just gotten worse. I need it figured out ASAP. I usually have only about 10 minutes or less to restart the car, before it just doesn’t want to start at all. And even when it restarts moment after shutting off, the tach will almost drop to 0, and then sputter back to normal. Sometimes it’ll just drop to 0 and fail unless I give it gas. I know that a throttle body cleaning has solved the dropping RPM in the past, but it doesn’t help the extended cranking issue.

Does this give anyone a clue?

[98_Q45]

So I pulled the camshaft sensor just to take a look and get to figure it out. Had a hell of a time getting back in though. Finally got it when I took off the plastic cap and installed it. It has to line up and it's almost impossible to do with the cap on. About as irritating as the oil pressure sensor and a/c lines leading to the expansion valve, ugh.

Anyhow, I don't have a new one on hand (idk why the f*** they're so goddamn expensive to begin with)...But i did notice 2 failing gaskets: the outer one was pushing out and the inner o ring cracked when removing it. So i put a new o ring and liquid gasket around the outside. I also seafoamed the cam sensor itself where it meets the oil. The FSM states it's a pretty high tech unit: has a camera and of course spins with the crankshaft itself. Hence why so expensive.

Haven't started or drove it yet as waiting for gasket to cure. But I just don't know if the unit needs replacing just by looking at it. But it seems to make sense why the problem would go away for awhile after oil changes: its sitting there in the engine getting gummed up. There was a lot of oily gunk in the area, but not sludge. Changed oil while I was at it though. Counting my lucky stars that it'll lead me to the right fix.