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Two starting problems- related?

I drive a 2001 Nissan Sentra. Last summer it had a problem with dying randomly when I was driving. This turned out to be caused by the oxygen sensor, which there was a recall for. I got it fixed and didn’t have any problems with that until now.

About a month ago it started having trouble starting, but only after I had been driving it within the last few hours. For example, it might have trouble restarting after a 15-min run inside the bank, but won’t have any trouble starting first thing in the morning, after it had been sitting still all night. It hadn’t happened in almost a week, but that might just be coincidence.

Then just today, it died out several times while I was in very slow traffic. I pulled over and restarted it, but was unable to idle long enough to get a chance to merge back into the flow of traffic. It stalled again and wouldn’t restart until I waited 15 minutes before trying to crank it again. Almost the exact same thing happened during my oxygen sensor saga, except that back then it would die out in any traffic conditions, not just when it was slow.

So, what’s causing these two new problems, and are they related?

It might also matter that I had just about 1/8th of a tank of gas this morning.

My guess is they are not related problems and you have a new issue. A good mechanic will find the problem, could be a failing fuel pump even.

This could be a problem with the cam position sensor. If this sensor fails, the PCM does not know when to fire the spark plugs. It is a LED optical device that might well be subject to intermittant heat related failure.

Lots of Luck on this.

There are a very large number of possible causes for the problems you describe. But there is good news, you have a newer model car, and it has codes. Take it to a parts store, and have them check to see what codes the on board computer is displaying, this is the first step in the diagnosis of your problem. Intermittant problems are the hardest to find, because they refuse to present themselves to the mechanic, we used to call them gremlins until the movie of the same name ruined the reputation of gremlins, oh, and yeah the car of the same name too did not do the reputation of real gremlins any good, but then I guess gremlins never really had a good rep to being with did they?

Ignoramus’ moniker may be incorrect, but his post is spot-on. The codes are a great place to start.

For the record, there are a number of possibilities. One comes to my mind…the fuel pump. The reason I’m wondering about that is your comment that you had 1/8 of a tank of gas left. Do you do this often?

Thanks, everyone! I wish I had thought to check this thread again before I took it in again today.

I took it to the dealer and for $200 they changed the oil and took care of both problems. I think they turned up the idle. Problem is that they didn’t fix either of the things wrong with it. It died out twice while I was driving from the dealership to work and twice when I was out for lunch. It also had difficulty restarting.

I called up the dealer and the person I talked to spoke with their boss and will be fixing it again at no additional charge. Weirdly, the problem of randomly dying out hasn’t happened since the day that they last tried to fix it, but the starting problem has persisted.

IIRC, I had plenty of gas in the car a couple of the times that it stalled out. I had forgotten about the fuel pump thing, but today I suggested that it might be the oxygen sensor again. When the oxygen sensor had been going bad last summer, they found it by running a diagnostic on it. That was also found on the second trip there regarding the same problem.

Update: I had it looked at by the dealer and they said that the two problems are (technically) related- According to them, the diagnostic said that the car’s main computer is going bad, which caused both the starter coil to die and the engine to begin malfunctioning. They said the engine is currently running on only three of its four cylinders because of this, and that buying a new ECU will fix this. They replaced the starter coil (for about $115- without asking, I might add. I found other ones on eBay for $25). I won’t be able to afford a new ECU until after I get my tax refund.

When I started it up again, the problem with the starter was gone, but the car was now shaking pretty noticeably. It hadn’t been doing that before. When I got home I looked under the hood and noticed that there was a broken purple wire sticking out of the engine (see pic). Would this have anything to do with anything?

My other questions are:

  1. Someone said I should get a second opinion before sinking at least $430 on a new ECU. Should I?

  2. Am I OK to keep driving this car for at least three more weeks?

  3. Any websites other than eBay where I can get that ECU for cheaper? I already have a coworker’s husband checking the local places for me.

  4. Will a new ECU really fix everything? Thanks.

Definitely get a second opinion. IMHO you need a whole new shop to look at it. Turning up the idle speed is not a “fix”. As you discovered, it does not correct the real cause of the problem. It only masks one of the symptoms.

I’m also really uncomfortable with that wire. And the ECU diagnosis. Too often that’s used when the real cause cannot be determined.

That “starter coil” you mentioned, can you be more specific? The only "coil"s involved with the starter would be in the solenoid and the starter relay. While either can become heat sensitive and the symptoms be a failure of the starter to operate when hot, with all the other symptoms you have I have real reservations about this having needed to be done also. A bad solenoid or relay would not affect operation of the engine once it started.

In short, I’d look for a good reputable independently owned and operated shop to diagnose it before going any further. Be sure he has the whole story.

Thanks! The only other truly reputable place on the island would be the Toyota dealer. They once solved something that the Nissan dealer plus a (crappy) independent mechanic couldn’t figure out. Only problem was that after they figured out what was wrong, they sent me back to the Nissan dealer to get the problem fixed, because only they had the right parts and had Nissan-specific knowledge. I guess I’ll try Toyota once I’ve got the money together.

The Nissan dealer left the box for the new starter coil in my car (shows just how professional they are). The label says “COIL-IGNITION.” Inside the box was what I’m guessing is the old coil. Pics below. I can give you the serial numbers on them if you want.

It would be nice to find out where that wire is supposed to go. It is strangely located near that ignition coil. Suspicious location.

I’m not totally sure where the ignition coil is, but I decided that the pic that I posted of that loose wire makes it look a bit bigger than it actually is and to some extent looks like it’s nearly connected to something that’s actually in the background, so I took another one from a more overhead angle. I’d definitely say that the loose purple wire is supposed to go into that bundle of electrical tape that the green and yellow wires are coming out of. All this is on top of the engine. Problem is, I have no idea what this wire does or if it’s important.

Also, I’m not 100% sure, but I think I have a vague memory of that wire or a similar one being that way before all of this started.

Actually, leaving the old parts in a box in the car is good professional practice. Some states require it. Parts to be returned for core credit are shown to the customer before returning them.

That wire still bothers me. Is it possible to get a wider angle view to see what that connector’s adjoining locations are?

I guess you’re right about the parts. I guess I was just annoyed because I thought it was just an empty box right up until the moment before I made the post. I’ve had a lot of problems with mechanics here leaving trash in my car, often things that have nothing to do with repairing it.

The place I took it to today kinda-sorta reconnected the wire (see the next post below), but I can take another picture of the area if you want.

UPDATE: It was getting worse on the drive home (shaking increased and the Check Engine light went from being on to flashing), so I decided to take it to the Toyota dealership that I mentioned as soon as they opened today. They told me that they couldn’t run a diagnostic on a non-Toyota, but offered to take a look at that stray wire coming out of the newly replaced starter coil. He hooked it back up to the bundle of wires underneath the electrical tape that I had earlier assumed that it’s supposed to be hooked up to. He also plugged back in something right behind it that I hadn’t noticed was there or unplugged. He has me start the car and it immediately STARTS BILLOWING SMOKE and giving off a burning oil smell. I shut it off and he unplugs the starter coil, rather than re-undoing the wiring to it.

He recommends me an independent mechanic that also runs diagnostics. I take it there, and he looks a heck of a lot like a Samoan version of Tom. He takes one look under the hood and does a double-take at the wiring. Apparently someone, I’m guessing the Nissan dealership because they mentioned doing wiring work, rewired something to make it bypass something else. He agreed with Mountainbike’s assessment that it probably isn’t the ECU. But he also said that in order to run a proper diagnostic, he’s going to have to put a lot of the wiring back the way it originally was, and to bring it back on Monday for that.

I’ll be happy to take and post more pictures if anyone needs them. Thanks!

UPDATE: I took it too a different independent mechanic. He reacted about the same way as the other independent guy to the wiring. He discovered that the starter coil in question has been rewired to get its power from the airflow instead of its usual source. He also happened to notice that one wire was very close to shorting out the alternator and the whole car with it (it hasn’t happened yet because of a thin piece of rubber over the wire).

Today he called back and told me that he just couldn’t figure out where all the wires are supposed to go without a schematic or something similar. He also suggested that it might help if I get a printout of the diagnostic reading that the dealer took. He hasn’t yet actually done anything with the car, because he doesn’t know where the wires belong.

So, does anyone know where I can get a schematic for a 2001 Nissan Sentra? Thanks.

Sorry I’ve not been responding. I’ve been offline for a bit.

You can get a schematic off the internet or a Haynes Repair manual from the parts store will have one. You may have to purchase it. Your Nissan dealer should be happy to print you one also.

The smoke…was that black? I’m wondering if it was blowing too much fuel into the cylinders and that was causing your smoke cloud. That would suggest that the stray wire should have been connected to one of the sensors that regulate fuel metering. A significant input would be a manifold absolute pressures sensor or an oxygen sensor.

The coil in your photo is a coil-on-plug ignition coil. One is mounted on each spark plug and fires the individual plug upon command. The igniter determines when each plug fires.

Another theory is that conecting that wire effectively weakened that spark plug and the smoke cloud was excess fuel that got partially burned up in the cylinder but not properly burned. It’s possible that the wire provided a parallel circuit with enough resistance to not provide a complete short.

A longshot is that the coil is the incorrect part number. Perhaps the shop didn;t have the correct one in stock and used one that fit but had an extra wire. You can verify whether it’s correct or not by comparing the part number to a parts list at the parts store.

Guys, anybody else got any other wild theories?

I’m surprized your shop doesn’t have an online subscription to a repair database, like Alldata or Mitchell’s.

I’m also surprized the Toyota dealership wouldn;t work on it. Normally they’ll work on any make or model (exotics excepted).

BIG update: It wasn’t fixed yet, but the guy who had been working on it allowed me to have it back for the three-day weekend we have here. He said that I wouldn’t be able to take it much over 20 MPH. I interpreted this to mean that it was incapable of going that fast, but he may have meant that I shouldn’t take it to any speed higher than that.

On the way to work, I took it up to 30 MPH to pass someone and the throttle stuck just a little bit, like at about 5 MPH. Wouldn’t have been so bad, except that it was sold stop-and-go traffic for the next mile or so, with no place to pull over. I finally found a place, stopped the engine and looked under the hood. The new ignition coil had been switched with the older one to its left. It all seemed a little hotter than it should have been, but nothing looked to horribly wrong. I left it cool off a little, started it back up, took it the rest of the way to work, getting out of the bad traffic pretty soon.

When I got to the parking lot of my workplace, it seemed as if the throttle-sticking problem was gone entirely. I drove it around in a few circles to see if it was, and I had just determined that it was going about 2 MPH on it’s own when I saw smoke billowing out of the hood. I stopped it, opened the hood and found that the ignition coil that had been switched into the trouble spot was ON FIRE!I quickly blew it out and took care of the smoldering bits around it with water (leaving the engine and power off, of course). One of my coworkers guessed that it was probably caused by a short circuit, and I’m inclined to agree with him.

I’m going to have it towed back to the mechanic after this. If I were anywhere else in the world, I’d be selling this car to a junkyard and buying a new one. But cars here in American Samoa are outrageously expensive. Pics below. I don’t think anything other than the ignition coil and the cloth-like covering on the underside of the hood were damaged.

Here are some photos of the aftermath:

I was able to find them online with some help. I’ve found that the trick is to search for the service manual.

The smoke was grey, just a little bit lighter than it was today when that ignition coil was burning. I’m guessing now that it was a short circuit of some sort. I know that the mechanic had unplugged something, I want to say a spark plug or the starter coil. Maybe today’s problems were caused by the unplugged part managing to touch and cause a short circuit.

American Samoa? Capt., sincere thanks for your service. Your location explains a lot.

I’m wondering of that coil is a different part number with a different connector wiring scheme and the shop butchered it to try to make it work. The unsuccessful attempt to connect the loose wire to the other loose end and that test’s results suggests my theory highly. I’m going to suggest that you order (if need be) a Haynes repair manual and look into the ignition system wiring. While waiting for the manual to arrive, compare the new coil’s part number to the other coils. They should be the same. Then compare the wiring, using a multimeter. I suspect that you’ll find the wiring on that coil is different.

You’ll need to replace the connector as well as the coil. I’d suggest verifying the wiring plan before doing so. I would not wire in a new connector the same way as the current one is wired, nor would I use the same part number of coil without verifying its correctness.

If any of my cohorts-in-crime out there has a susbscription and access to the ignition wiring diagrams, I know the OP and I would be appreciative to know what the wiring scheme on the coil should be.

I’m actually not in the military, if that’s what you mean by my service, although there are a lot of military personnel living here. But yeah, being in American Samoa makes a lot of difference. I just now realized that I hadn’t directly mentioned that yet.

I managed to find the complete official Nissan service manual on, which includes all of the wiring diagrams. Does that manual include the values for each wire? The mechanic said he would need to know them before he could fix it.

You’re theory about why they rewired it is probably right. The new coil looks completely different from the other ones (you can tell in some of the pics), and the new mechanic mentioned that it could be a possibility. The coil that was fried today was probably toasted because it was getting the higher amount of voltage intended for the new coil via the rewiring.

Now here’s a bit of an ethical question: Should I ask the dealer for all of my money back? To recap: I originally paid them $200 to change the oil and fix my original problems with stalling randomly and problems with starting. After quickly discovering that none of the original problems had been fixed, I took it back and they agreed that I wouldn’t be charged a second time for them to try it again, only for new parts. This was when they installed the questionable coil and did all the crazy rewiring to make it fit. This time, I only had to pay about $115 for the new coil.

I’m thinking that I should definitely be refunded the $200 and then be refunded the $115 if it turns out that the new coil is the wrong part, which it probably is.