I have a 1990 Sentra, four door, about 330K KM (not miles). It has the 1.6 L engine (I think -- I am not mechanically minded).
The car was driving great, other than the usual maintenance and little rattles you would expect from a car that age. Next to no rust because for 11 years of its life it was parked indoors, and I had hoped to get at least one more summer out of it.
Then, in May, it stalled and died. I am miles from a dealer here. A local mechanic said as best he could tell, the onboard computer under the front passenger seat had died. So he put in a used one. The car ran fine.
A month and a half later, the same thing happened, but by this time that mechanic was out of business. (Through no fault of his own, BTW, he had been in business for over 20 years and wasn't fly-by-night.)
I went to another guy, who said it was the computer again. He put in another used one, which took two weeks to find, arrive, and install. (I'm not in the city.)
In less than 3 days, the car died again. (I had it Friday and Saturday, and it died again on Sunday) It just stalls out while in motion, never to move again. But apparently if you stick in another computer, it starts up in a flash and runs until -- whatever. I would like to know what "whatever" might be, since these local guys have little or no Nissan or "import" experience.
(It had died once before this mess, but that turned out to be a loose wire to the fuel pump.)
The second mechanic said that he had checked for shorts and could find none, and said that the thingamajig for the fuel injector was fine. (Don't ask me. A sensor, I think)
Each time, this happened when the car was driving at a low speed, in town, after coming off a highway. (Each day was sunny and warm, if that matters too.) Prior to it happening, it seemed like the engine for a microsecond here and there wasn't getting gas. The engine smelled a bit gassy too, but I figured it was just because it was an old car. I found it to be idling a bit rough too, but I figured it just need a tune-up and when you have a 15 year old car you don't worry much about rough idling.
I should also add that the left turn signal acts up -- works sometimes, sometimes it doesn't, and it isn't the bulb. The CD player (an add-on) was buzzing a bit too. Reading some of the posts on this forum, it strikes me that the older Sentras seem to run into inexplicable electrical problems.
I have owned this car since it was almost new -- 5K km when I bought it -- and have maintained it with the usual fluid changes, etc.
Will give it one last shot for this summer if it is cheap,
hmm...my guess is one way or another you're getting a short somewhere. and no matter how good a mechanic is shorts are hard to find. another guess is somehow the computer is getting wet. my pulsar had a hole in the floor and i went through a water puddle and that was that. obviously this isn't that...but maybe if the heater leaked or something it could be possible.
__________________ Student at UTI Avondale 2nd place SkillsUSA/VICA WA State Automotive Maintenence '04 had an 87 pulsar...still planning CA20DET
1970 Chevy BelAir 350V8 300hp...soon to get M21
hmm...my guess is one way or another you're getting a short somewhere. and no matter how good a mechanic is shorts are hard to find. another guess is somehow the computer is getting wet. my pulsar had a hole in the floor and i went through a water puddle and that was that. obviously this isn't that...but maybe if the heater leaked or something it could be possible.
Hi,
Thanks for the suggestions.
We've had a pretty wet spring but each of these 3 events happened on a warm sunny day. Presumably, if water got at it, it would short when the water hit it and not later? I suppose water gets on the floor from wet shoes, but I had the car for many, many years with water and slush and road salt and God knows what all getting into the passenger seat area. I live on the coast in eastern Canada, and sometimes the rain or fog blows through the door sideways when someone gets in. One assumes these units are designed for such things. And what if someone shampoos the carpets -- which I have also done.
Not sure what you mean by the heater. This unit is attached underneath the front passenger seat, not in the dash.
What would be the most likely source of a short? The fuel pump? Why wouldn't a unit like this be grounded in some way to protect itself from such a short, since part of its function is to tell you what part of the car is screwing up?
The car does have AC, the retrofitted thing that uses the newer gas system. That was actually put in by a Nissan dealer, not just some guy. It is in need of some topping up, which I was going to do prior to this happening. I mention this because I understand some later Sentras have AC problems that can screw up the computer device.
When emptying the car, I noticed some water in the trunk. The seal must be a little off, or it could be from opening the trunk in a downpour. But I can't see how that would affect the unit in the front.
well a little water usually won't hurt...it has to get soaked enough for the water to work into the connectors. Reason i mention heater is cause heater uses the engine coolant, and if the heater unit leaks the first place it goes is the passenger floor panel. You'd know it if it was though. As for grounding yes they are grounded well but for this age of a car you can expect some corrosion in different places which can cause a bad ground or with a hot wire can cause an intermitent short.
__________________ Student at UTI Avondale 2nd place SkillsUSA/VICA WA State Automotive Maintenence '04 had an 87 pulsar...still planning CA20DET
1970 Chevy BelAir 350V8 300hp...soon to get M21
I should have mentioned that prior to the last two failures it had a new starter and a new battery installed. I had assumed -- perhaps incorrectly -- that these were not relevant to the situation because failure #1 was identical to the other two and no such work had been done prior to that event.
But failure #2 did happen only a few days after the new battery/starter work (but a month and a half after failure #1), and in fact mechanic #1 had also slightly moved ECU #2 (of 3) because it had just been sitting on the floor under the seat and I wanted it back into its bracket with the little plate in the front as it should have been. But failure #3 was after mechanic #2 had installed computer #3 under the seat, correctly as best I could tell.
All that said, I can't think of any water getting under there though.
I have a similar problem that I'm trying to track down. The computer is fine, but the car exhibits some of the syptoms you described, such as rough idling when cold, and an extreme loss of power below 2000 RPM or so. So far, I have swapped the distibutor and ECU, but made no progress.
I have an identical car, so sourcing parts to try out and swap is not a problem.
I hope I get to the bottom of this soon, and if I do, i'll let you know aht I found.
By the way, is there a database of the computer codes? I got the computer into diagnostic mode, it flashed 1 long, 2 long, 3 fast, 4 fast, 5 fast. I really dont know how to interpret this, and the sentra.net diagnostic code listing only goes back as far as OBD I (B13 sentra)
I wish that my only problem was rough idling and some loss of power. The computer dies completely.
There must surely be a limited number of things which could affect this primitive device. I read online that for a later Sentra, I think 92, the fuel pump and the AC can cause it to short out. My Sentra does have AC (converted by the Nissan dealer) but I can't see that this on/off form of AC has anything to do with the computer.
The fuel pump might be more likely?? In fact, the car died in the winter and a mechanic found a loose wire to the fuel pump, fixing it somehow. Possibly this is the short? What exactly does this computer control, and what feeds into it that would affect it? I'm still puzzled as to why it would short out and not have some internal device to deal with that kind of problem.
Since it does not short out immediately, does this mean that there is something moving that causes the short when the right bump is hit?
I hate electronic stuff in cars. The 1950s cars in Cuba are still on the road because they don't have to deal with this kind of thing.
By the way, is there a database of the computer codes? I got the computer into diagnostic mode, it flashed 1 long, 2 long, 3 fast, 4 fast, 5 fast. I really dont know how to interpret this, and the sentra.net diagnostic code listing only goes back as far as OBD I (B13 sentra)
That should be very close to your setup if you have a '91, but I don't know, canada got some weird engine/chassis combo's.
I think I have a manual around here somewhere with those codes in it. I'll see if I can find it. IIRC my manual's from England, but I don't trust it because quite often the illustration does not correspond at all with what I see in my own Sentra when I lift the hood.
My car is otherwise in pretty good shape because as I say it was parked indoors for many years, salt kept cleaned off, etc. I'd hate to junk it merely because of some loose wire. I mean, this kind of thing must have happened before, and somewhere there must exist a list of Probable Causes And Usual Suspects. What would a Nissan mechanic do and where would he look first? It still doesn't make sense to me that a short wouldn't blow a fuse somewhere rather than the computer itself. That's why we have fuses. Imagine if your house electricity worked that way.
I doubt a shorted fuel pump would affect your computer. I had the pump go in my first B12 and all it kept doing was blowing the fuel pump fuse. As soon as the fuse was replaced, it would start right back up again.
If your computer is blowing out and keeps going totally bad, it sounds like you have a short on the wiring harness from the computer ? It would be a pain, but you might want to tear your seat out, lift the carpet and follow that harness up through the dash and look for pinched or damaged wiring. check around your engine bay and look for anything that may have rubbed through and could be shorting out.
The mechanic claims that he can find no shorts, and is convinced that both replacement computers were defective. (And presumably the first one, the original, that went in May.) He noted rust on them and thinks they must have got damaged prior to being shipped from the junkyard. Two in such a short period of time sounds rather suspicious to me, and not a coincidence, although if anyone would have such luck it would be me.
Good news is the junkyard gave him $$ credit on the last computer. Bad news is he can't source a replacement. So:
1. He says that he has one for an 89, and one for a 91, Sentra. Mine remember is a 1990. But the plugs for hooking it up are different. Will these work if he changes the hook up thingees, or are they different in more than the way they hook up. I take it he means the jack-like things that plug it in.
2. Where on the Internet is there a reputable source, used by members of this forum, from which I can buy a replacement, shipped by Fedex . Preferably, a Canadian source although I'll consider American if there are no Canadians. (Nothing against Americans. It is Canada that causes the problems -- it is a costly hassle Fedexing such things over the border sometimes.)
Been trying to get around with a Volvo wagon. Today the starter went on it. I can't win . . . time to buy brand, spanking new I think.
even brand new will give you problems. You can try umm... www.partsamerica.com last i knew they had ECU's for most cars...a little expensive but depends on how much you want your car to run i suppose. Just keep looking for people and let it known in the forums that you need an ECU someone is bound to have one somewhere
__________________ Student at UTI Avondale 2nd place SkillsUSA/VICA WA State Automotive Maintenence '04 had an 87 pulsar...still planning CA20DET
1970 Chevy BelAir 350V8 300hp...soon to get M21
Where would I find the part number for this computer thing, if I was going to buy one online from some outfit? It's 1990 Sentra, 1.6 litre engine, automatic, 2 wheel drive, sold in Canada. Presumably if I bought the wrong one, evil things will happen again. I am surprised to see how expensive these ECU things seem to be online -- about 240 bucks US!! The first replacement cost me 75 CDN for the part from a junkyard, the second about 161 CDN.
I'd still like to know if the 89 or 91 part will work, if the cables are modified so it can plug in. I thought that the 89 was essentially the same car?
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