au201

Hello all. At 4xx,xxx miles (don't remember off the top of my head) my 89 maxima is having an issue that seems to be eluding me. During the day, it runs great. At night, however. It runs quite rough and is down on power. It almost feels like a misfire but it doesn't feel quite that rough. I suppose it could be though. When I apply power I can hear each spurt of fuel very loudly and not as rapidly as before. So far it has a new air filter and all new plugs and had one injector replaced on the cylinder that my trusted mechanic said was a problem. But it's really weird that it only happens at night and also, it only happens once the engine starts to warm up. On a cold start, it's perfectly fine, except that it also takes a couple of seconds longer than before to start. Any help would be appreciated.

chrome91

iTrader: (1)

are you sure another injector isnt bad? VG injectors are known to go bad, that and 80s and 90s Nissan injector O-rings get eaten away by ethanol in gas.

i cant see see how night is affecting it any unless you live in a place where its warm in the day and cold at night, then the cold air at night might be affecting fuel density.

Hectic

iTrader: (20)

Let's see a pic of that odometer. 4xxk is something to take pride in, surprised you don't know it off the head.

DanNY

iTrader: (14)

random guess....alternator?
you usually drive with the lights on at night (i hope)...with the lights on it's dropping the voltage and the car is acting all kinds of funny?...maybe?

cold start you have high idle so the engine/alternator is spinning faster. once warmed up the engine speed dips and you have your issues.

au201

You actually might be on to something. I also noticed when I put up the windows the other day the car almost stalled. Like the low windshield washer fluid low light on the dash actually flickered. It's at the shop now. I'll call and have them test it for me. Thanks. He's going to recheck the injectors too. As for the person asking for an odometer pic. I can get one, but (and I know this doesn't really give me credibility haha) it stopped working for I'm guessing around 100,000 miles at one point and then started working again. And it has actually just stopped working again. But like I said I can snap a pic of the 323k that's on there now lol.

chrome91

iTrader: (1)

alternators easy to do a quick test on. get a cheap voltmeter, with the car idling put voltmeter positive and negative to battery positive to negative respectively. should read 13.9-14.8V, something low like 12.5 means the alternators not charging

1990se5speed

You are wrong sir you also have to check the AC ripple effect

chrome91

iTrader: (1)

you can do the fancy tests with a charging test machine, but a voltmeter is a quick and easy method

TexasTex

iTrader: (1)

This was thought when I saw the title of the thread. I'm willing to bet you're correct.

Why Danny?

DanNY

iTrader: (14)

why what?

DanNY

iTrader: (14)

over kill for a simple yes/no test.

most shops will just clamp on a tester.

at home you can just use a simple volt meter.
http://www.wikihow.com/Check-an-Alternator

TexasTex

iTrader: (1)

Because racecar.

DanNY

iTrader: (14)

1990se5speed

You sir are below my skills first things first if your pro you know what im talking about

1990se5speed

Hey bro that is not the way to check there is more to it than that

chrome91

iTrader: (1)

you can load the alternator with a test machine, etc but that takes time. i work with "pro's", everybody uses a DVOM to quickly see if a alternator is bad or not. pros want to take as little time to fix something as possible, especially if youre working on flat rate. takes 5 seconds to start a car and hook up a voltmeter

and at calling Danny below your skills

TexasTex

iTrader: (1)

Please stop. That is such a childish thing to say.

1990se5speed

Then they are not pros making a quick buck. diagnostics is where the money is at not r&r you guys need to go to school

chrome91

iTrader: (1)

i DID go to technical school to become a mechanic. anything that makes things quicker and easier, the better

TexasTex

iTrader: (1)

Let's just all get along!

You're both pros in my book!!!!

DanNY

iTrader: (14)

please describe in detail on how YOU would do this test.
kthxbye

PS i'm not your "bro"

1990se5speed

No bro but you dont see that that will only check for output but wont check the ac ripple effect you also need to check Accessorie ground check to see if the battery will keep above 9.6 v while cranking engine for 15 seconds and voltage drop across. The system your teacher i mean parts changer must have sucked all that only takes 8min at the most and that tells you alot more than a load test.

1990se5speed

Ok

DanNY

iTrader: (14)

if your output test failed are you going to continue to check the other items?
BTW cranking voltage and and voltage drop is more of an battery issue and not alternator related. a load test (generally the test they do when you bring your battery to autozone or the clamp on tester that are sold to professional shops and mechanics) is usually done for battery test.

while you don't know any of us...try not to assume that we don't know what we're talking about. trying to "teach" us what a text book tell you will make you a through but poor automotive technician. it also shows you how naive you are in believing that everything you think you're doing is the right thing...maybe in a text book...but it doesn't work like that in the real world.

you're going to spend 30-45 minutes to figure out that you have a busted alternator that you can make maybe 1 hour labor on when someone can stick a volt meter and figure out the problem within 5 minutes...if you have been doing this for a while you probably don't need a volt meter to tell you that your alternator output is below spec. i'm going to go with the 5 minutes test...get paid for the job and move on to the next job.

1990se5speed

You do not know anything those testers dont work for **** dont trust autozone they are a retail place to test you battery with you telling me that i know you are a low grade tech shame to you parts changer what ever i know i can test my own battery thats why my charging. System is OEM

DanNY

iTrader: (14)

keep making those assumptions.

i can test my own battery too...you want a medal?

you really want to call me a parts changer after i called you that when you determined that unplugging a MAF and nothing changed is the correct test for a MAF? the member still having the same issue. yeah...stay with testing batteries.

please man...stop while you're ahead.

1990se5speed

You have to do a volumetric efficiency on mafs i said replace it if the reading is skewed not my fault he did it plus he said it actually helped out look at the post don't sound like you can 2 me.

DanNY

iTrader: (14)

he didn't respond...that usually means the problem is fixed...maybe.

where as he came back and said the MAF didn't do anything. it helped...but it didnt fix the root problem.

nice try.

at this point you're a waste of time for me and i'm going to stop responding.

chrome91

iTrader: (1)

the text books you read through in school are full of so much useless stuff that you will never use its ridiculous. i was taught all that stuff, how to rebuild a starter, rebuild a alternator, positive/negative side voltage drop tests on starters and alternators, etc but aint nobody got time for that. even with 1 on 1 time with instructors, they tell you your boss will most likely not let you screw around for 20 minutes to do those tests. some vehicles have the alternator nearly inaccessible for tests as well. if a vehicle has a newer battery thats going dead, and a DVOM says 12.8V at idle, im gonna bet my left nut 99% of the time the alternator is bad.

1990se5speed

Thats not in the books what im talking about