Wolf-Strong

Ok, first off I would like to note that this has progressivly been getting worse, until now it has gotten to this point. Simply put, whenever I accellerate the check engine light comes on. It is getting HORRIBLE (less than 10) mpg. When hooked up to a diagnostic tool it messes up the tool and the engine dies.

Now, someone had mentioned that it may be due to some cross wiring or bad wiring somewhere, but I wish I could figure out where! My thoughts are perhaps a bad o2 sensor? Bad MAF? Possibility water did get inside the engine bay. You can notice a slight miss or backfire (maybe both) type of sound when it is ~2000rpm.

Again, running VERY rich.

Greeny

iTrader: (43)

Sounds like one or two bad injectors to me..

Pearl93VE

iTrader: (14)

Yeah, also might want to check for a bad o2 sensor.

Wolf-Strong

That's what I thought at first, but then this occured to me: If it was a bad injector, wouldn't that just mean 'clogged' injector? In which case it would be running lean right?

When these injectors go 'bad', does that mean that they are clogged, or do they just stay open?

Also, how can I test for these things?

EDIT: Oh yeah, and how would a 'bad' injector cause the diagnosis tool not to work and make the car die?

Greeny

iTrader: (43)

You also need to pull the codes on the ecu,these cars have self dianostic that will flash the trouble codes through a series of flashes from the check engine light when the ecu screw is turned counterclockwise to activate it..

In other words...You do not need a code reader to read the codes..

Here is the autozone repair sticky link,it has directions on how to access the codes stored in the ecu..

http://forums.maxima.org/showthread.php?t=396706

1.click the link
2.click 1994
3.click nissan/datsun
4.click maxima
5.click driveability&emission controls
6.over to right,click trouble codes
7.below that,click reading reading codes or general info to learn more


Location of ecu..


Behind this panel on the passenger side

Greeny

iTrader: (43)

They can do either,some injectors fail to open,some fail to close..

Stick an ohm meter on each injector..A good reading will be 11-14 ohms iirc..


Most likely,your diagnostic tool is not OBDI compatible,hence the reason it kills the engine..

Wolf-Strong

I am confused. Which set of that autozone information do I use? There are 7 different ones to pick from...

Greeny

iTrader: (43)

...................

Wolf-Strong

I understand that.

I am curious though, do I use the 5 mode? the 2 mood? which of the two or five modes?

Greeny

iTrader: (43)

Most maximas have a mode 2 ecu....


Copy/paste from site,this is what you need to do....

Mode II

SELF DIAGNOSTIC RESULTS (IGNITION ON)

In this mode, Diagnostic Trouble Codes (DTC's) can be retrieved from the ECM. The DTC is indicated by the flashing sequence from the MIL or the red LED on the ECM.

1.Turn the ignition switch ON, but do not start the vehicle.

2.Turn the ECM diagnostic mode selector fully clockwise for two seconds, then turn it back fully counterclockwise.

3.Observe the red LED on the ECM or MIL light for stored codes.

Wolf-Strong

Ok so I ran this. First time I did it, got Code 55 (5 red, 5 Green). This, according to the chart, means none of the above items are detected. Cleared it, drove a bit to let it warm up, tried again, nothing. Gas problem still persists. I think the codes were put there when the guys hooked up their diagnostics tool.

So now, onto the fuel injectors/o2 sensor. Fuel Injectors are suppose to be 11-14ohms as you noted; how about the o2?

Greeny

iTrader: (43)

I'm pretty sure you can unplug the o2 sensor,if it is indeed malfunctioning,then your gas mileage should improve somewhat,but the engine light will stay on until it's plugged back in...

I personally think it's an injector issue,but it doesn't hurt to try the o2 first...

internetautomar

iTrader: (30)

pull your plugs for the answer
if any are wet then you have an injector that is stuck open.
otherwise read them as you would normally read a spark plug

elusivemax93

try using the snap-on scanner with the nissan 2 adaptor it works with the nissan VE ECU as for the the VG motors you can use the Genisys scan diagnostic tool

running rich can be caused by stuck open injectors. or a bad engine coolent temperature sensor, oxygen sensor, throttle position sensor, or MAF sensor.

Greeny

iTrader: (43)

Dude,for what he would pay for either one of those scanners,he could afford to take his car to the dealership to get fixed...

Scanners of that caliber are a necessity for your chosen field of work[automotive tech] but for the everyday guy just trying to find out one thing to get his car back running right,Snap on/Genisys scanners are way overkill...

elusivemax93

lolz very true but i have them at my disposal . So for me its juz far much easier to use them instead of having to watch for the flashing led on the side of the ECU. plus there is so much more he can also do while having a scan tool hooked up to his car that u cant do by watching a led light. with scan tools he can also preform incar tests with and without engine on on all sorts of parts and find out what is bad and not bad.

Wolf-Strong

Just checked the resistance on the injectors. #1, #2, #4, #6 were somewhat corroded, but still very readable. #3, #5 were perfectly clean and readable. #2 was a ***** to get to! These were the reading of all the injectors:

#1: 13
#2: 12.5
#3: 21
#4: 65
#5: 12.3
#6: 11.5

So now the question stands....what does this tell me? Obviously there is something wrong with #3 and #4 and they probably need to be replaced (oh hell, they definatly need to be replaced). What kind of work am I looking at?

I am sure I can do this myself, but I only would have about a 3 day period to do this...is this long enough? I would think this kind of work wouldn't take more than a day, possibly two if I run into lots of troubles. Where can I find the injectors (pepboys? autozone?)? Would I be better off paying someone to do this (as in labor for it would be cheap)? Am I better off just selling the car and getting another one (manual this time :X)

redwood_usa

iTrader: (4)

you can do it in a day and it will save you about 500-600 $ in labor and other markup. Use that savings to buy and change all 6 injectors NEW from the dealer.

Wolf-Strong

Concidering I do not have that kind of money atm, I think I will just go for 2, sell the car for ~$3000, and get a manual 3rd gen for ~$2300 or an old BMW.

Dirt Rich

Gonna be kinda hard to sell a misfiring, engine dieing, gas guzzling car for $3000. Not to mention the pride lost for selling your baby for the cost of a fuel injector...

Wolf-Strong

No no no. The engine runs very strong, and was actually just replaced 10,000 miles ago. Once I replace the injectors, possibly o2 sensor, it should be getting its usual ~25mpg. Paint is in great condition, same with the rear seat's leather. Front seats are kinda screwed up, but I am probably going to repair that myself for ~$100 and the thing will be in basically flawless condition with an engine that has low miles.

Concidering where I live, I definatly think I could get $3000 for it then. I was looking, and man, if I could find a BMW 6 series from late 70s, early 80s, for ~$3000, I would be a happy camper...but I doubt I can find one for that cheap. Either way! I will probably end up with another 3rd gen or a 80s bmw.

elusivemax93

to bad your so far from where i live and also the simple fact my teacher has already sold his 1982 633 csi which we juz replaced both fuel pumps and also leaking fuel line and just did a valves readjustment

Wolf-Strong

Sucks...I am also thinking of just saving up for a few months and buy (and living in if I have to) an e34 M5.

Should be getting my fuel injectors tomorrow from Nissan if they have them in stock which means that I will be spending the day reviewing the fix-it manual

Wolf-Strong

How would I go about testing the o2 sensor?

redwood_usa

iTrader: (4)

If your ECU hasn't thrown a code it should be ok. ( Dont confuse with CEL). Otherwise check Repair sticky in this forum.

maximapitko

if you had two bad injectors the engine would run pretty rough. Somehow, I don't get the feeling that it is from all your posts. There is a VERY goood chance that your Water temp sensor is bad(coolant temp sensor). It's a very cheap and easy to replace part(1min max) and can cause the engine to run rich. Give it a try....

Wolf-Strong

Ok so water temp sensor will be added to the list. If it is cheap and easy, why not. I wouldn't doubt that concidering my heater seems to not be working as well as it use to when it was getting better millage.

Actually come to think of it, I wouldn't doubt if that is the main cause! I seriously was trying to think on why my heater wasn't working when there are no leaks what-so-ever and it was directly related to my gas millage. Completely forgot about that!

What do you guys make of the fuel injectors though? #4 was giving me a reading from 30-120 whereas #3 was giving a solid 21-22. It runs ok (other than symptoms of being very rich) and idles perfectly. Slight (almost un-noticable to the casual person) blip at ~2000 which I think is the result of it being rich.

Could my Ohm readings been screwed up due to coroded injectors? Best way to clean them?

redwood_usa

iTrader: (4)

Check for a bad thermostat - that too will cause your engine to run rich, (though not by the huge amounts you are saying)

Wolf-Strong

I take that back....the heater is definatly working. Thermostat wouldn't make sense concidering it warms up just fine and doesn't overheat after hours of driving.

I just got back from Nissan, and picked up a Fuel filter (due for replacement) and the Coolent temp sensor. I have run into one more problem though...there are two sensors! I ended up getting this one concidering many sites linked it as the one connected to the fuel injection. I have no idea what the other one right next to it is for though, so I am just leaving it be.

Waiting for the engine to cool down, then I will install it. Wish me luck!

redwood_usa

iTrader: (4)

The other one goes to your temperature gauge in the dash. As for your thermostat. It could be stuck open and therefore no overheating and if the weather is warm where you are then the car will reach temp in about twice the time it would normally. So keep it in mind if your sensor changes dont help. Also you could have tested your coolant temp sensor with an ohmmeter before buying a new one.

maximapitko

Did you change it already(coolant temp sensor)?

Wolf-Strong

No. Been driving all day long and I really don't like burning myself.

That and the fact that I didn't have an open socket wrench big enough (thought I did) so I got to go and buy one. Will update tomorrow and let ya guys know the status of it all.

Wolf-Strong

Well everyone, the coolent temp sensor is in! Haven't gotten a chance to drive it yet, but if it worked, I won't run out of gas tomorrow during my drive to my grandmas

maximapitko

well,does it still run rich?

sal12345

I have a question, if I have a 1991 Maxima SE with the 160hp SOHC motor, could I swap in the newer 1992 motor with 190hp dohc possibly with an accompanying 5spd transmission. Would that work?

internetautomar

iTrader: (30)

with money, any swap is possible.
though swapping in a b18c1 would be easier

Wolf-Strong

Yeah it is...which leaves me with the fuel injectors and I do not have $250-300 to fix that. I get about 250 miles off one tank at best, and for right now that will have to do. I am going to save up some money for a month then try and sell it (sigh)

internetautomar

iTrader: (30)

I was only getting 170 per tank out of my VEs. but my commute is a whopping 2.5 miles each way

Wolf-Strong

Outch! That is not normal either way!

internetautomar

iTrader: (30)

actually it's totally normal.
short drives will do that to mileage.
heck my uncle only gets 20 mpg on his civic DX stick shift (typically a 35 mpg car)
for my short commute I needed something with more low end for better MPG.