Here is where it gets even more weird. When i'm giving it partial throttle at low speeds, the car VIOLENTLY hesitates and sounds like its badly misfiring and it's blowing black smoke. However when i accelerate past half throttle, it feels fine to me. The idle is also very loopy with the median being about 550-600rpm. When im stopped and turn the car off and take the key out, it stays running for a second or two longer, and runs perfectly(no misfire, nothing rough, perfect idle). Seems like when i have the car idling with the key in it, it's horrible, but when i take the key out, the car idles perfect for 2 seconds then dies.

What the heck is going on? I would greatly appreciate anyone's input.

 

First off, what sensors did you use off the used 97 motor ? Did you get a complete 97 motor and drop it in without swapping anything ?? If you did that and your still getting the misfiring and the horrible running, that would kinda rule out cam sensors, CTS, ex.

Might be a fuel pump issue or an ECU problem.

-matt

 

The new motor i got was pretty much ready to be dropped in, had all sensors on it. I used all of the sensors from the new engine besides the one that reads the flywheel, not sure what it's called, mounted with one bolt on the front bumper side on the tranny inside a hole.

I just remembered that on both engines i never connected the front valvecover breather tube to the intake and it smoked out of that hole sometimes, but i doubt that can cause a problem this big. Or can it?

 

I just searched some more and saw that a loopy/choppy idle and rough low rpm running and fine higher rpm running can come from leaving the valve cover vent open because it's unmetered air...i will connect it tomorrow and hope for the best, althought i think my problems reach further than a vacuum leak.

 

If all fails it might be a ECU fault, maybe a new one might be in order

 

I really hope not, all this bull**** came up right when im about to switch cars too, very nice timing POS maxima...

 

that throttle pressing and falling rpm's happened to me once. Turned out i could not blow thru my fuel filter.

 

Yea, I have to agree with matty and Snypa. since you are getting the same problems with the second motor, it sounds as if something fuel side is bad; i.e. fuel filter or fuel pump. i would start with the filter since its easiest, or at least check it, and then the pump.

 

What about the Mass Airflow Sensor? Could O2 sensors possibly cause something like that too?

Either way, if it were me I would check the fuel filter and fuel pump first though.

 

maybe your cat converter is clogged i had similar problems with altima i used to own when i swapped the motor

 

I had similar symptoms when my TPS was off spec. Check to make sure its near 500ohms at closed throttle and 4k ohms at WOT.

 

You also need to make sure the sweep is clean and linear.

The Haynes shop manual troubleshooting section says that a loopy idle is a symptom of a bad TPS.

I think the TPS should be the first place you start troubleshooting.

 

Interesting input. I'll go change the fuel filter(4 months old) and attach the vent hose right now and see what that does, and i'll check the CAT. I'll check the TPS, but i know that in my old engine i calibrated the TPS when i put all the 00vi stuff on, and i have the same problem with this new motor where the sensor is from the new motor. Of course it's possible that both are bad.

Keep the ideas coming, this is helping.

 

well look at it like this you have your variables and constants, your constants would be fuel filter, ECU, Wiring etc..... your variable would be your motor, look to your constants for troubleshooting since they were there causing the crap you experienced before the new motor

 

Really? My old Taurus has had some misfiring, and its known the catalytic converters have been clogged somewhat for some time now, but I had no idea that clogged cats could cause a misfire.

 

Ok so today checked everything, replaced TPS with a working one, new fuel filter, connected some missing hoses, replaced plugs, and now i'm having another problem. The 'misfire' sound did not change.

When i took the plugs out, every one of them was completely black, indicating that it's running extremely rich. To add to that, the exhaust is smoking a lot, and i'm getting about 5mpg.

Scanned the ECU, got a bunch of codes: MAF, misfire, IAT sensor, TPS(from old bad sensor), o2 bank 1 & 2. I know the o2 sensors would make it run rich, but it would definitely not make it run this badly and idle loopy. Cleared the ECU, and all codes erased besides MAF and IAT sensor. MAF sensor is new, and i think it did fix my 'waaaaa' sound when pressing the gas.

It's so rich that your eyes start to hurt when standing next to it when it's running.

All injectors and coil packs are fine, and all plugs looked the same.


The problem has got to be with the MAF, but i don't know what the heck is wrong with it. My maf plug has been broken for some time now and i've just been using the connectors; can somebody confirm the order of the wires, looking at the car from the front grille going left to right: white, red, black.

I also found some other wire inside of the white/black wire tape, but it wasn't covered with any plastic, just plain wire....


Does anybody know what the hell is going on with this damn car? Tomorrow i'll check the ECU harness wiring, but i highly doubt that's bad.

 

You dont have even have a working MAF plug on your MAF ?? Thats probably your problem. That has to be a good connection across the board and you may not even have them in the correct order ?!?!? JEEZZZ

Fix all that up and make it perfect, and if that doesnt fix your problem, it might be time to invest 100$ in a new uses ECU and see if that fixes your issue.

-matt

 

according to alldata looking at the harness connector facing you from left to right with the plug looking at you as if you were gonna plug it to your mouth wire should be
1 far left side white
2 middle black
3 far right side red
ill confirm that in a few seconds ill run out to the garage

 

Yep. It' definitely either the MAF connection or ECU.

 

matty-when i said that it's been broken for some time now, i mean it's been broken for a year plus....dont know why it would all the sudden cause a problem now, but i'll check everything. None of the auto stores have maf plugs, guess i have to get it online here?

allmaxxedout-thanks for the confirmation!

I'll go check everything once again; maybe i broke a wire when undoing the vafc, who knows....

would a BAD maf connection really cause it to run this bad? It's VERY VERY rich..the thing is, it's reving past 2300, which it wouldnt if the maf wasnt connected. Maybe you're right about the connection, i'll go check everything out...thanks

 

yes.........its called safe mode or limp mode, no MAF means the ECU has no means of measuring how much air it gets, so it retards timing and turns the A/F ratio way down 9.0 or something like that. While your at it, make a seperate ground for the MAF, That bare wire is probably because you crossed the wires and grounded them out, your best bet for the MAF plug is probably the junkyard, Good luck

 

With no MAF, would it rev past 2300rpm though?

 

Did you get a NEW MAF or a used one? Sounds an awful lot like MAF symptoms. it IS possible that you got a bad one as a replacement. If someone you know has a max see if they'll let you "borrow" theirs. Just to be sure...

 

Yeah right now it's sounding like a MAF issue to me as well. This one i got is from Autozone, it's refurbished.


So i checked everything, i fixed my old MAF plug and plugged all the wires in correctly.

I checked the voltage; the red wire and the ground wire are in spec, but the white one is supposed to indicate 1.7v with the car idling and rise to 3.0 when reving, and it's only inticating .2v at idle AND rev. So this problem i'm having could possibly be because of the new MAF being bad. Ideas? The voltage was also bad in that wire with the car on ACC. I ran a new wire from the ECU to the white MAF wire just to check, and that didn't help anything.

This is a MAF problem and not an ECU problem, correct(i'm just hoping!)? Thinking about it, this problem isn't the same as it was before; it developed this after the MAF switch...According to the diagram, the white(low voltage) wire doesn't pass through any relays, switches, or fuses on its way to the ECU, so it's nothing like that.

 

anybody?

 

Hey bro I am having the same problem with my 96 maxima. Started out of nowhere. I have the original motor but anyway the car has the same symptoms. I tested the MAF and it is bad. Mechanic says it's $400 for a new one!?

 

Hey bro I am having the same problem with my 96 maxima. Started out of nowhere. I have the original motor but anyway the car has the same symptoms. Help?

 

Well autozone is 212+tax for one, but i'm sure you can find one here or ebay for much cheaper

 

yeah did some research, much cheaper! See my car was sitting for 2 months while I got the money together to have the tranny rebuilt. That could be a problem as well? I started it when I could until the starter went. Gonna have my mechanic test the injectors too

The last thing I need is a hydrolocked motor from too much fuel

 

Anybody know if the white wire sends or receives signal? I guess i that way i could tell if it's the ECU or the MAF that's bad...

 

check that white wire, as in follow it all the way. I had this with my a/c, the wire had a little slice in it and was corroding, getting dirty and it would only turn on sometimes. If u know that its that wire(white) then follow it through, make sure nothin's f****d up.

 

Yep i checked the signal, and it was completely off. Put the maf on my buddy's maxima who was finally available, and it ran like azz. Went to autozone and got a replacement, and issue is fixed. I hate this type of ****, i wasted so much time on this just to find out that i got a bad new maf.

I still have a VERY slight rough running issue, but it's so tiny that only I would notice it; this is most likely some vacuum leak, and i can fix that no problem.

I really appreciate everyone's input, a big thanks to everybody who contributed!

 

How cool, the maf is broken again

 

Used MAF on our classified
http://forums.maxima.org/showthread....&highlight=maf
and another
http://forums.maxima.org/showthread.php?t=559076
http://forums.maxima.org/showthread.php?t=559398

 

Hey I finally fixed my problem as well!! With the exception of a bad coil in cylinder 5, here is what happed: I have a CAI. Now, I'm not sure if its from 95-98(mine's 96) but nissan decides that the connector for the MAF and the MAP sensor are EXACTLY THE SAME plug. My mechanic when putting everything back together switched the connectors, so the plug for the MAP was in the MAF and vise-versa. I had the same problem as you did running WAY rich and just horrible. After careful inspection I caught it. MY MAF wasn't bad but when I tested the connector I was getting battery voltage to the MAF!!! He really could have F*&$ed up my car. After switching the connectors and replacing the coil in cylinder 5 she runs like gold and purrs like a kitten. Hope no one else has to deal with this and it helps anyone.