my 91 GXE is really starting to **** me off!! Every once ina while it will start to shake real bad when idling and when the RPM's are low and it's hot outside or the A/C is on. And now it's starting to make the UH UH UH brr brr brrrrrrrrr and that gasp sound out of the exhaust, like it has air pockets or something. i got a glasspack on it and it sounds really crappy when it does this, and it looses HP and Torque. I was wondering maybe it could be a bad fuel injector? or Spark plugs or Timing? if any one could help me i'd greatlyyyyy appreciate it because it's been doing it for awhile now and no mechanic can tell me wtf is wrong with it.

 

Have you checked/changed the O2 sensors lately? If you are getting crappy MPG and shuddering that could be it.

Luck!

 

no i don't even know where/what that is
haha
i'll look through my Chilton's book and check it

 

it goes into your Y pipe...its a simple swap but an expensive part....it really will help improve the gas mileage if the sensor is bad....

 

Yup.. the day I replaced mine, my mileage went form ~260/tank to over 420/tank. not bad for $80.

 

420? im lucky to be getting 200. i guess i should check that out

 

but if it was bad would it do what i'm discribing?
so far it doesn't do it all the time, just most the time when like the car is stopped and warming up or at a long drive thru. long lights, stuff like that

 

Does it feel like it's going to stall when you go through an intersection after sitting at a light? My Honda did that until I replaced the O2 sensor, runs great now.

 

ya kinda sorta but now i got oil in a spark plug

 

but one question.. I have been running like 240-260, with 92 ocatane or higher at one point 94 with 1 1/2 gal left. And i have done a tune up could the o2 sensor be killing my mpg.. the best time i ever got 310 but that was during the winter. and my idle is at about 600.. jeff at maxxuimn tuning in long island adjusted my timing with out a gun and i hear no pinging, could the advance timing played with my mpg? its like 100 mile from full tank to half then another 100 miles from half to just over the 1/4 mark and then another 50+ until i am running empty, is that wierd or is this normal? i would be interesting that an o2 sensor would kill the mpg.... does this sound right?

 

Is there a way to test the O2 sensor? and is this the one on the intake or exhaust or both?

 

but i could be wrong.. i heard other later models of maxima;s having upto 3 o2 sensors

 

holy crap! but then again, you are in the heat. highway, i get 400 all day long. . .

i changed my 02 and noticed no difference, even though the car was running rich.

 

no there is only one on a 3rd gen. It is on the y pipe just before the flange that the rest of the exhaust connects to.

 

ok i am wrong.... but wut about the mpg.. could the o2 be the culprit

 

Correst me if I'm wrong; but if the O2 sensor is bad wouldn't it trip the check engine light? I get approx. 300-350 mpg in the city and mine runs great. However 400+ would be nice also.

 

after what i went through, i would say take it to someone who really really knows import engines well. that way you can rule out the expensive stuff. my car does pretty much what yours does and mine is toast. i dont want to scare you but its better than spending 1k on stuff thinking its going to fix it and then find out your screwed.

 

I get ~250 miles per tank in city driving, and my CEL just came on for 15-20 minutes this morning, the first time it has ever happened. I haven't noticed a recent change in mpg, but could the ECU have just detected a problem with the o2 sensor? Sorry for not being able to help you, Sith, but we may be in the same boat.

 

I got the same problem. I've replaced the o2 sensor, sparks, ingition wires, distributor cap and rotor, fuel filter, air filter, an engine mount and... that's it . I went to a shop for diagnostics and they said it's my fuel injectors. They said 3 of them are fairly shi*ty but not dead and the other three are better but not that great either. The only thing that worries me is that it might be the valves, which might be a mechanical problem that would not throw in the codes. If after I fix the injectors and spend about $600 on the repair I still have this problem, it is probably the valves 99%. If that's so I will need a new head which will be around $1000 if not more. And if that's true I shall proceed to killing myself with a 12 gauge in the face.

Sorry I mumbled on for so long but I think (I don't wanna scare you) you might have a similar situation. Oh yeah btw, my friend (he used to be a mechanic) said it might be the mass airflow sensor (MAF) or throttle sensor but that's not the case since those did not throw any error codes during the diagnostic.

 

so i can proceed with you and do a mass suicide j/k... man this stinks.. and it hurts my wallet.. spending 25 dollar every week and a half , two weeks on a tank of gas that gets used fast..... i need help diagnosing this problem.. yester day i put 87 octane b/c of short of cash and i have my timing adavnced and know i hear marbles in the can.. pining....

 

I noticed in your signature that you need new engine mounts. I am not sure about all of them but I've replaced the front one for $80 (parts only). My friend installed it so I dunno how much the labor goes for. I believe the other 2 mounts are like $80 and $150. One of them is the most expensive one. I think if you do all three I would guess it costs about $250 labor or so.