# "choking" throughout RPM's



## S12_forgotten_silvia (Mar 20, 2008)

I have a '96 MAxima SE, 5 speed. 246,000 miles.
well maintained. synthetic oil changes every 5k miles
i run it on premium. its been running beautifully until recently.

a little while ago i was driving home on a 55mph road and downshifted into 3rd to pass a neon on a 2 lane road. ok, fine. but when i get into the 30mph zone ahead. i go to tap the gas to keep at cruising speed and i get a "bucking" from the car. after driving a bit, i decide to finally replace the already bad ball joint. fixes the rattling i've had. but the bucking is still there.
so now that i trust the ball joint i decide to open her up to see what i get. 

and i get what feels like a choking sensation.
like its struggling to breathe. power is great until about 4k rpm, then its hit and miss. and its different every time. sometimes it feels like its choking until about 5k then out of nowhere you get whip lash and other times it just bogs from 3k on up. and NO DTC's

so then i think, maybe its the fuel filter, hasnt been changed in about 60k. 
starts quicker, but no performance difference
air filter is fine. (factory intake)
so then i thought, maybe the catalytic is clogged. looked at my tail pipe and the exhause looked like it had a misfire. and i used 1/2 a tank and only got 130 miles. by 1/2 tank i'm usually at about 200-230 miles. i so after work i put my car on a lift and hollowed out the cat. it was nice at first, until it got up to running temp. hollowing it out certainly made a difference. its not as bad as before. but its still hesitating above 3k @ WOT

any ideas? could this be something more than just a combustion chamber cleaning? i'm pretty sure its not one of the infamous coils. i have a new hi-flo cat coming. 
if that doesnt fix it, then i'm wondering if its the freaking timing chain or hoping its just something loose in the front end somewhere. 
gee, it only has 1/4 million miles on it.


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## eduardo (Mar 13, 2010)

man im having that exact problem with my 93 300zx iv done the same as you (changed fuel filter, both air filters, cleaned injectors, and changed the spark plugs) and very little difference i thought it would be a coil but no difference once i changed it. hope you find what it is because i havent jaja and its freakin getting on my nerves.


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## pulsar86 (Aug 13, 2009)

Have you both checked to see if your timing is correct and not too far retarded?


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## S12_forgotten_silvia (Mar 20, 2008)

ok, well i'm kicking my own ass for overthinking the situation and punching out my cat. i added a $4 bottle of Lucas injector cleaner to about 1/2 a tank of premium. for me it was as simple as that. i feel like such a dumass

I forgot to mention that i had switched to mid-grade fuel in a pinch for cash about 6 weeks ago and stuck with it because it didnt make my timing chain rattle like regular does. and my ck. eng. light for my b2s1 O2s went away when i switched to mid-grade. so i thought "cool". but apparently it gunks injectors. and thank god, no, its not my timing chain.


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## eduardo (Mar 13, 2010)

i did the same thing bought the lucas but no freakin difference im thinking it is going to be the timing


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## S12_forgotten_silvia (Mar 20, 2008)

ok, so driving thru town the other day, it happened again. and i took note of everything i was doing and turned off the radio "GASP!" so i'm going through town, 30mph, 5th gear, give a little throttle and it starts bucking. i back off, shift to 4th, give it throttle and instead of bucking i actually hear the timing chain rattling.
but ive been working with the car, and it seems to run fine all the way to redline if i ease my foot to the floor. i dont take it past 5G anymore, but still. its like drinking water, if you slowly tip the glass and pour it you can drink it just fine, but if you just flip the cup over and try to get a drink you'll just make a mess and 'choke'
so ive been looking around and found some timing chain kits for around $150. 3 chains and the full set of sprockets. you guys think i'll need the sprockets too, or will i be ok just replacing the 3 chains? whats the best way to go on this one? or am i just over reacting? she seems runs just fine as long as i dont over load the throttle


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## 4thGenTinkerer (Nov 1, 2009)

Is your check engine light on? 240k? I'm gonna have to say that your timing chain rattle and the choking are probably unrelated. @ 240k the guides tensioners etc are gonna be pretty worn. So too for that matter are the microfinished surfaces and stuff like wrist pins, piston rings, oil pump etc are gonna be so far outta spec that you are going to experience more worse problems as these parts start to fail. If I were in your shoes I would save my $ for an engine or a rebuild kit. I think a master rebuild kit is like $980 through rock auto. You can get a complete engine with less than 50k mi. for like $1600-2000 drop shipped to your shop or house. take it to a parts store and have them read the codes if you Mil is illuminated. Post the codes, we'll try to help you worth the choking if you want to go that route. Good luck.


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## S12_forgotten_silvia (Mar 20, 2008)

well, i didnt have any codes til i punched my cat. now thats the only code i have. ive got all the tools and my own lift at work, the problem is i work at a chevy dealership. and none of the guys i work with want "a damn thing to do with an import" so im basically on my own as far as working on it
but that does kinda set my mind at ease things like the chain guides and tensioners being worn. in the "that makes sense" kinda way. she runs smooth as a lion cub as long as i pay attention to to the throttle. sad truth is my lion cub is an old lioness. but what ive had in the back of mind almost since i got it 2 years ago was, i want to get it to 300k then celebrate by swapping a 3.5 w/ a 6 speed and put the 3.0 in my S12. probably just a pipe dream, but its an idea i like. 

but first things first. i need to replace my catalytic. i was going to get a cheap-o hi flo off ebay. til i realized it didnt have an adapter for the O2s. so now im procrastinating and saving my spare change for a good one. i'm not due for emissions til august


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## 4thGenTinkerer (Nov 1, 2009)

A good exaust shop should be able to drill a hole and weld in a bung for that downstream o2 sensor. Those chevy heads (and ford f*cks) just hate to admit that nissans are simply a higher quality vehicle. Do you have an FSM? If not i will hook you up with a .pdf version. Say the word and I'll post the link so you can download it. It has really helped me out. Alot can happen over the coarse of 60k so maybe figuring out that choking/bucking is a good idea. Have you checked things like TPS, clean the TB, injectors? Reading your post about the lucas injector cleaner temporarly fixing the problem makes me think its a fuel delivery issue. I remember there being a valve stem thingy you can test the fuel pressure on the engine side of the fuel filter. maybe fuel pump on its way out, like when you nail it, the pump is unable to keep up with the demand. Does it choke if you rev it while not driving? Maybe your clutch is on its way out. Bad motor mounts will make it seem like its gonna fly apart any second. Have you changed/checked them? Just keep at it. Eventually it will become clear after you have eliminated a few of these things. I always start with the simple/cheap things then move into the more complex stuff. 
Good luck and welcome to the forum.


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