alright guys i need some help sourcing out the root of my problem.

here are the symptoms...

while driving at partial throttle the car bucks and stumbles and really drives strange. while letting the clutch out in first gear if i dont give it a lot of throttle, the rpms drop to almost nothing and i have to re-clutch and give it more throttle.

once in gear and rolling at partial throttle the acceleration is very choppy and the car bucks and stumbles.

for example while driving along in 5th gear at 60 mph and i give it gas, it jumps around and until i move the throttle is smooths out a bit, but still not typical smooth acceleration. this is the same with all gears.

my first instinct was the TPS. i changed that, and it worked well for a couple days, but now its back and might be even worse. when i changed the TPS it was totally back to normal. when i first changed the TPS i did not have a ECU fault code for it, but i changed it anyway.

now when i pull the codes i get 0706 = fuel injection system lean or rich (right bank) i did have have that code prior to initally changing the TPS.

the haynes and the FSM do not have diagnosis on this particular code (0706). but for the other similar codes.

my question is what could be causing this type of problem. i cant see, hear or feel any type of air intake leak. the car revs above 2500 fine so that deturs me from speculating the MAF. only other things i can come up with are fuel pump, injectors, fuel regulator, or oxygen sensors.

i picked up another replacment TPS, but i dont want to change it until i can figure out what is making it go bad.

any thoughts or help on this is great appreciated guys. thanks for reading.

--Paul

 

sounds like you covered what I was going to suggest....TPS/MAF/Vacuum leak. What does your boost gauge read at idle?

 

boost gauge reads the same 20in/hg at idle. i forgot to mention that the car shuts off if i dont work the clutch correctly while going from a stop. i have to give it a ton of gas. it shut off on me twice yesterday while in traffic. i had to pull off to the side and it took 10 minutes to get it started again. it feels like its flooding itself. but idle feels totally normal. and it drives fairly normal in the first couple minutes of start-up after sitting for a while.

 

I'm not sure if this helps, as it relates to my beater car a 90 plymouth Laser with the DSM 2.0liter. I had to adjust the timing sensor because it would do just what your having problems with. My MAF sensor also had to be replaced.


Also the other day, driving my maxima I had a multiple cylinder misfire happen twice, I had my bov too loose and the vacuum line was leaking! Hope this helps.

 

mine reacted the same way when it was down a cylinder (90 in #6). Im hoping this isn't your case but I would do a compression check just to see where its sitting. Its just strange bc I had the same recrank issues if it stalled on me also, I would have to feather it for a good minute to get it to fire after stalling. Basically I would be cruising then try to give it a little gas and it would buck 6-8 times until it smoothed out. Good luck and let me know the issue.

PS I will have my POS running again hopefully this weekend with a little luck from UPS returning a gear. I will finally have some T-trim dynos after the 6 puck is broken in.

 

As far as the stumbling issue, what is the fuel pressure at? A bad MAF can cause those problems right before it totally stops working. If a MAF is dead or not connected it won't rev above 2500, but if it is just acting funky or the wiring is loose it can be sporatic like that.

 

is WOT normal throughh all the gears normal

 

sounds lean at partial throttle and rich at idle.

 

ok i just changed in the MAF from my little brother's 96 SE.

car starts fine then when it settles to idle, my vaccum goes to 10in/hg and it feels like its ready to shut off.

i checked everywhere for a possible vaccum leak (maybe i knocked something off while changing the MAF) but everything looks good. and i wasnt really near the vaccum lines.

the MAF worked perfectly fine in his car prior to changing it into mine.

this has me confused. any more help?

i guess i could try putting the Z32 MAF and Z32 chip back in the ECU.

--Paul

 

Check again for a vacuum leak - it really sounds like it. Check the gasket in between the upper/ lower intake plenums.

 

alright well i got it to somewhat idle...

every 30 seconds it goes from idling normally (20in/hg) to doing its rough idle (10in/hg)

with the previous MAF it idled fine. all that i did was change the MAF now its going weird.

i drove it around the neighborhood and it still does its stumbling and hesitation.

could it be a possible leak at my intake manifold and EGR? would that cause anything like this? i am not sure if i hear some kind of leakage when i rev it up while i am under the hood. i tried to listen on a stock maxima and it sort of gave off this same sound, just not quite as loud. just a thought, maybe i am working a leak there.

i guess i have ruled out the MAF. i think i am going to put the USIM on and see if that cures anything.

 

When i was having my problems after installing my injectors it turned out to be my intake manifold gasket and egr gasket. My symptoms were a little different than yours but it may be worth it to check

 

man, ill be curious to see if you figure this out because there were a lot of people with the same problem it seems after they replaced their clutch and flywheel. Im still NA but mine does the exact same thing when im cruising and give it a little gas through 4 and 5th gear.

 

THis is EXACTLY what happens to me when I install the Z32 MAF on the charged side and JWT Z32 Chip.

Let me know wha you find out. I got done beating my head on this months ago and finally gave up in the short term. Plan on tackling it again later this summer.

Requin - does your idle and hesitation improve when the car warms up at all?

http://69.57.150.24/showthread.php?t=362534

 

alrighty, just got done thinkering with it a bit more....

i let it idle horribly for a couple minutes just to see if it would work itself out. i adjusted the FP to 34 somehow it was up at 40. after letting it run for a couple minutes it the idle smoothened out a bit. but now i cant get it adjusted below 1500 rpms at idle. th idle fluctuates between 1500-2000rpms on a pulse. it pulses from 1500-2000 like every second. i took it out on the road and the acceleration has smoothened out a bit, but still not 100% smooth.

i have changed the MAF (still stock A32), TPS, and switched back to the USIM (just in case i had a leak on the MEVI at the EGR tube)

on a side note the USIM pulls sooooo much harder than the VI in the low to midrange its unreal.

anyways...any ideas on my pulsing idle? i am just hoping that i am not down a cylinder. i guess the only way to tell is to do a compression test. thanks guys.

 

I have this same problem. I replaced the pcv valve, no real change. Max seems to be fine after it warms up. I was reading in some old posts about a main vaccum line located on the back of the motor that was found to cause these types of symptoms. It is a brass looking line. I have not had the chance to check it out but my max runs fine after warm up. I do experience the same kinds of hesitation while driving when max is still cold ( operating temp but still cold). Once max is warmed up I have no other symptoms. Boost and performance is normal. Dang its hard getting used to the new lite fly and new clutch! good luck

 

also i am not getting a ECU fault code.

do faulty coil packs throw a CEL?

 

Sometimes - if it does, it'll be a Cylinder misfire code, or ignition circuit fault code.

 

i pulled the plugs after i got back...

the front 3 all looked the same. they were pretty black at the bottom of the strap. about halfway up the strap at the curve there was a white band covering the curve. on the horizontal portion of the strap it was normal metal.

on the rear 3 they also all looked the same. they had the same blackness at the bottom of the strap, and whiteness at the curve, but on the rear 3 the whiteness continued to the end of the strap.

even though i dont have a code for the coil packs, i have an extra set that i am thinking of just throwing on there to rule out that possibility.

might as well change the PCV while i am at it too, jsut to rule out all the possibilites.

 

Hey Paul....I can't really help you figure out what the problem is, but I have both Hanshin and Mitsubishi coils that I can't use anymore lying around if you want them.

I also have a compression tester kit if you want to borrow it.

I sure hope you can figure this out quickly and easily. I wouldn't want to see you part your baby out.....

 

vortechpower - I have the same symptoms also with the A32 MAF - some hesitation when cold, but after warming up it feels fine. The hesitation occurs mostly from 2000-4000RPM at partial throttle.

With the A32 - at idle it fluctuates a little between 750-800RPM constantly - warm or cold.

And like I said - with the Z32, it just runs like a** and bucks and stutters at any RPM until warmup - then it fluctuates a bit more than the A32 MAF at idle but is drivable once the engine is at operating temp.

I would love to figure this out.

Requin - are you getting what vortech and I mention or is your hesitation regardless of operating temp and RPMs??

 

its more than a hesitation, the car is not safe to drive on the road. it is at any temp and any rpm, and any throttle posistion it seems like.

 

When it did that to me (totally undrivable, hard bucking constantly) - it was the MAF wiring.

 

alrighty!

i went out today....started it up...it did its normal routine of starting fine and then barely being able to keep itself idling. so i shut it off. put a new PCV in, started it up...and voila, idles like a champ. took it out...much better. however i am still getting the noted 2000-3000 stutter, hesitation thing. if i punch it anywhere between 2000-3000 it kind of hiccups first and then does its thing. if i land the rpms after a gear change in that 2k-3k range it also does the same thing, then clears up once past 3k.

i am wondering if that is a drivetrain (clutch/flywheel) issue.

i am just happy that FOR NOW the car is driveable once again. but we shall see in the next couple days whether is stays like that. :fingerscrossed:

i am going to throw a new set of plugs in and see if that clears the hesitation up any.

thanks for the help, i will post back if the problems re-arise.

and on a side note...the USIM hauls some major **** with teh JWT. off the line torque and coming out of a gear change is like night and day to the MEVI. i am going to leave the USIM on for a while! its nice to have mucho torque again!

--Paul

 

Great news!

Please let me know if you solve the mid-range "hiccup" - I just replaced my tranny and verified my clutch was in great shape (clutchnet rocks) and am still having this hesitation - it's especially bad when cold.....(this is with A32 MAF)

 

I have been having some weird "hiccup" issues since getting my tranny fixed. I also got a new clutch and flywheel at the same time. I am placing the blame on a vacuum leak in my issue, but this greatly interests me.

I have the Fidanza Flywheel with the Clutchnet 6 puck spring hub.

Paul & Ian: Which combo are you running?
(or anyone else thats haveing the hiccup issue...)

 

Fidanza and Exedy Stage 1.

 

Fidanza and Clutchnet.

But this REALLY doesn't feel like clutch to me. The RPMs don't change the rate at which they are rising when this hiccup occurs, which tells me it's not the clutch dragging or slipping.

To me it certainly feels strictly engine related.

 

i was having similar problems, and after changing my bad maf, i still had a misfire/ stumbling thing going. I looked up which cyinder is which and played with the connector that connects/ controls that particular injector and it seems to have fixed it for now..

 

mine is fixed now thanks to a new PCV valve.

 

excellent! It's def not the drivetrain, mine is all new. I went with fidanza/clutchnet/$800 in trans parts. Im not really seeing any hesitation at any rpm after reaching normal temps. I disconnected the blower belt yesterday and I can hear some huge leak from somewhere near the passenger firewall area. Of course I couldn't hear sh#t with the blower running! I haven't had time to find the problem but it is there.
Hey Paul, you gotta love those simple fixes! I went to nissan looking for a pcv and I was told they don't sale them anymore... So I got mine from napa for $8 and change, pretty blue 1. Other then rough idle for about 15 mins my car runs really well except for my damn handicaping 26lbs wheels
Ian, can you hear any kinda of hissing sound from the passenger firewall area? I think the problem atleast for me is around there