Stutter When Shifting

[BSTN240]

i think i know where the problem is but want to check to see if anyone else has had this problem and fixed it...whenever i shift into the next gear (only when upshifting)...my car will start to throttle up when i step on the gas, then it will sutter then start to throttle up again...if i shift at a high rpm this doesnt happen...i think its either my TPS or my MAFS, more than likely the TPS. anyone have any ideas or suggestions...and yes i did use the search. thanks.

[Nismo_Freak]

02 sensor possibly... either that or spark plug gap.

Start with the easy stuff and move up.

[BSTN240]

i wouldnt think that would cause it to stop acceleration then start back up...a friend that is a mechanic said that he has seen it before and thinks there is a bad spot on my throttle position sensor. anyone else had this problem?

[Nismo_Freak]

studders are often caused by ignition problems... turbo cars love to studder w/ incorrect gapping.

[Phantom]

Yeah just try pushing in the plug wires for each cylinder and see if it helps. My truck did the same thing when I floored it and all I did was that and it went away.

[BSTN240]

oh ok, thanks guys...cars not boostin yet though, im ordering my sr20det in the next few weeks though...

[Jaegermeister2k]

Hey maybe you're just shifting into too high a gear too early,or maybe youre not giving enough gas,but are releasing the clutch too fast.Just a thought.

[BSTN240]

thanks for the advice but anyone that drives my car notices it...so its not that, its almost like a stall but not quite, the car just quits accelerating for a little bit then starts to again...which is why i think that it is something to do with the TPS

[89240sx]

I have the same problem with my auto and I replaced the TPS and O2 sensor and it still has that stutter.. but mine is more a stutter while driving a steady speed... when accellerating it only does it briefly ...

hope that helps

Mark

[bassboy3313]

i am having the same exact problem. it stutters when revving from idle and also stutters after shifting and getting back onto the accelerator. i was just about to replace my TPS, but if thats not the issue then i dont know what else to do. anyone????

[sx moneypit]

Sounds like you have a spark plug or spark plug wire breaking down.If the car is just falling on its face then you have other issues.

[bassboy3313]

no the car isnt falling on its face. its just a stutter or hesitation kind of thing when accelerating. if i lightly press the accelerator it revs and drives fine. if i step on the accelerator normally like everyone does it stutters/hesitates. i have to let off and go back on then its fine again. doesnt do it too much shifting from 4th to 5th.

[sx moneypit]

How old are your spark plug wires?

[bassboy3313]

not sure. the car came with blue plug wires, so im guessing they are not the original ones.

[sx moneypit]

Yeah if they are blue they are not original equipment, unless you just want to replace the cap,rotor,wires and plugs i would take the car to a shop you can trust and let them put the car on a scope and scan it to see what is going on.It will save time trouble and money.
Modified by sx moneypit at 12:44 PM 12/30/2009

[bassboy3313]

it seems to have gone away. it wasnt stuttering or hesitating after driving it awhile today. i dont know if resetting the ecu by disconnecting the negative on the battery from installing the alternator changed something. i noticed that the idle changed sometimes but not all the time. sometimes it will be at 1100 when at a stop light and sometimes it will be at 800 when at a stop light. more times than not its at 800 tho.

[sx moneypit]

I was under the impression that you were having this problem before you started having trouble with the alternator.If the alternator output is not correct it will cause all sorts of driveability problems. As far as the idle issue, the ecm takes a little time to relearn the idle strategy. Hopefully you have both problems fixed!

[bassboy3313]

yeah i was. lol. awesome! i will give it some time and see if the ecu relearns the idle. thank you so much sx moneypit. you have definitely saved me big time.

[sx moneypit]

Glad to help . Happy new year!

[bassboy3313]

Thanks. You too!!!

[bassboy3313]

doesnt seem like the ecu is relearning the idle that we thought earlier. sometimes it will fluctuate between 2k and 1200 rpm and sometimes it will fluctuate between 900 and 1200 rpm. it eve nchanges from stop light to stop light.

im thinking i might just need to clean the IAC and the MAF and maybe even replace the TPS. what do you think?

[Murdered_T]

is it auto or stick?

if it is stick, check the pilot bearing.

[zer0c123]

If you think it's the TPS, then check all the wires going to it. Wiggle them and bend them in weird directions and see if the car stutters.

[sx moneypit]

Thats a good idea,clean the throttle body also before you start replacing parts!

[bassboy3313]

its not the stutter thats the problem anymore. its the fluctuating idle that i need to fix.

[sx moneypit]

Did you clean the iac valve? Is your curb idle and timing correct?

[bassboy3313]

no i havent. i wont have time to do that for awhile. what do you mean by curb idle? timing is fine.

[sx moneypit]

Curb idle is your base idle speed.It is adjusted with the throttle stop screw. It should be ok unless the throttle shaft is worn out or somebody has been messing with it.
Modified by sx moneypit at 2:33 PM 1/4/2010

[bassboy3313]

oh ok. yeah im sure that is fine. throttle shaft is fine and no one has been messing with it at all.

[sx moneypit]

I would clean the iac valve and see what happens. Also check your coolant level and make sure it is free of any air. You might also check your electrical connectors and make sure they are clean and tight.Pay close attention to the one at the coolant sensor ,MAFS,TPS and IAC valve.Be sure you dont have any phantom vacuum leaks.