Sputtering at startup

H

hall1

Member
Anyone have any issues with a weak startup? about a month ago, an intermittent startup problem began. When I start it, it kinda falters, then vrooom.. picks up and sounds ready to go.

This only happens at a cold start in the morning and no other startup times throught the day. Usually only happens every few days so I took it to the dealer and they had to keep it for a week to replicate the problem

They ended up replacing the air flow sensor, but after pickign it up last Friday..it now has had the same weak startup every day since Monday :mad:

It is an automatic, and the way it sounds is similar to a manual transmission that isnt getting enough gas.......... evidently, the "master" tech at the dealership citied no driveability issues and didnt pull any codes off it.....I really just think they replaced the sensor to throw somethign at it. dont know what to do now!!!---- any suggestions. (oh, also cleaned and conditioned K&N air filter, so no probs there)
 
I had sputtering before, it was my error though. When I turn the ignition, I would turn it to fast and not long enough for the starter to finish. The car would start to come on then a noise from the intake (like air sound) and car dies.
It only happen to me 2 times.

Welcome to :iS:
 
clean your throttle body... that's causing what your talking about...


after you clean it it'll start up & jump to over 1k rpms & then come down as it used to... if you don't, eventually she'll start to start & stall...
 
turbocad6 said:
clean your throttle body... that's causing what your talking about...


after you clean it it'll start up & jump to over 1k rpms & then come down as it used to... if you don't, eventually she'll start to start & stall...
Click to expand...


as for my situation, I haven't had the problem since. I also cleaned the TB and Plenum when I did my spacer install.
:top:good point about the TB , make sure you don't move the butterfly valve when cleaning or else you need to recalibrate it. (see ECU reset procedures):nerd:

:tongue:
 
Yup, I would try what turbo has suggested it is probably your best bet. Good luck and welcome to :iS:!
 
themerchant said:
as for my situation, I haven't had the problem since. I also cleaned the TB and Plenum when I did my spacer install.
:top:good point about the TB , make sure you don't move the butterfly valve when cleaning or else you need to recalibrate it. (see ECU reset procedures):nerd:

:tongue:
Click to expand...


I wonder why the techs at inifiti didn't do that??!!?! argh. I'm going to try and do a slower ignition turn and explore the throttle body cleaning if it persists. I suspect its not my key turn since I havent really changed anything about that (?)

It' quite frustrating though..I'm so used to hearing it growl and now that growl is preceded by a little sputter....
 
there is no harm in moving the throttle plate with the ign off... it will build up carbon around the throttle butterfly, this is normal... just clean the ridge of carbon built up around the throttle body lip... push the plate open & wipe it with a rag with solvent, repeat until clean, both below & above the throttle plate... I use laquer thinner but many solvents will work... this should be done at every tune-up but most mechanics neglect this...

this is a very common problem & most don't even realize it until it gets bad enough to cause a startup stumble or worse yet start & stall... if you start your fx & it doesn't jump right up to well over 1k rpms before settling down, your throttle plate is dirty...

before:

1



after:

1
 
EXCELLENT!~~ thanks so much for the pics, this will help tremendously!

I'm relieved to know that its an issue that you guys are familiar with. I appreciate your knowledge and feedback.
 
no problem. I'm willing to bet that many guys throttle plates are somewhat dirty & if cleaned, an improvement in the startup would be seen... this just happens so progresively that it isn't normally noticed till it's pretty bad...
 
since it is still under warranty, would you recommend taking it back to the dealer and have them do it? Or would you think they may not take to kindly to me telling them how to do their job?
 
gto-dave said:
+1, they go out of calibration very easily. Careful with it.
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I've screwed with mine & never had issues... what would knock it out of calibration? it will still rest in the same position after cleaning & the reading wouldn't change at all if you didn't turn on the ign while moving the plate? what are the signs that it would need to be recalibrated, CEL & code? haven't ran across any issues there... of course never move it manually when the ign is on or then it'll see a fault...
 
Just dont be rough with it. My shop friend took a towel & was scrubbing inside . . flip flap . . before I noticed . . I was like dude! what the!?!? Be careful. He's like, dont worry, it'll be fine. Sure enough, idle was too high & needed re-calibration. It was a pain, cuz I was at TS later that day, & Tadashi was trying to troubleshoot as to why. I had to borrow his TB from the M, before it went to drift status, so I could get a tune that day & get the CEL turned off.
 
maybe he sprayed cleaner into it? I wouldn't do that, solvent on a rag & gently wipe... I've done a few of these already... also, maybe he was too rough with just flapping it open & letting it snap back... I could see that maybe changing the calibration or the actual resting place... guess it's good to add to be gentle with it, guess I just assumed anyone would be in the first place, no scraping & no poking with a screwdriver, just gently wipe it clean shouldn't change anything but allowing more cfm's of air past the throttle body at rest, which is the cause or result of this problem to begin with...

hall1, you or any halfway competent mechanic should be able to take care of this in 10min... of course you could bring it to the dealer & tell them that you researched this & the throttle body being dirty is what you have come up with... yeah, they'll probably roll there eyes, but if they had this in already for said problem & they didn't do this then you now have more information than there "master technician" :biggrin:
 
All of the above! He was hacking at it. Really screwed with with my day. Just be gentle was all I was really sayin, but ya, cars like clean TBs, but a lil carbon deposit aint really gonna effect much.
 
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