so lately at idle my engine makes a light sputter/vibration. goes away if the ac is on. my idle is good at 650. this has only happening recently. my cars a 2003 with 55k miles. one strange thing tho is when im coming to a stop and throw the car into neutral the rpm drops to about 800 rpm then slowly lowers to 650. is that normal? i never noticed it before.

things ive done so far
-cleaned tb
-cleaned maf

any suggestions. i was going to check for vacuum leaks later today

 

i was gonna say look into vac leak...sounds like you are heading that direction already...most vacuum leaks cause a higher than normal idle though..and can drop low to almost choke. It really depends on how big of a leak though.

Take a look at spark plugs too, they def help smooth it all out. i just changed mine again and i remember how smooth its supposed to be

 

^how many miles do you have? i thought spark plugs were good til aleast 80-100k miles

 

The manual states 105K mile interval for the platinum plugs

I replaced mine w/ Iridium and change them every 50k or so.

Every set of plugs that I have changed so far has seemed a noticeable improvement with the new plugs. Most stock ones seem very worn at 60K miles. That of course varies on driving style for some people but most the people i have helped swap out enjoy driving their cars

i have 178K miles on my 2003 now

if you have oil in spark plug chambers it could cause a slight hiccup too. #5 and #6 are susceptible to this, as i'm sure you have read on here before

 

^if i had oil in the spark plug chambers thats causing the hiccups would it go away when the ac is on?

 

AC on = higher engine load = different tune. Spark may be more aggressive and thereby less noticeable when something else isn't 100%.

Are you tuned? what mods do you have installed? It could very well be a vacuum leak as well - that was my first thought, but unless you are changing things that rarely happens on its own.

 

only engine mods i have is spacer and nismo cai. but these were done awhile ago. engine oil level is good too. when i do the vacuum leak check ima retighten the plenum bolts

 

yeah, double check those...especially the ones in the middle of the plenum, they are the first to loosen if any, from my experience

no harm in checking those 2 cylinders for oil either

 

I have had this issue but seems that if my stereo is on or my ac I do not have a problem most of the time it only happens when the car is cold. I have an 03 with 52 k

 

is this the correct firing order for the vq?



damn i was hoping not to have to do spark plug work yet

 

oh i also wanted to add that other then the sputter issue at idle the cars runs great

 

is carb cleaner the best store option i have to use to check for vacuum leaks? im reading online that is will screw up the hoses and harden it. can i use maf (plastic safe) instead? since its flammable too?

 

Jus checked with out carb cleaner and theres definitely a vacuum leak somewhere in the front area of the intake manifold. There's a very apparent hiss sound that goes soft n loud. I retightened the spacer but I didn't loosen then tighten the bolts I jus torqued each bolt down. Does that make a difference? About 5 of them were able to be tightened. the rest were good.

Anyone know exactly how many vacuum lines are in the front area of the intake manifold?

 

dang i think i have this problem also i here the vac lines aswell in my car, but i have yet to pin point it, good luck

 

So I tried carb cleaner can't find the freaking leak. It's definitely not the spacer tho. But it is coming from somewhere towards the front passenger side of the plenum. Any suggestions? Where's the ogs at?