I've experienced this since my S/C install awhile back. I had my tuner work on it, and it it improved a little but I am still experiencing my idle going up and down ~300-500 rpms when at idle in neutral. It happens more after a hard run or when switching a/c on/off.

The problem is intermittent, but annoying. Has anyone else experienced this/does anyone have any suggestions to alleviate the idle jump?

thx!

 

What is your vacuum at idle?

 

You have to up your idle or make sure there is no vacuum leak

 

if the car has no cams, there is no need to increase the idle - it will all be in the tuning

pressure test the intake system and moniter for leaks

 

stock cams. Car is tuned with fcon vpro and uprev reflash. The idle is at a good level when it is steady, but occasionally jumps at idle. I will have to check for vacuum leaks. I've heard others with certain S/C setups have experienced similar problems?

 

Actually, i'm experiencing the same problem but mine was after i installed basic bolt-ons. Full exhaust(headers back) and popcharger, no tune... i have an exhaust leak i need to get fixed but thats the only issue. I don't mean to "thread jack" on op's thread but i'm experiencing the same issues he discribed and i'm curious if its a vacuum leak as well. It will even idle high when i cold start it.

 

What injectors do you running? and RFS? You can search under my username, i don't know if that can give you an any info. My idle used run very rough with utec NO RFS/600injectors/reflash. And switch to Uprev and added RFS, now idle is pretty steady. During the uprev tuning, they found out my HFC core melted down, that made block my air flow. Jared thinks my HFC caused that problems, and i do believe that. Also i drove many days and i also " THINK " that no RFS and big injectors caused idle problem too.
Where is your idle set at? if your idle set too high, that can cause a rough idle as well.

You mention that after you run, idle gets really rough. So i would start look down from...
- leak test
- check the plugs proper gap
- Check the ignition timing. See the Vehicle Emission Control label for information.
- Check the exhaust system for restriction. A clogged catalytic converter will cause high speed as well as idle problems

This is just my two cents. Good luck, i know it's kinda pissing off..but you will feel a lot better once you figure things.

 

I think you did answer your own question.

 

ok sweet... i have read on the forum about if there is a point to getting a tune with only having basic bolt ons and from what i've heard it doesn't hurt but its not really neccessary, even though i plan on getting a tune soon. As far as the exhaust leak i didn't think/know if it would cause my idle to go all nuts. I had a 240 and a 3000gt that had minor exhaust leaks at one time and it didn't really affect the idle that badly but then all cars are different... Thanks for helping me see that i already knew my problem. haha

 

Sorry, my mistake. I thought you said procharger. But I read again, you said popcharger. No need tune with just a bolts on.

 

Thx for the reply chef. I am running GTM fuel rails, lines, and turbosmart fpr for frs. Injectors are DW 600's. I'n not sure what my idle is set at, I will need to check with my tuner..

It is interesting you mention the HFC's. I will need to check that. I have run really rich a few times when my vpro "lost" its tune, and although I am running PE metallic HFC's, I wonder how they have held up. I'm assuming the only realy way to check for restrictions is to unbolt the y-pipe and visually look inside the cats?

 

I'm also running GTM RFS expect rails and same injectors, your fuel setup is pretty much well done ( make sure all the injectors/return line installed correctly). Jared@uprev told me that if idle set too high that can cause rough idle. The best way to check inside the hfc is remove the cats from the car and suspect it. If HFC is still on the car, it will be pretty hard to see inside the HFC without any light. It may not the reason cause a idle on your case but it is one of reason can cause the rough idle.

And here is info about HFC, http://car-sound.com/04basics/04failures02.asp
Also, check with tuner again. It's good to hear an advice from your tuner, since he is actually front of your car.

 

Interestin article on the link. It talks about failures in ceramic HFC's, but not mettalic. From what I understand mettalic cores can withstand more heat and last longer than ceramic cores. Can mettalic cores still "meltdown" like the ceramic one in that article. The HFC's on my car are Power Enterprise mettalic 300 cell. I put them on when I was NA and they are still on my car now that I am S/C.

My car is pretty loud, and I was thinking about replacing my Tanabe y-pipe with a Motordyne xyz pipe and resonator to try to reduce noise. If I do that, I can have the HFC's inspected. But the tech does not suspect the HFC's. There is no rattling or other indication of HFC failure, but I guess I won't know for sure, unless I take them off for inspection..

 

Post #146: https://my350z.com/forum/forced-indu...my-sc-z-8.html ( it looks more bad, because jared tried gut that out so we can use it for TP)lol

Mine was metallic HFC as well, rated at 700whp(?). Company told me they assume that my car ran SUPER HOT and rich. But metallic ones are usually hold up pretty well though, i thought i was safe with those metallic HFCs. Anyway, there is many other issue may cause idle issue. If all the parts/install are looks good, then i would assume it is something with tune.

Edit: PE HFCs are super expensive...i'm sure it will be good.