RPMs are acting up

[Dante319]

Ok it's my friend's SOHC S13, it's completely stock he just bought it. I noticed that when you rev the engine and let go of the gas the RPMs drop normal until they hit 1700, then they stay there for approximately 4 secs and come down to a stable 800. It's kinda of weird any opinions on what might be causing this.
Thanks

[SpeedMonkeyInc]

Sticking throttle plate? Maybe it just needs a cleaning.

[mjjstang]

my shit does that too, i can never get a good idle, i set it then set the IACV to be perfect, then 5 minutes later, shit happens and it idles really low and shit, when i first start car, it idles at 2 grand then slowly goes down and then shuts off, this happnes the first few minutes, it really doesnt want to stay running, but then after warming up it will stay running but idle will still be Fed up. lemme know if you fix it, ever since i got the enthalpy tune, it has done this, but he game me a new tune and it is still the same, so i donno if its his, everyone else is happy with his work so i assume its something else, also got my new injectors and put them in at the same time, ehh o well lemme know if you fix yo shit.

[Ritz S14]

Yup. Mine does this too. I also get horrrrrible gas milage.. I'm almost led to believe that it may be a leaky injector.

[mjjstang]

terrible mileage same here. damn dude, i dont know what the problem is, i really should do a boost leak test and thnk ill go to the home depot tomarrow to get some parts for this. do you have enthalpy tune/new injectors. what can be done to check to see if its a leaky injector? actually though, when i turn my car off, it holds fuel pressure for a while (i have agauge on my fpr) so i would rule this out. well i hate to threadjack so forget it. but it all has to do with messy rpms. right.

[Dante319]

Well his car doesn't shut off, it just stays around 1700 for like a couple of secs when you let off gas in meutral, after that his idle is very stable. It does sound like the throtle plate is getting stuck. I'm gonna give that a try tomorrow.
Thanks

[SpeedMonkeyInc]

terrible mileage same here. do you have enthalpy tune/new injectors.

Damn my car has had issues since I put in the Enthalpy tune as well. Except for me its a very high idle cold, almost 2000rpm. Once the car is warm it stays right around 1000-1100rpm, and gas mileage is not so good.
Have you tested your fuel pressure? That is one possible cause I was thinking, but I have not been able to test my base pressure yet.

Sorry to threadjack. Dante: I hope you get your friend's car worked out.

[mjjstang]

yes pressure has been tested, I PM'ed you.

[undesiredshoe]

what kind of mileage are you getting, i put in 10 bucks for about 4 gallons and i get about 40 miles out of it, haha, so that equates to 10mpg. Zilvia should have a "Records" section, id probably make it for lowest mileage